[PATCH v2 0/9] Preemption support for A7XX

[PATCH v2 0/9] Preemption support for A7XX

[Antonino Maniscalco]

This series implements preemption for A7XX targets, which allows the GPU to
switch to an higher priority ring when work is pushed to it, reducing latency
for high priority submissions.

This series enables L1 preemption with skip_save_restore which requires
the following userspace patches to function:

https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30544

A flag is added to `msm_submitqueue_create` to only allow submissions
from compatible userspace to be preempted, therefore maintaining
compatibility.

Some commits from this series are based on a previous series to enable
preemption on A6XX targets:

https://lkml.kernel.org/1520489185-21828-1-git-send-email-smasetty@codeaurora.org

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
---
Changes in v2:
- Added preept_record_size for X185 in PATCH 3/7
- Added patches to reset perf counters
- Dropped unused defines
- Dropped unused variable (fixes warning)
- Only enable preemption on a750
- Reject MSM_SUBMITQUEUE_ALLOW_PREEMPT for unsupported targets
- Added Akhil's Reviewed-By tags to patches 1/9,2/9,3/9
- Added Neil's Tested-By tags
- Added explanation for UAPI changes in commit message
- Link to v1: https://lore.kernel.org/r/20240815-preemption-a750-t-v1-0-7bda26c34037@gmail.com

---
Antonino Maniscalco (9):
      drm/msm: Fix bv_fence being used as bv_rptr
      drm/msm: Add submitqueue setup and close
      drm/msm: Add a `preempt_record_size` field
      drm/msm/A6xx: Implement preemption for A7XX targets
      drm/msm/A6xx: Sync relevant adreno_pm4.xml changes
      drm/msm/A6xx: Use posamble to reset counters on preemption
      drm/msm/A6xx: Add traces for preemption
      drm/msm/A6XX: Add a flag to allow preemption to submitqueue_create
      drm/msm/A6xx: Enable preemption for A750

 drivers/gpu/drm/msm/Makefile                       |   1 +
 drivers/gpu/drm/msm/adreno/a6xx_catalog.c          |   4 +
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c              | 353 +++++++++++++++-
 drivers/gpu/drm/msm/adreno/a6xx_gpu.h              | 174 ++++++++
 drivers/gpu/drm/msm/adreno/a6xx_preempt.c          | 462 +++++++++++++++++++++
 drivers/gpu/drm/msm/adreno/adreno_gpu.h            |   8 +-
 drivers/gpu/drm/msm/msm_gpu.h                      |   7 +
 drivers/gpu/drm/msm/msm_gpu_trace.h                |  28 ++
 drivers/gpu/drm/msm/msm_ringbuffer.h               |   8 +
 drivers/gpu/drm/msm/msm_submitqueue.c              |  13 +
 .../gpu/drm/msm/registers/adreno/adreno_pm4.xml    |  39 +-
 include/uapi/drm/msm_drm.h                         |   5 +-
 12 files changed, 1062 insertions(+), 40 deletions(-)
---
base-commit: 7c626ce4bae1ac14f60076d00eafe71af30450ba
change-id: 20240815-preemption-a750-t-fcee9a844b39

Best regards,
-- 
Antonino Maniscalco <antomani103@gmail.com>

[PATCH v2 1/9] drm/msm: Fix bv_fence being used as bv_rptr

[Antonino Maniscalco]

The bv_fence field of rbmemptrs was being used incorrectly as the BV
rptr shadow pointer in some places.

Add a bv_rptr field and change the code to use that instead.

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 2 +-
 drivers/gpu/drm/msm/msm_ringbuffer.h  | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index bcaec86ac67a..32a4faa93d7f 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1132,7 +1132,7 @@ static int hw_init(struct msm_gpu *gpu)
 	/* ..which means "always" on A7xx, also for BV shadow */
 	if (adreno_is_a7xx(adreno_gpu)) {
 		gpu_write64(gpu, REG_A7XX_CP_BV_RB_RPTR_ADDR,
-			    rbmemptr(gpu->rb[0], bv_fence));
+			    rbmemptr(gpu->rb[0], bv_rptr));
 	}
 
 	/* Always come up on rb 0 */
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
index 0d6beb8cd39a..40791b2ade46 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.h
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
@@ -31,6 +31,7 @@ struct msm_rbmemptrs {
 	volatile uint32_t rptr;
 	volatile uint32_t fence;
 	/* Introduced on A7xx */
+	volatile uint32_t bv_rptr;
 	volatile uint32_t bv_fence;
 
 	volatile struct msm_gpu_submit_stats stats[MSM_GPU_SUBMIT_STATS_COUNT];

-- 
2.46.0

[PATCH v2 2/9] drm/msm: Add submitqueue setup and close

[Antonino Maniscalco]

This patch adds a bit of infrastructure to give the different Adreno
targets the flexibility to setup the submitqueues per their needs.

Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/msm_gpu.h         |  7 +++++++
 drivers/gpu/drm/msm/msm_submitqueue.c | 10 ++++++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index 1f02bb9956be..70f5c18e5aee 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -92,6 +92,10 @@ struct msm_gpu_funcs {
 	 * for cmdstream that is buffered in this FIFO upstream of the CP fw.
 	 */
 	bool (*progress)(struct msm_gpu *gpu, struct msm_ringbuffer *ring);
+	int (*submitqueue_setup)(struct msm_gpu *gpu,
+			struct msm_gpu_submitqueue *queue);
+	void (*submitqueue_close)(struct msm_gpu *gpu,
+			struct msm_gpu_submitqueue *queue);
 };
 
 /* Additional state for iommu faults: */
@@ -522,6 +526,9 @@ struct msm_gpu_submitqueue {
 	struct mutex lock;
 	struct kref ref;
 	struct drm_sched_entity *entity;
+	struct msm_gpu *gpu;
+	struct drm_gem_object *bo;
+	uint64_t bo_iova;
 };
 
 struct msm_gpu_state_bo {
diff --git a/drivers/gpu/drm/msm/msm_submitqueue.c b/drivers/gpu/drm/msm/msm_submitqueue.c
index 0e803125a325..4ffb336d9a60 100644
--- a/drivers/gpu/drm/msm/msm_submitqueue.c
+++ b/drivers/gpu/drm/msm/msm_submitqueue.c
@@ -71,6 +71,11 @@ void msm_submitqueue_destroy(struct kref *kref)
 	struct msm_gpu_submitqueue *queue = container_of(kref,
 		struct msm_gpu_submitqueue, ref);
 
+	struct msm_gpu *gpu = queue->gpu;
+
+	if (gpu && gpu->funcs->submitqueue_close)
+		gpu->funcs->submitqueue_close(gpu, queue);
+
 	idr_destroy(&queue->fence_idr);
 
 	msm_file_private_put(queue->ctx);
@@ -160,6 +165,7 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx,
 {
 	struct msm_drm_private *priv = drm->dev_private;
 	struct msm_gpu_submitqueue *queue;
+	struct msm_gpu *gpu = priv->gpu;
 	enum drm_sched_priority sched_prio;
 	unsigned ring_nr;
 	int ret;
@@ -195,6 +201,7 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx,
 
 	queue->ctx = msm_file_private_get(ctx);
 	queue->id = ctx->queueid++;
+	queue->gpu = gpu;
 
 	if (id)
 		*id = queue->id;
@@ -207,6 +214,9 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx,
 
 	write_unlock(&ctx->queuelock);
 
+	if (gpu && gpu->funcs->submitqueue_setup)
+		gpu->funcs->submitqueue_setup(gpu, queue);
+
 	return 0;
 }
 

-- 
2.46.0

[PATCH v2 3/9] drm/msm: Add a `preempt_record_size` field

[Antonino Maniscalco]

Adds a field to `adreno_info` to store the GPU specific preempt record
size.

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/adreno/a6xx_catalog.c | 4 ++++
 drivers/gpu/drm/msm/adreno/adreno_gpu.h   | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
index 68ba9aed5506..316f23ca9167 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
@@ -1190,6 +1190,7 @@ static const struct adreno_info a7xx_gpus[] = {
 			.protect = &a730_protect,
 		},
 		.address_space_size = SZ_16G,
+		.preempt_record_size = 2860 * SZ_1K,
 	}, {
 		.chip_ids = ADRENO_CHIP_IDS(0x43050a01), /* "C510v2" */
 		.family = ADRENO_7XX_GEN2,
@@ -1209,6 +1210,7 @@ static const struct adreno_info a7xx_gpus[] = {
 			.gmu_chipid = 0x7020100,
 		},
 		.address_space_size = SZ_16G,
+		.preempt_record_size = 4192 * SZ_1K,
 	}, {
 		.chip_ids = ADRENO_CHIP_IDS(0x43050c01), /* "C512v2" */
 		.family = ADRENO_7XX_GEN2,
@@ -1227,6 +1229,7 @@ static const struct adreno_info a7xx_gpus[] = {
 			.gmu_chipid = 0x7050001,
 		},
 		.address_space_size = SZ_256G,
+		.preempt_record_size = 4192 * SZ_1K,
 	}, {
 		.chip_ids = ADRENO_CHIP_IDS(0x43051401), /* "C520v2" */
 		.family = ADRENO_7XX_GEN3,
@@ -1245,6 +1248,7 @@ static const struct adreno_info a7xx_gpus[] = {
 			.gmu_chipid = 0x7090100,
 		},
 		.address_space_size = SZ_16G,
+		.preempt_record_size = 3572 * SZ_1K,
 	}
 };
 DECLARE_ADRENO_GPULIST(a7xx);
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
index 1ab523a163a0..6b1888280a83 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
@@ -111,6 +111,7 @@ struct adreno_info {
 	 * {SHRT_MAX, 0} sentinal.
 	 */
 	struct adreno_speedbin *speedbins;
+	u64 preempt_record_size;
 };
 
 #define ADRENO_CHIP_IDS(tbl...) (uint32_t[]) { tbl, 0 }

-- 
2.46.0

[PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Antonino Maniscalco]

This patch implements preemption feature for A6xx targets, this allows
the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
hardware as such supports multiple levels of preemption granularities,
ranging from coarse grained(ringbuffer level) to a more fine grained
such as draw-call level or a bin boundary level preemption. This patch
enables the basic preemption level, with more fine grained preemption
support to follow.

Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/Makefile              |   1 +
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
 drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
 drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
 5 files changed, 921 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
index f5e2838c6a76..32e915109a59 100644
--- a/drivers/gpu/drm/msm/Makefile
+++ b/drivers/gpu/drm/msm/Makefile
@@ -23,6 +23,7 @@ adreno-y := \
 	adreno/a6xx_gpu.o \
 	adreno/a6xx_gmu.o \
 	adreno/a6xx_hfi.o \
+	adreno/a6xx_preempt.o \
 
 adreno-$(CONFIG_DEBUG_FS) += adreno/a5xx_debugfs.o \
 
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 32a4faa93d7f..1a90db5759b8 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -16,6 +16,83 @@
 
 #define GPU_PAS_ID 13
 
+/* IFPC & Preemption static powerup restore list */
+static const uint32_t a7xx_pwrup_reglist[] = {
+	REG_A6XX_UCHE_TRAP_BASE,
+	REG_A6XX_UCHE_TRAP_BASE + 1,
+	REG_A6XX_UCHE_WRITE_THRU_BASE,
+	REG_A6XX_UCHE_WRITE_THRU_BASE + 1,
+	REG_A6XX_UCHE_GMEM_RANGE_MIN,
+	REG_A6XX_UCHE_GMEM_RANGE_MIN + 1,
+	REG_A6XX_UCHE_GMEM_RANGE_MAX,
+	REG_A6XX_UCHE_GMEM_RANGE_MAX + 1,
+	REG_A6XX_UCHE_CACHE_WAYS,
+	REG_A6XX_UCHE_MODE_CNTL,
+	REG_A6XX_RB_NC_MODE_CNTL,
+	REG_A6XX_RB_CMP_DBG_ECO_CNTL,
+	REG_A7XX_GRAS_NC_MODE_CNTL,
+	REG_A6XX_RB_CONTEXT_SWITCH_GMEM_SAVE_RESTORE,
+	REG_A6XX_UCHE_GBIF_GX_CONFIG,
+	REG_A6XX_UCHE_CLIENT_PF,
+};
+
+static const uint32_t a7xx_ifpc_pwrup_reglist[] = {
+	REG_A6XX_TPL1_NC_MODE_CNTL,
+	REG_A6XX_SP_NC_MODE_CNTL,
+	REG_A6XX_CP_DBG_ECO_CNTL,
+	REG_A6XX_CP_PROTECT_CNTL,
+	REG_A6XX_CP_PROTECT(0),
+	REG_A6XX_CP_PROTECT(1),
+	REG_A6XX_CP_PROTECT(2),
+	REG_A6XX_CP_PROTECT(3),
+	REG_A6XX_CP_PROTECT(4),
+	REG_A6XX_CP_PROTECT(5),
+	REG_A6XX_CP_PROTECT(6),
+	REG_A6XX_CP_PROTECT(7),
+	REG_A6XX_CP_PROTECT(8),
+	REG_A6XX_CP_PROTECT(9),
+	REG_A6XX_CP_PROTECT(10),
+	REG_A6XX_CP_PROTECT(11),
+	REG_A6XX_CP_PROTECT(12),
+	REG_A6XX_CP_PROTECT(13),
+	REG_A6XX_CP_PROTECT(14),
+	REG_A6XX_CP_PROTECT(15),
+	REG_A6XX_CP_PROTECT(16),
+	REG_A6XX_CP_PROTECT(17),
+	REG_A6XX_CP_PROTECT(18),
+	REG_A6XX_CP_PROTECT(19),
+	REG_A6XX_CP_PROTECT(20),
+	REG_A6XX_CP_PROTECT(21),
+	REG_A6XX_CP_PROTECT(22),
+	REG_A6XX_CP_PROTECT(23),
+	REG_A6XX_CP_PROTECT(24),
+	REG_A6XX_CP_PROTECT(25),
+	REG_A6XX_CP_PROTECT(26),
+	REG_A6XX_CP_PROTECT(27),
+	REG_A6XX_CP_PROTECT(28),
+	REG_A6XX_CP_PROTECT(29),
+	REG_A6XX_CP_PROTECT(30),
+	REG_A6XX_CP_PROTECT(31),
+	REG_A6XX_CP_PROTECT(32),
+	REG_A6XX_CP_PROTECT(33),
+	REG_A6XX_CP_PROTECT(34),
+	REG_A6XX_CP_PROTECT(35),
+	REG_A6XX_CP_PROTECT(36),
+	REG_A6XX_CP_PROTECT(37),
+	REG_A6XX_CP_PROTECT(38),
+	REG_A6XX_CP_PROTECT(39),
+	REG_A6XX_CP_PROTECT(40),
+	REG_A6XX_CP_PROTECT(41),
+	REG_A6XX_CP_PROTECT(42),
+	REG_A6XX_CP_PROTECT(43),
+	REG_A6XX_CP_PROTECT(44),
+	REG_A6XX_CP_PROTECT(45),
+	REG_A6XX_CP_PROTECT(46),
+	REG_A6XX_CP_PROTECT(47),
+	REG_A6XX_CP_AHB_CNTL,
+};
+
+
 static inline bool _a6xx_check_idle(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
@@ -68,6 +145,8 @@ static void update_shadow_rptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 
 static void a6xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 {
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 	uint32_t wptr;
 	unsigned long flags;
 
@@ -81,12 +160,26 @@ static void a6xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 	/* Make sure to wrap wptr if we need to */
 	wptr = get_wptr(ring);
 
-	spin_unlock_irqrestore(&ring->preempt_lock, flags);
-
 	/* Make sure everything is posted before making a decision */
 	mb();
 
-	gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
+	/* Update HW if this is the current ring and we are not in preempt*/
+	if (!a6xx_in_preempt(a6xx_gpu)) {
+		/*
+		 * Order the reads of the preempt state and cur_ring. This
+		 * matches the barrier after writing cur_ring.
+		 */
+		rmb();
+
+		if (a6xx_gpu->cur_ring == ring)
+			gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
+		else
+			ring->skip_inline_wptr = true;
+	} else {
+		ring->skip_inline_wptr = true;
+	}
+
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
 }
 
 static void get_stats_counter(struct msm_ringbuffer *ring, u32 counter,
@@ -138,12 +231,14 @@ static void a6xx_set_pagetable(struct a6xx_gpu *a6xx_gpu,
 
 	/*
 	 * Write the new TTBR0 to the memstore. This is good for debugging.
+	 * Needed for preemption
 	 */
-	OUT_PKT7(ring, CP_MEM_WRITE, 4);
+	OUT_PKT7(ring, CP_MEM_WRITE, 5);
 	OUT_RING(ring, CP_MEM_WRITE_0_ADDR_LO(lower_32_bits(memptr)));
 	OUT_RING(ring, CP_MEM_WRITE_1_ADDR_HI(upper_32_bits(memptr)));
 	OUT_RING(ring, lower_32_bits(ttbr));
-	OUT_RING(ring, (asid << 16) | upper_32_bits(ttbr));
+	OUT_RING(ring, upper_32_bits(ttbr));
+	OUT_RING(ring, ctx->seqno);
 
 	/*
 	 * Sync both threads after switching pagetables and enable BR only
@@ -268,12 +363,55 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	a6xx_flush(gpu, ring);
 }
 
+static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
+		struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
+{
+	u64 preempt_offset_priv_secure;
+
+	OUT_PKT7(ring, CP_SET_PSEUDO_REG, 15);
+
+	OUT_RING(ring, SMMU_INFO);
+	/* don't save SMMU, we write the record from the kernel instead */
+	OUT_RING(ring, 0);
+	OUT_RING(ring, 0);
+
+	/* privileged and non secure buffer save */
+	OUT_RING(ring, NON_SECURE_SAVE_ADDR);
+	OUT_RING(ring, lower_32_bits(
+		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE));
+	OUT_RING(ring, upper_32_bits(
+		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE));
+	OUT_RING(ring, SECURE_SAVE_ADDR);
+	preempt_offset_priv_secure =
+		PREEMPT_OFFSET_PRIV_SECURE(a6xx_gpu->base.info->preempt_record_size);
+	OUT_RING(ring, lower_32_bits(
+		a6xx_gpu->preempt_iova[ring->id] + preempt_offset_priv_secure));
+	OUT_RING(ring, upper_32_bits(
+		a6xx_gpu->preempt_iova[ring->id] + preempt_offset_priv_secure));
+
+	/* user context buffer save */
+	OUT_RING(ring, NON_PRIV_SAVE_ADDR);
+	if (queue) {
+		OUT_RING(ring, lower_32_bits(queue->bo_iova));
+		OUT_RING(ring, upper_32_bits(queue->bo_iova));
+	} else {
+		OUT_RING(ring, 0);
+		OUT_RING(ring, 0);
+	}
+
+	OUT_RING(ring, COUNTER);
+	/* seems OK to set to 0 to disable it */
+	OUT_RING(ring, 0);
+	OUT_RING(ring, 0);
+}
+
 static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 {
 	unsigned int index = submit->seqno % MSM_GPU_SUBMIT_STATS_COUNT;
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 	struct msm_ringbuffer *ring = submit->ring;
+	uint64_t scratch_dest = SCRATCH_USER_CTX_IOVA(ring->id, a6xx_gpu);
 	unsigned int i, ibs = 0;
 
 	/*
@@ -283,6 +421,25 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	OUT_PKT7(ring, CP_THREAD_CONTROL, 1);
 	OUT_RING(ring, CP_THREAD_CONTROL_0_SYNC_THREADS | CP_SET_THREAD_BR);
 
+	/*
+	 * If preemption is enabled, then set the pseudo register for the save
+	 * sequence
+	 */
+	if (gpu->nr_rings > 1) {
+		a6xx_emit_set_pseudo_reg(ring, a6xx_gpu, submit->queue);
+
+		/*
+		 * Ask CP to save the user context buffer's iova address to a
+		 * scratch memory region, this is needed if the CP preempts
+		 * this ring in between this submit's IB list.
+		 */
+		OUT_PKT7(ring, CP_MEM_WRITE, 4);
+		OUT_RING(ring, lower_32_bits(scratch_dest));
+		OUT_RING(ring, upper_32_bits(scratch_dest));
+		OUT_RING(ring, lower_32_bits(submit->queue->bo_iova));
+		OUT_RING(ring, upper_32_bits(submit->queue->bo_iova));
+	}
+
 	a6xx_set_pagetable(a6xx_gpu, ring, submit->queue->ctx);
 
 	get_stats_counter(ring, REG_A7XX_RBBM_PERFCTR_CP(0),
@@ -376,6 +533,8 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	OUT_RING(ring, upper_32_bits(rbmemptr(ring, bv_fence)));
 	OUT_RING(ring, submit->seqno);
 
+	a6xx_gpu->last_seqno[ring->id] = submit->seqno;
+
 	/* write the ringbuffer timestamp */
 	OUT_PKT7(ring, CP_EVENT_WRITE, 4);
 	OUT_RING(ring, CACHE_CLEAN | CP_EVENT_WRITE_0_IRQ | BIT(27));
@@ -389,10 +548,42 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	OUT_PKT7(ring, CP_SET_MARKER, 1);
 	OUT_RING(ring, 0x100); /* IFPC enable */
 
+	/* If preemption is enabled */
+	if (gpu->nr_rings > 1) {
+		/*
+		 * Reset the scratch region as we are done with the
+		 * IB list of this submission
+		 */
+		OUT_PKT7(ring, CP_MEM_WRITE, 4);
+		OUT_RING(ring, lower_32_bits(scratch_dest));
+		OUT_RING(ring, upper_32_bits(scratch_dest));
+		OUT_RING(ring, 0x00);
+		OUT_RING(ring, 0x00);
+
+		/* Yield the floor on command completion */
+		OUT_PKT7(ring, CP_CONTEXT_SWITCH_YIELD, 4);
+
+		/*
+		 * If dword[2:1] are non zero, they specify an address for
+		 * the CP to write the value of dword[3] to on preemption
+		 * complete. Write 0 to skip the write
+		 */
+		OUT_RING(ring, 0x00);
+		OUT_RING(ring, 0x00);
+		/* Data value - not used if the address above is 0 */
+		OUT_RING(ring, 0x01);
+		/* generate interrupt on preemption completion */
+		OUT_RING(ring, 0x00);
+	}
+
+
 	trace_msm_gpu_submit_flush(submit,
 		gpu_read64(gpu, REG_A6XX_CP_ALWAYS_ON_COUNTER));
 
 	a6xx_flush(gpu, ring);
+
+	/* Check to see if we need to start preemption */
+	a6xx_preempt_trigger(gpu);
 }
 
 static void a6xx_set_hwcg(struct msm_gpu *gpu, bool state)
@@ -588,6 +779,89 @@ static void a6xx_set_ubwc_config(struct msm_gpu *gpu)
 		  adreno_gpu->ubwc_config.min_acc_len << 23 | hbb_lo << 21);
 }
 
+static void a7xx_patch_pwrup_reglist(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	struct adreno_reglist_list reglist[2];
+	void *ptr = a6xx_gpu->pwrup_reglist_ptr;
+	struct cpu_gpu_lock *lock = ptr;
+	u32 *dest = (u32 *)&lock->regs[0];
+	int i, j;
+
+	lock->gpu_req = lock->cpu_req = lock->turn = 0;
+	lock->ifpc_list_len = ARRAY_SIZE(a7xx_ifpc_pwrup_reglist);
+	lock->preemption_list_len = ARRAY_SIZE(a7xx_pwrup_reglist);
+
+	/* Static IFPC-only registers */
+	reglist[0].regs = a7xx_ifpc_pwrup_reglist;
+	reglist[0].count = ARRAY_SIZE(a7xx_ifpc_pwrup_reglist);
+	lock->ifpc_list_len = reglist[0].count;
+
+	/* Static IFPC + preemption registers */
+	reglist[1].regs = a7xx_pwrup_reglist;
+	reglist[1].count = ARRAY_SIZE(a7xx_pwrup_reglist);
+	lock->preemption_list_len = reglist[1].count;
+
+	/*
+	 * For each entry in each of the lists, write the offset and the current
+	 * register value into the GPU buffer
+	 */
+	for (i = 0; i < 2; i++) {
+		const u32 *r = reglist[i].regs;
+
+		for (j = 0; j < reglist[i].count; j++) {
+			*dest++ = r[j];
+			*dest++ = gpu_read(gpu, r[j]);
+		}
+	}
+
+	/*
+	 * The overall register list is composed of
+	 * 1. Static IFPC-only registers
+	 * 2. Static IFPC + preemption registers
+	 * 3. Dynamic IFPC + preemption registers (ex: perfcounter selects)
+	 *
+	 * The first two lists are static. Size of these lists are stored as
+	 * number of pairs in ifpc_list_len and preemption_list_len
+	 * respectively. With concurrent binning, Some of the perfcounter
+	 * registers being virtualized, CP needs to know the pipe id to program
+	 * the aperture inorder to restore the same. Thus, third list is a
+	 * dynamic list with triplets as
+	 * (<aperture, shifted 12 bits> <address> <data>), and the length is
+	 * stored as number for triplets in dynamic_list_len.
+	 */
+	lock->dynamic_list_len = 0;
+}
+
+static int a7xx_preempt_start(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	struct msm_ringbuffer *ring = gpu->rb[0];
+
+	if (gpu->nr_rings <= 1)
+		return 0;
+
+	/* Turn CP protection off */
+	OUT_PKT7(ring, CP_SET_PROTECTED_MODE, 1);
+	OUT_RING(ring, 0);
+
+	a6xx_emit_set_pseudo_reg(ring, a6xx_gpu, NULL);
+
+	/* Yield the floor on command completion */
+	OUT_PKT7(ring, CP_CONTEXT_SWITCH_YIELD, 4);
+	OUT_RING(ring, 0x00);
+	OUT_RING(ring, 0x00);
+	OUT_RING(ring, 0x01);
+	/* Generate interrupt on preemption completion */
+	OUT_RING(ring, 0x00);
+
+	a6xx_flush(gpu, ring);
+
+	return a6xx_idle(gpu, ring) ? 0 : -EINVAL;
+}
+
 static int a6xx_cp_init(struct msm_gpu *gpu)
 {
 	struct msm_ringbuffer *ring = gpu->rb[0];
@@ -619,6 +893,8 @@ static int a6xx_cp_init(struct msm_gpu *gpu)
 
 static int a7xx_cp_init(struct msm_gpu *gpu)
 {
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 	struct msm_ringbuffer *ring = gpu->rb[0];
 	u32 mask;
 
@@ -626,6 +902,8 @@ static int a7xx_cp_init(struct msm_gpu *gpu)
 	OUT_PKT7(ring, CP_THREAD_CONTROL, 1);
 	OUT_RING(ring, BIT(27));
 
+	a7xx_patch_pwrup_reglist(gpu);
+
 	OUT_PKT7(ring, CP_ME_INIT, 7);
 
 	/* Use multiple HW contexts */
@@ -656,11 +934,11 @@ static int a7xx_cp_init(struct msm_gpu *gpu)
 
 	/* *Don't* send a power up reg list for concurrent binning (TODO) */
 	/* Lo address */
-	OUT_RING(ring, 0x00000000);
+	OUT_RING(ring, lower_32_bits(a6xx_gpu->pwrup_reglist_iova));
 	/* Hi address */
-	OUT_RING(ring, 0x00000000);
+	OUT_RING(ring, upper_32_bits(a6xx_gpu->pwrup_reglist_iova));
 	/* BIT(31) set => read the regs from the list */
-	OUT_RING(ring, 0x00000000);
+	OUT_RING(ring, BIT(31));
 
 	a6xx_flush(gpu, ring);
 	return a6xx_idle(gpu, ring) ? 0 : -EINVAL;
@@ -784,6 +1062,16 @@ static int a6xx_ucode_load(struct msm_gpu *gpu)
 		msm_gem_object_set_name(a6xx_gpu->shadow_bo, "shadow");
 	}
 
+	a6xx_gpu->pwrup_reglist_ptr = msm_gem_kernel_new(gpu->dev, PAGE_SIZE,
+							 MSM_BO_WC  | MSM_BO_MAP_PRIV,
+							 gpu->aspace, &a6xx_gpu->pwrup_reglist_bo,
+							 &a6xx_gpu->pwrup_reglist_iova);
+
+	if (IS_ERR(a6xx_gpu->pwrup_reglist_ptr))
+		return PTR_ERR(a6xx_gpu->pwrup_reglist_ptr);
+
+	msm_gem_object_set_name(a6xx_gpu->pwrup_reglist_bo, "pwrup_reglist");
+
 	return 0;
 }
 
@@ -1127,6 +1415,8 @@ static int hw_init(struct msm_gpu *gpu)
 	if (a6xx_gpu->shadow_bo) {
 		gpu_write64(gpu, REG_A6XX_CP_RB_RPTR_ADDR,
 			shadowptr(a6xx_gpu, gpu->rb[0]));
+		for (unsigned int i = 0; i < gpu->nr_rings; i++)
+			a6xx_gpu->shadow[i] = 0;
 	}
 
 	/* ..which means "always" on A7xx, also for BV shadow */
@@ -1135,6 +1425,8 @@ static int hw_init(struct msm_gpu *gpu)
 			    rbmemptr(gpu->rb[0], bv_rptr));
 	}
 
+	a6xx_preempt_hw_init(gpu);
+
 	/* Always come up on rb 0 */
 	a6xx_gpu->cur_ring = gpu->rb[0];
 
@@ -1180,6 +1472,10 @@ static int hw_init(struct msm_gpu *gpu)
 out:
 	if (adreno_has_gmu_wrapper(adreno_gpu))
 		return ret;
+
+	/* Last step - yield the ringbuffer */
+	a7xx_preempt_start(gpu);
+
 	/*
 	 * Tell the GMU that we are done touching the GPU and it can start power
 	 * management
@@ -1557,8 +1853,13 @@ static irqreturn_t a6xx_irq(struct msm_gpu *gpu)
 	if (status & A6XX_RBBM_INT_0_MASK_SWFUSEVIOLATION)
 		a7xx_sw_fuse_violation_irq(gpu);
 
-	if (status & A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS)
+	if (status & A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS) {
 		msm_gpu_retire(gpu);
+		a6xx_preempt_trigger(gpu);
+	}
+
+	if (status & A6XX_RBBM_INT_0_MASK_CP_SW)
+		a6xx_preempt_irq(gpu);
 
 	return IRQ_HANDLED;
 }
@@ -2165,6 +2466,8 @@ static const struct adreno_gpu_funcs funcs = {
 		.active_ring = a6xx_active_ring,
 		.irq = a6xx_irq,
 		.destroy = a6xx_destroy,
+		.submitqueue_setup = a6xx_preempt_submitqueue_setup,
+		.submitqueue_close = a6xx_preempt_submitqueue_close,
 #if defined(CONFIG_DRM_MSM_GPU_STATE)
 		.show = a6xx_show,
 #endif
@@ -2331,6 +2634,8 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
 				a6xx_fault_handler);
 
 	a6xx_calc_ubwc_config(adreno_gpu);
+	/* Set up the preemption specific bits and pieces for each ringbuffer */
+	a6xx_preempt_init(gpu);
 
 	return gpu;
 }
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
index e3e5c53ae8af..652e49f01428 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
@@ -12,6 +12,31 @@
 
 extern bool hang_debug;
 
+struct cpu_gpu_lock {
+	uint32_t gpu_req;
+	uint32_t cpu_req;
+	uint32_t turn;
+	union {
+		struct {
+			uint16_t list_length;
+			uint16_t list_offset;
+		};
+		struct {
+			uint8_t ifpc_list_len;
+			uint8_t preemption_list_len;
+			uint16_t dynamic_list_len;
+		};
+	};
+	uint64_t regs[62];
+};
+
+struct adreno_reglist_list {
+	/** @reg: List of register **/
+	const u32 *regs;
+	/** @count: Number of registers in the list **/
+	u32 count;
+};
+
 /**
  * struct a6xx_info - a6xx specific information from device table
  *
@@ -31,6 +56,24 @@ struct a6xx_gpu {
 	uint64_t sqe_iova;
 
 	struct msm_ringbuffer *cur_ring;
+	struct msm_ringbuffer *next_ring;
+
+	struct drm_gem_object *preempt_bo[MSM_GPU_MAX_RINGS];
+	void *preempt[MSM_GPU_MAX_RINGS];
+	uint64_t preempt_iova[MSM_GPU_MAX_RINGS];
+	uint32_t last_seqno[MSM_GPU_MAX_RINGS];
+
+	atomic_t preempt_state;
+	spinlock_t eval_lock;
+	struct timer_list preempt_timer;
+
+	unsigned int preempt_level;
+	bool uses_gmem;
+	bool skip_save_restore;
+
+	struct drm_gem_object *scratch_bo;
+	void *scratch_ptr;
+	uint64_t scratch_iova;
 
 	struct a6xx_gmu gmu;
 
@@ -38,6 +81,10 @@ struct a6xx_gpu {
 	uint64_t shadow_iova;
 	uint32_t *shadow;
 
+	struct drm_gem_object *pwrup_reglist_bo;
+	void *pwrup_reglist_ptr;
+	uint64_t pwrup_reglist_iova;
+
 	bool has_whereami;
 
 	void __iomem *llc_mmio;
@@ -49,6 +96,108 @@ struct a6xx_gpu {
 
 #define to_a6xx_gpu(x) container_of(x, struct a6xx_gpu, base)
 
+#define SCRATCH_USER_CTX_IOVA(ring_id, a6xx_gpu) \
+	(a6xx_gpu->scratch_iova + (ring_id * sizeof(uint64_t)))
+
+/*
+ * In order to do lockless preemption we use a simple state machine to progress
+ * through the process.
+ *
+ * PREEMPT_NONE - no preemption in progress.  Next state START.
+ * PREEMPT_START - The trigger is evaluating if preemption is possible. Next
+ * states: TRIGGERED, NONE
+ * PREEMPT_FINISH - An intermediate state before moving back to NONE. Next
+ * state: NONE.
+ * PREEMPT_TRIGGERED: A preemption has been executed on the hardware. Next
+ * states: FAULTED, PENDING
+ * PREEMPT_FAULTED: A preemption timed out (never completed). This will trigger
+ * recovery.  Next state: N/A
+ * PREEMPT_PENDING: Preemption complete interrupt fired - the callback is
+ * checking the success of the operation. Next state: FAULTED, NONE.
+ */
+
+enum a6xx_preempt_state {
+	PREEMPT_NONE = 0,
+	PREEMPT_START,
+	PREEMPT_FINISH,
+	PREEMPT_TRIGGERED,
+	PREEMPT_FAULTED,
+	PREEMPT_PENDING,
+};
+
+/*
+ * struct a6xx_preempt_record is a shared buffer between the microcode and the
+ * CPU to store the state for preemption. The record itself is much larger
+ * (2112k) but most of that is used by the CP for storage.
+ *
+ * There is a preemption record assigned per ringbuffer. When the CPU triggers a
+ * preemption, it fills out the record with the useful information (wptr, ring
+ * base, etc) and the microcode uses that information to set up the CP following
+ * the preemption.  When a ring is switched out, the CP will save the ringbuffer
+ * state back to the record. In this way, once the records are properly set up
+ * the CPU can quickly switch back and forth between ringbuffers by only
+ * updating a few registers (often only the wptr).
+ *
+ * These are the CPU aware registers in the record:
+ * @magic: Must always be 0xAE399D6EUL
+ * @info: Type of the record - written 0 by the CPU, updated by the CP
+ * @errno: preemption error record
+ * @data: Data field in YIELD and SET_MARKER packets, Written and used by CP
+ * @cntl: Value of RB_CNTL written by CPU, save/restored by CP
+ * @rptr: Value of RB_RPTR written by CPU, save/restored by CP
+ * @wptr: Value of RB_WPTR written by CPU, save/restored by CP
+ * @_pad: Reserved/padding
+ * @rptr_addr: Value of RB_RPTR_ADDR_LO|HI written by CPU, save/restored by CP
+ * @rbase: Value of RB_BASE written by CPU, save/restored by CP
+ * @counter: GPU address of the storage area for the preemption counters
+ */
+struct a6xx_preempt_record {
+	u32 magic;
+	u32 info;
+	u32 errno;
+	u32 data;
+	u32 cntl;
+	u32 rptr;
+	u32 wptr;
+	u32 _pad;
+	u64 rptr_addr;
+	u64 rbase;
+	u64 counter;
+	u64 bv_rptr_addr;
+};
+
+#define A6XX_PREEMPT_RECORD_MAGIC 0xAE399D6EUL
+
+#define PREEMPT_RECORD_SIZE_FALLBACK(size) \
+	((size) == 0 ? 4192 * SZ_1K : (size))
+
+#define PREEMPT_OFFSET_SMMU_INFO 0
+#define PREEMPT_OFFSET_PRIV_NON_SECURE (PREEMPT_OFFSET_SMMU_INFO + 4096)
+#define PREEMPT_OFFSET_PRIV_SECURE(size) \
+	(PREEMPT_OFFSET_PRIV_NON_SECURE + PREEMPT_RECORD_SIZE_FALLBACK(size))
+#define PREEMPT_SIZE(size) \
+	(PREEMPT_OFFSET_PRIV_SECURE(size) + PREEMPT_RECORD_SIZE_FALLBACK(size))
+
+/*
+ * The preemption counter block is a storage area for the value of the
+ * preemption counters that are saved immediately before context switch. We
+ * append it on to the end of the allocation for the preemption record.
+ */
+#define A6XX_PREEMPT_COUNTER_SIZE (16 * 4)
+
+#define A6XX_PREEMPT_USER_RECORD_SIZE (192 * 1024)
+
+struct a7xx_cp_smmu_info {
+	u32 magic;
+	u32 _pad4;
+	u64 ttbr0;
+	u32 asid;
+	u32 context_idr;
+	u32 context_bank;
+};
+
+#define GEN7_CP_SMMU_INFO_MAGIC 0x241350d5UL
+
 /*
  * Given a register and a count, return a value to program into
  * REG_CP_PROTECT_REG(n) - this will block both reads and writes for
@@ -106,6 +255,25 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node);
 int a6xx_gmu_wrapper_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node);
 void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu);
 
+void a6xx_preempt_init(struct msm_gpu *gpu);
+void a6xx_preempt_hw_init(struct msm_gpu *gpu);
+void a6xx_preempt_trigger(struct msm_gpu *gpu);
+void a6xx_preempt_irq(struct msm_gpu *gpu);
+void a6xx_preempt_fini(struct msm_gpu *gpu);
+int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
+		struct msm_gpu_submitqueue *queue);
+void a6xx_preempt_submitqueue_close(struct msm_gpu *gpu,
+		struct msm_gpu_submitqueue *queue);
+
+/* Return true if we are in a preempt state */
+static inline bool a6xx_in_preempt(struct a6xx_gpu *a6xx_gpu)
+{
+	int preempt_state = atomic_read(&a6xx_gpu->preempt_state);
+
+	return !(preempt_state == PREEMPT_NONE ||
+			preempt_state == PREEMPT_FINISH);
+}
+
 void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp,
 		       bool suspended);
 unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu);
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
new file mode 100644
index 000000000000..4b61b993f75f
--- /dev/null
+++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
@@ -0,0 +1,431 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018, The Linux Foundation. All rights reserved. */
+/* Copyright (c) 2023 Collabora, Ltd. */
+/* Copyright (c) 2024 Valve Corporation */
+
+#include "msm_gem.h"
+#include "a6xx_gpu.h"
+#include "a6xx_gmu.xml.h"
+#include "msm_mmu.h"
+
+/*
+ * Try to transition the preemption state from old to new. Return
+ * true on success or false if the original state wasn't 'old'
+ */
+static inline bool try_preempt_state(struct a6xx_gpu *a6xx_gpu,
+		enum a6xx_preempt_state old, enum a6xx_preempt_state new)
+{
+	enum a6xx_preempt_state cur = atomic_cmpxchg(&a6xx_gpu->preempt_state,
+		old, new);
+
+	return (cur == old);
+}
+
+/*
+ * Force the preemption state to the specified state.  This is used in cases
+ * where the current state is known and won't change
+ */
+static inline void set_preempt_state(struct a6xx_gpu *gpu,
+		enum a6xx_preempt_state new)
+{
+	/*
+	 * preempt_state may be read by other cores trying to trigger a
+	 * preemption or in the interrupt handler so barriers are needed
+	 * before...
+	 */
+	smp_mb__before_atomic();
+	atomic_set(&gpu->preempt_state, new);
+	/* ... and after*/
+	smp_mb__after_atomic();
+}
+
+/* Write the most recent wptr for the given ring into the hardware */
+static inline void update_wptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
+{
+	unsigned long flags;
+	uint32_t wptr;
+
+	if (!ring)
+		return;
+
+	spin_lock_irqsave(&ring->preempt_lock, flags);
+
+	if (ring->skip_inline_wptr) {
+		wptr = get_wptr(ring);
+
+		gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
+
+		ring->skip_inline_wptr = false;
+	}
+
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
+}
+
+/* Return the highest priority ringbuffer with something in it */
+static struct msm_ringbuffer *get_next_ring(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+
+	unsigned long flags;
+	int i;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		bool empty;
+		struct msm_ringbuffer *ring = gpu->rb[i];
+
+		spin_lock_irqsave(&ring->preempt_lock, flags);
+		empty = (get_wptr(ring) == gpu->funcs->get_rptr(gpu, ring));
+		if (!empty && ring == a6xx_gpu->cur_ring)
+			empty = ring->memptrs->fence == a6xx_gpu->last_seqno[i];
+		spin_unlock_irqrestore(&ring->preempt_lock, flags);
+
+		if (!empty)
+			return ring;
+	}
+
+	return NULL;
+}
+
+static void a6xx_preempt_timer(struct timer_list *t)
+{
+	struct a6xx_gpu *a6xx_gpu = from_timer(a6xx_gpu, t, preempt_timer);
+	struct msm_gpu *gpu = &a6xx_gpu->base.base;
+	struct drm_device *dev = gpu->dev;
+
+	if (!try_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED, PREEMPT_FAULTED))
+		return;
+
+	dev_err(dev->dev, "%s: preemption timed out\n", gpu->name);
+	kthread_queue_work(gpu->worker, &gpu->recover_work);
+}
+
+void a6xx_preempt_irq(struct msm_gpu *gpu)
+{
+	uint32_t status;
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	struct drm_device *dev = gpu->dev;
+
+	if (!try_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED, PREEMPT_PENDING))
+		return;
+
+	/* Delete the preemption watchdog timer */
+	del_timer(&a6xx_gpu->preempt_timer);
+
+	/*
+	 * The hardware should be setting the stop bit of CP_CONTEXT_SWITCH_CNTL
+	 * to zero before firing the interrupt, but there is a non zero chance
+	 * of a hardware condition or a software race that could set it again
+	 * before we have a chance to finish. If that happens, log and go for
+	 * recovery
+	 */
+	status = gpu_read(gpu, REG_A6XX_CP_CONTEXT_SWITCH_CNTL);
+	if (unlikely(status & 0x1)) {
+		DRM_DEV_ERROR(&gpu->pdev->dev,
+					  "!!!!!!!!!!!!!!!! preemption faulted !!!!!!!!!!!!!! irq\n");
+		set_preempt_state(a6xx_gpu, PREEMPT_FAULTED);
+		dev_err(dev->dev, "%s: Preemption failed to complete\n",
+			gpu->name);
+		kthread_queue_work(gpu->worker, &gpu->recover_work);
+		return;
+	}
+
+	a6xx_gpu->cur_ring = a6xx_gpu->next_ring;
+	a6xx_gpu->next_ring = NULL;
+
+	/* Make sure the write to cur_ring is posted before the change in state */
+	wmb();
+
+	set_preempt_state(a6xx_gpu, PREEMPT_FINISH);
+
+	update_wptr(gpu, a6xx_gpu->cur_ring);
+
+	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
+
+	/*
+	 * Retrigger preemption to avoid a deadlock that might occur when preemption
+	 * is skipped due to it being already in flight when requested.
+	 */
+	a6xx_preempt_trigger(gpu);
+}
+
+void a6xx_preempt_hw_init(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	int i;
+
+	/* No preemption if we only have one ring */
+	if (gpu->nr_rings == 1)
+		return;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		struct a6xx_preempt_record *record_ptr =
+			a6xx_gpu->preempt[i] + PREEMPT_OFFSET_PRIV_NON_SECURE;
+		record_ptr->wptr = 0;
+		record_ptr->rptr = 0;
+		record_ptr->rptr_addr = shadowptr(a6xx_gpu, gpu->rb[i]);
+		record_ptr->info = 0;
+		record_ptr->data = 0;
+		record_ptr->rbase = gpu->rb[i]->iova;
+	}
+
+	/* Write a 0 to signal that we aren't switching pagetables */
+	gpu_write64(gpu, REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO, 0);
+
+	/* Enable the GMEM save/restore feature for preemption */
+	gpu_write(gpu, REG_A6XX_RB_CONTEXT_SWITCH_GMEM_SAVE_RESTORE, 0x1);
+
+	/* Reset the preemption state */
+	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
+
+	spin_lock_init(&a6xx_gpu->eval_lock);
+
+	/* Always come up on rb 0 */
+	a6xx_gpu->cur_ring = gpu->rb[0];
+}
+
+void a6xx_preempt_trigger(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	u64 preempt_offset_priv_secure;
+	unsigned long flags;
+	struct msm_ringbuffer *ring;
+	uint64_t user_ctx_iova;
+	unsigned int cntl;
+
+	if (gpu->nr_rings == 1)
+		return;
+
+	/*
+	 * Lock to make sure another thread attempting preemption doesn't skip it
+	 * while we are still evaluating the next ring. This makes sure the other
+	 * thread does start preemption if we abort it and avoids a soft lock.
+	 */
+	spin_lock_irqsave(&a6xx_gpu->eval_lock, flags);
+
+	/*
+	 * Try to start preemption by moving from NONE to START. If
+	 * unsuccessful, a preemption is already in flight
+	 */
+	if (!try_preempt_state(a6xx_gpu, PREEMPT_NONE, PREEMPT_START)) {
+		spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
+		return;
+	}
+
+	cntl = (((a6xx_gpu->preempt_level << 6) & 0xC0) |
+		((a6xx_gpu->skip_save_restore << 9) & 0x200) |
+		((a6xx_gpu->uses_gmem << 8) & 0x100) | 0x1);
+
+	/* Get the next ring to preempt to */
+	ring = get_next_ring(gpu);
+
+	/*
+	 * If no ring is populated or the highest priority ring is the current
+	 * one do nothing except to update the wptr to the latest and greatest
+	 */
+	if (!ring || (a6xx_gpu->cur_ring == ring)) {
+		set_preempt_state(a6xx_gpu, PREEMPT_FINISH);
+		update_wptr(gpu, a6xx_gpu->cur_ring);
+		set_preempt_state(a6xx_gpu, PREEMPT_NONE);
+		spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
+		return;
+	}
+
+	spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
+
+	spin_lock_irqsave(&ring->preempt_lock, flags);
+
+	struct a7xx_cp_smmu_info *smmu_info_ptr =
+		a6xx_gpu->preempt[ring->id] + PREEMPT_OFFSET_SMMU_INFO;
+	struct a6xx_preempt_record *record_ptr =
+		a6xx_gpu->preempt[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE;
+	u64 ttbr0 = ring->memptrs->ttbr0;
+	u32 context_idr = ring->memptrs->context_idr;
+
+	smmu_info_ptr->ttbr0 = ttbr0;
+	smmu_info_ptr->context_idr = context_idr;
+	record_ptr->wptr = get_wptr(ring);
+
+	/*
+	 * The GPU will write the wptr we set above when we preempt. Reset
+	 * skip_inline_wptr to make sure that we don't write WPTR to the same
+	 * thing twice. It's still possible subsequent submissions will update
+	 * wptr again, in which case they will set the flag to true. This has
+	 * to be protected by the lock for setting the flag and updating wptr
+	 * to be atomic.
+	 */
+	ring->skip_inline_wptr = false;
+
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
+
+	gpu_write64(gpu,
+		REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO,
+		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_SMMU_INFO);
+
+	gpu_write64(gpu,
+		REG_A6XX_CP_CONTEXT_SWITCH_PRIV_NON_SECURE_RESTORE_ADDR,
+		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE);
+
+	preempt_offset_priv_secure =
+		PREEMPT_OFFSET_PRIV_SECURE(adreno_gpu->info->preempt_record_size);
+	gpu_write64(gpu,
+		REG_A6XX_CP_CONTEXT_SWITCH_PRIV_SECURE_RESTORE_ADDR,
+		a6xx_gpu->preempt_iova[ring->id] + preempt_offset_priv_secure);
+
+	/*
+	 * Use the user context iova from the scratch memory that the CP may
+	 * have written as part of the ring switch out.
+	 */
+	user_ctx_iova = *((uint64_t *)a6xx_gpu->scratch_ptr + ring->id);
+
+	gpu_write64(gpu,
+		REG_A6XX_CP_CONTEXT_SWITCH_NON_PRIV_RESTORE_ADDR,
+		user_ctx_iova);
+
+	a6xx_gpu->next_ring = ring;
+
+	/* Start a timer to catch a stuck preemption */
+	mod_timer(&a6xx_gpu->preempt_timer, jiffies + msecs_to_jiffies(10000));
+
+	/* Set the preemption state to triggered */
+	set_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED);
+
+	/* Make sure any previous writes to WPTR are posted */
+	gpu_read(gpu, REG_A6XX_CP_RB_WPTR);
+
+	/* Make sure everything is written before hitting the button */
+	wmb();
+
+	/* Trigger the preemption */
+	gpu_write(gpu, REG_A6XX_CP_CONTEXT_SWITCH_CNTL, cntl);
+}
+
+static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
+		struct msm_ringbuffer *ring)
+{
+	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
+	struct msm_gpu *gpu = &adreno_gpu->base;
+	struct drm_gem_object *bo = NULL;
+	phys_addr_t ttbr;
+	u64 iova = 0;
+	void *ptr;
+	int asid;
+
+	ptr = msm_gem_kernel_new(gpu->dev,
+		PREEMPT_SIZE(adreno_gpu->info->preempt_record_size),
+		MSM_BO_WC | MSM_BO_MAP_PRIV, gpu->aspace, &bo, &iova);
+
+	memset(ptr, 0, PREEMPT_SIZE(adreno_gpu->info->preempt_record_size));
+
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	a6xx_gpu->preempt_bo[ring->id] = bo;
+	a6xx_gpu->preempt_iova[ring->id] = iova;
+	a6xx_gpu->preempt[ring->id] = ptr;
+
+	struct a7xx_cp_smmu_info *smmu_info_ptr = ptr + PREEMPT_OFFSET_SMMU_INFO;
+	struct a6xx_preempt_record *record_ptr = ptr + PREEMPT_OFFSET_PRIV_NON_SECURE;
+
+	msm_iommu_pagetable_params(gpu->aspace->mmu, &ttbr, &asid);
+
+	smmu_info_ptr->magic = GEN7_CP_SMMU_INFO_MAGIC;
+	smmu_info_ptr->ttbr0 = ttbr;
+	smmu_info_ptr->asid = 0xdecafbad;
+	smmu_info_ptr->context_idr = 0;
+
+	/* Set up the defaults on the preemption record */
+	record_ptr->magic = A6XX_PREEMPT_RECORD_MAGIC;
+	record_ptr->info = 0;
+	record_ptr->data = 0;
+	record_ptr->rptr = 0;
+	record_ptr->wptr = 0;
+	record_ptr->cntl = MSM_GPU_RB_CNTL_DEFAULT;
+	record_ptr->rbase = ring->iova;
+	record_ptr->counter = 0;
+	record_ptr->bv_rptr_addr = rbmemptr(ring, bv_rptr);
+
+	return 0;
+}
+
+void a6xx_preempt_fini(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	int i;
+
+	for (i = 0; i < gpu->nr_rings; i++)
+		msm_gem_kernel_put(a6xx_gpu->preempt_bo[i], gpu->aspace);
+}
+
+void a6xx_preempt_init(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	int i;
+
+	/* No preemption if we only have one ring */
+	if (gpu->nr_rings <= 1)
+		return;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		if (preempt_init_ring(a6xx_gpu, gpu->rb[i]))
+			goto fail;
+	}
+
+	/* TODO: make this configurable? */
+	a6xx_gpu->preempt_level = 1;
+	a6xx_gpu->uses_gmem = 1;
+	a6xx_gpu->skip_save_restore = 1;
+
+	a6xx_gpu->scratch_ptr  = msm_gem_kernel_new(gpu->dev,
+			gpu->nr_rings * sizeof(uint64_t), MSM_BO_WC,
+			gpu->aspace, &a6xx_gpu->scratch_bo,
+			&a6xx_gpu->scratch_iova);
+
+	if (IS_ERR(a6xx_gpu->scratch_ptr))
+		goto fail;
+
+	timer_setup(&a6xx_gpu->preempt_timer, a6xx_preempt_timer, 0);
+
+	return;
+fail:
+	/*
+	 * On any failure our adventure is over. Clean up and
+	 * set nr_rings to 1 to force preemption off
+	 */
+	a6xx_preempt_fini(gpu);
+	gpu->nr_rings = 1;
+
+	return;
+}
+
+void a6xx_preempt_submitqueue_close(struct msm_gpu *gpu,
+		struct msm_gpu_submitqueue *queue)
+{
+	if (!queue->bo)
+		return;
+
+	msm_gem_kernel_put(queue->bo, gpu->aspace);
+}
+
+int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
+		struct msm_gpu_submitqueue *queue)
+{
+	void *ptr;
+
+	/*
+	 * Create a per submitqueue buffer for the CP to save and restore user
+	 * specific information such as the VPC streamout data.
+	 */
+	ptr = msm_gem_kernel_new(gpu->dev, A6XX_PREEMPT_USER_RECORD_SIZE,
+			MSM_BO_WC, gpu->aspace, &queue->bo, &queue->bo_iova);
+
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
index 40791b2ade46..7dde6a312511 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.h
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
@@ -36,6 +36,7 @@ struct msm_rbmemptrs {
 
 	volatile struct msm_gpu_submit_stats stats[MSM_GPU_SUBMIT_STATS_COUNT];
 	volatile u64 ttbr0;
+	volatile u32 context_idr;
 };
 
 struct msm_cp_state {
@@ -100,6 +101,12 @@ struct msm_ringbuffer {
 	 * preemption.  Can be aquired from irq context.
 	 */
 	spinlock_t preempt_lock;
+
+	/*
+	 * Whether we skipped writing wptr and it needs to be updated in the
+	 * future when the ring becomes current.
+	 */
+	bool skip_inline_wptr;
 };
 
 struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id,

-- 
2.46.0

Re: [PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Rob Clark]

On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
<antomani103@gmail.com> wrote:
>
> This patch implements preemption feature for A6xx targets, this allows
> the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> hardware as such supports multiple levels of preemption granularities,
> ranging from coarse grained(ringbuffer level) to a more fine grained
> such as draw-call level or a bin boundary level preemption. This patch
> enables the basic preemption level, with more fine grained preemption
> support to follow.
>
> Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> ---
>  drivers/gpu/drm/msm/Makefile              |   1 +
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
>  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
>  5 files changed, 921 insertions(+), 9 deletions(-)
>

[snip]

> +
> +int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
> +               struct msm_gpu_submitqueue *queue)
> +{
> +       void *ptr;
> +
> +       /*
> +        * Create a per submitqueue buffer for the CP to save and restore user
> +        * specific information such as the VPC streamout data.
> +        */
> +       ptr = msm_gem_kernel_new(gpu->dev, A6XX_PREEMPT_USER_RECORD_SIZE,
> +                       MSM_BO_WC, gpu->aspace, &queue->bo, &queue->bo_iova);

Can this be MSM_BO_MAP_PRIV?  Otherwise it is visible (and writeable)
by other proceess's userspace generated cmdstream.

And a similar question for the scratch_bo..  I'd have to give some
thought to what sort of mischief could be had, but generall kernel
mappings that are not MAP_PRIV are a thing to be careful about.

BR,
-R

Re: [PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Connor Abbott]

On Fri, Aug 30, 2024 at 7:08 PM Rob Clark <robdclark@gmail.com> wrote:
>
> On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
> <antomani103@gmail.com> wrote:
> >
> > This patch implements preemption feature for A6xx targets, this allows
> > the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> > hardware as such supports multiple levels of preemption granularities,
> > ranging from coarse grained(ringbuffer level) to a more fine grained
> > such as draw-call level or a bin boundary level preemption. This patch
> > enables the basic preemption level, with more fine grained preemption
> > support to follow.
> >
> > Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> > Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> > Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> > ---
> >  drivers/gpu/drm/msm/Makefile              |   1 +
> >  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
> >  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
> >  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
> >  5 files changed, 921 insertions(+), 9 deletions(-)
> >
>
> [snip]
>
> > +
> > +int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
> > +               struct msm_gpu_submitqueue *queue)
> > +{
> > +       void *ptr;
> > +
> > +       /*
> > +        * Create a per submitqueue buffer for the CP to save and restore user
> > +        * specific information such as the VPC streamout data.
> > +        */
> > +       ptr = msm_gem_kernel_new(gpu->dev, A6XX_PREEMPT_USER_RECORD_SIZE,
> > +                       MSM_BO_WC, gpu->aspace, &queue->bo, &queue->bo_iova);
>
> Can this be MSM_BO_MAP_PRIV?  Otherwise it is visible (and writeable)
> by other proceess's userspace generated cmdstream.
>
> And a similar question for the scratch_bo..  I'd have to give some
> thought to what sort of mischief could be had, but generall kernel
> mappings that are not MAP_PRIV are a thing to be careful about.
>

It seems like the idea behind this is that it's supposed to be
per-context. kgsl allocates it as part of the context, as part of the
userspace address space, and then in order to know which user record
to use when preempting, before each submit (although really it only
needs to be done when setting the pagetable) it does a CP_MEM_WRITE of
the user record address to a scratch buffer holding an array of the
current user record for each ring. Then when preempting it reads the
address for the next ring from the scratch buffer and sets it. I think
we need to do that dance too.

Connor

> BR,
> -R

Re: [PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Rob Clark]

On Fri, Aug 30, 2024 at 11:54 AM Connor Abbott <cwabbott0@gmail.com> wrote:
>
> On Fri, Aug 30, 2024 at 7:08 PM Rob Clark <robdclark@gmail.com> wrote:
> >
> > On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
> > <antomani103@gmail.com> wrote:
> > >
> > > This patch implements preemption feature for A6xx targets, this allows
> > > the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> > > hardware as such supports multiple levels of preemption granularities,
> > > ranging from coarse grained(ringbuffer level) to a more fine grained
> > > such as draw-call level or a bin boundary level preemption. This patch
> > > enables the basic preemption level, with more fine grained preemption
> > > support to follow.
> > >
> > > Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> > > Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> > > Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> > > ---
> > >  drivers/gpu/drm/msm/Makefile              |   1 +
> > >  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
> > >  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
> > >  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
> > >  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
> > >  5 files changed, 921 insertions(+), 9 deletions(-)
> > >
> >
> > [snip]
> >
> > > +
> > > +int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
> > > +               struct msm_gpu_submitqueue *queue)
> > > +{
> > > +       void *ptr;
> > > +
> > > +       /*
> > > +        * Create a per submitqueue buffer for the CP to save and restore user
> > > +        * specific information such as the VPC streamout data.
> > > +        */
> > > +       ptr = msm_gem_kernel_new(gpu->dev, A6XX_PREEMPT_USER_RECORD_SIZE,
> > > +                       MSM_BO_WC, gpu->aspace, &queue->bo, &queue->bo_iova);
> >
> > Can this be MSM_BO_MAP_PRIV?  Otherwise it is visible (and writeable)
> > by other proceess's userspace generated cmdstream.
> >
> > And a similar question for the scratch_bo..  I'd have to give some
> > thought to what sort of mischief could be had, but generall kernel
> > mappings that are not MAP_PRIV are a thing to be careful about.
> >
>
> It seems like the idea behind this is that it's supposed to be
> per-context. kgsl allocates it as part of the context, as part of the
> userspace address space, and then in order to know which user record
> to use when preempting, before each submit (although really it only
> needs to be done when setting the pagetable) it does a CP_MEM_WRITE of
> the user record address to a scratch buffer holding an array of the
> current user record for each ring. Then when preempting it reads the
> address for the next ring from the scratch buffer and sets it. I think
> we need to do that dance too.

Moving it into userspace's address space (vm) would be better.

I assume the preempt record is where state is saved/restored?  So
would need to be in kernel aspace/vm?  Or is the fw changing ttbr0
after saving state but before restoring?

BR,
-R

> Connor
>
> > BR,
> > -R

Re: [PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Connor Abbott]

On Fri, Aug 30, 2024 at 8:00 PM Rob Clark <robdclark@gmail.com> wrote:
>
> On Fri, Aug 30, 2024 at 11:54 AM Connor Abbott <cwabbott0@gmail.com> wrote:
> >
> > On Fri, Aug 30, 2024 at 7:08 PM Rob Clark <robdclark@gmail.com> wrote:
> > >
> > > On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
> > > <antomani103@gmail.com> wrote:
> > > >
> > > > This patch implements preemption feature for A6xx targets, this allows
> > > > the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> > > > hardware as such supports multiple levels of preemption granularities,
> > > > ranging from coarse grained(ringbuffer level) to a more fine grained
> > > > such as draw-call level or a bin boundary level preemption. This patch
> > > > enables the basic preemption level, with more fine grained preemption
> > > > support to follow.
> > > >
> > > > Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> > > > Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> > > > Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> > > > ---
> > > >  drivers/gpu/drm/msm/Makefile              |   1 +
> > > >  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
> > > >  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
> > > >  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
> > > >  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
> > > >  5 files changed, 921 insertions(+), 9 deletions(-)
> > > >
> > >
> > > [snip]
> > >
> > > > +
> > > > +int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
> > > > +               struct msm_gpu_submitqueue *queue)
> > > > +{
> > > > +       void *ptr;
> > > > +
> > > > +       /*
> > > > +        * Create a per submitqueue buffer for the CP to save and restore user
> > > > +        * specific information such as the VPC streamout data.
> > > > +        */
> > > > +       ptr = msm_gem_kernel_new(gpu->dev, A6XX_PREEMPT_USER_RECORD_SIZE,
> > > > +                       MSM_BO_WC, gpu->aspace, &queue->bo, &queue->bo_iova);
> > >
> > > Can this be MSM_BO_MAP_PRIV?  Otherwise it is visible (and writeable)
> > > by other proceess's userspace generated cmdstream.
> > >
> > > And a similar question for the scratch_bo..  I'd have to give some
> > > thought to what sort of mischief could be had, but generall kernel
> > > mappings that are not MAP_PRIV are a thing to be careful about.
> > >
> >
> > It seems like the idea behind this is that it's supposed to be
> > per-context. kgsl allocates it as part of the context, as part of the
> > userspace address space, and then in order to know which user record
> > to use when preempting, before each submit (although really it only
> > needs to be done when setting the pagetable) it does a CP_MEM_WRITE of
> > the user record address to a scratch buffer holding an array of the
> > current user record for each ring. Then when preempting it reads the
> > address for the next ring from the scratch buffer and sets it. I think
> > we need to do that dance too.
>
> Moving it into userspace's address space (vm) would be better.
>
> I assume the preempt record is where state is saved/restored?  So
> would need to be in kernel aspace/vm?  Or is the fw changing ttbr0
> after saving state but before restoring?
>
> BR,
> -R

The preempt record is split into a number of pieces, each with their
own address. One of those pieces is the SMMU record with ttbr0 and
other SMMU things. Another piece is the "private" context record with
sensitive things like RB address/rptr/wptr, although actually the bulk
of the registers are saved here. Then the user or "non-private" record
is its own piece, which is presumably saved before switching ttbr0 and
restored after the SMMU record is restored and ttbr0 is switched.

Connor

>
> > Connor
> >
> > > BR,
> > > -R

Re: [PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Rob Clark]

On Fri, Aug 30, 2024 at 12:09 PM Connor Abbott <cwabbott0@gmail.com> wrote:
>
> On Fri, Aug 30, 2024 at 8:00 PM Rob Clark <robdclark@gmail.com> wrote:
> >
> > On Fri, Aug 30, 2024 at 11:54 AM Connor Abbott <cwabbott0@gmail.com> wrote:
> > >
> > > On Fri, Aug 30, 2024 at 7:08 PM Rob Clark <robdclark@gmail.com> wrote:
> > > >
> > > > On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
> > > > <antomani103@gmail.com> wrote:
> > > > >
> > > > > This patch implements preemption feature for A6xx targets, this allows
> > > > > the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> > > > > hardware as such supports multiple levels of preemption granularities,
> > > > > ranging from coarse grained(ringbuffer level) to a more fine grained
> > > > > such as draw-call level or a bin boundary level preemption. This patch
> > > > > enables the basic preemption level, with more fine grained preemption
> > > > > support to follow.
> > > > >
> > > > > Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> > > > > Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> > > > > Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> > > > > ---
> > > > >  drivers/gpu/drm/msm/Makefile              |   1 +
> > > > >  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
> > > > >  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
> > > > >  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
> > > > >  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
> > > > >  5 files changed, 921 insertions(+), 9 deletions(-)
> > > > >
> > > >
> > > > [snip]
> > > >
> > > > > +
> > > > > +int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
> > > > > +               struct msm_gpu_submitqueue *queue)
> > > > > +{
> > > > > +       void *ptr;
> > > > > +
> > > > > +       /*
> > > > > +        * Create a per submitqueue buffer for the CP to save and restore user
> > > > > +        * specific information such as the VPC streamout data.
> > > > > +        */
> > > > > +       ptr = msm_gem_kernel_new(gpu->dev, A6XX_PREEMPT_USER_RECORD_SIZE,
> > > > > +                       MSM_BO_WC, gpu->aspace, &queue->bo, &queue->bo_iova);
> > > >
> > > > Can this be MSM_BO_MAP_PRIV?  Otherwise it is visible (and writeable)
> > > > by other proceess's userspace generated cmdstream.
> > > >
> > > > And a similar question for the scratch_bo..  I'd have to give some
> > > > thought to what sort of mischief could be had, but generall kernel
> > > > mappings that are not MAP_PRIV are a thing to be careful about.
> > > >
> > >
> > > It seems like the idea behind this is that it's supposed to be
> > > per-context. kgsl allocates it as part of the context, as part of the
> > > userspace address space, and then in order to know which user record
> > > to use when preempting, before each submit (although really it only
> > > needs to be done when setting the pagetable) it does a CP_MEM_WRITE of
> > > the user record address to a scratch buffer holding an array of the
> > > current user record for each ring. Then when preempting it reads the
> > > address for the next ring from the scratch buffer and sets it. I think
> > > we need to do that dance too.
> >
> > Moving it into userspace's address space (vm) would be better.
> >
> > I assume the preempt record is where state is saved/restored?  So
> > would need to be in kernel aspace/vm?  Or is the fw changing ttbr0
> > after saving state but before restoring?
> >
> > BR,
> > -R
>
> The preempt record is split into a number of pieces, each with their
> own address. One of those pieces is the SMMU record with ttbr0 and
> other SMMU things. Another piece is the "private" context record with
> sensitive things like RB address/rptr/wptr, although actually the bulk
> of the registers are saved here. Then the user or "non-private" record
> is its own piece, which is presumably saved before switching ttbr0 and
> restored after the SMMU record is restored and ttbr0 is switched.
>

Ok, and all these are offsets in the preempt record.. but that part is
allocated with MAP_PRIV, so that part should be ok.

Why is the VPC streamout state handled differently?

BR,
-R

Re: [PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Rob Clark]

On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
<antomani103@gmail.com> wrote:
>
> This patch implements preemption feature for A6xx targets, this allows
> the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> hardware as such supports multiple levels of preemption granularities,
> ranging from coarse grained(ringbuffer level) to a more fine grained
> such as draw-call level or a bin boundary level preemption. This patch
> enables the basic preemption level, with more fine grained preemption
> support to follow.
>
> Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> ---
>  drivers/gpu/drm/msm/Makefile              |   1 +
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
>  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
>  5 files changed, 921 insertions(+), 9 deletions(-)
>

[snip]

> @@ -784,6 +1062,16 @@ static int a6xx_ucode_load(struct msm_gpu *gpu)
>                 msm_gem_object_set_name(a6xx_gpu->shadow_bo, "shadow");
>         }
>
> +       a6xx_gpu->pwrup_reglist_ptr = msm_gem_kernel_new(gpu->dev, PAGE_SIZE,
> +                                                        MSM_BO_WC  | MSM_BO_MAP_PRIV,
> +                                                        gpu->aspace, &a6xx_gpu->pwrup_reglist_bo,
> +                                                        &a6xx_gpu->pwrup_reglist_iova);

I guess this could also be MSM_BO_GPU_READONLY?

BR,
-R

Re: [PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Antonino Maniscalco]

On 8/30/24 10:25 PM, Rob Clark wrote:
> On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
> <antomani103@gmail.com> wrote:
>>
>> This patch implements preemption feature for A6xx targets, this allows
>> the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
>> hardware as such supports multiple levels of preemption granularities,
>> ranging from coarse grained(ringbuffer level) to a more fine grained
>> such as draw-call level or a bin boundary level preemption. This patch
>> enables the basic preemption level, with more fine grained preemption
>> support to follow.
>>
>> Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
>> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
>> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
>> ---
>>   drivers/gpu/drm/msm/Makefile              |   1 +
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
>>   drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
>>   drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
>>   5 files changed, 921 insertions(+), 9 deletions(-)
>>
> 
> [snip]
> 
>> @@ -784,6 +1062,16 @@ static int a6xx_ucode_load(struct msm_gpu *gpu)
>>                  msm_gem_object_set_name(a6xx_gpu->shadow_bo, "shadow");
>>          }
>>
>> +       a6xx_gpu->pwrup_reglist_ptr = msm_gem_kernel_new(gpu->dev, PAGE_SIZE,
>> +                                                        MSM_BO_WC  | MSM_BO_MAP_PRIV,
>> +                                                        gpu->aspace, &a6xx_gpu->pwrup_reglist_bo,
>> +                                                        &a6xx_gpu->pwrup_reglist_iova);
> 
> I guess this could also be MSM_BO_GPU_READONLY?
> 
> BR,
> -R

Besides containing the the actual reglist this buffer also contains the 
`cpu_gpu_lock` structure which is written by the SQE so adding the 
`MSM_BO_GPU_READONLY` flag would cause it to fault.

Best regards,
-- 
Antonino Maniscalco <antomani103@gmail.com>

Re: [PATCH v2 4/9] drm/msm/A6xx: Implement preemption for A7XX targets

[Rob Clark]

On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
<antomani103@gmail.com> wrote:
>
> This patch implements preemption feature for A6xx targets, this allows
> the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> hardware as such supports multiple levels of preemption granularities,
> ranging from coarse grained(ringbuffer level) to a more fine grained
> such as draw-call level or a bin boundary level preemption. This patch
> enables the basic preemption level, with more fine grained preemption
> support to follow.
>
> Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> ---
>  drivers/gpu/drm/msm/Makefile              |   1 +
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 323 +++++++++++++++++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 ++++++++++++
>  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 431 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
>  5 files changed, 921 insertions(+), 9 deletions(-)
>

[snip]

> +void a6xx_preempt_trigger(struct msm_gpu *gpu)
> +{
> +       struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +       struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +       u64 preempt_offset_priv_secure;
> +       unsigned long flags;
> +       struct msm_ringbuffer *ring;
> +       uint64_t user_ctx_iova;
> +       unsigned int cntl;
> +
> +       if (gpu->nr_rings == 1)
> +               return;
> +
> +       /*
> +        * Lock to make sure another thread attempting preemption doesn't skip it
> +        * while we are still evaluating the next ring. This makes sure the other
> +        * thread does start preemption if we abort it and avoids a soft lock.
> +        */
> +       spin_lock_irqsave(&a6xx_gpu->eval_lock, flags);
> +
> +       /*
> +        * Try to start preemption by moving from NONE to START. If
> +        * unsuccessful, a preemption is already in flight
> +        */
> +       if (!try_preempt_state(a6xx_gpu, PREEMPT_NONE, PREEMPT_START)) {
> +               spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
> +               return;
> +       }
> +
> +       cntl = (((a6xx_gpu->preempt_level << 6) & 0xC0) |
> +               ((a6xx_gpu->skip_save_restore << 9) & 0x200) |
> +               ((a6xx_gpu->uses_gmem << 8) & 0x100) | 0x1);

nit, could we define these fields in the xml, and not open-code
register building?

BR,
-R

[PATCH v2 5/9] drm/msm/A6xx: Sync relevant adreno_pm4.xml changes

[Antonino Maniscalco]

In mesa CP_SET_CTXSWITCH_IB is renamed to CP_SET_AMBLE and some other
names are changed to match KGSL. Import those changes.

The changes have not been merged yet in mesa but are necessary for this
series.

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
---
 .../gpu/drm/msm/registers/adreno/adreno_pm4.xml    | 39 ++++++++++------------
 1 file changed, 17 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/msm/registers/adreno/adreno_pm4.xml b/drivers/gpu/drm/msm/registers/adreno/adreno_pm4.xml
index cab01af55d22..55a35182858c 100644
--- a/drivers/gpu/drm/msm/registers/adreno/adreno_pm4.xml
+++ b/drivers/gpu/drm/msm/registers/adreno/adreno_pm4.xml
@@ -581,8 +581,7 @@ xsi:schemaLocation="https://gitlab.freedesktop.org/freedreno/ rules-fd.xsd">
                 and forcibly switch to the indicated context.
 	</doc>
 	<value name="CP_CONTEXT_SWITCH" value="0x54" variants="A6XX"/>
-	<!-- Note, kgsl calls this CP_SET_AMBLE: -->
-	<value name="CP_SET_CTXSWITCH_IB" value="0x55" variants="A6XX-"/>
+	<value name="CP_SET_AMBLE" value="0x55" variants="A6XX-"/>
 
 	<!--
 	Seems to always have the payload:
@@ -2013,42 +2012,38 @@ opcode: CP_LOAD_STATE4 (30) (4 dwords)
 	</reg32>
 </domain>
 
-<domain name="CP_SET_CTXSWITCH_IB" width="32">
+<domain name="CP_SET_AMBLE" width="32">
 	<doc>
-                Used by the userspace driver to set various IB's which are
-                executed during context save/restore for handling
-                state that isn't restored by the
-                context switch routine itself.
-	</doc>
-	<enum name="ctxswitch_ib">
-		<value name="RESTORE_IB" value="0">
+                Used by the userspace and kernel drivers to set various IB's
+                which are executed during context save/restore for handling
+                state that isn't restored by the context switch routine itself.
+  </doc>
+	<enum name="amble_type">
+		<value name="PREAMBLE_AMBLE_TYPE" value="0">
 			<doc>Executed unconditionally when switching back to the context.</doc>
 		</value>
-		<value name="YIELD_RESTORE_IB" value="1">
+		<value name="BIN_PREAMBLE_AMBLE_TYPE" value="1">
                         <doc>
 				Executed when switching back after switching
 				away during execution of
-				a CP_SET_MARKER packet with RM6_YIELD as the
-				payload *and* the normal save routine was
-				bypassed for a shorter one. I think this is
-				connected to the "skipsaverestore" bit set by
-				the kernel when preempting.
+				a CP_SET_MARKER packet with RM6_BIN_RENDER_END as the
+				payload *and* skipsaverestore is set. This is
+				expected to restore static register values not
+				saved when skipsaverestore is set.
 			</doc>
 		</value>
-		<value name="SAVE_IB" value="2">
+		<value name="POSTAMBLE_AMBLE_TYPE" value="2">
                         <doc>
 				Executed when switching away from the context,
 				except for context switches initiated via
 				CP_YIELD.
                         </doc>
 		</value>
-		<value name="RB_SAVE_IB" value="3">
+		<value name="KMD_AMBLE_TYPE" value="3">
 			<doc>
 				This can only be set by the RB (i.e. the kernel)
 				and executes with protected mode off, but
-				is otherwise similar to SAVE_IB.
-
-				Note, kgsl calls this CP_KMD_AMBLE_TYPE
+				is otherwise similar to POSTAMBLE_AMBLE_TYPE.
 			</doc>
 		</value>
 	</enum>
@@ -2060,7 +2055,7 @@ opcode: CP_LOAD_STATE4 (30) (4 dwords)
 	</reg32>
 	<reg32 offset="2" name="2">
 		<bitfield name="DWORDS" low="0" high="19" type="uint"/>
-		<bitfield name="TYPE" low="20" high="21" type="ctxswitch_ib"/>
+		<bitfield name="TYPE" low="20" high="21" type="amble_type"/>
 	</reg32>
 </domain>
 

-- 
2.46.0

[PATCH v2 6/9] drm/msm/A6xx: Use posamble to reset counters on preemption

[Antonino Maniscalco]

Use the postamble to reset perf counters when switching between rings,
except when sysprof is enabled, analogously to how they are reset
between submissions when switching pagetables.

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 14 +++++++++++++-
 drivers/gpu/drm/msm/adreno/a6xx_gpu.h     |  6 ++++++
 drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 26 +++++++++++++++++++++++++-
 drivers/gpu/drm/msm/adreno/adreno_gpu.h   |  7 +++++--
 4 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 1a90db5759b8..3528ecbbc1ab 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -366,7 +366,8 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
 		struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
 {
-	u64 preempt_offset_priv_secure;
+	bool sysprof = refcount_read(&a6xx_gpu->base.base.sysprof_active) > 1;
+	u64 preempt_offset_priv_secure, preempt_postamble;
 
 	OUT_PKT7(ring, CP_SET_PSEUDO_REG, 15);
 
@@ -403,6 +404,17 @@ static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
 	/* seems OK to set to 0 to disable it */
 	OUT_RING(ring, 0);
 	OUT_RING(ring, 0);
+
+	if (!sysprof && a6xx_gpu->preempt_postamble_len) {
+		preempt_postamble = SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu);
+
+		OUT_PKT7(ring, CP_SET_AMBLE, 3);
+		OUT_RING(ring, lower_32_bits(preempt_postamble));
+		OUT_RING(ring, upper_32_bits(preempt_postamble));
+		OUT_RING(ring, CP_SET_AMBLE_2_DWORDS(
+					a6xx_gpu->preempt_postamble_len) |
+				CP_SET_AMBLE_2_TYPE(KMD_AMBLE_TYPE));
+	}
 }
 
 static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
index 652e49f01428..2338e36c8f47 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
@@ -66,6 +66,7 @@ struct a6xx_gpu {
 	atomic_t preempt_state;
 	spinlock_t eval_lock;
 	struct timer_list preempt_timer;
+	uint64_t preempt_postamble_len;
 
 	unsigned int preempt_level;
 	bool uses_gmem;
@@ -99,6 +100,11 @@ struct a6xx_gpu {
 #define SCRATCH_USER_CTX_IOVA(ring_id, a6xx_gpu) \
 	(a6xx_gpu->scratch_iova + (ring_id * sizeof(uint64_t)))
 
+#define SCRATCH_PREEMPT_POSTAMBLE_OFFSET (100 * sizeof(u64))
+
+#define SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu) \
+	(a6xx_gpu->scratch_iova + SCRATCH_PREEMPT_POSTAMBLE_OFFSET)
+
 /*
  * In order to do lockless preemption we use a simple state machine to progress
  * through the process.
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
index 4b61b993f75f..f586615db97e 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
@@ -351,6 +351,28 @@ static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
 	return 0;
 }
 
+static void preempt_prepare_postamble(struct a6xx_gpu *a6xx_gpu)
+{
+	u32 *postamble = a6xx_gpu->scratch_ptr + SCRATCH_PREEMPT_POSTAMBLE_OFFSET;
+	u32 count = 0;
+
+	postamble[count++] = PKT7(CP_REG_RMW, 3);
+	postamble[count++] = REG_A6XX_RBBM_PERFCTR_SRAM_INIT_CMD;
+	postamble[count++] = 0;
+	postamble[count++] = 1;
+
+	postamble[count++] = PKT7(CP_WAIT_REG_MEM, 6);
+	postamble[count++] = CP_WAIT_REG_MEM_0_FUNCTION(WRITE_EQ);
+	postamble[count++] = CP_WAIT_REG_MEM_1_POLL_ADDR_LO(
+				REG_A6XX_RBBM_PERFCTR_SRAM_INIT_STATUS);
+	postamble[count++] = CP_WAIT_REG_MEM_2_POLL_ADDR_HI(0);
+	postamble[count++] = CP_WAIT_REG_MEM_3_REF(0x1);
+	postamble[count++] = CP_WAIT_REG_MEM_4_MASK(0x1);
+	postamble[count++] = CP_WAIT_REG_MEM_5_DELAY_LOOP_CYCLES(0);
+
+	a6xx_gpu->preempt_postamble_len = count;
+}
+
 void a6xx_preempt_fini(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
@@ -382,10 +404,12 @@ void a6xx_preempt_init(struct msm_gpu *gpu)
 	a6xx_gpu->skip_save_restore = 1;
 
 	a6xx_gpu->scratch_ptr  = msm_gem_kernel_new(gpu->dev,
-			gpu->nr_rings * sizeof(uint64_t), MSM_BO_WC,
+			PAGE_SIZE, MSM_BO_WC,
 			gpu->aspace, &a6xx_gpu->scratch_bo,
 			&a6xx_gpu->scratch_iova);
 
+	preempt_prepare_postamble(a6xx_gpu);
+
 	if (IS_ERR(a6xx_gpu->scratch_ptr))
 		goto fail;
 
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
index 6b1888280a83..87098567483b 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
@@ -610,12 +610,15 @@ OUT_PKT4(struct msm_ringbuffer *ring, uint16_t regindx, uint16_t cnt)
 	OUT_RING(ring, PKT4(regindx, cnt));
 }
 
+#define PKT7(opcode, cnt) \
+	(CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) | \
+		((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23))
+
 static inline void
 OUT_PKT7(struct msm_ringbuffer *ring, uint8_t opcode, uint16_t cnt)
 {
 	adreno_wait_ring(ring, cnt + 1);
-	OUT_RING(ring, CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) |
-		((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23));
+	OUT_RING(ring, PKT7(opcode, cnt));
 }
 
 struct msm_gpu *a2xx_gpu_init(struct drm_device *dev);

-- 
2.46.0

Re: [PATCH v2 6/9] drm/msm/A6xx: Use posamble to reset counters on preemption

[Rob Clark]

On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
<antomani103@gmail.com> wrote:
>
> Use the postamble to reset perf counters when switching between rings,
> except when sysprof is enabled, analogously to how they are reset
> between submissions when switching pagetables.
>
> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 14 +++++++++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     |  6 ++++++
>  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 26 +++++++++++++++++++++++++-
>  drivers/gpu/drm/msm/adreno/adreno_gpu.h   |  7 +++++--
>  4 files changed, 49 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 1a90db5759b8..3528ecbbc1ab 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -366,7 +366,8 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>  static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
>                 struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
>  {
> -       u64 preempt_offset_priv_secure;
> +       bool sysprof = refcount_read(&a6xx_gpu->base.base.sysprof_active) > 1;
> +       u64 preempt_offset_priv_secure, preempt_postamble;
>
>         OUT_PKT7(ring, CP_SET_PSEUDO_REG, 15);
>
> @@ -403,6 +404,17 @@ static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
>         /* seems OK to set to 0 to disable it */
>         OUT_RING(ring, 0);
>         OUT_RING(ring, 0);
> +
> +       if (!sysprof && a6xx_gpu->preempt_postamble_len) {
> +               preempt_postamble = SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu);
> +
> +               OUT_PKT7(ring, CP_SET_AMBLE, 3);
> +               OUT_RING(ring, lower_32_bits(preempt_postamble));
> +               OUT_RING(ring, upper_32_bits(preempt_postamble));
> +               OUT_RING(ring, CP_SET_AMBLE_2_DWORDS(
> +                                       a6xx_gpu->preempt_postamble_len) |
> +                               CP_SET_AMBLE_2_TYPE(KMD_AMBLE_TYPE));
> +       }

Hmm, ok, we set this in the submit path.. but do we need to clear it
somehow when transitioning from !sysprof to sysprof?

Also, how does this interact with UMD perfctr queries, I would expect
they would prefer save/restore?

BR,
-R

>  }
>
>  static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> index 652e49f01428..2338e36c8f47 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> @@ -66,6 +66,7 @@ struct a6xx_gpu {
>         atomic_t preempt_state;
>         spinlock_t eval_lock;
>         struct timer_list preempt_timer;
> +       uint64_t preempt_postamble_len;
>
>         unsigned int preempt_level;
>         bool uses_gmem;
> @@ -99,6 +100,11 @@ struct a6xx_gpu {
>  #define SCRATCH_USER_CTX_IOVA(ring_id, a6xx_gpu) \
>         (a6xx_gpu->scratch_iova + (ring_id * sizeof(uint64_t)))
>
> +#define SCRATCH_PREEMPT_POSTAMBLE_OFFSET (100 * sizeof(u64))
> +
> +#define SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu) \
> +       (a6xx_gpu->scratch_iova + SCRATCH_PREEMPT_POSTAMBLE_OFFSET)
> +
>  /*
>   * In order to do lockless preemption we use a simple state machine to progress
>   * through the process.
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> index 4b61b993f75f..f586615db97e 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> @@ -351,6 +351,28 @@ static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
>         return 0;
>  }
>
> +static void preempt_prepare_postamble(struct a6xx_gpu *a6xx_gpu)
> +{
> +       u32 *postamble = a6xx_gpu->scratch_ptr + SCRATCH_PREEMPT_POSTAMBLE_OFFSET;
> +       u32 count = 0;
> +
> +       postamble[count++] = PKT7(CP_REG_RMW, 3);
> +       postamble[count++] = REG_A6XX_RBBM_PERFCTR_SRAM_INIT_CMD;
> +       postamble[count++] = 0;
> +       postamble[count++] = 1;
> +
> +       postamble[count++] = PKT7(CP_WAIT_REG_MEM, 6);
> +       postamble[count++] = CP_WAIT_REG_MEM_0_FUNCTION(WRITE_EQ);
> +       postamble[count++] = CP_WAIT_REG_MEM_1_POLL_ADDR_LO(
> +                               REG_A6XX_RBBM_PERFCTR_SRAM_INIT_STATUS);
> +       postamble[count++] = CP_WAIT_REG_MEM_2_POLL_ADDR_HI(0);
> +       postamble[count++] = CP_WAIT_REG_MEM_3_REF(0x1);
> +       postamble[count++] = CP_WAIT_REG_MEM_4_MASK(0x1);
> +       postamble[count++] = CP_WAIT_REG_MEM_5_DELAY_LOOP_CYCLES(0);
> +
> +       a6xx_gpu->preempt_postamble_len = count;
> +}
> +
>  void a6xx_preempt_fini(struct msm_gpu *gpu)
>  {
>         struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> @@ -382,10 +404,12 @@ void a6xx_preempt_init(struct msm_gpu *gpu)
>         a6xx_gpu->skip_save_restore = 1;
>
>         a6xx_gpu->scratch_ptr  = msm_gem_kernel_new(gpu->dev,
> -                       gpu->nr_rings * sizeof(uint64_t), MSM_BO_WC,
> +                       PAGE_SIZE, MSM_BO_WC,
>                         gpu->aspace, &a6xx_gpu->scratch_bo,
>                         &a6xx_gpu->scratch_iova);
>
> +       preempt_prepare_postamble(a6xx_gpu);
> +
>         if (IS_ERR(a6xx_gpu->scratch_ptr))
>                 goto fail;
>
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> index 6b1888280a83..87098567483b 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> @@ -610,12 +610,15 @@ OUT_PKT4(struct msm_ringbuffer *ring, uint16_t regindx, uint16_t cnt)
>         OUT_RING(ring, PKT4(regindx, cnt));
>  }
>
> +#define PKT7(opcode, cnt) \
> +       (CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) | \
> +               ((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23))
> +
>  static inline void
>  OUT_PKT7(struct msm_ringbuffer *ring, uint8_t opcode, uint16_t cnt)
>  {
>         adreno_wait_ring(ring, cnt + 1);
> -       OUT_RING(ring, CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) |
> -               ((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23));
> +       OUT_RING(ring, PKT7(opcode, cnt));
>  }
>
>  struct msm_gpu *a2xx_gpu_init(struct drm_device *dev);
>
> --
> 2.46.0
>

Re: [PATCH v2 6/9] drm/msm/A6xx: Use posamble to reset counters on preemption

[Antonino Maniscalco]

On 8/30/24 8:32 PM, Rob Clark wrote:
> On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
> <antomani103@gmail.com> wrote:
>>
>> Use the postamble to reset perf counters when switching between rings,
>> except when sysprof is enabled, analogously to how they are reset
>> between submissions when switching pagetables.
>>
>> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
>> ---
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 14 +++++++++++++-
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.h     |  6 ++++++
>>   drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 26 +++++++++++++++++++++++++-
>>   drivers/gpu/drm/msm/adreno/adreno_gpu.h   |  7 +++++--
>>   4 files changed, 49 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> index 1a90db5759b8..3528ecbbc1ab 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> @@ -366,7 +366,8 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>>   static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
>>                  struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
>>   {
>> -       u64 preempt_offset_priv_secure;
>> +       bool sysprof = refcount_read(&a6xx_gpu->base.base.sysprof_active) > 1;
>> +       u64 preempt_offset_priv_secure, preempt_postamble;
>>
>>          OUT_PKT7(ring, CP_SET_PSEUDO_REG, 15);
>>
>> @@ -403,6 +404,17 @@ static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
>>          /* seems OK to set to 0 to disable it */
>>          OUT_RING(ring, 0);
>>          OUT_RING(ring, 0);
>> +
>> +       if (!sysprof && a6xx_gpu->preempt_postamble_len) {
>> +               preempt_postamble = SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu);
>> +
>> +               OUT_PKT7(ring, CP_SET_AMBLE, 3);
>> +               OUT_RING(ring, lower_32_bits(preempt_postamble));
>> +               OUT_RING(ring, upper_32_bits(preempt_postamble));
>> +               OUT_RING(ring, CP_SET_AMBLE_2_DWORDS(
>> +                                       a6xx_gpu->preempt_postamble_len) |
>> +                               CP_SET_AMBLE_2_TYPE(KMD_AMBLE_TYPE));
>> +       }
> 
> Hmm, ok, we set this in the submit path.. but do we need to clear it
> somehow when transitioning from !sysprof to sysprof?
> 

We can always emit the packet and 0 fields out when sysprof is enabled. 
Would that be ok for you? Only emitting it when needed might be 
nontrivial given that there are multiple rings and we would be paying 
the overhead for emitting it in the more common case (not profiling) anyway.

> Also, how does this interact with UMD perfctr queries, I would expect
> they would prefer save/restore?

Right so my understanding given previous discussions is that we want to 
disable preemption from userspace in that case? The vulkan extension 
requires to acquire and release a lock so we could use that to emit the 
packets that enable and disable preemption perhaps.

> 
> BR,
> -R
> 
>>   }
>>
>>   static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
>> index 652e49f01428..2338e36c8f47 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
>> @@ -66,6 +66,7 @@ struct a6xx_gpu {
>>          atomic_t preempt_state;
>>          spinlock_t eval_lock;
>>          struct timer_list preempt_timer;
>> +       uint64_t preempt_postamble_len;
>>
>>          unsigned int preempt_level;
>>          bool uses_gmem;
>> @@ -99,6 +100,11 @@ struct a6xx_gpu {
>>   #define SCRATCH_USER_CTX_IOVA(ring_id, a6xx_gpu) \
>>          (a6xx_gpu->scratch_iova + (ring_id * sizeof(uint64_t)))
>>
>> +#define SCRATCH_PREEMPT_POSTAMBLE_OFFSET (100 * sizeof(u64))
>> +
>> +#define SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu) \
>> +       (a6xx_gpu->scratch_iova + SCRATCH_PREEMPT_POSTAMBLE_OFFSET)
>> +
>>   /*
>>    * In order to do lockless preemption we use a simple state machine to progress
>>    * through the process.
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
>> index 4b61b993f75f..f586615db97e 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
>> @@ -351,6 +351,28 @@ static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
>>          return 0;
>>   }
>>
>> +static void preempt_prepare_postamble(struct a6xx_gpu *a6xx_gpu)
>> +{
>> +       u32 *postamble = a6xx_gpu->scratch_ptr + SCRATCH_PREEMPT_POSTAMBLE_OFFSET;
>> +       u32 count = 0;
>> +
>> +       postamble[count++] = PKT7(CP_REG_RMW, 3);
>> +       postamble[count++] = REG_A6XX_RBBM_PERFCTR_SRAM_INIT_CMD;
>> +       postamble[count++] = 0;
>> +       postamble[count++] = 1;
>> +
>> +       postamble[count++] = PKT7(CP_WAIT_REG_MEM, 6);
>> +       postamble[count++] = CP_WAIT_REG_MEM_0_FUNCTION(WRITE_EQ);
>> +       postamble[count++] = CP_WAIT_REG_MEM_1_POLL_ADDR_LO(
>> +                               REG_A6XX_RBBM_PERFCTR_SRAM_INIT_STATUS);
>> +       postamble[count++] = CP_WAIT_REG_MEM_2_POLL_ADDR_HI(0);
>> +       postamble[count++] = CP_WAIT_REG_MEM_3_REF(0x1);
>> +       postamble[count++] = CP_WAIT_REG_MEM_4_MASK(0x1);
>> +       postamble[count++] = CP_WAIT_REG_MEM_5_DELAY_LOOP_CYCLES(0);
>> +
>> +       a6xx_gpu->preempt_postamble_len = count;
>> +}
>> +
>>   void a6xx_preempt_fini(struct msm_gpu *gpu)
>>   {
>>          struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
>> @@ -382,10 +404,12 @@ void a6xx_preempt_init(struct msm_gpu *gpu)
>>          a6xx_gpu->skip_save_restore = 1;
>>
>>          a6xx_gpu->scratch_ptr  = msm_gem_kernel_new(gpu->dev,
>> -                       gpu->nr_rings * sizeof(uint64_t), MSM_BO_WC,
>> +                       PAGE_SIZE, MSM_BO_WC,
>>                          gpu->aspace, &a6xx_gpu->scratch_bo,
>>                          &a6xx_gpu->scratch_iova);
>>
>> +       preempt_prepare_postamble(a6xx_gpu);
>> +
>>          if (IS_ERR(a6xx_gpu->scratch_ptr))
>>                  goto fail;
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
>> index 6b1888280a83..87098567483b 100644
>> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
>> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
>> @@ -610,12 +610,15 @@ OUT_PKT4(struct msm_ringbuffer *ring, uint16_t regindx, uint16_t cnt)
>>          OUT_RING(ring, PKT4(regindx, cnt));
>>   }
>>
>> +#define PKT7(opcode, cnt) \
>> +       (CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) | \
>> +               ((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23))
>> +
>>   static inline void
>>   OUT_PKT7(struct msm_ringbuffer *ring, uint8_t opcode, uint16_t cnt)
>>   {
>>          adreno_wait_ring(ring, cnt + 1);
>> -       OUT_RING(ring, CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) |
>> -               ((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23));
>> +       OUT_RING(ring, PKT7(opcode, cnt));
>>   }
>>
>>   struct msm_gpu *a2xx_gpu_init(struct drm_device *dev);
>>
>> --
>> 2.46.0
>>

Best regards,
-- 
Antonino Maniscalco <antomani103@gmail.com>

Re: [PATCH v2 6/9] drm/msm/A6xx: Use posamble to reset counters on preemption

[Rob Clark]

On Wed, Sep 4, 2024 at 6:39 AM Antonino Maniscalco
<antomani103@gmail.com> wrote:
>
> On 8/30/24 8:32 PM, Rob Clark wrote:
> > On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
> > <antomani103@gmail.com> wrote:
> >>
> >> Use the postamble to reset perf counters when switching between rings,
> >> except when sysprof is enabled, analogously to how they are reset
> >> between submissions when switching pagetables.
> >>
> >> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> >> ---
> >>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 14 +++++++++++++-
> >>   drivers/gpu/drm/msm/adreno/a6xx_gpu.h     |  6 ++++++
> >>   drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 26 +++++++++++++++++++++++++-
> >>   drivers/gpu/drm/msm/adreno/adreno_gpu.h   |  7 +++++--
> >>   4 files changed, 49 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >> index 1a90db5759b8..3528ecbbc1ab 100644
> >> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >> @@ -366,7 +366,8 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
> >>   static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
> >>                  struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
> >>   {
> >> -       u64 preempt_offset_priv_secure;
> >> +       bool sysprof = refcount_read(&a6xx_gpu->base.base.sysprof_active) > 1;
> >> +       u64 preempt_offset_priv_secure, preempt_postamble;
> >>
> >>          OUT_PKT7(ring, CP_SET_PSEUDO_REG, 15);
> >>
> >> @@ -403,6 +404,17 @@ static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
> >>          /* seems OK to set to 0 to disable it */
> >>          OUT_RING(ring, 0);
> >>          OUT_RING(ring, 0);
> >> +
> >> +       if (!sysprof && a6xx_gpu->preempt_postamble_len) {
> >> +               preempt_postamble = SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu);
> >> +
> >> +               OUT_PKT7(ring, CP_SET_AMBLE, 3);
> >> +               OUT_RING(ring, lower_32_bits(preempt_postamble));
> >> +               OUT_RING(ring, upper_32_bits(preempt_postamble));
> >> +               OUT_RING(ring, CP_SET_AMBLE_2_DWORDS(
> >> +                                       a6xx_gpu->preempt_postamble_len) |
> >> +                               CP_SET_AMBLE_2_TYPE(KMD_AMBLE_TYPE));
> >> +       }
> >
> > Hmm, ok, we set this in the submit path.. but do we need to clear it
> > somehow when transitioning from !sysprof to sysprof?
> >
>
> We can always emit the packet and 0 fields out when sysprof is enabled.
> Would that be ok for you? Only emitting it when needed might be
> nontrivial given that there are multiple rings and we would be paying
> the overhead for emitting it in the more common case (not profiling) anyway.

That sounds like it would work

> > Also, how does this interact with UMD perfctr queries, I would expect
> > they would prefer save/restore?
>
> Right so my understanding given previous discussions is that we want to
> disable preemption from userspace in that case? The vulkan extension
> requires to acquire and release a lock so we could use that to emit the
> packets that enable and disable preemption perhaps.

ack

BR,
-R

> >
> > BR,
> > -R
> >
> >>   }
> >>
> >>   static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
> >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> >> index 652e49f01428..2338e36c8f47 100644
> >> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> >> @@ -66,6 +66,7 @@ struct a6xx_gpu {
> >>          atomic_t preempt_state;
> >>          spinlock_t eval_lock;
> >>          struct timer_list preempt_timer;
> >> +       uint64_t preempt_postamble_len;
> >>
> >>          unsigned int preempt_level;
> >>          bool uses_gmem;
> >> @@ -99,6 +100,11 @@ struct a6xx_gpu {
> >>   #define SCRATCH_USER_CTX_IOVA(ring_id, a6xx_gpu) \
> >>          (a6xx_gpu->scratch_iova + (ring_id * sizeof(uint64_t)))
> >>
> >> +#define SCRATCH_PREEMPT_POSTAMBLE_OFFSET (100 * sizeof(u64))
> >> +
> >> +#define SCRATCH_PREEMPT_POSTAMBLE_IOVA(a6xx_gpu) \
> >> +       (a6xx_gpu->scratch_iova + SCRATCH_PREEMPT_POSTAMBLE_OFFSET)
> >> +
> >>   /*
> >>    * In order to do lockless preemption we use a simple state machine to progress
> >>    * through the process.
> >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> >> index 4b61b993f75f..f586615db97e 100644
> >> --- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> >> @@ -351,6 +351,28 @@ static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
> >>          return 0;
> >>   }
> >>
> >> +static void preempt_prepare_postamble(struct a6xx_gpu *a6xx_gpu)
> >> +{
> >> +       u32 *postamble = a6xx_gpu->scratch_ptr + SCRATCH_PREEMPT_POSTAMBLE_OFFSET;
> >> +       u32 count = 0;
> >> +
> >> +       postamble[count++] = PKT7(CP_REG_RMW, 3);
> >> +       postamble[count++] = REG_A6XX_RBBM_PERFCTR_SRAM_INIT_CMD;
> >> +       postamble[count++] = 0;
> >> +       postamble[count++] = 1;
> >> +
> >> +       postamble[count++] = PKT7(CP_WAIT_REG_MEM, 6);
> >> +       postamble[count++] = CP_WAIT_REG_MEM_0_FUNCTION(WRITE_EQ);
> >> +       postamble[count++] = CP_WAIT_REG_MEM_1_POLL_ADDR_LO(
> >> +                               REG_A6XX_RBBM_PERFCTR_SRAM_INIT_STATUS);
> >> +       postamble[count++] = CP_WAIT_REG_MEM_2_POLL_ADDR_HI(0);
> >> +       postamble[count++] = CP_WAIT_REG_MEM_3_REF(0x1);
> >> +       postamble[count++] = CP_WAIT_REG_MEM_4_MASK(0x1);
> >> +       postamble[count++] = CP_WAIT_REG_MEM_5_DELAY_LOOP_CYCLES(0);
> >> +
> >> +       a6xx_gpu->preempt_postamble_len = count;
> >> +}
> >> +
> >>   void a6xx_preempt_fini(struct msm_gpu *gpu)
> >>   {
> >>          struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> >> @@ -382,10 +404,12 @@ void a6xx_preempt_init(struct msm_gpu *gpu)
> >>          a6xx_gpu->skip_save_restore = 1;
> >>
> >>          a6xx_gpu->scratch_ptr  = msm_gem_kernel_new(gpu->dev,
> >> -                       gpu->nr_rings * sizeof(uint64_t), MSM_BO_WC,
> >> +                       PAGE_SIZE, MSM_BO_WC,
> >>                          gpu->aspace, &a6xx_gpu->scratch_bo,
> >>                          &a6xx_gpu->scratch_iova);
> >>
> >> +       preempt_prepare_postamble(a6xx_gpu);
> >> +
> >>          if (IS_ERR(a6xx_gpu->scratch_ptr))
> >>                  goto fail;
> >>
> >> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> >> index 6b1888280a83..87098567483b 100644
> >> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> >> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> >> @@ -610,12 +610,15 @@ OUT_PKT4(struct msm_ringbuffer *ring, uint16_t regindx, uint16_t cnt)
> >>          OUT_RING(ring, PKT4(regindx, cnt));
> >>   }
> >>
> >> +#define PKT7(opcode, cnt) \
> >> +       (CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) | \
> >> +               ((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23))
> >> +
> >>   static inline void
> >>   OUT_PKT7(struct msm_ringbuffer *ring, uint8_t opcode, uint16_t cnt)
> >>   {
> >>          adreno_wait_ring(ring, cnt + 1);
> >> -       OUT_RING(ring, CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) |
> >> -               ((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23));
> >> +       OUT_RING(ring, PKT7(opcode, cnt));
> >>   }
> >>
> >>   struct msm_gpu *a2xx_gpu_init(struct drm_device *dev);
> >>
> >> --
> >> 2.46.0
> >>
>
> Best regards,
> --
> Antonino Maniscalco <antomani103@gmail.com>
>

[PATCH v2 7/9] drm/msm/A6xx: Add traces for preemption

[Antonino Maniscalco]

Add trace points corresponding to preemption being triggered and being
completed for latency measurement purposes.

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/adreno/a6xx_preempt.c |  7 +++++++
 drivers/gpu/drm/msm/msm_gpu_trace.h       | 28 ++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
index f586615db97e..bf05f987d3a2 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
@@ -7,6 +7,7 @@
 #include "a6xx_gpu.h"
 #include "a6xx_gmu.xml.h"
 #include "msm_mmu.h"
+#include "msm_gpu_trace.h"
 
 /*
  * Try to transition the preemption state from old to new. Return
@@ -143,6 +144,8 @@ void a6xx_preempt_irq(struct msm_gpu *gpu)
 
 	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
 
+	trace_msm_gpu_preemption_irq(a6xx_gpu->cur_ring->id);
+
 	/*
 	 * Retrigger preemption to avoid a deadlock that might occur when preemption
 	 * is skipped due to it being already in flight when requested.
@@ -259,6 +262,10 @@ void a6xx_preempt_trigger(struct msm_gpu *gpu)
 	 */
 	ring->skip_inline_wptr = false;
 
+	trace_msm_gpu_preemption_trigger(
+		a6xx_gpu->cur_ring ? a6xx_gpu->cur_ring->id : -1,
+		ring ? ring->id : -1);
+
 	spin_unlock_irqrestore(&ring->preempt_lock, flags);
 
 	gpu_write64(gpu,
diff --git a/drivers/gpu/drm/msm/msm_gpu_trace.h b/drivers/gpu/drm/msm/msm_gpu_trace.h
index ac40d857bc45..7f863282db0d 100644
--- a/drivers/gpu/drm/msm/msm_gpu_trace.h
+++ b/drivers/gpu/drm/msm/msm_gpu_trace.h
@@ -177,6 +177,34 @@ TRACE_EVENT(msm_gpu_resume,
 		TP_printk("%u", __entry->dummy)
 );
 
+TRACE_EVENT(msm_gpu_preemption_trigger,
+		TP_PROTO(int ring_id_from, int ring_id_to),
+		TP_ARGS(ring_id_from, ring_id_to),
+		TP_STRUCT__entry(
+			__field(int, ring_id_from)
+			__field(int, ring_id_to)
+			),
+		TP_fast_assign(
+			__entry->ring_id_from = ring_id_from;
+			__entry->ring_id_to = ring_id_to;
+			),
+		TP_printk("preempting %u -> %u",
+			  __entry->ring_id_from,
+			  __entry->ring_id_to)
+);
+
+TRACE_EVENT(msm_gpu_preemption_irq,
+		TP_PROTO(u32 ring_id),
+		TP_ARGS(ring_id),
+		TP_STRUCT__entry(
+			__field(u32, ring_id)
+			),
+		TP_fast_assign(
+			__entry->ring_id = ring_id;
+			),
+		TP_printk("preempted to %u", __entry->ring_id)
+);
+
 #endif
 
 #undef TRACE_INCLUDE_PATH

-- 
2.46.0

[PATCH v2 8/9] drm/msm/A6XX: Add a flag to allow preemption to submitqueue_create

[Antonino Maniscalco]

Some userspace changes are necessary so add a flag for userspace to
advertise support for preemption when creating the submitqueue.

When this flag is not set preemption will not be allowed in the middle
of the submitted IBs therefore mantaining compatibility with older
userspace.

The flag is rejected if preemption is not supported on the target, this
allows userspace to know whether preemption is supported.

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 12 ++++++++----
 drivers/gpu/drm/msm/msm_submitqueue.c |  3 +++
 include/uapi/drm/msm_drm.h            |  5 ++++-
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 3528ecbbc1ab..a2853309288b 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -465,8 +465,10 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	OUT_PKT7(ring, CP_SET_MARKER, 1);
 	OUT_RING(ring, 0x101); /* IFPC disable */
 
-	OUT_PKT7(ring, CP_SET_MARKER, 1);
-	OUT_RING(ring, 0x00d); /* IB1LIST start */
+	if (submit->queue->flags & MSM_SUBMITQUEUE_ALLOW_PREEMPT) {
+		OUT_PKT7(ring, CP_SET_MARKER, 1);
+		OUT_RING(ring, 0x00d); /* IB1LIST start */
+	}
 
 	/* Submit the commands */
 	for (i = 0; i < submit->nr_cmds; i++) {
@@ -497,8 +499,10 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 			update_shadow_rptr(gpu, ring);
 	}
 
-	OUT_PKT7(ring, CP_SET_MARKER, 1);
-	OUT_RING(ring, 0x00e); /* IB1LIST end */
+	if (submit->queue->flags & MSM_SUBMITQUEUE_ALLOW_PREEMPT) {
+		OUT_PKT7(ring, CP_SET_MARKER, 1);
+		OUT_RING(ring, 0x00e); /* IB1LIST end */
+	}
 
 	get_stats_counter(ring, REG_A7XX_RBBM_PERFCTR_CP(0),
 		rbmemptr_stats(ring, index, cpcycles_end));
diff --git a/drivers/gpu/drm/msm/msm_submitqueue.c b/drivers/gpu/drm/msm/msm_submitqueue.c
index 4ffb336d9a60..0a8fc4262026 100644
--- a/drivers/gpu/drm/msm/msm_submitqueue.c
+++ b/drivers/gpu/drm/msm/msm_submitqueue.c
@@ -176,6 +176,9 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx,
 	if (!priv->gpu)
 		return -ENODEV;
 
+	if (flags & MSM_SUBMITQUEUE_ALLOW_PREEMPT && gpu->nr_rings == 1)
+		return -EINVAL;
+
 	ret = msm_gpu_convert_priority(priv->gpu, prio, &ring_nr, &sched_prio);
 	if (ret)
 		return ret;
diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
index 3fca72f73861..f37858db34e6 100644
--- a/include/uapi/drm/msm_drm.h
+++ b/include/uapi/drm/msm_drm.h
@@ -345,7 +345,10 @@ struct drm_msm_gem_madvise {
  * backwards compatibility as a "default" submitqueue
  */
 
-#define MSM_SUBMITQUEUE_FLAGS (0)
+#define MSM_SUBMITQUEUE_ALLOW_PREEMPT	0x00000001
+#define MSM_SUBMITQUEUE_FLAGS		    ( \
+		MSM_SUBMITQUEUE_ALLOW_PREEMPT | \
+		0)
 
 /*
  * The submitqueue priority should be between 0 and MSM_PARAM_PRIORITIES-1,

-- 
2.46.0

[PATCH v2 9/9] drm/msm/A6xx: Enable preemption for A750

[Antonino Maniscalco]

Initialize with 4 rings to enable preemption.

For now only on A750 as other targets require testing.

Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index a2853309288b..ea518209c03d 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -2609,7 +2609,9 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
 		return ERR_PTR(ret);
 	}
 
-	if (is_a7xx)
+	if (adreno_is_a750(adreno_gpu))
+		ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_a7xx, 4);
+	else if (is_a7xx)
 		ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_a7xx, 1);
 	else if (adreno_has_gmu_wrapper(adreno_gpu))
 		ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_gmuwrapper, 1);

-- 
2.46.0

Re: [PATCH v2 9/9] drm/msm/A6xx: Enable preemption for A750

[Rob Clark]

On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
<antomani103@gmail.com> wrote:
>
> Initialize with 4 rings to enable preemption.
>
> For now only on A750 as other targets require testing.
>
> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index a2853309288b..ea518209c03d 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -2609,7 +2609,9 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
>                 return ERR_PTR(ret);
>         }
>
> -       if (is_a7xx)
> +       if (adreno_is_a750(adreno_gpu))
> +               ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_a7xx, 4);

perhaps it would be useful (to enable others to more easily test), to
allow this to be overridden with a modparam.. something like

       if ((enable_preemption == 1) || (enable_preemption == -1 &&
(config->info->quirks & ADRENO_QUIRK_PREEMPTION))

That would allow overriding enable_preemption to 1 or 0 on cmdline to
force enable/disable preemption.

That plus some instructions about how to test preemption (ie. what
deqp tests to run, or similar) would make it easier to "crowd source"
the testing (assuming you don't have every a7xx device there is)

BR,
-R

> +       else if (is_a7xx)
>                 ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_a7xx, 1);
>         else if (adreno_has_gmu_wrapper(adreno_gpu))
>                 ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_gmuwrapper, 1);
>
> --
> 2.46.0
>