Adding upstream version 6.1.76.upstream/6.1.76upstream

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

5 files changed, 396 insertions, 0 deletions

diff --git a/Documentation/virt/kvm/s390/index.rst b/Documentation/virt/kvm/s390/index.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+KVM for s390 systems
+====================
+
+.. toctree::
+   :maxdepth: 2
+
+   s390-diag
+   s390-pv
+   s390-pv-boot
+   s390-pv-dump
diff --git a/Documentation/virt/kvm/s390/s390-diag.rst b/Documentation/virt/kvm/s390/s390-diag.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+The s390 DIAGNOSE call on KVM
+=============================
+
+KVM on s390 supports the DIAGNOSE call for making hypercalls, both for
+native hypercalls and for selected hypercalls found on other s390
+hypervisors.
+
+Note that bits are numbered as by the usual s390 convention (most significant
+bit on the left).
+
+
+General remarks
+---------------
+
+DIAGNOSE calls by the guest cause a mandatory intercept. This implies
+all supported DIAGNOSE calls need to be handled by either KVM or its
+userspace.
+
+All DIAGNOSE calls supported by KVM use the RS-a format::
+
+  --------------------------------------
+  |  '83'  | R1 | R3 | B2 |     D2     |
+  --------------------------------------
+  0        8    12   16   20           31
+
+The second-operand address (obtained by the base/displacement calculation)
+is not used to address data. Instead, bits 48-63 of this address specify
+the function code, and bits 0-47 are ignored.
+
+The supported DIAGNOSE function codes vary by the userspace used. For
+DIAGNOSE function codes not specific to KVM, please refer to the
+documentation for the s390 hypervisors defining them.
+
+
+DIAGNOSE function code 'X'500' - KVM virtio functions
+-----------------------------------------------------
+
+If the function code specifies 0x500, various virtio-related functions
+are performed.
+
+General register 1 contains the virtio subfunction code. Supported
+virtio subfunctions depend on KVM's userspace. Generally, userspace
+provides either s390-virtio (subcodes 0-2) or virtio-ccw (subcode 3).
+
+Upon completion of the DIAGNOSE instruction, general register 2 contains
+the function's return code, which is either a return code or a subcode
+specific value.
+
+Subcode 0 - s390-virtio notification and early console printk
+    Handled by userspace.
+
+Subcode 1 - s390-virtio reset
+    Handled by userspace.
+
+Subcode 2 - s390-virtio set status
+    Handled by userspace.
+
+Subcode 3 - virtio-ccw notification
+    Handled by either userspace or KVM (ioeventfd case).
+
+    General register 2 contains a subchannel-identification word denoting
+    the subchannel of the virtio-ccw proxy device to be notified.
+
+    General register 3 contains the number of the virtqueue to be notified.
+
+    General register 4 contains a 64bit identifier for KVM usage (the
+    kvm_io_bus cookie). If general register 4 does not contain a valid
+    identifier, it is ignored.
+
+    After completion of the DIAGNOSE call, general register 2 may contain
+    a 64bit identifier (in the kvm_io_bus cookie case), or a negative
+    error value, if an internal error occurred.
+
+    See also the virtio standard for a discussion of this hypercall.
+
+
+DIAGNOSE function code 'X'501 - KVM breakpoint
+----------------------------------------------
+
+If the function code specifies 0x501, breakpoint functions may be performed.
+This function code is handled by userspace.
+
+This diagnose function code has no subfunctions and uses no parameters.
+
+
+DIAGNOSE function code 'X'9C - Voluntary Time Slice Yield
+---------------------------------------------------------
+
+General register 1 contains the target CPU address.
+
+In a guest of a hypervisor like LPAR, KVM or z/VM using shared host CPUs,
+DIAGNOSE with function code 0x9c may improve system performance by
+yielding the host CPU on which the guest CPU is running to be assigned
+to another guest CPU, preferably the logical CPU containing the specified
+target CPU.
+
+
+DIAG 'X'9C forwarding
++++++++++++++++++++++
+
+The guest may send a DIAGNOSE 0x9c in order to yield to a certain
+other vcpu. An example is a Linux guest that tries to yield to the vcpu
+that is currently holding a spinlock, but not running.
+
+However, on the host the real cpu backing the vcpu may itself not be
+running.
+Forwarding the DIAGNOSE 0x9c initially sent by the guest to yield to
+the backing cpu will hopefully cause that cpu, and thus subsequently
+the guest's vcpu, to be scheduled.
+
+
+diag9c_forwarding_hz
+    KVM kernel parameter allowing to specify the maximum number of DIAGNOSE
+    0x9c forwarding per second in the purpose of avoiding a DIAGNOSE 0x9c
+    forwarding storm.
+    A value of 0 turns the forwarding off.
diff --git a/Documentation/virt/kvm/s390/s390-pv-boot.rst b/Documentation/virt/kvm/s390/s390-pv-boot.rst
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index 000000000..96c48480a
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+.. SPDX-License-Identifier: GPL-2.0
+
+======================================
+s390 (IBM Z) Boot/IPL of Protected VMs
+======================================
+
+Summary
+-------
+The memory of Protected Virtual Machines (PVMs) is not accessible to
+I/O or the hypervisor. In those cases where the hypervisor needs to
+access the memory of a PVM, that memory must be made accessible.
+Memory made accessible to the hypervisor will be encrypted. See
+Documentation/virt/kvm/s390/s390-pv.rst for details."
+
+On IPL (boot) a small plaintext bootloader is started, which provides
+information about the encrypted components and necessary metadata to
+KVM to decrypt the protected virtual machine.
+
+Based on this data, KVM will make the protected virtual machine known
+to the Ultravisor (UV) and instruct it to secure the memory of the
+PVM, decrypt the components and verify the data and address list
+hashes, to ensure integrity. Afterwards KVM can run the PVM via the
+SIE instruction which the UV will intercept and execute on KVM's
+behalf.
+
+As the guest image is just like an opaque kernel image that does the
+switch into PV mode itself, the user can load encrypted guest
+executables and data via every available method (network, dasd, scsi,
+direct kernel, ...) without the need to change the boot process.
+
+
+Diag308
+-------
+This diagnose instruction is the basic mechanism to handle IPL and
+related operations for virtual machines. The VM can set and retrieve
+IPL information blocks, that specify the IPL method/devices and
+request VM memory and subsystem resets, as well as IPLs.
+
+For PVMs this concept has been extended with new subcodes:
+
+Subcode 8: Set an IPL Information Block of type 5 (information block
+for PVMs)
+Subcode 9: Store the saved block in guest memory
+Subcode 10: Move into Protected Virtualization mode
+
+The new PV load-device-specific-parameters field specifies all data
+that is necessary to move into PV mode.
+
+* PV Header origin
+* PV Header length
+* List of Components composed of
+   * AES-XTS Tweak prefix
+   * Origin
+   * Size
+
+The PV header contains the keys and hashes, which the UV will use to
+decrypt and verify the PV, as well as control flags and a start PSW.
+
+The components are for instance an encrypted kernel, kernel parameters
+and initrd. The components are decrypted by the UV.
+
+After the initial import of the encrypted data, all defined pages will
+contain the guest content. All non-specified pages will start out as
+zero pages on first access.
+
+
+When running in protected virtualization mode, some subcodes will result in
+exceptions or return error codes.
+
+Subcodes 4 and 7, which specify operations that do not clear the guest
+memory, will result in specification exceptions. This is because the
+UV will clear all memory when a secure VM is removed, and therefore
+non-clearing IPL subcodes are not allowed.
+
+Subcodes 8, 9, 10 will result in specification exceptions.
+Re-IPL into a protected mode is only possible via a detour into non
+protected mode.
+
+Keys
+----
+Every CEC will have a unique public key to enable tooling to build
+encrypted images.
+See  `s390-tools <https://github.com/ibm-s390-linux/s390-tools/>`_
+for the tooling.
diff --git a/Documentation/virt/kvm/s390/s390-pv-dump.rst b/Documentation/virt/kvm/s390/s390-pv-dump.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+===========================================
+s390 (IBM Z) Protected Virtualization dumps
+===========================================
+
+Summary
+-------
+
+Dumping a VM is an essential tool for debugging problems inside
+it. This is especially true when a protected VM runs into trouble as
+there's no way to access its memory and registers from the outside
+while it's running.
+
+However when dumping a protected VM we need to maintain its
+confidentiality until the dump is in the hands of the VM owner who
+should be the only one capable of analysing it.
+
+The confidentiality of the VM dump is ensured by the Ultravisor who
+provides an interface to KVM over which encrypted CPU and memory data
+can be requested. The encryption is based on the Customer
+Communication Key which is the key that's used to encrypt VM data in a
+way that the customer is able to decrypt.
+
+
+Dump process
+------------
+
+A dump is done in 3 steps:
+
+**Initiation**
+
+This step initializes the dump process, generates cryptographic seeds
+and extracts dump keys with which the VM dump data will be encrypted.
+
+**Data gathering**
+
+Currently there are two types of data that can be gathered from a VM:
+the memory and the vcpu state.
+
+The vcpu state contains all the important registers, general, floating
+point, vector, control and tod/timers of a vcpu. The vcpu dump can
+contain incomplete data if a vcpu is dumped while an instruction is
+emulated with help of the hypervisor. This is indicated by a flag bit
+in the dump data. For the same reason it is very important to not only
+write out the encrypted vcpu state, but also the unencrypted state
+from the hypervisor.
+
+The memory state is further divided into the encrypted memory and its
+metadata comprised of the encryption tweaks and status flags. The
+encrypted memory can simply be read once it has been exported. The
+time of the export does not matter as no re-encryption is
+needed. Memory that has been swapped out and hence was exported can be
+read from the swap and written to the dump target without need for any
+special actions.
+
+The tweaks / status flags for the exported pages need to be requested
+from the Ultravisor.
+
+**Finalization**
+
+The finalization step will provide the data needed to be able to
+decrypt the vcpu and memory data and end the dump process. When this
+step completes successfully a new dump initiation can be started.
diff --git a/Documentation/virt/kvm/s390/s390-pv.rst b/Documentation/virt/kvm/s390/s390-pv.rst
new file mode 100644
index 000000000..8e41a3b63
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+.. SPDX-License-Identifier: GPL-2.0
+
+=========================================
+s390 (IBM Z) Ultravisor and Protected VMs
+=========================================
+
+Summary
+-------
+Protected virtual machines (PVM) are KVM VMs that do not allow KVM to
+access VM state like guest memory or guest registers. Instead, the
+PVMs are mostly managed by a new entity called Ultravisor (UV). The UV
+provides an API that can be used by PVMs and KVM to request management
+actions.
+
+Each guest starts in non-protected mode and then may make a request to
+transition into protected mode. On transition, KVM registers the guest
+and its VCPUs with the Ultravisor and prepares everything for running
+it.
+
+The Ultravisor will secure and decrypt the guest's boot memory
+(i.e. kernel/initrd). It will safeguard state changes like VCPU
+starts/stops and injected interrupts while the guest is running.
+
+As access to the guest's state, such as the SIE state description, is
+normally needed to be able to run a VM, some changes have been made in
+the behavior of the SIE instruction. A new format 4 state description
+has been introduced, where some fields have different meanings for a
+PVM. SIE exits are minimized as much as possible to improve speed and
+reduce exposed guest state.
+
+
+Interrupt injection
+-------------------
+Interrupt injection is safeguarded by the Ultravisor. As KVM doesn't
+have access to the VCPUs' lowcores, injection is handled via the
+format 4 state description.
+
+Machine check, external, IO and restart interruptions each can be
+injected on SIE entry via a bit in the interrupt injection control
+field (offset 0x54). If the guest cpu is not enabled for the interrupt
+at the time of injection, a validity interception is recognized. The
+format 4 state description contains fields in the interception data
+block where data associated with the interrupt can be transported.
+
+Program and Service Call exceptions have another layer of
+safeguarding; they can only be injected for instructions that have
+been intercepted into KVM. The exceptions need to be a valid outcome
+of an instruction emulation by KVM, e.g. we can never inject a
+addressing exception as they are reported by SIE since KVM has no
+access to the guest memory.
+
+
+Mask notification interceptions
+-------------------------------
+KVM cannot intercept lctl(g) and lpsw(e) anymore in order to be
+notified when a PVM enables a certain class of interrupt.  As a
+replacement, two new interception codes have been introduced: One
+indicating that the contents of CRs 0, 6, or 14 have been changed,
+indicating different interruption subclasses; and one indicating that
+PSW bit 13 has been changed, indicating that a machine check
+intervention was requested and those are now enabled.
+
+Instruction emulation
+---------------------
+With the format 4 state description for PVMs, the SIE instruction already
+interprets more instructions than it does with format 2. It is not able
+to interpret every instruction, but needs to hand some tasks to KVM;
+therefore, the SIE and the ultravisor safeguard emulation inputs and outputs.
+
+The control structures associated with SIE provide the Secure
+Instruction Data Area (SIDA), the Interception Parameters (IP) and the
+Secure Interception General Register Save Area.  Guest GRs and most of
+the instruction data, such as I/O data structures, are filtered.
+Instruction data is copied to and from the SIDA when needed.  Guest
+GRs are put into / retrieved from the Secure Interception General
+Register Save Area.
+
+Only GR values needed to emulate an instruction will be copied into this
+save area and the real register numbers will be hidden.
+
+The Interception Parameters state description field still contains
+the bytes of the instruction text, but with pre-set register values
+instead of the actual ones. I.e. each instruction always uses the same
+instruction text, in order not to leak guest instruction text.
+This also implies that the register content that a guest had in r<n>
+may be in r<m> from the hypervisor's point of view.
+
+The Secure Instruction Data Area contains instruction storage
+data. Instruction data, i.e. data being referenced by an instruction
+like the SCCB for sclp, is moved via the SIDA. When an instruction is
+intercepted, the SIE will only allow data and program interrupts for
+this instruction to be moved to the guest via the two data areas
+discussed before. Other data is either ignored or results in validity
+interceptions.
+
+
+Instruction emulation interceptions
+-----------------------------------
+There are two types of SIE secure instruction intercepts: the normal
+and the notification type. Normal secure instruction intercepts will
+make the guest pending for instruction completion of the intercepted
+instruction type, i.e. on SIE entry it is attempted to complete
+emulation of the instruction with the data provided by KVM. That might
+be a program exception or instruction completion.
+
+The notification type intercepts inform KVM about guest environment
+changes due to guest instruction interpretation. Such an interception
+is recognized, for example, for the store prefix instruction to provide
+the new lowcore location. On SIE reentry, any KVM data in the data areas
+is ignored and execution continues as if the guest instruction had
+completed. For that reason KVM is not allowed to inject a program
+interrupt.
+
+Links
+-----
+`KVM Forum 2019 presentation <https://static.sched.com/hosted_files/kvmforum2019/3b/ibm_protected_vms_s390x.pdf>`_