Adding upstream version 7.0.14-dfsg.upstream/7.0.14-dfsg

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1476 insertions, 0 deletions

diff --git a/src/VBox/Devices/VirtIO/VirtioCore.h b/src/VBox/Devices/VirtIO/VirtioCore.h
new file mode 100644
index 00000000..00bcb43c
--- /dev/null
+++ b/src/VBox/Devices/VirtIO/VirtioCore.h
@@ -0,0 +1,1476 @@
+/* $Id: VirtioCore.h $ */
+
+/** @file
+ * VirtioCore.h - Virtio Declarations
+ */
+
+/*
+ * Copyright (C) 2009-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#ifndef VBOX_INCLUDED_SRC_VirtIO_VirtioCore_h
+#define VBOX_INCLUDED_SRC_VirtIO_VirtioCore_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+/* Do not allocate VIRTQBUF from the heap when possible */
+#define VIRTIO_VBUF_ON_STACK 1
+
+#include <iprt/ctype.h>
+#include <iprt/sg.h>
+#include <iprt/types.h>
+
+#ifdef LOG_ENABLED
+# define VIRTIO_HEX_DUMP(logLevel, pv, cb, base, title) \
+    do { \
+        if (LogIsItEnabled(logLevel, LOG_GROUP)) \
+            virtioCoreHexDump((pv), (cb), (base), (title)); \
+    } while (0)
+#else
+# define VIRTIO_HEX_DUMP(logLevel, pv, cb, base, title) do { } while (0)
+#endif
+
+/** Marks the start of the virtio saved state (just for sanity). */
+#define VIRTIO_SAVEDSTATE_MARKER                        UINT64_C(0x1133557799bbddff)
+
+/** Pointer to the shared VirtIO state. */
+typedef struct VIRTIOCORE *PVIRTIOCORE;
+/** Pointer to the ring-3 VirtIO state. */
+typedef struct VIRTIOCORER3 *PVIRTIOCORER3;
+/** Pointer to the ring-0 VirtIO state. */
+typedef struct VIRTIOCORER0 *PVIRTIOCORER0;
+/** Pointer to the raw-mode VirtIO state. */
+typedef struct VIRTIOCORERC *PVIRTIOCORERC;
+/** Pointer to the instance data for the current context. */
+typedef CTX_SUFF(PVIRTIOCORE) PVIRTIOCORECC;
+
+#define VIRTIO_MAX_VIRTQ_NAME_SIZE          32                   /**< Maximum length of a queue name           */
+#define VIRTQ_SIZE                        1024                   /**< Max size (# entries) of a virtq          */
+#define VIRTQ_MAX_COUNT                     24                   /**< Max queues we allow guest to create      */
+#define VIRTIO_NOTIFY_OFFSET_MULTIPLIER     2                    /**< VirtIO Notify Cap. MMIO config param     */
+#define VIRTIO_REGION_LEGACY_IO             0                    /**< BAR for VirtIO legacy drivers MBZ        */
+#define VIRTIO_REGION_PCI_CAP               2                    /**< BAR for VirtIO Cap. MMIO (impl specific) */
+#define VIRTIO_REGION_MSIX_CAP              0                    /**< Bar for MSI-X handling                   */
+#define VIRTIO_PAGE_SIZE                 4096                    /**< Page size used by VirtIO specification   */
+
+/**
+ * @todo Move the following virtioCoreGCPhysChain*() functions mimic the functionality of the related
+ *       into some VirtualBox source tree common location and out of this code.
+ *
+ *       They behave identically to the S/G utilities in the RT library, except they work with that
+ *       GCPhys data type specifically instead of void *, to avoid potentially disastrous mismatch
+ *       between sizeof(void *) and sizeof(GCPhys).
+ *
+ */
+typedef struct VIRTIOSGSEG                                      /**< An S/G entry                              */
+{
+    RTGCPHYS GCPhys;                                            /**< Pointer to the segment buffer             */
+    size_t  cbSeg;                                              /**< Size of the segment buffer                */
+} VIRTIOSGSEG;
+
+typedef VIRTIOSGSEG *PVIRTIOSGSEG, **PPVIRTIOSGSEG;
+typedef const VIRTIOSGSEG *PCVIRTIOSGSEG;
+
+typedef struct VIRTIOSGBUF
+{
+    PVIRTIOSGSEG paSegs;                                        /**< Pointer to the scatter/gather array       */
+    unsigned  cSegs;                                            /**< Number of segs in scatter/gather array    */
+    unsigned  idxSeg;                                           /**< Current segment we are in                 */
+    RTGCPHYS  GCPhysCur;                                        /**< Ptr to byte within the current seg        */
+    size_t    cbSegLeft;                                        /**< # of bytes left in the current segment    */
+} VIRTIOSGBUF;
+
+typedef VIRTIOSGBUF *PVIRTIOSGBUF, **PPVIRTIOSGBUF;
+typedef const VIRTIOSGBUF *PCVIRTIOSGBUF;
+
+/**
+ * VirtIO buffers are descriptor chains (e.g. scatter-gather vectors). A VirtIO buffer is referred to by the index
+ * of its head descriptor. Each descriptor optionally chains to another descriptor, and so on.
+ *
+ * For any given descriptor, each length and GCPhys pair in the chain represents either an OUT segment (e.g. guest-to-host)
+ * or an IN segment (host-to-guest).
+ *
+ * A VIRTQBUF is created and retured from a call to to either virtioCoreR3VirtqAvailBufPeek() or virtioCoreR3VirtqAvailBufGet().
+ *
+ * Those functions consolidate the VirtIO descriptor chain into a single representation where:
+ *
+ *     pSgPhysSend    GCPhys s/g buffer containing all of the (VirtIO) OUT descriptors
+ *     pSgPhysReturn  GCPhys s/g buffer containing all of the (VirtIO)  IN descriptors
+ *
+ * The OUT descriptors are data sent from guest to host (dev-specific commands and/or data)
+ * The IN are to be filled with data (converted to physical) on host, to be returned to guest
+ *
+ */
+typedef struct VIRTQBUF
+{
+    uint32_t            u32Magic;                                /**< Magic value, VIRTQBUF_MAGIC.             */
+    uint16_t            uVirtq;                                  /**< VirtIO index of associated virtq         */
+    uint16_t            pad;
+    uint32_t volatile   cRefs;                                   /**< Reference counter.                       */
+    uint32_t            uHeadIdx;                                /**< Head idx of associated desc chain        */
+    size_t              cbPhysSend;                              /**< Total size of src buffer                 */
+    PVIRTIOSGBUF        pSgPhysSend;                             /**< Phys S/G buf for data from guest         */
+    size_t              cbPhysReturn;                            /**< Total size of dst buffer                 */
+    PVIRTIOSGBUF        pSgPhysReturn;                           /**< Phys S/G buf to store result for guest   */
+
+    /** @name Internal (bird combined 5 allocations into a single), fingers off.
+     * @{ */
+    VIRTIOSGBUF         SgBufIn;
+    VIRTIOSGBUF         SgBufOut;
+    VIRTIOSGSEG         aSegsIn[VIRTQ_SIZE];
+    VIRTIOSGSEG         aSegsOut[VIRTQ_SIZE];
+    /** @} */
+} VIRTQBUF_T;
+
+/** Pointers to a Virtio descriptor chain. */
+typedef VIRTQBUF_T *PVIRTQBUF, **PPVIRTQBUF;
+
+/** Magic value for VIRTQBUF_T::u32Magic. */
+#define VIRTQBUF_MAGIC             UINT32_C(0x19600219)
+
+typedef struct VIRTIOPCIPARAMS
+{
+    uint16_t  uDeviceId;                                         /**< PCI Cfg Device ID                         */
+    uint16_t  uClassBase;                                        /**< PCI Cfg Base Class                        */
+    uint16_t  uClassSub;                                         /**< PCI Cfg Subclass                          */
+    uint16_t  uClassProg;                                        /**< PCI Cfg Programming Interface Class       */
+    uint16_t  uSubsystemId;                                      /**< PCI Cfg Card Manufacturer Vendor ID       */
+    uint16_t  uInterruptLine;                                    /**< PCI Cfg Interrupt line                    */
+    uint16_t  uInterruptPin;                                     /**< PCI Cfg Interrupt pin                     */
+} VIRTIOPCIPARAMS, *PVIRTIOPCIPARAMS;
+
+
+/* Virtio Platform Independent Reserved Feature Bits (see 1.1 specification section 6) */
+
+#define VIRTIO_F_NOTIFY_ON_EMPTY            RT_BIT_64(24)        /**< Legacy feature: Force intr if no AVAIL    */
+#define VIRTIO_F_ANY_LAYOUT                 RT_BIT_64(27)        /**< Doc bug: Goes under two names in spec     */
+#define VIRTIO_F_RING_INDIRECT_DESC         RT_BIT_64(28)        /**< Doc bug: Goes under two names in spec     */
+#define VIRTIO_F_INDIRECT_DESC              RT_BIT_64(28)        /**< Allow descs to point to list of descs     */
+#define VIRTIO_F_RING_EVENT_IDX             RT_BIT_64(29)        /**< Doc bug: Goes under two names in spec     */
+#define VIRTIO_F_EVENT_IDX                  RT_BIT_64(29)        /**< Allow notification disable for n elems    */
+#define VIRTIO_F_BAD_FEATURE                RT_BIT_64(30)        /**< QEMU kludge.  UNUSED as of >= VirtIO 1.0  */
+#define VIRTIO_F_VERSION_1                  RT_BIT_64(32)        /**< Required feature bit for 1.0 devices      */
+#define VIRTIO_F_ACCESS_PLATFORM            RT_BIT_64(33)        /**< Funky guest mem access   (VirtIO 1.1 NYI) */
+#define VIRTIO_F_RING_PACKED                RT_BIT_64(34)        /**< Packed Queue Layout      (VirtIO 1.1 NYI) */
+#define VIRTIO_F_IN_ORDER                   RT_BIT_64(35)        /**< Honor guest buf order    (VirtIO 1.1 NYI) */
+#define VIRTIO_F_ORDER_PLATFORM             RT_BIT_64(36)        /**< Host mem access honored  (VirtIO 1.1 NYI) */
+#define VIRTIO_F_SR_IOV                     RT_BIT_64(37)        /**< Dev Single Root I/O virt (VirtIO 1.1 NYI) */
+#define VIRTIO_F_NOTIFICAITON_DATA          RT_BIT_64(38)        /**< Driver passes extra data (VirtIO 1.1 NYI) */
+
+typedef struct VIRTIO_FEATURES_LIST
+{
+    uint64_t fFeatureBit;
+    const char *pcszDesc;
+} VIRTIO_FEATURES_LIST, *PVIRTIO_FEATURES_LIST;
+
+static const VIRTIO_FEATURES_LIST s_aCoreFeatures[] =
+{
+    { VIRTIO_F_VERSION_1,               "   VERSION_1            Guest driver supports VirtIO specification V1.0+ (e.g. \"modern\")\n" },
+    { VIRTIO_F_RING_EVENT_IDX,          "   RING_EVENT_IDX       Enables use_event and avail_event fields described in 2.4.7, 2.4.8\n" },
+    { VIRTIO_F_RING_INDIRECT_DESC,      "   RING_INDIRECT_DESC   Driver can use descriptors with VIRTQ_DESC_F_INDIRECT flag set\n" },
+};
+
+#define VIRTIO_DEV_INDEPENDENT_FEATURES_OFFERED ( 0 )            /**< TBD: Add VIRTIO_F_INDIRECT_DESC           */
+#define VIRTIO_DEV_INDEPENDENT_LEGACY_FEATURES_OFFERED ( 0 )     /**< Only offered to legacy drivers            */
+
+#define VIRTIO_ISR_VIRTQ_INTERRUPT           RT_BIT_32(0)        /**< Virtq interrupt bit of ISR register       */
+#define VIRTIO_ISR_DEVICE_CONFIG             RT_BIT_32(1)        /**< Device configuration changed bit of ISR   */
+#define DEVICE_PCI_NETWORK_SUBSYSTEM                    1        /**< Network Card, per VirtIO legacy spec.     */
+#define DEVICE_PCI_REVISION_ID_VIRTIO_TRANS             0        /**< VirtIO Transitional device revision (MBZ) */
+#define DEVICE_PCI_REVISION_ID_VIRTIO_V1                1        /**< VirtIO device revision (SHOULD be >= 1)   */
+
+#define DEVICE_PCI_VENDOR_ID_VIRTIO                0x1AF4        /**< Guest driver locates dev via (mandatory)  */
+
+/**
+ * Start of the PCI device id range for non-transitional devices.
+ *
+ * "Devices ... have the PCI Device ID calculated by adding 0x1040 to
+ * the Virtio Device ID, as indicated in section [Device Types]. ...
+ * Non-transitional devices SHOULD have a PCI Device ID in the range
+ * 0x1040 to 0x107f.
+ */
+#define DEVICE_PCI_DEVICE_ID_VIRTIO_BASE           0x1040
+
+/** Reserved (*negotiated*) Feature Bits (e.g. device independent features, VirtIO 1.0 spec,section 6) */
+
+#define VIRTIO_MSI_NO_VECTOR                       0xffff        /**< Vector value to disable MSI for queue     */
+
+/** Device Status field constants (from Virtio 1.0 spec) */
+#define VIRTIO_STATUS_ACKNOWLEDGE                    0x01        /**< Guest driver: Located this VirtIO device  */
+#define VIRTIO_STATUS_DRIVER                         0x02        /**< Guest driver: Can drive this VirtIO dev.  */
+#define VIRTIO_STATUS_DRIVER_OK                      0x04        /**< Guest driver: Driver set-up and ready     */
+#define VIRTIO_STATUS_FEATURES_OK                    0x08        /**< Guest driver: Feature negotiation done    */
+#define VIRTIO_STATUS_FAILED                         0x80        /**< Guest driver: Fatal error, gave up        */
+#define VIRTIO_STATUS_DEVICE_NEEDS_RESET             0x40        /**< Device experienced unrecoverable error    */
+
+typedef enum VIRTIOVMSTATECHANGED
+{
+    kvirtIoVmStateChangedInvalid = 0,
+    kvirtIoVmStateChangedReset,
+    kvirtIoVmStateChangedSuspend,
+    kvirtIoVmStateChangedPowerOff,
+    kvirtIoVmStateChangedResume,
+    kvirtIoVmStateChangedFor32BitHack = 0x7fffffff
+} VIRTIOVMSTATECHANGED;
+
+/** @def Virtio Device PCI Capabilities type codes */
+#define VIRTIO_PCI_CAP_COMMON_CFG                       1        /**< Common configuration PCI capability ID    */
+#define VIRTIO_PCI_CAP_NOTIFY_CFG                       2        /**< Notification area PCI capability ID       */
+#define VIRTIO_PCI_CAP_ISR_CFG                          3        /**< ISR PCI capability id                     */
+#define VIRTIO_PCI_CAP_DEVICE_CFG                       4        /**< Device-specific PCI cfg capability ID     */
+#define VIRTIO_PCI_CAP_PCI_CFG                          5        /**< PCI CFG capability ID                     */
+
+#define VIRTIO_PCI_CAP_ID_VENDOR                     0x09        /**< Vendor-specific PCI CFG Device Cap. ID    */
+
+/**
+ * The following is the PCI capability struct common to all VirtIO capability types
+ */
+typedef struct virtio_pci_cap
+{
+    /* All little-endian */
+    uint8_t   uCapVndr;                                          /**< Generic PCI field: PCI_CAP_ID_VNDR        */
+    uint8_t   uCapNext;                                          /**< Generic PCI field: next ptr.              */
+    uint8_t   uCapLen;                                           /**< Generic PCI field: capability length      */
+    uint8_t   uCfgType;                                          /**< Identifies the structure.                 */
+    uint8_t   uBar;                                              /**< Where to find it.                         */
+    uint8_t   uPadding[3];                                       /**< Pad to full dword.                        */
+    uint32_t  uOffset;                                           /**< Offset within bar.  (L.E.)                */
+    uint32_t  uLength;                                           /**< Length of struct, in bytes. (L.E.)        */
+}  VIRTIO_PCI_CAP_T, *PVIRTIO_PCI_CAP_T;
+
+/**
+ * VirtIO Legacy Capabilities' related MMIO-mapped structs (see virtio-0.9.5 spec)
+ *
+ * Note: virtio_pci_device_cap is dev-specific, implemented by client. Definition unknown here.
+ */
+typedef struct virtio_legacy_pci_common_cfg
+{
+    /* Device-specific fields */
+    uint32_t  uDeviceFeatures;                                   /**< RO (device reports features to driver)    */
+    uint32_t  uDriverFeatures;                                   /**< RW (driver-accepted device features)      */
+    uint32_t  uVirtqPfn;                                         /**< RW (driver writes queue page number)      */
+    uint16_t  uQueueSize;                                        /**< RW (queue size, 0 - 2^n)                  */
+    uint16_t  uVirtqSelect;                                      /**< RW (selects queue focus for these fields) */
+    uint16_t  uQueueNotify;                                      /**< RO (offset into virtqueue; see spec)      */
+    uint8_t   fDeviceStatus;                                     /**< RW (driver writes device status, 0=reset) */
+    uint8_t   fIsrStatus;                                        /**< RW (driver writes ISR status, 0=reset)    */
+#ifdef LEGACY_MSIX_SUPPORTED
+    uint16_t  uMsixConfig;                                       /**< RW (driver sets MSI-X config vector)      */
+    uint16_t  uMsixVector;                                       /**< RW (driver sets MSI-X config vector)      */
+#endif
+} VIRTIO_LEGACY_PCI_COMMON_CFG_T, *PVIRTIO_LEGACY_PCI_COMMON_CFG_T;
+
+/**
+ * VirtIO 1.0 Capabilities' related MMIO-mapped structs:
+ *
+ * Note: virtio_pci_device_cap is dev-specific, implemented by client. Definition unknown here.
+ */
+typedef struct virtio_pci_common_cfg
+{
+    /* Device-specific fields */
+    uint32_t  uDeviceFeaturesSelect;                             /**< RW (driver selects device features)       */
+    uint32_t  uDeviceFeatures;                                   /**< RO (device reports features to driver)    */
+    uint32_t  uDriverFeaturesSelect;                             /**< RW (driver selects driver features)       */
+    uint32_t  uDriverFeatures;                                   /**< RW (driver-accepted device features)      */
+    uint16_t  uMsixConfig;                                       /**< RW (driver sets MSI-X config vector)      */
+    uint16_t  uNumVirtqs;                                        /**< RO (device specifies max queues)          */
+    uint8_t   fDeviceStatus;                                     /**< RW (driver writes device status, 0=reset) */
+    uint8_t   uConfigGeneration;                                 /**< RO (device changes when changing configs) */
+
+    /* Virtq-specific fields (values reflect (via MMIO) info related to queue indicated by uVirtqSelect. */
+    uint16_t  uVirtqSelect;                                      /**< RW (selects queue focus for these fields) */
+    uint16_t  uQueueSize;                                        /**< RW (queue size, 0 - 2^n)                  */
+    uint16_t  uMsixVector;                                       /**< RW (driver selects MSI-X queue vector)    */
+    uint16_t  uEnable;                                           /**< RW (driver controls usability of queue)   */
+    uint16_t  uNotifyOffset;                                     /**< RO (offset into virtqueue; see spec)      */
+    uint64_t  GCPhysVirtqDesc;                                   /**< RW (driver writes desc table phys addr)   */
+    uint64_t  GCPhysVirtqAvail;                                  /**< RW (driver writes avail ring phys addr)   */
+    uint64_t  GCPhysVirtqUsed;                                   /**< RW (driver writes used ring  phys addr)   */
+} VIRTIO_PCI_COMMON_CFG_T, *PVIRTIO_PCI_COMMON_CFG_T;
+
+typedef struct virtio_pci_notify_cap
+{
+    struct virtio_pci_cap pciCap;                                /**< Notification MMIO mapping capability      */
+    uint32_t uNotifyOffMultiplier;                               /**< notify_off_multiplier                     */
+} VIRTIO_PCI_NOTIFY_CAP_T, *PVIRTIO_PCI_NOTIFY_CAP_T;
+
+typedef struct virtio_pci_cfg_cap
+{
+    struct virtio_pci_cap pciCap;                                /**< Cap. defines the BAR/off/len to access    */
+    uint8_t uPciCfgData[4];                                      /**< I/O buf for above cap.                    */
+} VIRTIO_PCI_CFG_CAP_T, *PVIRTIO_PCI_CFG_CAP_T;
+
+/**
+ * PCI capability data locations (PCI CFG and MMIO).
+ */
+typedef struct VIRTIO_PCI_CAP_LOCATIONS_T
+{
+    uint16_t        offMmio;
+    uint16_t        cbMmio;
+    uint16_t        offPci;
+    uint16_t        cbPci;
+} VIRTIO_PCI_CAP_LOCATIONS_T;
+
+typedef struct VIRTQUEUE
+{
+    RTGCPHYS                    GCPhysVirtqDesc;                  /**< (MMIO) Addr of virtq's desc  ring   GUEST */
+    RTGCPHYS                    GCPhysVirtqAvail;                 /**< (MMIO) Addr of virtq's avail ring   GUEST */
+    RTGCPHYS                    GCPhysVirtqUsed;                  /**< (MMIO) Addr of virtq's used  ring   GUEST */
+    uint16_t                    uMsixVector;                      /**< (MMIO) MSI-X vector                 GUEST */
+    uint16_t                    uEnable;                          /**< (MMIO) Queue enable flag            GUEST */
+    uint16_t                    uNotifyOffset;                    /**< (MMIO) Notification offset for queue HOST */
+    uint16_t                    uQueueSize;                       /**< (MMIO) Size of queue           HOST/GUEST */
+    uint16_t                    uAvailIdxShadow;                  /**< Consumer's position in avail ring         */
+    uint16_t                    uUsedIdxShadow;                   /**< Consumer's position in used ring          */
+    uint16_t                    uVirtq;                           /**< Index of this queue                       */
+    char                        szName[32];                       /**< Dev-specific name of queue                */
+    bool                        fUsedRingEvent;                   /**< Flags if used idx to notify guest reached */
+    bool                        fAttached;                        /**< Flags if dev-specific client attached     */
+} VIRTQUEUE, *PVIRTQUEUE;
+
+/**
+ * The core/common state of the VirtIO PCI devices, shared edition.
+ */
+typedef struct VIRTIOCORE
+{
+    char                        szInstance[16];                   /**< Instance name, e.g. "VIRTIOSCSI0"         */
+    PPDMDEVINS                  pDevInsR0;                        /**< Client device instance                    */
+    PPDMDEVINS                  pDevInsR3;                        /**< Client device instance                    */
+    VIRTQUEUE                   aVirtqueues[VIRTQ_MAX_COUNT];     /**< (MMIO) VirtIO contexts for queues         */
+    uint64_t                    uDeviceFeatures;                  /**< (MMIO) Host features offered         HOST */
+    uint64_t                    uDriverFeatures;                  /**< (MMIO) Host features accepted       GUEST */
+    uint32_t                    fDriverFeaturesWritten;           /**< (MMIO) Host features complete tracking    */
+    uint32_t                    uDeviceFeaturesSelect;            /**< (MMIO) hi/lo select uDeviceFeatures GUEST */
+    uint32_t                    uDriverFeaturesSelect;            /**< (MMIO) hi/lo select uDriverFeatures GUEST */
+    uint32_t                    uMsixConfig;                      /**< (MMIO) MSI-X vector                 GUEST */
+    uint8_t                     fDeviceStatus;                    /**< (MMIO) Device Status                GUEST */
+    uint8_t                     fPrevDeviceStatus;                /**< (MMIO) Prev Device Status           GUEST */
+    uint8_t                     uConfigGeneration;                /**< (MMIO) Device config sequencer       HOST */
+    uint16_t                    uQueueNotify;                     /**< Caches queue idx in legacy mode     GUEST */
+    bool                        fGenUpdatePending;                /**< If set, update cfg gen after driver reads */
+    uint8_t                     uPciCfgDataOff;                   /**< Offset to PCI configuration data area     */
+    uint8_t                     uISR;                             /**< Interrupt Status Register.                */
+    uint8_t                     fMsiSupport;                      /**< Flag set if using MSI instead of ISR      */
+    uint16_t                    uVirtqSelect;                     /**< (MMIO) queue selector               GUEST */
+    uint32_t                    fLegacyDriver;                    /**< Set if guest drv < VirtIO 1.0 and allowed */
+    uint32_t                    fOfferLegacy;                     /**< Set at init call from dev-specific code   */
+
+    /** @name The locations of the capability structures in PCI config space and the BAR.
+     * @{ */
+    VIRTIO_PCI_CAP_LOCATIONS_T  LocPciCfgCap;                     /**< VIRTIO_PCI_CFG_CAP_T                      */
+    VIRTIO_PCI_CAP_LOCATIONS_T  LocNotifyCap;                     /**< VIRTIO_PCI_NOTIFY_CAP_T                   */
+    VIRTIO_PCI_CAP_LOCATIONS_T  LocCommonCfgCap;                  /**< VIRTIO_PCI_CAP_T                          */
+    VIRTIO_PCI_CAP_LOCATIONS_T  LocIsrCap;                        /**< VIRTIO_PCI_CAP_T                          */
+    VIRTIO_PCI_CAP_LOCATIONS_T  LocDeviceCap;                     /**< VIRTIO_PCI_CAP_T + custom data.           */
+    /** @} */
+
+    IOMMMIOHANDLE               hMmioPciCap;                      /**< MMIO handle of PCI cap. region (\#2)      */
+    IOMIOPORTHANDLE             hLegacyIoPorts;                   /**< Handle of legacy I/O port range.          */
+
+#ifdef VBOX_WITH_STATISTICS
+    /** @name Statistics
+     * @{ */
+    STAMCOUNTER                 StatDescChainsAllocated;
+    STAMCOUNTER                 StatDescChainsFreed;
+    STAMCOUNTER                 StatDescChainsSegsIn;
+    STAMCOUNTER                 StatDescChainsSegsOut;
+    STAMPROFILEADV              StatReadR3;                        /** I/O port and MMIO R3 Read profiling       */
+    STAMPROFILEADV              StatReadR0;                        /** I/O port and MMIO R0 Read profiling       */
+    STAMPROFILEADV              StatReadRC;                        /** I/O port and MMIO R3 Read profiling       */
+    STAMPROFILEADV              StatWriteR3;                       /** I/O port and MMIO R3 Write profiling      */
+    STAMPROFILEADV              StatWriteR0;                       /** I/O port and MMIO R3 Write profiling      */
+    STAMPROFILEADV              StatWriteRC;                       /** I/O port and MMIO R3 Write profiling      */
+#endif
+    /** @} */
+
+} VIRTIOCORE;
+
+#define MAX_NAME 64
+
+/**
+ * The core/common state of the VirtIO PCI devices, ring-3 edition.
+ */
+typedef struct VIRTIOCORER3
+{
+    /** @name Callbacks filled by the device before calling virtioCoreR3Init.
+     * @{  */
+    /**
+     * Implementation-specific client callback to report VirtIO when feature negotiation is
+     * complete. It should be invoked by the VirtIO core only once.
+     *
+     * @param   pVirtio           Pointer to the shared virtio state.
+     * @param   fDriverFeatures   Bitmask of features the guest driver has accepted/declined.
+     * @param   fLegacy           true if legacy mode offered and until guest driver identifies itself
+     *                            as modern(e.g. VirtIO 1.0 featured)
+     */
+    DECLCALLBACKMEMBER(void, pfnFeatureNegotiationComplete, (PVIRTIOCORE pVirtio, uint64_t fDriverFeatures, uint32_t fLegacy));
+
+    /**
+     * Implementation-specific client callback to notify client of significant device status
+     * changes.
+     *
+     * @param   pVirtio    Pointer to the shared virtio state.
+     * @param   pVirtioCC  Pointer to the ring-3 virtio state.
+     * @param   fDriverOk  True if guest driver is okay (thus queues, etc... are
+     *                     valid)
+     */
+    DECLCALLBACKMEMBER(void, pfnStatusChanged,(PVIRTIOCORE pVirtio, PVIRTIOCORECC pVirtioCC, uint32_t fDriverOk));
+
+    /**
+     * Implementation-specific client callback to access VirtIO Device-specific capabilities
+     * (other VirtIO capabilities and features are handled in VirtIO implementation)
+     *
+     * @param   pDevIns    The device instance.
+     * @param   offCap     Offset within device specific capabilities struct.
+     * @param   pvBuf      Buffer in which to save read data.
+     * @param   cbToRead   Number of bytes to read.
+     */
+    DECLCALLBACKMEMBER(int, pfnDevCapRead,(PPDMDEVINS pDevIns, uint32_t offCap, void *pvBuf, uint32_t cbToRead));
+
+    /**
+     * Implementation-specific client callback to access VirtIO Device-specific capabilities
+     * (other VirtIO capabilities and features are handled in VirtIO implementation)
+     *
+     * @param   pDevIns    The device instance.
+     * @param   offCap     Offset within device specific capabilities struct.
+     * @param   pvBuf      Buffer with the bytes to write.
+     * @param   cbToWrite  Number of bytes to write.
+     */
+    DECLCALLBACKMEMBER(int, pfnDevCapWrite,(PPDMDEVINS pDevIns, uint32_t offCap, const void *pvBuf, uint32_t cbWrite));
+
+    /**
+     * When guest-to-host queue notifications are enabled, the guest driver notifies the host
+     * that the avail queue has buffers, and this callback informs the client.
+     *
+     * @param   pVirtio    Pointer to the shared virtio state.
+     * @param   pVirtioCC  Pointer to the ring-3 virtio state.
+     * @param   uVirtqNbr   Index of the notified queue
+     */
+    DECLCALLBACKMEMBER(void, pfnVirtqNotified,(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr));
+
+    /** @} */
+
+    R3PTRTYPE(PVIRTIO_PCI_CFG_CAP_T)    pPciCfgCap;                /**< Pointer to struct in PCI config area.     */
+    R3PTRTYPE(PVIRTIO_PCI_NOTIFY_CAP_T) pNotifyCap;                /**< Pointer  to struct in PCI config area.    */
+    R3PTRTYPE(PVIRTIO_PCI_CAP_T)        pCommonCfgCap;             /**< Pointer to struct in PCI config area.     */
+    R3PTRTYPE(PVIRTIO_PCI_CAP_T)        pIsrCap;                   /**< Pointer to struct in PCI config area.     */
+    R3PTRTYPE(PVIRTIO_PCI_CAP_T)        pDeviceCap;                /**< Pointer to struct in PCI config area.     */
+
+    uint32_t                            cbDevSpecificCfg;          /**< Size of client's dev-specific config data */
+    R3PTRTYPE(uint8_t *)                pbDevSpecificCfg;          /**< Pointer to client's struct                */
+    R3PTRTYPE(uint8_t *)                pbPrevDevSpecificCfg;      /**< Previous read dev-specific cfg of client  */
+    bool                                fGenUpdatePending;         /**< If set, update cfg gen after driver reads */
+    char                                szMmioName[MAX_NAME];      /**< MMIO mapping name                         */
+    char                                szPortIoName[MAX_NAME];    /**< PORT mapping name                         */
+} VIRTIOCORER3;
+
+/**
+ * The core/common state of the VirtIO PCI devices, ring-0 edition.
+ */
+typedef struct VIRTIOCORER0
+{
+    /**
+     * This callback notifies the device-specific portion of this device implementation (if guest-to-host
+     * queue notifications are enabled), that the guest driver has notified the host (this device)
+     * that the VirtIO "avail" ring of a queue has some new s/g buffers added by the guest VirtIO driver.
+     *
+     * @param   pVirtio    Pointer to the shared virtio state.
+     * @param   pVirtioCC  Pointer to the ring-3 virtio state.
+     * @param   uVirtqNbr  Index of the notified queue
+     */
+    DECLCALLBACKMEMBER(void, pfnVirtqNotified,(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr));
+
+} VIRTIOCORER0;
+
+/**
+ * The core/common state of the VirtIO PCI devices, raw-mode edition.
+ */
+typedef struct VIRTIOCORERC
+{
+    uint64_t                    uUnusedAtTheMoment;
+} VIRTIOCORERC;
+
+/** @typedef VIRTIOCORECC
+ * The instance data for the current context. */
+typedef CTX_SUFF(VIRTIOCORE) VIRTIOCORECC;
+
+/** @name API for VirtIO parent device
+ * @{ */
+
+/**
+ * Setup PCI device controller and Virtio state
+ *
+ * This should be called from PDMDEVREGR3::pfnConstruct.
+ *
+ * @param   pDevIns                 Device instance.
+ * @param   pVirtio                 Pointer to the shared virtio state.  This
+ *                                  must be the first member in the shared
+ *                                  device instance data!
+ * @param   pVirtioCC               Pointer to the ring-3 virtio state.  This
+ *                                  must be the first member in the ring-3
+ *                                  device instance data!
+ * @param   pPciParams              Values to populate industry standard PCI Configuration Space data structure
+ * @param   pcszInstance            Device instance name (format-specifier)
+ * @param   fDevSpecificFeatures    VirtIO device-specific features offered by
+ *                                  client
+ * @param   cbDevSpecificCfg        Size of virtio_pci_device_cap device-specific struct
+ * @param   pvDevSpecificCfg        Address of client's dev-specific
+ *                                  configuration struct.
+ */
+int virtioCoreR3Init(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, PVIRTIOCORECC pVirtioCC,
+                          PVIRTIOPCIPARAMS pPciParams, const char *pcszInstance,
+                          uint64_t fDevSpecificFeatures, uint32_t fOfferLegacy, void *pvDevSpecificCfg, uint16_t cbDevSpecificCfg);
+/**
+ * Initiate orderly reset procedure. This is an exposed API for clients that might need it.
+ * Invoked by client to reset the device and driver (see VirtIO 1.0 section 2.1.1/2.1.2)
+ *
+ * @param   pVirtio     Pointer to the virtio state.
+ */
+void  virtioCoreResetAll(PVIRTIOCORE pVirtio);
+
+/**
+ * Resets the device state upon a VM reset for instance.
+ *
+ * @param   pVirtio     Pointer to the virtio state.
+ *
+ * @note Calls back into the upper device when the status changes.
+ */
+DECLHIDDEN(void) virtioCoreR3ResetDevice(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, PVIRTIOCORECC pVirtioCC);
+
+/**
+ * 'Attaches' host device-specific implementation's queue state to host VirtIO core
+ * virtqueue management infrastructure, informing the virtio core of the name of the
+ * queue to associate with the queue number.
+
+ * Note: uVirtqNbr (ordinal index) is used as the 'handle' for virtqs in this VirtioCore
+ * implementation's API (as an opaque selector into the VirtIO core's array of queues' states).
+ *
+ * Virtqueue numbers are actually VirtIO-specification defined device-specifically
+ * (i.e. they are unique within each VirtIO device type), but are in some cases scalable
+ * so only the pattern of queue numbers is defined by the spec and implementations may contain
+ * a self-determined plurality of queues.
+ *
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   pcszName    Name to give queue
+ *
+ * @returns VBox status code.
+ */
+int  virtioCoreR3VirtqAttach(PVIRTIOCORE pVirtio, uint16_t uVirtqNbr, const char *pcszName);
+
+/**
+ * Detaches host device-specific implementation's queue state from the host VirtIO core
+ * virtqueue management infrastructure, informing the VirtIO core that the queue is
+ * not utilized by the device-specific code.
+ *
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   pcszName    Name to give queue
+ *
+ * @returns VBox status code.
+ */
+int  virtioCoreR3VirtqDetach(PVIRTIOCORE pVirtio, uint16_t uVirtqNbr);
+
+/**
+ * Checks to see whether queue is attached to core.
+ *
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ *
+ * Returns boolean true or false indicating whether dev-specific reflection
+ * of queue is attached to core.
+ */
+bool  virtioCoreR3VirtqIsAttached(PVIRTIOCORE pVirtio, uint16_t uVirtqNbr);
+
+/**
+ * Checks to see whether queue is enabled.
+ *
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ *
+ * Returns boolean true or false indicating core queue enable state.
+ * There is no API function to enable the queue, because the actual enabling is handled
+ * by the guest via MMIO.
+ *
+ * NOTE: Guest VirtIO driver's claim over this state is overridden (which violates VirtIO 1.0 spec
+ * in a carefully controlled manner) in the case where the queue MUST be disabled, due to observed
+ * control queue corruption (e.g. null GCPhys virtq base addr) while restoring legacy-only device's
+ * (DevVirtioNet.cpp) as a way to flag that the queue is unusable-as-saved and must to be removed.
+ * That is all handled in the load/save exec logic. Device reset could potentially, depending on
+ * parameters passed from host VirtIO device to guest VirtIO driver, result in guest re-establishing
+ * queue, except, in that situation, the queue operational state would be valid.
+ */
+bool  virtioCoreR3VirtqIsEnabled(PVIRTIOCORE pVirtio, uint16_t uVirtqNbr);
+
+/**
+ * Enable or disable notification for the specified queue.
+ *
+ * When queue notifications are enabled, the guest VirtIO driver notifies host VirtIO device
+ * (via MMIO, see VirtIO 1.0, 4.1.4.4 "Notification Structure Layout") whenever guest driver adds
+ * a new s/g buffer to the "avail" ring of the queue.
+ *
+ * Note: VirtIO queue layout includes flags the device controls in "used" ring to inform guest
+ * driver if it should notify host of guest's buffer additions to the "avail" ring, and
+ * conversely, the guest driver sets flags in the "avail" ring to communicate to host device
+ * whether or not to interrupt guest when it adds buffers to used ring.
+ *
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   fEnable     Selects notification mode (enabled or disabled)
+ */
+void  virtioCoreVirtqEnableNotify(PVIRTIOCORE pVirtio, uint16_t uVirtqNbr, bool fEnable);
+
+/**
+ * Notifies guest (via ISR or MSI-X) of device configuration change
+ *
+ * @param   pVirtio     Pointer to the shared virtio state.
+ */
+void  virtioCoreNotifyConfigChanged(PVIRTIOCORE pVirtio);
+
+/**
+ * Displays a well-formatted human-readable translation of otherwise inscrutable bitmasks
+ * that embody features VirtIO specification definitions, indicating: Totality of features
+ * that can be implemented by host and guest, which features were offered by the host, and
+ * which were actually accepted by the guest. It displays it as a summary view of the device's
+ * finalized operational state (host-guest negotiated architecture) in such a way that shows
+ * which options are available for implementing or enabling.
+ *
+ * The non-device-specific VirtIO features list are managed by core API (e.g. implied).
+ * Only dev-specific features must be passed as parameter.
+
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   pHlp        Pointer to the debug info hlp struct
+ * @param   s_aDevSpecificFeatures  Dev-specific features (virtio-net, virtio-scsi...)
+ * @param   cFeatures   Number of features in aDevSpecificFeatures
+ */
+void  virtioCorePrintDeviceFeatures(VIRTIOCORE *pVirtio, PCDBGFINFOHLP pHlp,
+    const VIRTIO_FEATURES_LIST *aDevSpecificFeatures, int cFeatures);
+
+/*
+ * Debug-assist utility function to display state of the VirtIO core code, including
+ * an overview of the state of all of the queues.
+ *
+ * This can be invoked when running the VirtualBox debugger, or from the command line
+ * using the command: "VboxManage debugvm <VM name or id> info <device name> [args]"
+ *
+ * Example:  VBoxManage debugvm myVnetVm info "virtio-net" help
+ *
+ * This is implemented currently to be invoked by the inheriting device-specific code
+ * (see the the VirtualBox virtio-net (VirtIO network controller device implementation)
+ * for an example of code that receive debugvm callback directly).
+ *
+ * DevVirtioNet lists available sub-options if no arguments are provided. In that
+ * example this virtq info related function is invoked hierarchically when virtio-net
+ * displays its device-specific queue info.
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pHlp        Pointer to the debug info hlp struct
+ * @param   pszArgs     Arguments to function
+ */
+void  virtioCoreR3VirtqInfo(PPDMDEVINS pDevIns, PCDBGFINFOHLP pHlp, const char *pszArgs, int uVirtqNbr);
+
+/**
+ * Returns the number of avail bufs in the virtq.
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtqueue to return the count of buffers available for.
+ */
+uint16_t virtioCoreVirtqAvailBufCount(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr);
+
+#ifdef VIRTIO_VBUF_ON_STACK
+/**
+ * This function is identical to virtioCoreR3VirtqAvailBufGet(), *except* it doesn't consume
+ * peeked buffer from avail ring of the virtq. The function *becomes* identical to the
+ * virtioCoreR3VirtqAvailBufGet() only if virtioCoreR3VirtqAvailRingNext() is invoked to
+ * consume buf from the queue's avail ring, followed by invocation of virtioCoreR3VirtqUsedBufPut(),
+ * to hand host-processed buffer back to guest, which completes guest-initiated virtq buffer circuit.
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   pVirtqBuf   Pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int  virtioCoreR3VirtqAvailBufPeek(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                   PVIRTQBUF pVirtqBuf);
+
+/**
+ * This function fetches the next buffer (descriptor chain) from the VirtIO "avail" ring of
+ * indicated queue, separating the buf's s/g vectors into OUT (e.g. guest-to-host)
+ * components and and IN (host-to-guest) components.
+ *
+ * Caller is responsible for GCPhys to host virtual memory conversions. If the
+ * virtq buffer being peeked at is "consumed", virtioCoreR3VirtqAvailRingNext() must
+ * be called, and after that virtioCoreR3VirtqUsedBufPut() must be called to
+ * complete the buffer transfer cycle with the guest.
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   pVirtqBuf   Pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ * @param   fRemove     flags whether to remove desc chain from queue (false = peek)
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int  virtioCoreR3VirtqAvailBufGet(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                  PVIRTQBUF pVirtqBuf, bool fRemove);
+
+/**
+ * Fetches a specific descriptor chain using avail ring of indicated queue and converts the
+ * descriptor chain into its OUT (to device) and IN (to guest) components.
+ *
+ * The caller is responsible for GCPhys to host virtual memory conversions and *must*
+ * return the virtq buffer using virtioCoreR3VirtqUsedBufPut() to complete the roundtrip
+ * virtq transaction.
+ * *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   pVirtqBuf   Pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ * @param   fRemove     flags whether to remove desc chain from queue (false = peek)
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int virtioCoreR3VirtqAvailBufGet(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                  uint16_t uHeadIdx, PVIRTQBUF pVirtqBuf);
+#else /* !VIRTIO_VBUF_ON_STACK */
+/**
+ * This function is identical to virtioCoreR3VirtqAvailBufGet(), *except* it doesn't consume
+ * peeked buffer from avail ring of the virtq. The function *becomes* identical to the
+ * virtioCoreR3VirtqAvailBufGet() only if virtioCoreR3VirtqAvailRingNext() is invoked to
+ * consume buf from the queue's avail ring, followed by invocation of virtioCoreR3VirtqUsedBufPut(),
+ * to hand host-processed buffer back to guest, which completes guest-initiated virtq buffer circuit.
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   ppVirtqBuf  Address to store pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int  virtioCoreR3VirtqAvailBufPeek(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                   PPVIRTQBUF ppVirtqBuf);
+
+/**
+ * This function fetches the next buffer (descriptor chain) from the VirtIO "avail" ring of
+ * indicated queue, separating the buf's s/g vectors into OUT (e.g. guest-to-host)
+ * components and and IN (host-to-guest) components.
+ *
+ * Caller is responsible for GCPhys to host virtual memory conversions. If the
+ * virtq buffer being peeked at is "consumed", virtioCoreR3VirtqAvailRingNext() must
+ * be called, and after that virtioCoreR3VirtqUsedBufPut() must be called to
+ * complete the buffer transfer cycle with the guest.
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   ppVirtqBuf  Address to store pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ *                      Returned reference must be released by calling
+ *                      virtioCoreR3VirtqBufRelease().
+ * @param   fRemove     flags whether to remove desc chain from queue (false = peek)
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int  virtioCoreR3VirtqAvailBufGet(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                  PPVIRTQBUF ppVirtqBuf, bool fRemove);
+
+/**
+ * Fetches a specific descriptor chain using avail ring of indicated queue and converts the
+ * descriptor chain into its OUT (to device) and IN (to guest) components.
+ *
+ * The caller is responsible for GCPhys to host virtual memory conversions and *must*
+ * return the virtq buffer using virtioCoreR3VirtqUsedBufPut() to complete the roundtrip
+ * virtq transaction.
+ * *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ * @param   ppVirtqBuf  Address to store pointer to descriptor chain that contains the
+ *                      pre-processed transaction information pulled from the virtq.
+ *                      Returned reference must be released by calling
+ *                      virtioCoreR3VirtqBufRelease().
+ * @param   fRemove     flags whether to remove desc chain from queue (false = peek)
+ *
+ * @returns VBox status code:
+ * @retval  VINF_SUCCESS         Success
+ * @retval  VERR_INVALID_STATE   VirtIO not in ready state (asserted).
+ * @retval  VERR_NOT_AVAILABLE   If the queue is empty.
+ */
+int virtioCoreR3VirtqAvailBufGet(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr,
+                                  uint16_t uHeadIdx, PPVIRTQBUF ppVirtqBuf);
+#endif /* !VIRTIO_VBUF_ON_STACK */
+
+/**
+ * Returns data to the guest to complete a transaction initiated by virtioCoreR3VirtqAvailBufGet(),
+ * (or virtioCoreR3VirtqAvailBufPeek()/virtioCoreR3VirtqBufSync() call pair), to complete each
+ * buffer transfer transaction (guest-host buffer cycle), ultimately moving each descriptor chain
+ * from the avail ring of a queue onto the used ring of the queue. Note that VirtIO buffer
+ * transactions are *always* initiated by the guest and completed by the host. In other words,
+ * for the host to send any I/O related data to the guest (and in some cases configuration data),
+ * the guest must provide buffers via the virtq's avail ring, for the host to fill.
+ *
+ * At some some point virtioCoreR3VirtqUsedRingSync() must be called to return data to the guest,
+ * completing all pending virtioCoreR3VirtqAvailBufPut() operations that have accumulated since
+ * the last call to virtioCoreR3VirtqUsedRingSync().
+
+ * @note This function effectively performs write-ahead to the used ring of the virtq.
+ *       Data written won't be seen by the guest until the next call to virtioCoreVirtqUsedRingSync()
+ *
+ * @param   pDevIns         The device instance (for reading).
+ * @param   pVirtio         Pointer to the shared virtio state.
+ * @param   uVirtqNbr       Virtq number
+ *
+ * @param   pSgVirtReturn   Points to scatter-gather buffer of virtual memory
+ *                          segments the caller is returning to the guest.
+ *
+ * @param   pVirtqBuf       This contains the context of the scatter-gather
+ *                          buffer originally pulled from the queue.
+ *
+ * @param   fFence          If true (default), put up copy-fence (memory barrier) after
+ *                          copying to guest phys. mem.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS       Success
+ * @retval  VERR_INVALID_STATE VirtIO not in ready state
+ * @retval  VERR_NOT_AVAILABLE Virtq is empty
+ *
+ * @note    This function will not release any reference to pVirtqBuf.  The
+ *          caller must take care of that.
+ */
+int virtioCoreR3VirtqUsedBufPut(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr, PRTSGBUF pSgVirtReturn,
+                                 PVIRTQBUF pVirtqBuf, bool fFence = true);
+
+
+/**
+ * Quicker variant of same-named function (directly above) that it overloads,
+ * Instead, this variant accepts as input a pointer to a buffer and count,
+ * instead of S/G buffer thus doesn't have to copy between two S/G buffers and avoids some overhead.
+ *
+ * @param   pDevIns         The device instance (for reading).
+ * @param   pVirtio         Pointer to the shared virtio state.
+ * @param   uVirtqNbr       Virtq number
+ * @param   cb              Number of bytes to add to copy to phys. buf.
+ * @param   pv              Virtual mem buf to copy to phys buf.
+ * @param   cbEnqueue       How many bytes in packet to enqueue (0 = don't enqueue)
+ * @param   fFence          If true (default), put up copy-fence (memory barrier) after
+ *                          copying to guest phys. mem.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS       Success
+ * @retval  VERR_INVALID_STATE VirtIO not in ready state
+ * @retval  VERR_NOT_AVAILABLE Virtq is empty
+ *
+ * @note    This function will not release any reference to pVirtqBuf.  The
+ *          caller must take care of that.
+ */
+int virtioCoreR3VirtqUsedBufPut(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtq, size_t cb, const void *pv,
+                            PVIRTQBUF pVirtqBuf, size_t cbEnqueue, bool fFence = true);
+
+
+/**
+ * Advance index of avail ring to next entry in specified virtq (see virtioCoreR3VirtqAvailBufPeek())
+ *
+ * @param   pVirtio      Pointer to the virtio state.
+ * @param   uVirtqNbr    Index of queue
+ */
+int virtioCoreR3VirtqAvailBufNext(PVIRTIOCORE pVirtio, uint16_t uVirtqNbr);
+
+/**
+ * Checks to see if guest has accepted host device's VIRTIO_F_VERSION_1 (i.e. "modern")
+ * behavioral modeling, indicating guest agreed to comply with the modern VirtIO 1.0+ specification.
+ * Otherwise unavoidable presumption is that the host device is dealing with legacy VirtIO
+ * guest driver, thus must be prepared to cope with less mature architecture and behaviors
+ * from prototype era of VirtIO. (see comments in PDM-invoked device constructor for more
+ * information).
+ *
+ * @param   pVirtio      Pointer to the virtio state.
+ */
+int virtioCoreIsLegacyMode(PVIRTIOCORE pVirtio);
+
+/**
+ * This VirtIO transitional device supports "modern" (rev 1.0+) as well as "legacy" (e.g. < 1.0) VirtIO drivers.
+ * Some legacy guest drivers are known to mishandle PCI bus mastering wherein the PCI flavor of GC phys
+ * access functions can't be used. The following wrappers select the memory access method based on whether the
+ * device is operating in legacy mode or not.
+ */
+DECLINLINE(int) virtioCoreGCPhysWrite(PVIRTIOCORE pVirtio, PPDMDEVINS pDevIns, RTGCPHYS GCPhys, void *pvBuf, size_t cbWrite)
+{
+    int rc;
+    if (virtioCoreIsLegacyMode(pVirtio))
+        rc = PDMDevHlpPhysWrite(pDevIns, GCPhys, pvBuf, cbWrite);
+    else
+        rc = PDMDevHlpPCIPhysWrite(pDevIns, GCPhys, pvBuf, cbWrite);
+    return rc;
+}
+
+DECLINLINE(int) virtioCoreGCPhysRead(PVIRTIOCORE pVirtio, PPDMDEVINS pDevIns, RTGCPHYS GCPhys, void *pvBuf, size_t cbRead)
+{
+    int rc;
+    if (virtioCoreIsLegacyMode(pVirtio))
+        rc = PDMDevHlpPhysRead(pDevIns, GCPhys, pvBuf, cbRead);
+    else
+        rc = PDMDevHlpPCIPhysRead(pDevIns, GCPhys, pvBuf, cbRead);
+    return rc;
+}
+
+/*
+ * (See comments for corresponding function in sg.h)
+ */
+DECLINLINE(void) virtioCoreGCPhysChainInit(PVIRTIOSGBUF pGcSgBuf, PVIRTIOSGSEG paSegs, size_t cSegs)
+{
+    AssertPtr(pGcSgBuf);
+    Assert((cSegs > 0 && RT_VALID_PTR(paSegs)) || (!cSegs && !paSegs));
+    Assert(cSegs < (~(unsigned)0 >> 1));
+
+    pGcSgBuf->paSegs = paSegs;
+    pGcSgBuf->cSegs  = (unsigned)cSegs;
+    pGcSgBuf->idxSeg = 0;
+    if (cSegs && paSegs)
+    {
+        pGcSgBuf->GCPhysCur = paSegs[0].GCPhys;
+        pGcSgBuf->cbSegLeft = paSegs[0].cbSeg;
+    }
+    else
+    {
+        pGcSgBuf->GCPhysCur = 0;
+        pGcSgBuf->cbSegLeft = 0;
+    }
+}
+
+/*
+ * (See comments for corresponding function in sg.h)
+ */
+DECLINLINE(RTGCPHYS) virtioCoreGCPhysChainGet(PVIRTIOSGBUF pGcSgBuf, size_t *pcbData)
+{
+    size_t cbData;
+    RTGCPHYS pGcBuf;
+
+    /* Check that the S/G buffer has memory left. */
+    if (RT_LIKELY(pGcSgBuf->idxSeg < pGcSgBuf->cSegs || pGcSgBuf->cbSegLeft))
+    { /* likely */ }
+    else
+    {
+        *pcbData = 0;
+        return 0;
+    }
+
+    AssertMsg(    pGcSgBuf->cbSegLeft <= 128 * _1M
+              && (RTGCPHYS)pGcSgBuf->GCPhysCur >= (RTGCPHYS)pGcSgBuf->paSegs[pGcSgBuf->idxSeg].GCPhys
+              && (RTGCPHYS)pGcSgBuf->GCPhysCur + pGcSgBuf->cbSegLeft <=
+                   (RTGCPHYS)pGcSgBuf->paSegs[pGcSgBuf->idxSeg].GCPhys + pGcSgBuf->paSegs[pGcSgBuf->idxSeg].cbSeg,
+                 ("pGcSgBuf->idxSeg=%d pGcSgBuf->cSegs=%d pGcSgBuf->GCPhysCur=%p pGcSgBuf->cbSegLeft=%zd "
+                  "pGcSgBuf->paSegs[%d].GCPhys=%p pGcSgBuf->paSegs[%d].cbSeg=%zd\n",
+                  pGcSgBuf->idxSeg, pGcSgBuf->cSegs, pGcSgBuf->GCPhysCur, pGcSgBuf->cbSegLeft,
+                  pGcSgBuf->idxSeg, pGcSgBuf->paSegs[pGcSgBuf->idxSeg].GCPhys, pGcSgBuf->idxSeg,
+                  pGcSgBuf->paSegs[pGcSgBuf->idxSeg].cbSeg));
+
+    cbData = RT_MIN(*pcbData, pGcSgBuf->cbSegLeft);
+    pGcBuf = pGcSgBuf->GCPhysCur;
+    pGcSgBuf->cbSegLeft -= cbData;
+    if (!pGcSgBuf->cbSegLeft)
+    {
+        pGcSgBuf->idxSeg++;
+
+        if (pGcSgBuf->idxSeg < pGcSgBuf->cSegs)
+        {
+            pGcSgBuf->GCPhysCur = pGcSgBuf->paSegs[pGcSgBuf->idxSeg].GCPhys;
+            pGcSgBuf->cbSegLeft = pGcSgBuf->paSegs[pGcSgBuf->idxSeg].cbSeg;
+        }
+        *pcbData = cbData;
+    }
+    else
+        pGcSgBuf->GCPhysCur = pGcSgBuf->GCPhysCur + cbData;
+
+    return pGcBuf;
+}
+
+/*
+ * (See comments for corresponding function in sg.h)
+ */
+DECLINLINE(void) virtioCoreGCPhysChainReset(PVIRTIOSGBUF pGcSgBuf)
+{
+    AssertPtrReturnVoid(pGcSgBuf);
+
+    pGcSgBuf->idxSeg = 0;
+    if (pGcSgBuf->cSegs)
+    {
+        pGcSgBuf->GCPhysCur = pGcSgBuf->paSegs[0].GCPhys;
+        pGcSgBuf->cbSegLeft = pGcSgBuf->paSegs[0].cbSeg;
+    }
+    else
+    {
+        pGcSgBuf->GCPhysCur = 0;
+        pGcSgBuf->cbSegLeft = 0;
+    }
+}
+
+/*
+ * (See comments for corresponding function in sg.h)
+ */
+DECLINLINE(RTGCPHYS) virtioCoreGCPhysChainAdvance(PVIRTIOSGBUF pGcSgBuf, size_t cbAdvance)
+{
+    AssertReturn(pGcSgBuf, 0);
+
+    size_t cbLeft = cbAdvance;
+    while (cbLeft)
+    {
+        size_t cbThisAdvance = cbLeft;
+        virtioCoreGCPhysChainGet(pGcSgBuf, &cbThisAdvance);
+        if (!cbThisAdvance)
+            break;
+
+        cbLeft -= cbThisAdvance;
+    }
+    return cbAdvance - cbLeft;
+}
+
+/*
+ * (See comments for corresponding function in sg.h)
+ */
+DECLINLINE(RTGCPHYS) virtioCoreGCPhysChainGetNextSeg(PVIRTIOSGBUF pGcSgBuf, size_t *pcbSeg)
+{
+    AssertReturn(pGcSgBuf, 0);
+    AssertPtrReturn(pcbSeg, 0);
+
+    if (!*pcbSeg)
+        *pcbSeg = pGcSgBuf->cbSegLeft;
+
+    return virtioCoreGCPhysChainGet(pGcSgBuf, pcbSeg);
+}
+
+/**
+ * Calculate the length of a GCPhys s/g buffer by tallying the size of each segment.
+ *
+ * @param   pGcSgBuf        Guest Context (GCPhys) S/G buffer to calculate length of
+ */
+DECLINLINE(size_t) virtioCoreGCPhysChainCalcBufSize(PCVIRTIOSGBUF pGcSgBuf)
+{
+    size_t   cb = 0;
+    unsigned i  = pGcSgBuf->cSegs;
+    while (i-- > 0)
+        cb += pGcSgBuf->paSegs[i].cbSeg;
+    return cb;
+}
+
+/*
+ * (See comments for corresponding function in sg.h)
+ */
+DECLINLINE(size_t) virtioCoreGCPhysChainCalcLengthLeft(PVIRTIOSGBUF pGcSgBuf)
+{
+    size_t   cb = pGcSgBuf->cbSegLeft;
+    unsigned i  = pGcSgBuf->cSegs;
+    while (i-- > pGcSgBuf->idxSeg + 1)
+        cb += pGcSgBuf->paSegs[i].cbSeg;
+    return cb;
+}
+#define VIRTQNAME(a_pVirtio, a_uVirtq) ((a_pVirtio)->aVirtqueues[(a_uVirtq)].szName)
+
+/**
+ * Convert and append bytes from a virtual-memory simple buffer to VirtIO guest's
+ * physical memory described by a buffer pulled form the avail ring of a virtq.
+ *
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   pVirtqBuf   VirtIO buffer to fill
+ * @param   pv          input: virtual memory buffer to receive bytes
+ * @param   cb          number of bytes to add to the s/g buffer.
+ */
+DECLINLINE(void) virtioCoreR3VirqBufFill(PVIRTIOCORE pVirtio, PVIRTQBUF pVirtqBuf, void *pv, size_t cb)
+{
+    uint8_t *pvBuf = (uint8_t *)pv;
+    size_t cbRemain = cb, cbTotal = 0;
+    PVIRTIOSGBUF pSgPhysReturn = pVirtqBuf->pSgPhysReturn;
+    while (cbRemain)
+    {
+        size_t cbBounded = RT_MIN(pSgPhysReturn->cbSegLeft, cbRemain);
+        Assert(cbBounded > 0);
+        virtioCoreGCPhysWrite(pVirtio, CTX_SUFF(pVirtio->pDevIns), (RTGCPHYS)pSgPhysReturn->GCPhysCur, pvBuf, cbBounded);
+        virtioCoreGCPhysChainAdvance(pSgPhysReturn, cbBounded);
+        pvBuf += cbBounded;
+        cbRemain -= cbBounded;
+        cbTotal += cbBounded;
+    }
+    LogFunc(("Appended %d bytes to guest phys buf [head: %u]. %d bytes unused in buf.)\n",
+             cbTotal, pVirtqBuf->uHeadIdx, virtioCoreGCPhysChainCalcLengthLeft(pSgPhysReturn)));
+}
+
+/**
+ * Extract some bytes from of a virtq s/g buffer, converting them from GCPhys space to
+ * to ordinary virtual memory (i.e. making data directly accessible to host device code)
+ *
+ * As a performance optimization, it is left to the caller to validate buffer size.
+ *
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   pVirtqBuf   input: virtq buffer
+ * @param   pv          output: virtual memory buffer to receive bytes
+ * @param   cb          number of bytes to Drain from buffer
+ */
+DECLINLINE(void) virtioCoreR3VirtqBufDrain(PVIRTIOCORE pVirtio, PVIRTQBUF pVirtqBuf, void *pv, size_t cb)
+{
+    uint8_t *pb = (uint8_t *)pv;
+    size_t cbLim = RT_MIN(pVirtqBuf->cbPhysSend, cb);
+    while (cbLim)
+    {
+        size_t cbSeg = cbLim;
+        RTGCPHYS GCPhys = virtioCoreGCPhysChainGetNextSeg(pVirtqBuf->pSgPhysSend, &cbSeg);
+        PDMDevHlpPCIPhysRead(pVirtio->pDevInsR3, GCPhys, pb, cbSeg);
+        pb += cbSeg;
+        cbLim -= cbSeg;
+        pVirtqBuf->cbPhysSend -= cbSeg;
+    }
+    LogFunc(("Drained %d/%d bytes from %s buffer, head idx: %u (%d bytes left)\n",
+             cb - cbLim, cb, VIRTQNAME(pVirtio, pVirtqBuf->uVirtq),
+             pVirtqBuf->uHeadIdx, virtioCoreGCPhysChainCalcLengthLeft(pVirtqBuf->pSgPhysReturn)));
+}
+
+#undef VIRTQNAME
+
+/**
+ * Updates indicated virtq's "used ring" descriptor index to match "shadow" index that tracks
+ * pending buffers added to the used ring, thus exposing all the data added by virtioCoreR3VirtqUsedBufPut()
+ * to the "used ring" since the last virtioCoreVirtqUsedRingSync().
+ *
+ * This *must* be invoked after one or more virtioCoreR3VirtqUsedBufPut() calls to inform guest driver
+ * there is data in the queue. If enabled by guest, IRQ or MSI-X signalling will notify guest
+ * proactively, otherwise guest detects updates by polling. (see VirtIO 1.0, Section 2.4 "Virtqueues").
+ *
+ * @param   pDevIns     The device instance.
+ * @param   pVirtio     Pointer to the shared virtio state.
+ * @param   uVirtqNbr   Virtq number
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS       Success
+ * @retval  VERR_INVALID_STATE VirtIO not in ready state
+ */
+int  virtioCoreVirtqUsedRingSync(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, uint16_t uVirtqNbr);
+
+#ifdef VIRTIO_VBUF_ON_STACK
+/**
+ * Allocates a descriptor chain object with the reference count of one. Copying the reference
+ * to this object requires a call to virtioCoreR3VirtqBufRetain. All references must be later
+ * released with virtioCoreR3VirtqBufRelease. Just to be clear, one alloc plus one retain will
+ * require two releases.
+ *
+ * @returns A descriptor chain object.
+ *
+ * @retval  NULL if out of memory.
+ *
+ * NOTE: VIRTQBUF_T objects allocated on the stack will have garbage in the u32Magic field,
+ * triggering an assertion if virtioCoreR3VirtqBufRelease is called on them.
+ */
+PVIRTQBUF virtioCoreR3VirtqBufAlloc(void);
+#endif /* VIRTIO_VBUF_ON_STACK */
+
+/**
+ * Retains a reference to the given descriptor chain.
+ *
+ * @param   pVirtqBuf      The descriptor chain to reference.
+ *
+ * @returns New reference count.
+ * @retval  UINT32_MAX on invalid parameter.
+ */
+uint32_t virtioCoreR3VirtqBufRetain(PVIRTQBUF pVirtqBuf);
+
+/**
+ * Releases a reference to the given descriptor chain.
+ *
+ * @param   pVirtio         Pointer to the shared virtio state.
+ * @param   pVirtqBuf       The descriptor chain to reference.  NULL is quietly
+ *                          ignored (returns 0).
+ * @returns New reference count.
+ * @retval  0 if freed or invalid parameter.
+ */
+uint32_t virtioCoreR3VirtqBufRelease(PVIRTIOCORE pVirtio, PVIRTQBUF pVirtqBuf);
+
+/**
+ * Return queue enable state
+ *
+ * @param   pVirtio      Pointer to the virtio state.
+ * @param   uVirtqNbr    Virtq number.
+ *
+ * @returns true or false indicating queue is enabled or not.
+ */
+DECLINLINE(bool) virtioCoreIsVirtqEnabled(PVIRTIOCORE pVirtio, uint16_t uVirtqNbr)
+{
+    Assert(uVirtqNbr < RT_ELEMENTS(pVirtio->aVirtqueues));
+    if (pVirtio->fLegacyDriver)
+        return pVirtio->aVirtqueues[uVirtqNbr].GCPhysVirtqDesc != 0;
+    return pVirtio->aVirtqueues[uVirtqNbr].uEnable != 0;
+}
+
+/**
+ * Get name of queue, via uVirtqNbr, assigned during virtioCoreR3VirtqAttach()
+ *
+ * @param   pVirtio     Pointer to the virtio state.
+ * @param   uVirtqNbr   Virtq number.
+ *
+ * @returns Pointer to read-only queue name.
+ */
+DECLINLINE(const char *) virtioCoreVirtqGetName(PVIRTIOCORE pVirtio, uint16_t uVirtqNbr)
+{
+    Assert((size_t)uVirtqNbr < RT_ELEMENTS(pVirtio->aVirtqueues));
+    return pVirtio->aVirtqueues[uVirtqNbr].szName;
+}
+
+/**
+ * Get the bitmask of features VirtIO is running with. This is called by the device-specific
+ * VirtIO implementation to identify this device's operational configuration after features
+ * have been negotiated with guest VirtIO driver. Feature negotiation entails host indicating
+ * to guest which features it supports, then guest accepting from among the offered, which features
+ * it will enable. That becomes the agreement between the host and guest. The bitmask containing
+ * virtio core features plus device-specific features is provided as a parameter to virtioCoreR3Init()
+ * by the host side device-specific virtio implementation.
+ *
+ * @param   pVirtio     Pointer to the virtio state.
+ *
+ * @returns Features the guest driver has accepted, finalizing the operational features
+ */
+DECLINLINE(uint64_t) virtioCoreGetNegotiatedFeatures(PVIRTIOCORE pVirtio)
+{
+    return pVirtio->uDriverFeatures;
+}
+
+/**
+ * Get name of the VM state change associated with the enumeration variable
+ *
+ * @param enmState       VM state (enumeration value)
+ *
+ * @returns associated text.
+ */
+const char *virtioCoreGetStateChangeText(VIRTIOVMSTATECHANGED enmState);
+
+/**
+ * Debug assist code for any consumer that inherits VIRTIOCORE.
+ * Log memory-mapped I/O input or output value.
+ *
+ * This is to be invoked by macros that assume they are invoked in functions with
+ * the relevant arguments. (See Virtio_1_0.cpp).
+ *
+ * It is exposed via the API so inheriting device-specific clients can provide similar
+ * logging capabilities for a consistent look-and-feel.
+ *
+ * @param   pszFunc     To avoid displaying this function's name via __FUNCTION__ or LogFunc()
+ * @param   pszMember   Name of struct member
+ * @param   pv          pointer to value
+ * @param   cb          size of value
+ * @param   uOffset     offset into member where value starts
+ * @param   fWrite      True if write I/O
+ * @param   fHasIndex   True if the member is indexed
+ * @param   idx         The index if fHasIndex
+ */
+void virtioCoreLogMappedIoValue(const char *pszFunc, const char *pszMember, uint32_t uMemberSize,
+                                const void *pv, uint32_t cb, uint32_t uOffset,
+                                int fWrite, int fHasIndex, uint32_t idx);
+
+/**
+ * Debug assist for any consumer
+ *
+ * Does a formatted hex dump using Log(()), recommend using VIRTIO_HEX_DUMP() macro to
+ * control enabling of logging efficiently.
+ *
+ * @param   pv          pointer to buffer to dump contents of
+ * @param   cb          count of characters to dump from buffer
+ * @param   uBase       base address of per-row address prefixing of hex output
+ * @param   pszTitle    Optional title. If present displays title that lists
+ *                      provided text with value of cb to indicate VIRTQ_SIZE next to it.
+ */
+void virtioCoreHexDump(uint8_t *pv, uint32_t cb, uint32_t uBase, const char *pszTitle);
+
+/**
+ * Debug assist for any consumer device code
+ * Do a hex dump of memory in guest physical context
+ *
+ * @param   GCPhys      pointer to buffer to dump contents of
+ * @param   cb          count of characters to dump from buffer
+ * @param   uBase       base address of per-row address prefixing of hex output
+ * @param   pszTitle    Optional title. If present displays title that lists
+ *                      provided text with value of cb to indicate size next to it.
+ */
+void virtioCoreGCPhysHexDump(PPDMDEVINS pDevIns, RTGCPHYS GCPhys, uint16_t cb, uint32_t uBase, const char *pszTitle);
+
+/**
+ * The following API is functions identically to the similarly-named calls pertaining to the RTSGBUF
+ */
+
+/** Misc VM and PDM boilerplate */
+int      virtioCoreR3SaveExec(PVIRTIOCORE pVirtio, PCPDMDEVHLPR3 pHlp, PSSMHANDLE pSSM, uint32_t uVersion, uint32_t cQueues);
+int      virtioCoreR3ModernDeviceLoadExec(PVIRTIOCORE pVirtio, PCPDMDEVHLPR3 pHlp, PSSMHANDLE pSSM, uint32_t uVersion, uint32_t uTestVersion, uint32_t cQueues);
+int      virtioCoreR3LegacyDeviceLoadExec(PVIRTIOCORE pVirtio, PCPDMDEVHLPR3 pHlp, PSSMHANDLE pSSM, uint32_t uVersion, uint32_t uVirtioLegacy_3_1_Beta);
+void     virtioCoreR3VmStateChanged(PVIRTIOCORE pVirtio, VIRTIOVMSTATECHANGED enmState);
+void     virtioCoreR3Term(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio, PVIRTIOCORECC pVirtioCC);
+int      virtioCoreRZInit(PPDMDEVINS pDevIns, PVIRTIOCORE pVirtio);
+const char *virtioCoreGetStateChangeText(VIRTIOVMSTATECHANGED enmState);
+
+/*
+ * The following macros assist with handling/logging MMIO accesses to VirtIO dev-specific config area,
+ * in a way that enhances code readability and debug logging consistency.
+ *
+ * cb, pv and fWrite are implicit parameters and must be defined by the invoker.
+ */
+#ifdef LOG_ENABLED
+
+# define VIRTIO_DEV_CONFIG_LOG_ACCESS(member, tCfgStruct, uOffsetOfAccess) \
+    if (LogIs7Enabled()) { \
+        uint32_t uMbrOffset = uOffsetOfAccess - RT_UOFFSETOF(tCfgStruct, member); \
+        uint32_t uMbrSize   = RT_SIZEOFMEMB(tCfgStruct, member); \
+        virtioCoreLogMappedIoValue(__FUNCTION__, #member, uMbrSize, pv, cb, uMbrOffset, fWrite, false, 0); \
+    }
+
+# define VIRTIO_DEV_CONFIG_LOG_INDEXED_ACCESS(member, tCfgStruct, uOffsetOfAccess, uIdx) \
+    if (LogIs7Enabled()) { \
+        uint32_t uMbrOffset = uOffsetOfAccess - RT_UOFFSETOF(tCfgStruct, member); \
+        uint32_t uMbrSize   = RT_SIZEOFMEMB(tCfgStruct, member); \
+        virtioCoreLogMappedIoValue(__FUNCTION__, #member, uMbrSize,  pv, cb, uMbrOffset, fWrite, true, uIdx); \
+    }
+#else
+# define VIRTIO_DEV_CONFIG_LOG_ACCESS(member, tCfgStruct, uMbrOffset) do { } while (0)
+# define VIRTIO_DEV_CONFIG_LOG_INDEXED_ACCESS(member, tCfgStruct, uMbrOffset, uIdx) do { } while (0)
+#endif
+
+DECLINLINE(bool) virtioCoreMatchMember(uint32_t uOffset, uint32_t cb, uint32_t uMemberOff,
+                                       size_t uMemberSize, bool fSubFieldMatch)
+{
+    /* Test for 8-byte field (always accessed as two 32-bit components) */
+    if (uMemberSize == 8)
+        return (cb == sizeof(uint32_t)) && (uOffset == uMemberOff || uOffset == (uMemberOff + sizeof(uint32_t)));
+
+    if (fSubFieldMatch)
+        return (uOffset >= uMemberOff) && (cb <= uMemberSize - (uOffset - uMemberOff));
+
+    /* Test for exact match */
+    return (uOffset == uMemberOff) && (cb == uMemberSize);
+}
+
+/**
+ * Yields boolean true if uOffsetOfAccess falls within bytes of specified member of config struct
+ */
+#define VIRTIO_DEV_CONFIG_SUBMATCH_MEMBER(member, tCfgStruct, uOffsetOfAccess) \
+            virtioCoreMatchMember(uOffsetOfAccess, cb, \
+                                  RT_UOFFSETOF(tCfgStruct, member),  \
+                                  RT_SIZEOFMEMB(tCfgStruct, member), true /* fSubfieldMatch */)
+
+#define VIRTIO_DEV_CONFIG_MATCH_MEMBER(member, tCfgStruct, uOffsetOfAccess) \
+            virtioCoreMatchMember(uOffsetOfAccess, cb, \
+                                  RT_UOFFSETOF(tCfgStruct, member),  \
+                                  RT_SIZEOFMEMB(tCfgStruct, member), false /* fSubfieldMatch */)
+
+
+
+/**
+ * Copy reads or copy writes specified member field of config struct (based on fWrite),
+ * the memory described by cb and pv.
+ *
+ * cb, pv and fWrite are implicit parameters and must be defined by invoker.
+ */
+#define VIRTIO_DEV_CONFIG_ACCESS(member, tCfgStruct, uOffsetOfAccess, pCfgStruct) \
+    do \
+    { \
+        uint32_t uOffsetInMember = uOffsetOfAccess - RT_UOFFSETOF(tCfgStruct, member); \
+        if (fWrite) \
+            memcpy(((char *)&(pCfgStruct)->member) + uOffsetInMember, pv, cb); \
+        else \
+            memcpy(pv, ((const char *)&(pCfgStruct)->member) + uOffsetInMember, cb); \
+        VIRTIO_DEV_CONFIG_LOG_ACCESS(member, tCfgStruct, uOffsetOfAccess); \
+    } while(0)
+
+/**
+ * Copies bytes into memory described by cb, pv from the specified member field of the config struct.
+ * The operation is a NOP, logging an error if an implied parameter, fWrite, is boolean true.
+ *
+ * cb, pv and fWrite are implicit parameters and must be defined by the invoker.
+ */
+#define VIRTIO_DEV_CONFIG_ACCESS_READONLY(member, tCfgStruct, uOffsetOfAccess, pCfgStruct) \
+    do \
+    { \
+        uint32_t uOffsetInMember = uOffsetOfAccess - RT_UOFFSETOF(tCfgStruct, member); \
+        if (fWrite) \
+            LogFunc(("Guest attempted to write readonly virtio config struct (member %s)\n", #member)); \
+        else \
+        { \
+            memcpy(pv, ((const char *)&(pCfgStruct)->member) + uOffsetInMember, cb); \
+            VIRTIO_DEV_CONFIG_LOG_ACCESS(member, tCfgStruct, uOffsetOfAccess); \
+        } \
+    } while(0)
+
+/**
+ * Copies into or out of specified member field of config struct (based on fWrite),
+ * the memory described by cb and pv.
+ *
+ * cb, pv and fWrite are implicit parameters and must be defined by invoker.
+ */
+#define VIRTIO_DEV_CONFIG_ACCESS_INDEXED(member, uIdx, tCfgStruct, uOffsetOfAccess, pCfgStruct) \
+    do \
+    { \
+        uint32_t uOffsetInMember = uOffsetOfAccess - RT_UOFFSETOF(tCfgStruct, member); \
+        if (fWrite) \
+            memcpy(((char *)&(pCfgStruct[uIdx].member)) + uOffsetInMember, pv, cb); \
+        else \
+            memcpy(pv, ((const char *)&(pCfgStruct[uIdx].member)) + uOffsetInMember, cb); \
+        VIRTIO_DEV_CONFIG_LOG_INDEXED_ACCESS(member, tCfgStruct, uOffsetOfAccess, uIdx); \
+    } while(0)
+
+/**
+ * Copies bytes into memory described by cb, pv from the specified member field of the config struct.
+ * The operation is a nop and logs error if implied parameter fWrite is true.
+ *
+ * cb, pv and fWrite are implicit parameters and must be defined by invoker.
+ */
+#define VIRTIO_DEV_CONFIG_ACCESS_INDEXED_READONLY(member, uidx, tCfgStruct, uOffsetOfAccess, pCfgStruct) \
+    do \
+    { \
+        uint32_t uOffsetInMember = uOffsetOfAccess - RT_UOFFSETOF(tCfgStruct, member); \
+        if (fWrite) \
+            LogFunc(("Guest attempted to write readonly virtio config struct (member %s)\n", #member)); \
+        else \
+        { \
+            memcpy(pv, ((const char *)&(pCfgStruct[uIdx].member)) + uOffsetInMember, cb); \
+            VIRTIO_DEV_CONFIG_LOG_INDEXED_ACCESS(member, tCfgStruct, uOffsetOfAccess, uIdx); \
+        } \
+    } while(0)
+
+/** @} */
+
+/** @name API for VirtIO parent device
+ * @{ */
+
+#endif /* !VBOX_INCLUDED_SRC_VirtIO_VirtioCore_h */