diff options
Diffstat (limited to 'drivers/pci/vgaarb.c')
| -rw-r--r-- | drivers/pci/vgaarb.c | 1559 |
1 files changed, 1559 insertions, 0 deletions
diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c new file mode 100644 index 0000000000..5e6b1eb54c --- /dev/null +++ b/drivers/pci/vgaarb.c @@ -0,0 +1,1559 @@ +// SPDX-License-Identifier: MIT +/* + * vgaarb.c: Implements VGA arbitration. For details refer to + * Documentation/gpu/vgaarbiter.rst + * + * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org> + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com> + * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org> + */ + +#define pr_fmt(fmt) "vgaarb: " fmt + +#define vgaarb_dbg(dev, fmt, arg...) dev_dbg(dev, "vgaarb: " fmt, ##arg) +#define vgaarb_info(dev, fmt, arg...) dev_info(dev, "vgaarb: " fmt, ##arg) +#define vgaarb_err(dev, fmt, arg...) dev_err(dev, "vgaarb: " fmt, ##arg) + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/pci.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/list.h> +#include <linux/sched/signal.h> +#include <linux/wait.h> +#include <linux/spinlock.h> +#include <linux/poll.h> +#include <linux/miscdevice.h> +#include <linux/slab.h> +#include <linux/screen_info.h> +#include <linux/vt.h> +#include <linux/console.h> +#include <linux/acpi.h> +#include <linux/uaccess.h> +#include <linux/vgaarb.h> + +static void vga_arbiter_notify_clients(void); + +/* + * We keep a list of all VGA devices in the system to speed + * up the various operations of the arbiter + */ +struct vga_device { + struct list_head list; + struct pci_dev *pdev; + unsigned int decodes; /* what it decodes */ + unsigned int owns; /* what it owns */ + unsigned int locks; /* what it locks */ + unsigned int io_lock_cnt; /* legacy IO lock count */ + unsigned int mem_lock_cnt; /* legacy MEM lock count */ + unsigned int io_norm_cnt; /* normal IO count */ + unsigned int mem_norm_cnt; /* normal MEM count */ + bool bridge_has_one_vga; + bool is_firmware_default; /* device selected by firmware */ + unsigned int (*set_decode)(struct pci_dev *pdev, bool decode); +}; + +static LIST_HEAD(vga_list); +static int vga_count, vga_decode_count; +static bool vga_arbiter_used; +static DEFINE_SPINLOCK(vga_lock); +static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue); + +static const char *vga_iostate_to_str(unsigned int iostate) +{ + /* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */ + iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM; + switch (iostate) { + case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM: + return "io+mem"; + case VGA_RSRC_LEGACY_IO: + return "io"; + case VGA_RSRC_LEGACY_MEM: + return "mem"; + } + return "none"; +} + +static int vga_str_to_iostate(char *buf, int str_size, unsigned int *io_state) +{ + /* + * In theory, we could hand out locks on IO and MEM separately to + * userspace, but this can cause deadlocks. + */ + if (strncmp(buf, "none", 4) == 0) { + *io_state = VGA_RSRC_NONE; + return 1; + } + + /* XXX We're not checking the str_size! */ + if (strncmp(buf, "io+mem", 6) == 0) + goto both; + else if (strncmp(buf, "io", 2) == 0) + goto both; + else if (strncmp(buf, "mem", 3) == 0) + goto both; + return 0; +both: + *io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM; + return 1; +} + +/* This is only used as a cookie, it should not be dereferenced */ +static struct pci_dev *vga_default; + +/* Find somebody in our list */ +static struct vga_device *vgadev_find(struct pci_dev *pdev) +{ + struct vga_device *vgadev; + + list_for_each_entry(vgadev, &vga_list, list) + if (pdev == vgadev->pdev) + return vgadev; + return NULL; +} + +/** + * vga_default_device - return the default VGA device, for vgacon + * + * This can be defined by the platform. The default implementation is + * rather dumb and will probably only work properly on single VGA card + * setups and/or x86 platforms. + * + * If your VGA default device is not PCI, you'll have to return NULL here. + * In this case, I assume it will not conflict with any PCI card. If this + * is not true, I'll have to define two arch hooks for enabling/disabling + * the VGA default device if that is possible. This may be a problem with + * real _ISA_ VGA cards, in addition to a PCI one. I don't know at this + * point how to deal with that card. Can their IOs be disabled at all? If + * not, then I suppose it's a matter of having the proper arch hook telling + * us about it, so we basically never allow anybody to succeed a vga_get(). + */ +struct pci_dev *vga_default_device(void) +{ + return vga_default; +} +EXPORT_SYMBOL_GPL(vga_default_device); + +void vga_set_default_device(struct pci_dev *pdev) +{ + if (vga_default == pdev) + return; + + pci_dev_put(vga_default); + vga_default = pci_dev_get(pdev); +} + +/** + * vga_remove_vgacon - deactivate VGA console + * + * Unbind and unregister vgacon in case pdev is the default VGA device. + * Can be called by GPU drivers on initialization to make sure VGA register + * access done by vgacon will not disturb the device. + * + * @pdev: PCI device. + */ +#if !defined(CONFIG_VGA_CONSOLE) +int vga_remove_vgacon(struct pci_dev *pdev) +{ + return 0; +} +#elif !defined(CONFIG_DUMMY_CONSOLE) +int vga_remove_vgacon(struct pci_dev *pdev) +{ + return -ENODEV; +} +#else +int vga_remove_vgacon(struct pci_dev *pdev) +{ + int ret = 0; + + if (pdev != vga_default) + return 0; + vgaarb_info(&pdev->dev, "deactivate vga console\n"); + + console_lock(); + if (con_is_bound(&vga_con)) + ret = do_take_over_console(&dummy_con, 0, + MAX_NR_CONSOLES - 1, 1); + if (ret == 0) { + ret = do_unregister_con_driver(&vga_con); + + /* Ignore "already unregistered". */ + if (ret == -ENODEV) + ret = 0; + } + console_unlock(); + + return ret; +} +#endif +EXPORT_SYMBOL(vga_remove_vgacon); + +/* + * If we don't ever use VGA arbitration, we should avoid turning off + * anything anywhere due to old X servers getting confused about the boot + * device not being VGA. + */ +static void vga_check_first_use(void) +{ + /* + * Inform all GPUs in the system that VGA arbitration has occurred + * so they can disable resources if possible. + */ + if (!vga_arbiter_used) { + vga_arbiter_used = true; + vga_arbiter_notify_clients(); + } +} + +static struct vga_device *__vga_tryget(struct vga_device *vgadev, + unsigned int rsrc) +{ + struct device *dev = &vgadev->pdev->dev; + unsigned int wants, legacy_wants, match; + struct vga_device *conflict; + unsigned int pci_bits; + u32 flags = 0; + + /* + * Account for "normal" resources to lock. If we decode the legacy, + * counterpart, we need to request it as well + */ + if ((rsrc & VGA_RSRC_NORMAL_IO) && + (vgadev->decodes & VGA_RSRC_LEGACY_IO)) + rsrc |= VGA_RSRC_LEGACY_IO; + if ((rsrc & VGA_RSRC_NORMAL_MEM) && + (vgadev->decodes & VGA_RSRC_LEGACY_MEM)) + rsrc |= VGA_RSRC_LEGACY_MEM; + + vgaarb_dbg(dev, "%s: %d\n", __func__, rsrc); + vgaarb_dbg(dev, "%s: owns: %d\n", __func__, vgadev->owns); + + /* Check what resources we need to acquire */ + wants = rsrc & ~vgadev->owns; + + /* We already own everything, just mark locked & bye bye */ + if (wants == 0) + goto lock_them; + + /* + * We don't need to request a legacy resource, we just enable + * appropriate decoding and go. + */ + legacy_wants = wants & VGA_RSRC_LEGACY_MASK; + if (legacy_wants == 0) + goto enable_them; + + /* Ok, we don't, let's find out who we need to kick off */ + list_for_each_entry(conflict, &vga_list, list) { + unsigned int lwants = legacy_wants; + unsigned int change_bridge = 0; + + /* Don't conflict with myself */ + if (vgadev == conflict) + continue; + + /* + * We have a possible conflict. Before we go further, we must + * check if we sit on the same bus as the conflicting device. + * If we don't, then we must tie both IO and MEM resources + * together since there is only a single bit controlling + * VGA forwarding on P2P bridges. + */ + if (vgadev->pdev->bus != conflict->pdev->bus) { + change_bridge = 1; + lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM; + } + + /* + * Check if the guy has a lock on the resource. If he does, + * return the conflicting entry. + */ + if (conflict->locks & lwants) + return conflict; + + /* + * Ok, now check if it owns the resource we want. We can + * lock resources that are not decoded; therefore a device + * can own resources it doesn't decode. + */ + match = lwants & conflict->owns; + if (!match) + continue; + + /* + * Looks like he doesn't have a lock, we can steal them + * from him. + */ + + flags = 0; + pci_bits = 0; + + /* + * If we can't control legacy resources via the bridge, we + * also need to disable normal decoding. + */ + if (!conflict->bridge_has_one_vga) { + if ((match & conflict->decodes) & VGA_RSRC_LEGACY_MEM) + pci_bits |= PCI_COMMAND_MEMORY; + if ((match & conflict->decodes) & VGA_RSRC_LEGACY_IO) + pci_bits |= PCI_COMMAND_IO; + + if (pci_bits) + flags |= PCI_VGA_STATE_CHANGE_DECODES; + } + + if (change_bridge) + flags |= PCI_VGA_STATE_CHANGE_BRIDGE; + + pci_set_vga_state(conflict->pdev, false, pci_bits, flags); + conflict->owns &= ~match; + + /* If we disabled normal decoding, reflect it in owns */ + if (pci_bits & PCI_COMMAND_MEMORY) + conflict->owns &= ~VGA_RSRC_NORMAL_MEM; + if (pci_bits & PCI_COMMAND_IO) + conflict->owns &= ~VGA_RSRC_NORMAL_IO; + } + +enable_them: + /* + * Ok, we got it, everybody conflicting has been disabled, let's + * enable us. Mark any bits in "owns" regardless of whether we + * decoded them. We can lock resources we don't decode, therefore + * we must track them via "owns". + */ + flags = 0; + pci_bits = 0; + + if (!vgadev->bridge_has_one_vga) { + flags |= PCI_VGA_STATE_CHANGE_DECODES; + if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM)) + pci_bits |= PCI_COMMAND_MEMORY; + if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO)) + pci_bits |= PCI_COMMAND_IO; + } + if (wants & VGA_RSRC_LEGACY_MASK) + flags |= PCI_VGA_STATE_CHANGE_BRIDGE; + + pci_set_vga_state(vgadev->pdev, true, pci_bits, flags); + + vgadev->owns |= wants; +lock_them: + vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK); + if (rsrc & VGA_RSRC_LEGACY_IO) + vgadev->io_lock_cnt++; + if (rsrc & VGA_RSRC_LEGACY_MEM) + vgadev->mem_lock_cnt++; + if (rsrc & VGA_RSRC_NORMAL_IO) + vgadev->io_norm_cnt++; + if (rsrc & VGA_RSRC_NORMAL_MEM) + vgadev->mem_norm_cnt++; + + return NULL; +} + +static void __vga_put(struct vga_device *vgadev, unsigned int rsrc) +{ + struct device *dev = &vgadev->pdev->dev; + unsigned int old_locks = vgadev->locks; + + vgaarb_dbg(dev, "%s\n", __func__); + + /* + * Update our counters and account for equivalent legacy resources + * if we decode them. + */ + if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) { + vgadev->io_norm_cnt--; + if (vgadev->decodes & VGA_RSRC_LEGACY_IO) + rsrc |= VGA_RSRC_LEGACY_IO; + } + if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) { + vgadev->mem_norm_cnt--; + if (vgadev->decodes & VGA_RSRC_LEGACY_MEM) + rsrc |= VGA_RSRC_LEGACY_MEM; + } + if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0) + vgadev->io_lock_cnt--; + if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0) + vgadev->mem_lock_cnt--; + + /* + * Just clear lock bits, we do lazy operations so we don't really + * have to bother about anything else at this point. + */ + if (vgadev->io_lock_cnt == 0) + vgadev->locks &= ~VGA_RSRC_LEGACY_IO; + if (vgadev->mem_lock_cnt == 0) + vgadev->locks &= ~VGA_RSRC_LEGACY_MEM; + + /* + * Kick the wait queue in case somebody was waiting if we actually + * released something. + */ + if (old_locks != vgadev->locks) + wake_up_all(&vga_wait_queue); +} + +/** + * vga_get - acquire & lock VGA resources + * @pdev: PCI device of the VGA card or NULL for the system default + * @rsrc: bit mask of resources to acquire and lock + * @interruptible: blocking should be interruptible by signals ? + * + * Acquire VGA resources for the given card and mark those resources + * locked. If the resources requested are "normal" (and not legacy) + * resources, the arbiter will first check whether the card is doing legacy + * decoding for that type of resource. If yes, the lock is "converted" into + * a legacy resource lock. + * + * The arbiter will first look for all VGA cards that might conflict and disable + * their IOs and/or Memory access, including VGA forwarding on P2P bridges if + * necessary, so that the requested resources can be used. Then, the card is + * marked as locking these resources and the IO and/or Memory accesses are + * enabled on the card (including VGA forwarding on parent P2P bridges if any). + * + * This function will block if some conflicting card is already locking one of + * the required resources (or any resource on a different bus segment, since P2P + * bridges don't differentiate VGA memory and IO afaik). You can indicate + * whether this blocking should be interruptible by a signal (for userland + * interface) or not. + * + * Must not be called at interrupt time or in atomic context. If the card + * already owns the resources, the function succeeds. Nested calls are + * supported (a per-resource counter is maintained) + * + * On success, release the VGA resource again with vga_put(). + * + * Returns: + * + * 0 on success, negative error code on failure. + */ +int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible) +{ + struct vga_device *vgadev, *conflict; + unsigned long flags; + wait_queue_entry_t wait; + int rc = 0; + + vga_check_first_use(); + /* The caller should check for this, but let's be sure */ + if (pdev == NULL) + pdev = vga_default_device(); + if (pdev == NULL) + return 0; + + for (;;) { + spin_lock_irqsave(&vga_lock, flags); + vgadev = vgadev_find(pdev); + if (vgadev == NULL) { + spin_unlock_irqrestore(&vga_lock, flags); + rc = -ENODEV; + break; + } + conflict = __vga_tryget(vgadev, rsrc); + spin_unlock_irqrestore(&vga_lock, flags); + if (conflict == NULL) + break; + + /* + * We have a conflict; we wait until somebody kicks the + * work queue. Currently we have one work queue that we + * kick each time some resources are released, but it would + * be fairly easy to have a per-device one so that we only + * need to attach to the conflicting device. + */ + init_waitqueue_entry(&wait, current); + add_wait_queue(&vga_wait_queue, &wait); + set_current_state(interruptible ? + TASK_INTERRUPTIBLE : + TASK_UNINTERRUPTIBLE); + if (interruptible && signal_pending(current)) { + __set_current_state(TASK_RUNNING); + remove_wait_queue(&vga_wait_queue, &wait); + rc = -ERESTARTSYS; + break; + } + schedule(); + remove_wait_queue(&vga_wait_queue, &wait); + } + return rc; +} +EXPORT_SYMBOL(vga_get); + +/** + * vga_tryget - try to acquire & lock legacy VGA resources + * @pdev: PCI device of VGA card or NULL for system default + * @rsrc: bit mask of resources to acquire and lock + * + * Perform the same operation as vga_get(), but return an error (-EBUSY) + * instead of blocking if the resources are already locked by another card. + * Can be called in any context. + * + * On success, release the VGA resource again with vga_put(). + * + * Returns: + * + * 0 on success, negative error code on failure. + */ +static int vga_tryget(struct pci_dev *pdev, unsigned int rsrc) +{ + struct vga_device *vgadev; + unsigned long flags; + int rc = 0; + + vga_check_first_use(); + + /* The caller should check for this, but let's be sure */ + if (pdev == NULL) + pdev = vga_default_device(); + if (pdev == NULL) + return 0; + spin_lock_irqsave(&vga_lock, flags); + vgadev = vgadev_find(pdev); + if (vgadev == NULL) { + rc = -ENODEV; + goto bail; + } + if (__vga_tryget(vgadev, rsrc)) + rc = -EBUSY; +bail: + spin_unlock_irqrestore(&vga_lock, flags); + return rc; +} + +/** + * vga_put - release lock on legacy VGA resources + * @pdev: PCI device of VGA card or NULL for system default + * @rsrc: bit mask of resource to release + * + * Release resources previously locked by vga_get() or vga_tryget(). The + * resources aren't disabled right away, so that a subsequent vga_get() on + * the same card will succeed immediately. Resources have a counter, so + * locks are only released if the counter reaches 0. + */ +void vga_put(struct pci_dev *pdev, unsigned int rsrc) +{ + struct vga_device *vgadev; + unsigned long flags; + + /* The caller should check for this, but let's be sure */ + if (pdev == NULL) + pdev = vga_default_device(); + if (pdev == NULL) + return; + spin_lock_irqsave(&vga_lock, flags); + vgadev = vgadev_find(pdev); + if (vgadev == NULL) + goto bail; + __vga_put(vgadev, rsrc); +bail: + spin_unlock_irqrestore(&vga_lock, flags); +} +EXPORT_SYMBOL(vga_put); + +static bool vga_is_firmware_default(struct pci_dev *pdev) +{ +#if defined(CONFIG_X86) || defined(CONFIG_IA64) + u64 base = screen_info.lfb_base; + u64 size = screen_info.lfb_size; + struct resource *r; + u64 limit; + + /* Select the device owning the boot framebuffer if there is one */ + + if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE) + base |= (u64)screen_info.ext_lfb_base << 32; + + limit = base + size; + + /* Does firmware framebuffer belong to us? */ + pci_dev_for_each_resource(pdev, r) { + if (resource_type(r) != IORESOURCE_MEM) + continue; + + if (!r->start || !r->end) + continue; + + if (base < r->start || limit >= r->end) + continue; + + return true; + } +#endif + return false; +} + +static bool vga_arb_integrated_gpu(struct device *dev) +{ +#if defined(CONFIG_ACPI) + struct acpi_device *adev = ACPI_COMPANION(dev); + + return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID); +#else + return false; +#endif +} + +/* + * Return true if vgadev is a better default VGA device than the best one + * we've seen so far. + */ +static bool vga_is_boot_device(struct vga_device *vgadev) +{ + struct vga_device *boot_vga = vgadev_find(vga_default_device()); + struct pci_dev *pdev = vgadev->pdev; + u16 cmd, boot_cmd; + + /* + * We select the default VGA device in this order: + * Firmware framebuffer (see vga_arb_select_default_device()) + * Legacy VGA device (owns VGA_RSRC_LEGACY_MASK) + * Non-legacy integrated device (see vga_arb_select_default_device()) + * Non-legacy discrete device (see vga_arb_select_default_device()) + * Other device (see vga_arb_select_default_device()) + */ + + /* + * We always prefer a firmware default device, so if we've already + * found one, there's no need to consider vgadev. + */ + if (boot_vga && boot_vga->is_firmware_default) + return false; + + if (vga_is_firmware_default(pdev)) { + vgadev->is_firmware_default = true; + return true; + } + + /* + * A legacy VGA device has MEM and IO enabled and any bridges + * leading to it have PCI_BRIDGE_CTL_VGA enabled so the legacy + * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are + * routed to it. + * + * We use the first one we find, so if we've already found one, + * vgadev is no better. + */ + if (boot_vga && + (boot_vga->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK) + return false; + + if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK) + return true; + + /* + * If we haven't found a legacy VGA device, accept a non-legacy + * device. It may have either IO or MEM enabled, and bridges may + * not have PCI_BRIDGE_CTL_VGA enabled, so it may not be able to + * use legacy VGA resources. Prefer an integrated GPU over others. + */ + pci_read_config_word(pdev, PCI_COMMAND, &cmd); + if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) { + + /* + * An integrated GPU overrides a previous non-legacy + * device. We expect only a single integrated GPU, but if + * there are more, we use the *last* because that was the + * previous behavior. + */ + if (vga_arb_integrated_gpu(&pdev->dev)) + return true; + + /* + * We prefer the first non-legacy discrete device we find. + * If we already found one, vgadev is no better. + */ + if (boot_vga) { + pci_read_config_word(boot_vga->pdev, PCI_COMMAND, + &boot_cmd); + if (boot_cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) + return false; + } + return true; + } + + /* + * Vgadev has neither IO nor MEM enabled. If we haven't found any + * other VGA devices, it is the best candidate so far. + */ + if (!boot_vga) + return true; + + return false; +} + +/* + * Rules for using a bridge to control a VGA descendant decoding: if a bridge + * has only one VGA descendant then it can be used to control the VGA routing + * for that device. It should always use the bridge closest to the device to + * control it. If a bridge has a direct VGA descendant, but also have a sub- + * bridge VGA descendant then we cannot use that bridge to control the direct + * VGA descendant. So for every device we register, we need to iterate all + * its parent bridges so we can invalidate any devices using them properly. + */ +static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev) +{ + struct vga_device *same_bridge_vgadev; + struct pci_bus *new_bus, *bus; + struct pci_dev *new_bridge, *bridge; + + vgadev->bridge_has_one_vga = true; + + if (list_empty(&vga_list)) { + vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n"); + return; + } + + /* Iterate the new device's bridge hierarchy */ + new_bus = vgadev->pdev->bus; + while (new_bus) { + new_bridge = new_bus->self; + + /* Go through list of devices already registered */ + list_for_each_entry(same_bridge_vgadev, &vga_list, list) { + bus = same_bridge_vgadev->pdev->bus; + bridge = bus->self; + + /* See if it shares a bridge with this device */ + if (new_bridge == bridge) { + /* + * If its direct parent bridge is the same + * as any bridge of this device then it can't + * be used for that device. + */ + same_bridge_vgadev->bridge_has_one_vga = false; + } + + /* + * Now iterate the previous device's bridge hierarchy. + * If the new device's parent bridge is in the other + * device's hierarchy, we can't use it to control this + * device. + */ + while (bus) { + bridge = bus->self; + + if (bridge && bridge == vgadev->pdev->bus->self) + vgadev->bridge_has_one_vga = false; + + bus = bus->parent; + } + } + new_bus = new_bus->parent; + } + + if (vgadev->bridge_has_one_vga) + vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n"); + else + vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n"); +} + +/* + * Currently, we assume that the "initial" setup of the system is not sane, + * that is, we come up with conflicting devices and let the arbiter's + * client decide if devices decodes legacy things or not. + */ +static bool vga_arbiter_add_pci_device(struct pci_dev *pdev) +{ + struct vga_device *vgadev; + unsigned long flags; + struct pci_bus *bus; + struct pci_dev *bridge; + u16 cmd; + + /* Only deal with VGA class devices */ + if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA) + return false; + + /* Allocate structure */ + vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL); + if (vgadev == NULL) { + vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n"); + /* + * What to do on allocation failure? For now, let's just do + * nothing, I'm not sure there is anything saner to be done. + */ + return false; + } + + /* Take lock & check for duplicates */ + spin_lock_irqsave(&vga_lock, flags); + if (vgadev_find(pdev) != NULL) { + BUG_ON(1); + goto fail; + } + vgadev->pdev = pdev; + + /* By default, assume we decode everything */ + vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM | + VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM; + + /* By default, mark it as decoding */ + vga_decode_count++; + + /* + * Mark that we "own" resources based on our enables, we will + * clear that below if the bridge isn't forwarding. + */ + pci_read_config_word(pdev, PCI_COMMAND, &cmd); + if (cmd & PCI_COMMAND_IO) + vgadev->owns |= VGA_RSRC_LEGACY_IO; + if (cmd & PCI_COMMAND_MEMORY) + vgadev->owns |= VGA_RSRC_LEGACY_MEM; + + /* Check if VGA cycles can get down to us */ + bus = pdev->bus; + while (bus) { + bridge = bus->self; + if (bridge) { + u16 l; + + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, &l); + if (!(l & PCI_BRIDGE_CTL_VGA)) { + vgadev->owns = 0; + break; + } + } + bus = bus->parent; + } + + if (vga_is_boot_device(vgadev)) { + vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n", + vga_default_device() ? + " (overriding previous)" : ""); + vga_set_default_device(pdev); + } + + vga_arbiter_check_bridge_sharing(vgadev); + + /* Add to the list */ + list_add_tail(&vgadev->list, &vga_list); + vga_count++; + vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n", + vga_iostate_to_str(vgadev->decodes), + vga_iostate_to_str(vgadev->owns), + vga_iostate_to_str(vgadev->locks)); + + spin_unlock_irqrestore(&vga_lock, flags); + return true; +fail: + spin_unlock_irqrestore(&vga_lock, flags); + kfree(vgadev); + return false; +} + +static bool vga_arbiter_del_pci_device(struct pci_dev *pdev) +{ + struct vga_device *vgadev; + unsigned long flags; + bool ret = true; + + spin_lock_irqsave(&vga_lock, flags); + vgadev = vgadev_find(pdev); + if (vgadev == NULL) { + ret = false; + goto bail; + } + + if (vga_default == pdev) + vga_set_default_device(NULL); + + if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM)) + vga_decode_count--; + + /* Remove entry from list */ + list_del(&vgadev->list); + vga_count--; + + /* Wake up all possible waiters */ + wake_up_all(&vga_wait_queue); +bail: + spin_unlock_irqrestore(&vga_lock, flags); + kfree(vgadev); + return ret; +} + +/* Called with the lock */ +static void vga_update_device_decodes(struct vga_device *vgadev, + unsigned int new_decodes) +{ + struct device *dev = &vgadev->pdev->dev; + unsigned int old_decodes = vgadev->decodes; + unsigned int decodes_removed = ~new_decodes & old_decodes; + unsigned int decodes_unlocked = vgadev->locks & decodes_removed; + + vgadev->decodes = new_decodes; + + vgaarb_info(dev, "VGA decodes changed: olddecodes=%s,decodes=%s:owns=%s\n", + vga_iostate_to_str(old_decodes), + vga_iostate_to_str(vgadev->decodes), + vga_iostate_to_str(vgadev->owns)); + + /* If we removed locked decodes, lock count goes to zero, and release */ + if (decodes_unlocked) { + if (decodes_unlocked & VGA_RSRC_LEGACY_IO) + vgadev->io_lock_cnt = 0; + if (decodes_unlocked & VGA_RSRC_LEGACY_MEM) + vgadev->mem_lock_cnt = 0; + __vga_put(vgadev, decodes_unlocked); + } + + /* Change decodes counter */ + if (old_decodes & VGA_RSRC_LEGACY_MASK && + !(new_decodes & VGA_RSRC_LEGACY_MASK)) + vga_decode_count--; + if (!(old_decodes & VGA_RSRC_LEGACY_MASK) && + new_decodes & VGA_RSRC_LEGACY_MASK) + vga_decode_count++; + vgaarb_dbg(dev, "decoding count now is: %d\n", vga_decode_count); +} + +static void __vga_set_legacy_decoding(struct pci_dev *pdev, + unsigned int decodes, + bool userspace) +{ + struct vga_device *vgadev; + unsigned long flags; + + decodes &= VGA_RSRC_LEGACY_MASK; + + spin_lock_irqsave(&vga_lock, flags); + vgadev = vgadev_find(pdev); + if (vgadev == NULL) + goto bail; + + /* Don't let userspace futz with kernel driver decodes */ + if (userspace && vgadev->set_decode) + goto bail; + + /* Update the device decodes + counter */ + vga_update_device_decodes(vgadev, decodes); + + /* + * XXX If somebody is going from "doesn't decode" to "decodes" + * state here, additional care must be taken as we may have pending + * ownership of non-legacy region. + */ +bail: + spin_unlock_irqrestore(&vga_lock, flags); +} + +/** + * vga_set_legacy_decoding + * @pdev: PCI device of the VGA card + * @decodes: bit mask of what legacy regions the card decodes + * + * Indicate to the arbiter if the card decodes legacy VGA IOs, legacy VGA + * Memory, both, or none. All cards default to both, the card driver (fbdev for + * example) should tell the arbiter if it has disabled legacy decoding, so the + * card can be left out of the arbitration process (and can be safe to take + * interrupts at any time. + */ +void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes) +{ + __vga_set_legacy_decoding(pdev, decodes, false); +} +EXPORT_SYMBOL(vga_set_legacy_decoding); + +/** + * vga_client_register - register or unregister a VGA arbitration client + * @pdev: PCI device of the VGA client + * @set_decode: VGA decode change callback + * + * Clients have two callback mechanisms they can use. + * + * @set_decode callback: If a client can disable its GPU VGA resource, it + * will get a callback from this to set the encode/decode state. + * + * Rationale: we cannot disable VGA decode resources unconditionally + * because some single GPU laptops seem to require ACPI or BIOS access to + * the VGA registers to control things like backlights etc. Hopefully newer + * multi-GPU laptops do something saner, and desktops won't have any + * special ACPI for this. The driver will get a callback when VGA + * arbitration is first used by userspace since some older X servers have + * issues. + * + * Does not check whether a client for @pdev has been registered already. + * + * To unregister, call vga_client_unregister(). + * + * Returns: 0 on success, -ENODEV on failure + */ +int vga_client_register(struct pci_dev *pdev, + unsigned int (*set_decode)(struct pci_dev *pdev, bool decode)) +{ + unsigned long flags; + struct vga_device *vgadev; + + spin_lock_irqsave(&vga_lock, flags); + vgadev = vgadev_find(pdev); + if (vgadev) + vgadev->set_decode = set_decode; + spin_unlock_irqrestore(&vga_lock, flags); + if (!vgadev) + return -ENODEV; + return 0; +} +EXPORT_SYMBOL(vga_client_register); + +/* + * Char driver implementation + * + * Semantics is: + * + * open : Open user instance of the arbiter. By default, it's + * attached to the default VGA device of the system. + * + * close : Close user instance, release locks + * + * read : Return a string indicating the status of the target. + * An IO state string is of the form {io,mem,io+mem,none}, + * mc and ic are respectively mem and io lock counts (for + * debugging/diagnostic only). "decodes" indicate what the + * card currently decodes, "owns" indicates what is currently + * enabled on it, and "locks" indicates what is locked by this + * card. If the card is unplugged, we get "invalid" then for + * card_ID and an -ENODEV error is returned for any command + * until a new card is targeted + * + * "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)" + * + * write : write a command to the arbiter. List of commands is: + * + * target <card_ID> : switch target to card <card_ID> (see below) + * lock <io_state> : acquire locks on target ("none" is invalid io_state) + * trylock <io_state> : non-blocking acquire locks on target + * unlock <io_state> : release locks on target + * unlock all : release all locks on target held by this user + * decodes <io_state> : set the legacy decoding attributes for the card + * + * poll : event if something change on any card (not just the target) + * + * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default" + * to go back to the system default card (TODO: not implemented yet). + * Currently, only PCI is supported as a prefix, but the userland API may + * support other bus types in the future, even if the current kernel + * implementation doesn't. + * + * Note about locks: + * + * The driver keeps track of which user has what locks on which card. It + * supports stacking, like the kernel one. This complicates the implementation + * a bit, but makes the arbiter more tolerant to userspace problems and able + * to properly cleanup in all cases when a process dies. + * Currently, a max of 16 cards simultaneously can have locks issued from + * userspace for a given user (file descriptor instance) of the arbiter. + * + * If the device is hot-unplugged, there is a hook inside the module to notify + * it being added/removed in the system and automatically added/removed in + * the arbiter. + */ + +#define MAX_USER_CARDS CONFIG_VGA_ARB_MAX_GPUS +#define PCI_INVALID_CARD ((struct pci_dev *)-1UL) + +/* Each user has an array of these, tracking which cards have locks */ +struct vga_arb_user_card { + struct pci_dev *pdev; + unsigned int mem_cnt; + unsigned int io_cnt; +}; + +struct vga_arb_private { + struct list_head list; + struct pci_dev *target; + struct vga_arb_user_card cards[MAX_USER_CARDS]; + spinlock_t lock; +}; + +static LIST_HEAD(vga_user_list); +static DEFINE_SPINLOCK(vga_user_lock); + + +/* + * Take a string in the format: "PCI:domain:bus:dev.fn" and return the + * respective values. If the string is not in this format, return 0. + */ +static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain, + unsigned int *bus, unsigned int *devfn) +{ + int n; + unsigned int slot, func; + + n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func); + if (n != 4) + return 0; + + *devfn = PCI_DEVFN(slot, func); + + return 1; +} + +static ssize_t vga_arb_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + struct vga_arb_private *priv = file->private_data; + struct vga_device *vgadev; + struct pci_dev *pdev; + unsigned long flags; + size_t len; + int rc; + char *lbuf; + + lbuf = kmalloc(1024, GFP_KERNEL); + if (lbuf == NULL) + return -ENOMEM; + + /* Protect vga_list */ + spin_lock_irqsave(&vga_lock, flags); + + /* If we are targeting the default, use it */ + pdev = priv->target; + if (pdev == NULL || pdev == PCI_INVALID_CARD) { + spin_unlock_irqrestore(&vga_lock, flags); + len = sprintf(lbuf, "invalid"); + goto done; + } + + /* Find card vgadev structure */ + vgadev = vgadev_find(pdev); + if (vgadev == NULL) { + /* + * Wow, it's not in the list, that shouldn't happen, let's + * fix us up and return invalid card. + */ + spin_unlock_irqrestore(&vga_lock, flags); + len = sprintf(lbuf, "invalid"); + goto done; + } + + /* Fill the buffer with info */ + len = snprintf(lbuf, 1024, + "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%u:%u)\n", + vga_decode_count, pci_name(pdev), + vga_iostate_to_str(vgadev->decodes), + vga_iostate_to_str(vgadev->owns), + vga_iostate_to_str(vgadev->locks), + vgadev->io_lock_cnt, vgadev->mem_lock_cnt); + + spin_unlock_irqrestore(&vga_lock, flags); +done: + + /* Copy that to user */ + if (len > count) + len = count; + rc = copy_to_user(buf, lbuf, len); + kfree(lbuf); + if (rc) + return -EFAULT; + return len; +} + +/* + * TODO: To avoid parsing inside kernel and to improve the speed we may + * consider use ioctl here + */ +static ssize_t vga_arb_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + struct vga_arb_private *priv = file->private_data; + struct vga_arb_user_card *uc = NULL; + struct pci_dev *pdev; + + unsigned int io_state; + + char kbuf[64], *curr_pos; + size_t remaining = count; + + int ret_val; + int i; + + if (count >= sizeof(kbuf)) + return -EINVAL; + if (copy_from_user(kbuf, buf, count)) + return -EFAULT; + curr_pos = kbuf; + kbuf[count] = '\0'; + + if (strncmp(curr_pos, "lock ", 5) == 0) { + curr_pos += 5; + remaining -= 5; + + pr_debug("client 0x%p called 'lock'\n", priv); + + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) { + ret_val = -EPROTO; + goto done; + } + if (io_state == VGA_RSRC_NONE) { + ret_val = -EPROTO; + goto done; + } + + pdev = priv->target; + if (priv->target == NULL) { + ret_val = -ENODEV; + goto done; + } + + vga_get_uninterruptible(pdev, io_state); + + /* Update the client's locks lists */ + for (i = 0; i < MAX_USER_CARDS; i++) { + if (priv->cards[i].pdev == pdev) { + if (io_state & VGA_RSRC_LEGACY_IO) + priv->cards[i].io_cnt++; + if (io_state & VGA_RSRC_LEGACY_MEM) + priv->cards[i].mem_cnt++; + break; + } + } + + ret_val = count; + goto done; + } else if (strncmp(curr_pos, "unlock ", 7) == 0) { + curr_pos += 7; + remaining -= 7; + + pr_debug("client 0x%p called 'unlock'\n", priv); + + if (strncmp(curr_pos, "all", 3) == 0) + io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM; + else { + if (!vga_str_to_iostate + (curr_pos, remaining, &io_state)) { + ret_val = -EPROTO; + goto done; + } + /* TODO: Add this? + if (io_state == VGA_RSRC_NONE) { + ret_val = -EPROTO; + goto done; + } + */ + } + + pdev = priv->target; + if (priv->target == NULL) { + ret_val = -ENODEV; + goto done; + } + for (i = 0; i < MAX_USER_CARDS; i++) { + if (priv->cards[i].pdev == pdev) + uc = &priv->cards[i]; + } + + if (!uc) { + ret_val = -EINVAL; + goto done; + } + + if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0) { + ret_val = -EINVAL; + goto done; + } + + if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0) { + ret_val = -EINVAL; + goto done; + } + + vga_put(pdev, io_state); + + if (io_state & VGA_RSRC_LEGACY_IO) + uc->io_cnt--; + if (io_state & VGA_RSRC_LEGACY_MEM) + uc->mem_cnt--; + + ret_val = count; + goto done; + } else if (strncmp(curr_pos, "trylock ", 8) == 0) { + curr_pos += 8; + remaining -= 8; + + pr_debug("client 0x%p called 'trylock'\n", priv); + + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) { + ret_val = -EPROTO; + goto done; + } + /* TODO: Add this? + if (io_state == VGA_RSRC_NONE) { + ret_val = -EPROTO; + goto done; + } + */ + + pdev = priv->target; + if (priv->target == NULL) { + ret_val = -ENODEV; + goto done; + } + + if (vga_tryget(pdev, io_state)) { + /* Update the client's locks lists... */ + for (i = 0; i < MAX_USER_CARDS; i++) { + if (priv->cards[i].pdev == pdev) { + if (io_state & VGA_RSRC_LEGACY_IO) + priv->cards[i].io_cnt++; + if (io_state & VGA_RSRC_LEGACY_MEM) + priv->cards[i].mem_cnt++; + break; + } + } + ret_val = count; + goto done; + } else { + ret_val = -EBUSY; + goto done; + } + + } else if (strncmp(curr_pos, "target ", 7) == 0) { + unsigned int domain, bus, devfn; + struct vga_device *vgadev; + + curr_pos += 7; + remaining -= 7; + pr_debug("client 0x%p called 'target'\n", priv); + /* If target is default */ + if (!strncmp(curr_pos, "default", 7)) + pdev = pci_dev_get(vga_default_device()); + else { + if (!vga_pci_str_to_vars(curr_pos, remaining, + &domain, &bus, &devfn)) { + ret_val = -EPROTO; + goto done; + } + pdev = pci_get_domain_bus_and_slot(domain, bus, devfn); + if (!pdev) { + pr_debug("invalid PCI address %04x:%02x:%02x.%x\n", + domain, bus, PCI_SLOT(devfn), + PCI_FUNC(devfn)); + ret_val = -ENODEV; + goto done; + } + + pr_debug("%s ==> %04x:%02x:%02x.%x pdev %p\n", curr_pos, + domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn), + pdev); + } + + vgadev = vgadev_find(pdev); + pr_debug("vgadev %p\n", vgadev); + if (vgadev == NULL) { + if (pdev) { + vgaarb_dbg(&pdev->dev, "not a VGA device\n"); + pci_dev_put(pdev); + } + + ret_val = -ENODEV; + goto done; + } + + priv->target = pdev; + for (i = 0; i < MAX_USER_CARDS; i++) { + if (priv->cards[i].pdev == pdev) + break; + if (priv->cards[i].pdev == NULL) { + priv->cards[i].pdev = pdev; + priv->cards[i].io_cnt = 0; + priv->cards[i].mem_cnt = 0; + break; + } + } + if (i == MAX_USER_CARDS) { + vgaarb_dbg(&pdev->dev, "maximum user cards (%d) number reached, ignoring this one!\n", + MAX_USER_CARDS); + pci_dev_put(pdev); + /* XXX: Which value to return? */ + ret_val = -ENOMEM; + goto done; + } + + ret_val = count; + pci_dev_put(pdev); + goto done; + + + } else if (strncmp(curr_pos, "decodes ", 8) == 0) { + curr_pos += 8; + remaining -= 8; + pr_debug("client 0x%p called 'decodes'\n", priv); + + if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) { + ret_val = -EPROTO; + goto done; + } + pdev = priv->target; + if (priv->target == NULL) { + ret_val = -ENODEV; + goto done; + } + + __vga_set_legacy_decoding(pdev, io_state, true); + ret_val = count; + goto done; + } + /* If we got here, the message written is not part of the protocol! */ + return -EPROTO; + +done: + return ret_val; +} + +static __poll_t vga_arb_fpoll(struct file *file, poll_table *wait) +{ + pr_debug("%s\n", __func__); + + poll_wait(file, &vga_wait_queue, wait); + return EPOLLIN; +} + +static int vga_arb_open(struct inode *inode, struct file *file) +{ + struct vga_arb_private *priv; + unsigned long flags; + + pr_debug("%s\n", __func__); + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (priv == NULL) + return -ENOMEM; + spin_lock_init(&priv->lock); + file->private_data = priv; + + spin_lock_irqsave(&vga_user_lock, flags); + list_add(&priv->list, &vga_user_list); + spin_unlock_irqrestore(&vga_user_lock, flags); + + /* Set the client's lists of locks */ + priv->target = vga_default_device(); /* Maybe this is still null! */ + priv->cards[0].pdev = priv->target; + priv->cards[0].io_cnt = 0; + priv->cards[0].mem_cnt = 0; + + return 0; +} + +static int vga_arb_release(struct inode *inode, struct file *file) +{ + struct vga_arb_private *priv = file->private_data; + struct vga_arb_user_card *uc; + unsigned long flags; + int i; + + pr_debug("%s\n", __func__); + + spin_lock_irqsave(&vga_user_lock, flags); + list_del(&priv->list); + for (i = 0; i < MAX_USER_CARDS; i++) { + uc = &priv->cards[i]; + if (uc->pdev == NULL) + continue; + vgaarb_dbg(&uc->pdev->dev, "uc->io_cnt == %d, uc->mem_cnt == %d\n", + uc->io_cnt, uc->mem_cnt); + while (uc->io_cnt--) + vga_put(uc->pdev, VGA_RSRC_LEGACY_IO); + while (uc->mem_cnt--) + vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM); + } + spin_unlock_irqrestore(&vga_user_lock, flags); + + kfree(priv); + + return 0; +} + +/* + * Callback any registered clients to let them know we have a change in VGA + * cards. + */ +static void vga_arbiter_notify_clients(void) +{ + struct vga_device *vgadev; + unsigned long flags; + unsigned int new_decodes; + bool new_state; + + if (!vga_arbiter_used) + return; + + new_state = (vga_count > 1) ? false : true; + + spin_lock_irqsave(&vga_lock, flags); + list_for_each_entry(vgadev, &vga_list, list) { + if (vgadev->set_decode) { + new_decodes = vgadev->set_decode(vgadev->pdev, + new_state); + vga_update_device_decodes(vgadev, new_decodes); + } + } + spin_unlock_irqrestore(&vga_lock, flags); +} + +static int pci_notify(struct notifier_block *nb, unsigned long action, + void *data) +{ + struct device *dev = data; + struct pci_dev *pdev = to_pci_dev(dev); + bool notify = false; + + vgaarb_dbg(dev, "%s\n", __func__); + + /* + * For now, we're only interested in devices added and removed. + * I didn't test this thing here, so someone needs to double check + * for the cases of hot-pluggable VGA cards. + */ + if (action == BUS_NOTIFY_ADD_DEVICE) + notify = vga_arbiter_add_pci_device(pdev); + else if (action == BUS_NOTIFY_DEL_DEVICE) + notify = vga_arbiter_del_pci_device(pdev); + + if (notify) + vga_arbiter_notify_clients(); + return 0; +} + +static struct notifier_block pci_notifier = { + .notifier_call = pci_notify, +}; + +static const struct file_operations vga_arb_device_fops = { + .read = vga_arb_read, + .write = vga_arb_write, + .poll = vga_arb_fpoll, + .open = vga_arb_open, + .release = vga_arb_release, + .llseek = noop_llseek, +}; + +static struct miscdevice vga_arb_device = { + MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops +}; + +static int __init vga_arb_device_init(void) +{ + int rc; + struct pci_dev *pdev; + + rc = misc_register(&vga_arb_device); + if (rc < 0) + pr_err("error %d registering device\n", rc); + + bus_register_notifier(&pci_bus_type, &pci_notifier); + + /* Add all VGA class PCI devices by default */ + pdev = NULL; + while ((pdev = + pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, + PCI_ANY_ID, pdev)) != NULL) + vga_arbiter_add_pci_device(pdev); + + pr_info("loaded\n"); + return rc; +} +subsys_initcall_sync(vga_arb_device_init); |