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FAILED: patch "[PATCH] drm/amdgpu: Fix context pstate override handling" failed to apply to 6.18-stable tree

PATCH New [email protected] 2 participants 2 messages Jul 29 – Jul 31

Subsystems (3)
Stable branch DRM drivers Radeon and amdgpu DRM drivers
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author maintainer
#0 lore raw

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x c1dc4ccb82c9e56325d8e7514ca4c90bd1efb351
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026072933-rack-tipping-c899@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c1dc4ccb82c9e56325d8e7514ca4c90bd1efb351 Mon Sep 17 00:00:00 2001
From: Tvrtko Ursulin <[email protected]>
Date: Mon, 1 Jun 2026 15:08:22 +0100
Subject: [PATCH] drm/amdgpu: Fix context pstate override handling
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

There are several problems in the context pstate handling code.

The most serious ones are potential use-after-free and NULL pointer dereferences at context initialization time. Both are due amdgpu_ctx_init() not holding the adev->pm.stable_pstate_ctx_lock, which is otherwise used from both sysfs and the context code itself for modifying and clearing the stored context pointer.

Second issue is that context fini can trample over the pstate configuration set via sysfs. This is due the restore state (ctx->stable_pstate) being saved at context init time, and not if, or when the context actually changes the pstate. As the context exits it will therefore incorrectly restore to what was set before the sysfs override was requested.

The simplest fix is to drastically simplify how the state is tracked, by clearly defining the points at which pstate ownership is taken and released, and to handle all transitions under the correct lock.

Instead of at context init time, the previous state is saved only at the point the context overrides the current state, and is restored on context exit only if the context is still the owner of the current override state.

Signed-off-by Tvrtko Ursulin <[email protected]>
Fixes 79610d304133 ("drm/amdgpu: fix pstate setting issue")
Cc Chengming Gui <[email protected]>
Cc Alex Deucher <[email protected]>
Cc "Christian König" <[email protected]>
Signed-off-by Alex Deucher <[email protected]>
(cherry picked from commit 1b5e413713c0a93bc1818394d0ce49aaad21bd27)
Cc <[email protected]> # v6.1+
drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c +43 -30
index 0d7f6cd74f79..ce35b415093d 100644
@@ -326,7 +326,6 @@ static int amdgpu_ctx_init(struct amdgpu_ctx_mgr *mgr, int32_t priority,
 			   struct drm_file *filp, struct amdgpu_ctx *ctx)
 {
 	struct amdgpu_fpriv *fpriv = filp->driver_priv;
-	u32 current_stable_pstate;
 	int r;
 
 	r = amdgpu_ctx_priority_permit(filp, priority);

@@ -344,36 +343,21 @@ static int amdgpu_ctx_init(struct amdgpu_ctx_mgr *mgr, int32_t priority,
 	ctx->generation = amdgpu_vm_generation(mgr->adev, &fpriv->vm);
 	ctx->init_priority = priority;
 	ctx->override_priority = AMDGPU_CTX_PRIORITY_UNSET;
-
-	r = amdgpu_ctx_get_stable_pstate(ctx, &current_stable_pstate);
-	if (r)
-		return r;
-
-	if (mgr->adev->pm.stable_pstate_ctx)
-		ctx->stable_pstate = mgr->adev->pm.stable_pstate_ctx->stable_pstate;
-	else
-		ctx->stable_pstate = current_stable_pstate;
+	ctx->stable_pstate = AMDGPU_CTX_STABLE_PSTATE_NONE;
 
 	return 0;
 }
 
-static int amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
-					u32 stable_pstate)
+static int __amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
+					  u32 stable_pstate)
 {
 	struct amdgpu_device *adev = ctx->mgr->adev;
 	enum amd_dpm_forced_level level;
+	struct amdgpu_ctx *current_ctx;
 	u32 current_stable_pstate;
-	int r;
+	int r = 0;
 
-	mutex_lock(&adev->pm.stable_pstate_ctx_lock);
-	if (adev->pm.stable_pstate_ctx && adev->pm.stable_pstate_ctx != ctx) {
-		r = -EBUSY;
-		goto done;
-	}
-
-	r = amdgpu_ctx_get_stable_pstate(ctx, &current_stable_pstate);
-	if (r || (stable_pstate == current_stable_pstate))
-		goto done;
+	lockdep_assert_held(&adev->pm.stable_pstate_ctx_lock);
 
 	switch (stable_pstate) {
 	case AMDGPU_CTX_STABLE_PSTATE_NONE:

@@ -392,17 +376,41 @@ static int amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
 		level = AMD_DPM_FORCED_LEVEL_PROFILE_PEAK;
 		break;
 	default:
-		r = -EINVAL;
-		goto done;
+		return -EINVAL;
 	}
 
-	r = amdgpu_dpm_force_performance_level(adev, level);
+	current_ctx = adev->pm.stable_pstate_ctx;
+	if (current_ctx && current_ctx != ctx)
+		return -EBUSY;
 
-	if (level == AMD_DPM_FORCED_LEVEL_AUTO)
-		adev->pm.stable_pstate_ctx = NULL;
-	else
+	r = amdgpu_ctx_get_stable_pstate(ctx, &current_stable_pstate);
+	if (r || current_stable_pstate == stable_pstate)
+		return r;
+
+	r = amdgpu_dpm_force_performance_level(adev, level);
+	if (r)
+		return r;
+
+	if (!current_ctx) {
 		adev->pm.stable_pstate_ctx = ctx;
-done:
+		/*
+		 * Serialized by context taking ownership for the first time
+		 * while holding adev->pm.stable_pstate_ctx_lock).
+		 */
+		WRITE_ONCE(ctx->stable_pstate, current_stable_pstate);
+	}
+
+	return 0;
+}
+
+static int amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
+					u32 stable_pstate)
+{
+	struct amdgpu_device *adev = ctx->mgr->adev;
+	int r;
+
+	mutex_lock(&adev->pm.stable_pstate_ctx_lock);
+	r = __amdgpu_ctx_set_stable_pstate(ctx, stable_pstate);
 	mutex_unlock(&adev->pm.stable_pstate_ctx_lock);
 
 	return r;

@@ -428,7 +436,12 @@ static void amdgpu_ctx_fini(struct kref *ref)
 	}
 
 	if (drm_dev_enter(adev_to_drm(adev), &idx)) {
-		amdgpu_ctx_set_stable_pstate(ctx, ctx->stable_pstate);
+		mutex_lock(&adev->pm.stable_pstate_ctx_lock);
+		if (adev->pm.stable_pstate_ctx == ctx) {
+			__amdgpu_ctx_set_stable_pstate(ctx, ctx->stable_pstate);
+			adev->pm.stable_pstate_ctx = NULL;
+		}
+		mutex_unlock(&adev->pm.stable_pstate_ctx_lock);
 		drm_dev_exit(idx);
 	}
maintainer
#1 lore raw

PATCH 1/1 drm/amdgpu: Fix context pstate override handling

From: Tvrtko Ursulin <[email protected]>

[ Upstream commit c1dc4ccb82c9e56325d8e7514ca4c90bd1efb351 ]

There are several problems in the context pstate handling code.

The most serious ones are potential use-after-free and NULL pointer dereferences at context initialization time. Both are due amdgpu_ctx_init() not holding the adev->pm.stable_pstate_ctx_lock, which is otherwise used from both sysfs and the context code itself for modifying and clearing the stored context pointer.

Second issue is that context fini can trample over the pstate configuration set via sysfs. This is due the restore state (ctx->stable_pstate) being saved at context init time, and not if, or when the context actually changes the pstate. As the context exits it will therefore incorrectly restore to what was set before the sysfs override was requested.

The simplest fix is to drastically simplify how the state is tracked, by clearly defining the points at which pstate ownership is taken and released, and to handle all transitions under the correct lock.

Instead of at context init time, the previous state is saved only at the point the context overrides the current state, and is restored on context exit only if the context is still the owner of the current override state.

Signed-off-by Tvrtko Ursulin <[email protected]>
Fixes 79610d304133 ("drm/amdgpu: fix pstate setting issue")
Cc Chengming Gui <[email protected]>
Cc Alex Deucher <[email protected]>
Cc "Christian König" <[email protected]>
Signed-off-by Alex Deucher <[email protected]>
(cherry picked from commit 1b5e413713c0a93bc1818394d0ce49aaad21bd27)
Cc <[email protected]> # v6.1+
Signed-off-by Sasha Levin <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 71 +++++++++++++++----------
 1 file changed, 42 insertions(+), 29 deletions(-)
drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c +42 -29
index afedea02188d..32f3d7c49e1f 100644
@@ -321,7 +321,6 @@ static int amdgpu_ctx_init(struct amdgpu_ctx_mgr *mgr, int32_t priority,
 			   struct drm_file *filp, struct amdgpu_ctx *ctx)
 {
 	struct amdgpu_fpriv *fpriv = filp->driver_priv;
-	u32 current_stable_pstate;
 	int r;
 
 	r = amdgpu_ctx_priority_permit(filp, priority);

@@ -339,37 +338,22 @@ static int amdgpu_ctx_init(struct amdgpu_ctx_mgr *mgr, int32_t priority,
 	ctx->generation = amdgpu_vm_generation(mgr->adev, &fpriv->vm);
 	ctx->init_priority = priority;
 	ctx->override_priority = AMDGPU_CTX_PRIORITY_UNSET;
-
-	r = amdgpu_ctx_get_stable_pstate(ctx, &current_stable_pstate);
-	if (r)
-		return r;
-
-	if (mgr->adev->pm.stable_pstate_ctx)
-		ctx->stable_pstate = mgr->adev->pm.stable_pstate_ctx->stable_pstate;
-	else
-		ctx->stable_pstate = current_stable_pstate;
+	ctx->stable_pstate = AMDGPU_CTX_STABLE_PSTATE_NONE;
 
 	ctx->ctx_mgr = &(fpriv->ctx_mgr);
 	return 0;
 }
 
-static int amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
-					u32 stable_pstate)
+static int __amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
+					  u32 stable_pstate)
 {
 	struct amdgpu_device *adev = ctx->mgr->adev;
 	enum amd_dpm_forced_level level;
+	struct amdgpu_ctx *current_ctx;
 	u32 current_stable_pstate;
-	int r;
+	int r = 0;
 
-	mutex_lock(&adev->pm.stable_pstate_ctx_lock);
-	if (adev->pm.stable_pstate_ctx && adev->pm.stable_pstate_ctx != ctx) {
-		r = -EBUSY;
-		goto done;
-	}
-
-	r = amdgpu_ctx_get_stable_pstate(ctx, &current_stable_pstate);
-	if (r || (stable_pstate == current_stable_pstate))
-		goto done;
+	lockdep_assert_held(&adev->pm.stable_pstate_ctx_lock);
 
 	switch (stable_pstate) {
 	case AMDGPU_CTX_STABLE_PSTATE_NONE:

@@ -388,17 +372,41 @@ static int amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
 		level = AMD_DPM_FORCED_LEVEL_PROFILE_PEAK;
 		break;
 	default:
-		r = -EINVAL;
-		goto done;
+		return -EINVAL;
 	}
 
+	current_ctx = adev->pm.stable_pstate_ctx;
+	if (current_ctx && current_ctx != ctx)
+		return -EBUSY;
+
+	r = amdgpu_ctx_get_stable_pstate(ctx, &current_stable_pstate);
+	if (r || current_stable_pstate == stable_pstate)
+		return r;
+
 	r = amdgpu_dpm_force_performance_level(adev, level);
+	if (r)
+		return r;
 
-	if (level == AMD_DPM_FORCED_LEVEL_AUTO)
-		adev->pm.stable_pstate_ctx = NULL;
-	else
+	if (!current_ctx) {
 		adev->pm.stable_pstate_ctx = ctx;
-done:
+		/*
+		 * Serialized by context taking ownership for the first time
+		 * while holding adev->pm.stable_pstate_ctx_lock).
+		 */
+		WRITE_ONCE(ctx->stable_pstate, current_stable_pstate);
+	}
+
+	return 0;
+}
+
+static int amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
+					u32 stable_pstate)
+{
+	struct amdgpu_device *adev = ctx->mgr->adev;
+	int r;
+
+	mutex_lock(&adev->pm.stable_pstate_ctx_lock);
+	r = __amdgpu_ctx_set_stable_pstate(ctx, stable_pstate);
 	mutex_unlock(&adev->pm.stable_pstate_ctx_lock);
 
 	return r;

@@ -424,7 +432,12 @@ static void amdgpu_ctx_fini(struct kref *ref)
 	}
 
 	if (drm_dev_enter(adev_to_drm(adev), &idx)) {
-		amdgpu_ctx_set_stable_pstate(ctx, ctx->stable_pstate);
+		mutex_lock(&adev->pm.stable_pstate_ctx_lock);
+		if (adev->pm.stable_pstate_ctx == ctx) {
+			__amdgpu_ctx_set_stable_pstate(ctx, ctx->stable_pstate);
+			adev->pm.stable_pstate_ctx = NULL;
+		}
+		mutex_unlock(&adev->pm.stable_pstate_ctx_lock);
 		drm_dev_exit(idx);
 	}
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