cregit-Linux how code gets into the kernel

Release 4.14 drivers/gpu/vga/vgaarb.c

Directory: drivers/gpu/vga
 * vgaarb.c: Implements the VGA arbitration. For details refer to
 * Documentation/vgaarbiter.txt
 * (C) Copyright 2005 Benjamin Herrenschmidt <>
 * (C) Copyright 2007 Paulo R. Zanoni <>
 * (C) Copyright 2007, 2009 Tiago Vignatti <>
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.

#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/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 does it decodes */
unsigned int owns;	/* what does it owns */
unsigned int locks;	/* what does 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;
	/* allow IRQ enable/disable hook */
void *cookie;
void (*irq_set_state)(void *cookie, bool enable);
unsigned int (*set_vga_decode)(void *cookie, 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"; }


Benjamin Herrenschmidt48100.00%1100.00%

static int vga_str_to_iostate(char *buf, int str_size, int *io_state) { /* we could in theory hand out locks on IO and mem * separately to userspace but it can cause deadlocks */ if (strncmp(buf, "none", 4) == 0) { *io_state = VGA_RSRC_NONE; return 1; } /* XXX We're not chekcing 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; }


Benjamin Herrenschmidt107100.00%1100.00%

/* this is only used a cookie - it should not be dereferenced */ static struct pci_dev *vga_default; static void vga_arb_device_card_gone(struct pci_dev *pdev); /* 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; }


Benjamin Herrenschmidt40100.00%1100.00%

/** * 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 archs * 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 theirs 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; }


Benjamin Herrenschmidt12100.00%1100.00%

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); }


Yinghai Lu1551.72%150.00%
Matthew Garrett1448.28%150.00%

static inline void vga_irq_set_state(struct vga_device *vgadev, bool state) { if (vgadev->irq_set_state) vgadev->irq_set_state(vgadev->cookie, state); }


Benjamin Herrenschmidt32100.00%1100.00%

/* If we don't ever use VGA arb 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) { /* we should inform all GPUs in the system that * VGA arb has occurred and to try and disable resources * if they can */ if (!vga_arbiter_used) { vga_arbiter_used = true; vga_arbiter_notify_clients(); } }


Benjamin Herrenschmidt2295.65%150.00%
Lucas De Marchi14.35%150.00%

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 how 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; /* Check if the architecture allows a conflict between those * 2 devices or if they are on separate domains */ if (!vga_conflicts(vgadev->pdev, conflict->pdev)) 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) { vga_irq_set_state(conflict, false); 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 dude, 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); if (!vgadev->bridge_has_one_vga) vga_irq_set_state(vgadev, true); 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; }


Benjamin Herrenschmidt40676.60%120.00%
Dave Airlie6612.45%120.00%
Alex Williamson407.55%240.00%
Björn Helgaas183.40%120.00%

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); }


Benjamin Herrenschmidt18092.31%150.00%
Björn Helgaas157.69%150.00%

/** * vga_get - acquire & locks 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 ? * * This function acquires VGA resources for the given card and mark those * resources locked. If the resource 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 one who calls us should check for this, but lets 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; }


Benjamin Herrenschmidt18491.09%133.33%
Kirill A. Shutemov178.42%133.33%
Ingo Molnar10.50%133.33%

EXPORT_SYMBOL(vga_get); /** * vga_tryget - try to acquire & lock legacy VGA resources * @pdev: pci devivce of VGA card or NULL for system default * @rsrc: bit mask of resources to acquire and lock * * This function performs the same operation as vga_get(), but will return an * error (-EBUSY) instead of blocking if the resources are already locked by * another card. It 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. */
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 one who calls us should check for this, but lets 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; }


Benjamin Herrenschmidt110100.00%1100.00%

EXPORT_SYMBOL(vga_tryget); /** * vga_put - release lock on legacy VGA resources * @pdev: pci device of VGA card or NULL for system default * @rsrc: but mask of resource to release * * This fuction releases resources previously locked by vga_get() or * vga_tryget(). The resources aren't disabled right away, so that a subsequence * 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 one who calls us should check for this, but lets 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); }


Benjamin Herrenschmidt83100.00%1100.00%

EXPORT_SYMBOL(vga_put); /* * 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)) return; /* okay iterate the new devices bridge hierarachy */ 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 the share a bridge with this device */ if (new_bridge == bridge) { /* * If their 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 devices bridge hierarchy. * If the new devices parent bridge is in the other * devices hierarchy then 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; } }


Dave Airlie15198.05%150.00%
Thierry Reding31.95%150.00%

/* * 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 decides if devices decodes or not legacy * things. */
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; } /* Deal with VGA default device. Use first enabled one * by default if arch doesn't have it's own hook */ if (vga_default == NULL && ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)) { vgaarb_info(&pdev->dev, "setting as boot VGA device\n"); vga_set_default_device(pdev); } vga_arbiter_check_bridge_sharing(vgadev); /* Add to the list */ list_add(&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; }


Benjamin Herrenschmidt31690.54%114.29%
Björn Helgaas195.44%114.29%
Bruno Prémont61.72%114.29%
Dave Airlie51.43%114.29%
Yinghai Lu10.29%114.29%
Rasmus Villemoes10.29%114.29%
Thierry Reding10.29%114.29%

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--; /* Notify userland driver that the device is gone so it discards * it's copies of the pci_dev pointer */ vga_arb_device_card_gone(pdev); /* Wake up all possible waiters */ wake_up_all(&vga_wait_queue); bail: spin_unlock_irqrestore(&vga_lock, flags); kfree(vgadev); return ret; }


Benjamin Herrenschmidt12298.39%150.00%
Yinghai Lu21.61%150.00%

/* this is called with the lock */
static inline void vga_update_device_decodes(struct vga_device *vgadev, int new_decodes) { struct device *dev = &vgadev->pdev->dev; int old_decodes, decodes_removed, decodes_unlocked; old_decodes = vgadev->decodes; decodes_removed = ~new_decodes & old_decodes; decodes_unlocked = vgadev->locks & decodes_removed; vgadev->decodes = new_decodes; vgaarb_info(dev, "changed VGA decodes: 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); }


Benjamin Herrenschmidt8752.10%120.00%
Alex Williamson5633.53%120.00%
Björn Helgaas1810.78%120.00%
Tiago Vignatti52.99%120.00%
Thierry Reding10.60%120.00%

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_vga_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 owner * ship of non-legacy region ... */ bail: spin_unlock_irqrestore(&vga_lock, flags); }


Benjamin Herrenschmidt8598.84%150.00%
Daniel J Blueman11.16%150.00%

void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes) { __vga_set_legacy_decoding(pdev, decodes, false); }


Benjamin Herrenschmidt23100.00%1100.00%

EXPORT_SYMBOL(vga_set_legacy_decoding); /** * vga_client_register - register or unregister a VGA arbitration client * @pdev: pci device of the VGA client * @cookie: client cookie to be used in callbacks * @irq_set_state: irq state change callback * @set_vga_decode: vga decode change callback * * Clients have two callback mechanisms they can use. * * @irq_set_state callback: If a client can't disable its GPUs VGA * resources, then we need to be able to ask it to turn off its irqs when we * turn off its mem and io decoding. * * @set_vga_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 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. * * This function does not check whether a client for @pdev has been registered * already. * * To unregister just call this function with @irq_set_state and @set_vga_decode * both set to NULL for the same @pdev as originally used to register them. * * Returns: 0 on success, -1 on failure */ int vga_client_register(struct pci_dev *pdev, void *cookie, void (*irq_set_state)(void *cookie, bool state), unsigned int (*set_vga_decode)(void *cookie, bool decode)) { int ret = -ENODEV; struct vga_device *vgadev; unsigned long flags; spin_lock_irqsave(&vga_lock, flags); vgadev = vgadev_find(pdev); if (!vgadev) goto bail; vgadev->irq_set_state = irq_set_state; vgadev->set_vga_decode = set_vga_decode; vgadev->cookie = cookie; ret = 0; bail: spin_unlock_irqrestore(&vga_lock, flags); return ret; } EXPORT_SYMBOL(vga_client_register); /* * Char driver implementation * * Semantics is: * * open : open user instance of the arbitrer. 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> : acquires 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 complexifies 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 * they 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); /* * This function gets a string in the format: "PCI:domain:bus:dev.fn" and * returns the respective values. If the string is not in this format, * it returns 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; }


Benjamin Herrenschmidt78100.00%1100.00%

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; /* Shields against vga_arb_device_card_gone (pci_dev going * away), and allows ac