[PATCH 1/6] drm/xe: Introduce a simple busted state

[Lucas De Marchi]

On Fri, Mar 15, 2024 at 10:01:03AM -0400, Rodrigo Vivi wrote:
>Introduce a very simple 'busted' state where any attempt
>to access the GPU is entirely blocked.
>
>On some critical cases, like on gt_reset failure, we need to
>block any other attempt to use the GPU. Otherwise we are at
>a risk of reaching cases that would force us to reboot the machine.
>
>So, when this cases are identified we corner and block any GPU
>access. No IOCTL and not even another GT reset should be attempted.
>
>The 'busted' state in Xe is an end state with no way back.
>Only a device "re-probe" (unbind + bind) can restore the GPU access.
>
>v2: - s/wedged/busted (Lucas)
>    - use unbind+bind instead of module reload (Lucas)
>    - added more info on unbind operations and instruction on bug report
>    - only print the message once.
>
>Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>Cc: Anshuman Gupta <anshuman.gupta at intel.com>
>Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
>Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
>---
> drivers/gpu/drm/xe/xe_device.c       |  6 ++++++
> drivers/gpu/drm/xe/xe_device.h       | 18 ++++++++++++++++++
> drivers/gpu/drm/xe/xe_device_types.h |  3 +++
> drivers/gpu/drm/xe/xe_gt.c           |  4 ++++
> drivers/gpu/drm/xe/xe_migrate.c      |  6 ++++++
> 5 files changed, 37 insertions(+)
>
>diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
>index b0bfe75eb59f..d02e59fb49eb 100644
>--- a/drivers/gpu/drm/xe/xe_device.c
>+++ b/drivers/gpu/drm/xe/xe_device.c
>@@ -142,6 +142,9 @@ static long xe_drm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> 	struct xe_device *xe = to_xe_device(file_priv->minor->dev);
> 	long ret;
>
>+	if (xe_device_busted(xe))
>+		return -ECANCELED;
>+
> 	ret = xe_pm_runtime_get_ioctl(xe);
> 	if (ret >= 0)
> 		ret = drm_ioctl(file, cmd, arg);
>@@ -157,6 +160,9 @@ static long xe_drm_compat_ioctl(struct file *file, unsigned int cmd, unsigned lo
> 	struct xe_device *xe = to_xe_device(file_priv->minor->dev);
> 	long ret;
>
>+	if (xe_device_busted(xe))
>+		return -ECANCELED;
>+
> 	ret = xe_pm_runtime_get_ioctl(xe);
> 	if (ret >= 0)
> 		ret = drm_compat_ioctl(file, cmd, arg);
>diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
>index 14be34d9f543..2c6d9b77821a 100644
>--- a/drivers/gpu/drm/xe/xe_device.h
>+++ b/drivers/gpu/drm/xe/xe_device.h
>@@ -176,4 +176,22 @@ void xe_device_snapshot_print(struct xe_device *xe, struct drm_printer *p);
> u64 xe_device_canonicalize_addr(struct xe_device *xe, u64 address);
> u64 xe_device_uncanonicalize_addr(struct xe_device *xe, u64 address);
>
>+static inline bool xe_device_busted(struct xe_device *xe)
>+{
>+	return atomic_read(&xe->busted);
>+}
>+
>+static inline void xe_device_declare_busted(struct xe_device *xe)
>+{
>+	if (!atomic_xchg(&xe->busted, 1))
>+		drm_err(&xe->drm,
>+			"CRITICAL: Xe has declared device %s as busted.\n"
>+			"IOCTLs and executions are blocked until device is probed again with unbind and bind operations:\n"
>+			"echo '%s' | sudo tee /sys/bus/pci/drivers/xe/unbind\n"
>+			"echo '%s' | sudo tee /sys/bus/pci/drivers/xe/bind\n"

rather than assume people have sudo/tee around, assume it's executed by a
user with proper perm, so just "echo '%s' > /sys/bus/pci/drivers/xe/bind"?

Consider this more a nit than a blocking comment.


Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>

thanks
Lucas De Marchi

>+			"Please file a _new_ bug report at https://gitlab.freedesktop.org/drm/xe/kernel/issues/new\n",
>+			dev_name(xe->drm.dev), dev_name(xe->drm.dev),
>+			dev_name(xe->drm.dev));
>+}
>+
> #endif
>diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
>index 9785eef2e5a4..2633fdfc1a38 100644
>--- a/drivers/gpu/drm/xe/xe_device_types.h
>+++ b/drivers/gpu/drm/xe/xe_device_types.h
>@@ -455,6 +455,9 @@ struct xe_device {
> 	/** @needs_flr_on_fini: requests function-reset on fini */
> 	bool needs_flr_on_fini;
>
>+	/** @busted: Xe device faced a critical error and is now blocked. */
>+	atomic_t busted;
>+
> 	/* private: */
>
> #if IS_ENABLED(CONFIG_DRM_XE_DISPLAY)
>diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
>index 85408e7a932b..2f29f7fa682b 100644
>--- a/drivers/gpu/drm/xe/xe_gt.c
>+++ b/drivers/gpu/drm/xe/xe_gt.c
>@@ -633,6 +633,9 @@ static int gt_reset(struct xe_gt *gt)
> {
> 	int err;
>
>+	if (xe_device_busted(gt_to_xe(gt)))
>+		return -ECANCELED;
>+
> 	/* We only support GT resets with GuC submission */
> 	if (!xe_device_uc_enabled(gt_to_xe(gt)))
> 		return -ENODEV;
>@@ -686,6 +689,7 @@ static int gt_reset(struct xe_gt *gt)
> 	xe_gt_err(gt, "reset failed (%pe)\n", ERR_PTR(err));
>
> 	gt_to_xe(gt)->needs_flr_on_fini = true;
>+	xe_device_declare_busted(gt_to_xe(gt));
>
> 	return err;
> }
>diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
>index ee1bb938c493..d7eb409e8415 100644
>--- a/drivers/gpu/drm/xe/xe_migrate.c
>+++ b/drivers/gpu/drm/xe/xe_migrate.c
>@@ -713,6 +713,9 @@ struct dma_fence *xe_migrate_copy(struct xe_migrate *m,
> 		xe_bo_needs_ccs_pages(src_bo) && xe_bo_needs_ccs_pages(dst_bo);
> 	bool copy_system_ccs = copy_ccs && (!src_is_vram || !dst_is_vram);
>
>+	if (xe_device_busted(xe))
>+		return ERR_PTR(-ECANCELED);
>+
> 	/* Copying CCS between two different BOs is not supported yet. */
> 	if (XE_WARN_ON(copy_ccs && src_bo != dst_bo))
> 		return ERR_PTR(-EINVAL);
>@@ -986,6 +989,9 @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
> 	int err;
> 	int pass = 0;
>
>+	if (xe_device_busted(xe))
>+		return ERR_PTR(-ECANCELED);
>+
> 	if (!clear_vram)
> 		xe_res_first_sg(xe_bo_sg(bo), 0, bo->size, &src_it);
> 	else
>-- 
>2.44.0
>