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kernel/drivers/pci/vgaarb.c

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// 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;
/* 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__);
/* Only deal with VGA class devices */
if (!pci_is_vga(pdev))
return 0;
/*
* 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) {
if (pci_is_vga(pdev))
vga_arbiter_add_pci_device(pdev);
}
pr_info("loaded\n");
return rc;
}
subsys_initcall_sync(vga_arb_device_init);
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