[PATCH v4 02/11] drm/msm/A6XX: Track current_ctx_seqno per ring

[Antonino Maniscalco <antomani103@gmail.com>]

With preemption it is not enough to track the current_ctx_seqno globally
as execution might switch between rings.

This is especially problematic when current_ctx_seqno is used to
determine whether a page table switch is necessary as it might lead to
security bugs.

Track current context per ring.

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
---
 drivers/gpu/drm/msm/adreno/a2xx_gpu.c |  2 +-
 drivers/gpu/drm/msm/adreno/a3xx_gpu.c |  2 +-
 drivers/gpu/drm/msm/adreno/a4xx_gpu.c |  2 +-
 drivers/gpu/drm/msm/adreno/a5xx_gpu.c |  6 +++---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 10 ++++++----
 drivers/gpu/drm/msm/msm_gpu.c         |  2 +-
 drivers/gpu/drm/msm/msm_gpu.h         | 11 -----------
 drivers/gpu/drm/msm/msm_ringbuffer.h  | 10 ++++++++++
 8 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a2xx_gpu.c b/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
index 0dc255ddf5ce..379a3d346c30 100644
--- a/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
@@ -22,7 +22,7 @@ static void a2xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 			break;
 		case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
 			/* ignore if there has not been a ctx switch: */
-			if (gpu->cur_ctx_seqno == submit->queue->ctx->seqno)
+			if (ring->cur_ctx_seqno == submit->queue->ctx->seqno)
 				break;
 			fallthrough;
 		case MSM_SUBMIT_CMD_BUF:
diff --git a/drivers/gpu/drm/msm/adreno/a3xx_gpu.c b/drivers/gpu/drm/msm/adreno/a3xx_gpu.c
index 5273dc849838..945fe64f835c 100644
--- a/drivers/gpu/drm/msm/adreno/a3xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a3xx_gpu.c
@@ -40,7 +40,7 @@ static void a3xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 			break;
 		case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
 			/* ignore if there has not been a ctx switch: */
-			if (gpu->cur_ctx_seqno == submit->queue->ctx->seqno)
+			if (ring->cur_ctx_seqno == submit->queue->ctx->seqno)
 				break;
 			fallthrough;
 		case MSM_SUBMIT_CMD_BUF:
diff --git a/drivers/gpu/drm/msm/adreno/a4xx_gpu.c b/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
index 8b4cdf95f445..50c490b492f0 100644
--- a/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
@@ -34,7 +34,7 @@ static void a4xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 			break;
 		case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
 			/* ignore if there has not been a ctx switch: */
-			if (gpu->cur_ctx_seqno == submit->queue->ctx->seqno)
+			if (ring->cur_ctx_seqno == submit->queue->ctx->seqno)
 				break;
 			fallthrough;
 		case MSM_SUBMIT_CMD_BUF:
diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
index c0b5373e90d7..80b441fe8e3a 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
@@ -75,7 +75,7 @@ static void a5xx_submit_in_rb(struct msm_gpu *gpu, struct msm_gem_submit *submit
 		case MSM_SUBMIT_CMD_IB_TARGET_BUF:
 			break;
 		case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
-			if (gpu->cur_ctx_seqno == submit->queue->ctx->seqno)
+			if (ring->cur_ctx_seqno == submit->queue->ctx->seqno)
 				break;
 			fallthrough;
 		case MSM_SUBMIT_CMD_BUF:
@@ -129,7 +129,7 @@ static void a5xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	unsigned int i, ibs = 0;
 
 	if (IS_ENABLED(CONFIG_DRM_MSM_GPU_SUDO) && submit->in_rb) {
-		gpu->cur_ctx_seqno = 0;
+		ring->cur_ctx_seqno = 0;
 		a5xx_submit_in_rb(gpu, submit);
 		return;
 	}
@@ -164,7 +164,7 @@ static void a5xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 		case MSM_SUBMIT_CMD_IB_TARGET_BUF:
 			break;
 		case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
-			if (gpu->cur_ctx_seqno == submit->queue->ctx->seqno)
+			if (ring->cur_ctx_seqno == submit->queue->ctx->seqno)
 				break;
 			fallthrough;
 		case MSM_SUBMIT_CMD_BUF:
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 32a4faa93d7f..6e065500b64d 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -109,7 +109,7 @@ static void a6xx_set_pagetable(struct a6xx_gpu *a6xx_gpu,
 	u32 asid;
 	u64 memptr = rbmemptr(ring, ttbr0);
 
-	if (ctx->seqno == a6xx_gpu->base.base.cur_ctx_seqno)
+	if (ctx->seqno == ring->cur_ctx_seqno)
 		return;
 
 	if (msm_iommu_pagetable_params(ctx->aspace->mmu, &ttbr, &asid))
@@ -219,7 +219,7 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 		case MSM_SUBMIT_CMD_IB_TARGET_BUF:
 			break;
 		case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
-			if (gpu->cur_ctx_seqno == submit->queue->ctx->seqno)
+			if (ring->cur_ctx_seqno == submit->queue->ctx->seqno)
 				break;
 			fallthrough;
 		case MSM_SUBMIT_CMD_BUF:
@@ -305,7 +305,7 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 		case MSM_SUBMIT_CMD_IB_TARGET_BUF:
 			break;
 		case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
-			if (gpu->cur_ctx_seqno == submit->queue->ctx->seqno)
+			if (ring->cur_ctx_seqno == submit->queue->ctx->seqno)
 				break;
 			fallthrough;
 		case MSM_SUBMIT_CMD_BUF:
@@ -843,6 +843,7 @@ static int hw_init(struct msm_gpu *gpu)
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 	struct a6xx_gmu *gmu = &a6xx_gpu->gmu;
 	u64 gmem_range_min;
+	unsigned int i;
 	int ret;
 
 	if (!adreno_has_gmu_wrapper(adreno_gpu)) {
@@ -1138,7 +1139,8 @@ static int hw_init(struct msm_gpu *gpu)
 	/* Always come up on rb 0 */
 	a6xx_gpu->cur_ring = gpu->rb[0];
 
-	gpu->cur_ctx_seqno = 0;
+	for (i = 0; i < gpu->nr_rings; i++)
+		gpu->rb[i]->cur_ctx_seqno = 0;
 
 	/* Enable the SQE_to start the CP engine */
 	gpu_write(gpu, REG_A6XX_CP_SQE_CNTL, 1);
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 3666b42b4ecd..c063b3896dc1 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -783,7 +783,7 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	mutex_unlock(&gpu->active_lock);
 
 	gpu->funcs->submit(gpu, submit);
-	gpu->cur_ctx_seqno = submit->queue->ctx->seqno;
+	submit->ring->cur_ctx_seqno = submit->queue->ctx->seqno;
 
 	pm_runtime_put(&gpu->pdev->dev);
 	hangcheck_timer_reset(gpu);
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 1f02bb9956be..7cabc8480d7c 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -193,17 +193,6 @@ struct msm_gpu {
 	 */
 	refcount_t sysprof_active;
 
-	/**
-	 * cur_ctx_seqno:
-	 *
-	 * The ctx->seqno value of the last context to submit rendering,
-	 * and the one with current pgtables installed (for generations
-	 * that support per-context pgtables).  Tracked by seqno rather
-	 * than pointer value to avoid dangling pointers, and cases where
-	 * a ctx can be freed and a new one created with the same address.
-	 */
-	int cur_ctx_seqno;
-
 	/**
 	 * lock:
 	 *
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
index 40791b2ade46..174f83137a49 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.h
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
@@ -100,6 +100,16 @@ struct msm_ringbuffer {
 	 * preemption.  Can be aquired from irq context.
 	 */
 	spinlock_t preempt_lock;
+
+	/**
+	 * cur_ctx_seqno:
+	 *
+	 * The ctx->seqno value of the last context to submit to this ring
+	 * Tracked by seqno rather than pointer value to avoid dangling
+	 * pointers, and cases where a ctx can be freed and a new one created
+	 * with the same address.
+	 */
+	int cur_ctx_seqno;
 };
 
 struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id,

-- 
2.46.0