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drm/i915: Disable mmio debugging during user access

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If the user bypasses i915 and accesses mmio directly, that easily
confuses our automatic mmio debugging (any error we then detect is
likely to be as a result of the user). Since we expect userspace to open
debugfs/i915_forcewake_user if i915.ko is loaded and they want mmio
access, that makes the opportune time to disable our debugging for
duration of the bypass.

v2: Move the fiddling of uncore internals to uncore.c

References: https://bugs.freedesktop.org/show_bug.cgi?id=102543
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170907134441.12881-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2017-09-07 14:44:41 +01:00
parent d2d4f39b1e
commit d7a133d886
3 changed files with 72 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

19
drivers/gpu/drm/i915/i915_debugfs.c
View file

@ -1421,6 +1421,9 @@ static int i915_forcewake_domains(struct seq_file *m, void *data)
struct intel_uncore_forcewake_domain *fw_domain;
unsigned int tmp;
seq_printf(m, "user.bypass_count = %u\n",
i915->uncore.user_forcewake.count);
for_each_fw_domain(fw_domain, i915, tmp)
seq_printf(m, "%s.wake_count = %u\n",
intel_uncore_forcewake_domain_to_str(fw_domain->id),
@ -4724,26 +4727,26 @@ static int i915_sseu_status(struct seq_file *m, void *unused)
static int i915_forcewake_open(struct inode *inode, struct file *file)
{
struct drm_i915_private *dev_priv = inode->i_private;
struct drm_i915_private *i915 = inode->i_private;
if (INTEL_GEN(dev_priv) < 6)
if (INTEL_GEN(i915) < 6)
return 0;
intel_runtime_pm_get(dev_priv);
intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
intel_runtime_pm_get(i915);
intel_uncore_forcewake_user_get(i915);
return 0;
}
static int i915_forcewake_release(struct inode *inode, struct file *file)
{
struct drm_i915_private *dev_priv = inode->i_private;
struct drm_i915_private *i915 = inode->i_private;
if (INTEL_GEN(dev_priv) < 6)
if (INTEL_GEN(i915) < 6)
return 0;
intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
intel_runtime_pm_put(dev_priv);
intel_uncore_forcewake_user_put(i915);
intel_runtime_pm_put(i915);
return 0;
}

51
drivers/gpu/drm/i915/intel_uncore.c
View file

@ -489,6 +489,57 @@ void intel_uncore_forcewake_get(struct drm_i915_private *dev_priv,
spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
}
/**
* intel_uncore_forcewake_user_get - claim forcewake on behalf of userspace
* @dev_priv: i915 device instance
*
* This function is a wrapper around intel_uncore_forcewake_get() to acquire
* the GT powerwell and in the process disable our debugging for the
* duration of userspace's bypass.
*/
void intel_uncore_forcewake_user_get(struct drm_i915_private *dev_priv)
{
spin_lock_irq(&dev_priv->uncore.lock);
if (!dev_priv->uncore.user_forcewake.count++) {
intel_uncore_forcewake_get__locked(dev_priv, FORCEWAKE_ALL);
/* Save and disable mmio debugging for the user bypass */
dev_priv->uncore.user_forcewake.saved_mmio_check =
dev_priv->uncore.unclaimed_mmio_check;
dev_priv->uncore.user_forcewake.saved_mmio_debug =
i915.mmio_debug;
dev_priv->uncore.unclaimed_mmio_check = 0;
i915.mmio_debug = 0;
}
spin_unlock_irq(&dev_priv->uncore.lock);
}
/**
* intel_uncore_forcewake_user_put - release forcewake on behalf of userspace
* @dev_priv: i915 device instance
*
* This function complements intel_uncore_forcewake_user_get() and releases
* the GT powerwell taken on behalf of the userspace bypass.
*/
void intel_uncore_forcewake_user_put(struct drm_i915_private *dev_priv)
{
spin_lock_irq(&dev_priv->uncore.lock);
if (!--dev_priv->uncore.user_forcewake.count) {
if (intel_uncore_unclaimed_mmio(dev_priv))
dev_info(dev_priv->drm.dev,
"Invalid mmio detected during user access\n");
dev_priv->uncore.unclaimed_mmio_check =
dev_priv->uncore.user_forcewake.saved_mmio_check;
i915.mmio_debug =
dev_priv->uncore.user_forcewake.saved_mmio_debug;
intel_uncore_forcewake_put__locked(dev_priv, FORCEWAKE_ALL);
}
spin_unlock_irq(&dev_priv->uncore.lock);
}
/**
* intel_uncore_forcewake_get__locked - grab forcewake domain references
* @dev_priv: i915 device instance

10
drivers/gpu/drm/i915/intel_uncore.h
View file

@ -102,6 +102,13 @@ struct intel_uncore {
i915_reg_t reg_ack;
} fw_domain[FW_DOMAIN_ID_COUNT];
struct {
unsigned int count;
int saved_mmio_check;
int saved_mmio_debug;
} user_forcewake;
int unclaimed_mmio_check;
};
@ -144,6 +151,9 @@ void intel_uncore_forcewake_get__locked(struct drm_i915_private *dev_priv,
void intel_uncore_forcewake_put__locked(struct drm_i915_private *dev_priv,
enum forcewake_domains domains);
void intel_uncore_forcewake_user_get(struct drm_i915_private *dev_priv);
void intel_uncore_forcewake_user_put(struct drm_i915_private *dev_priv);
int intel_wait_for_register(struct drm_i915_private *dev_priv,
i915_reg_t reg,
u32 mask,