I'm working on the TLB flushing code and noticed a problem with this
commit. See inline ...
On 2019-11-21 10:47 a.m., Changfeng.Zhu wrote:
From: changzhu <Changfeng.Zhu@xxxxxxx>
It may lose gpuvm invalidate acknowldege state across power-gating off
cycle. To avoid this issue in gmc9/gmc10 invalidation, add semaphore acquire
before invalidation and semaphore release after invalidation.
After adding semaphore acquire before invalidation, the semaphore
register become read-only if another process try to acquire semaphore.
Then it will not be able to release this semaphore. Then it may cause
deadlock problem. If this deadlock problem happens, it needs a semaphore
firmware fix.
Change-Id: I9942a2f451265c1f1038ccfe2f70042c7c8118af
Signed-off-by: changzhu <Changfeng.Zhu@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c | 52 ++++++++++++++++++++++++++
drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 52 ++++++++++++++++++++++++++
drivers/gpu/drm/amd/amdgpu/soc15.h | 4 +-
3 files changed, 106 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
index af2615ba52aa..e0104b985c42 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
@@ -234,6 +234,27 @@ static void gmc_v10_0_flush_vm_hub(struct amdgpu_device *adev, uint32_t vmid,
const unsigned eng = 17;
unsigned int i;
+ spin_lock(&adev->gmc.invalidate_lock);
+ /*
+ * It may lose gpuvm invalidate acknowldege state across power-gating
+ * off cycle, add semaphore acquire before invalidation and semaphore
+ * release after invalidation to avoid entering power gated state
+ * to WA the Issue
+ */
+ if (vmhub == AMDGPU_MMHUB_0 ||
+ vmhub == AMDGPU_MMHUB_1) {
+ for (i = 0; i < adev->usec_timeout; i++) {
+ /* a read return value of 1 means semaphore acuqire */
+ tmp = RREG32_NO_KIQ(hub->vm_inv_eng0_sem + eng);
+ if (tmp & 0x1)
+ break;
+ udelay(1);
+ }
+
+ if (i >= adev->usec_timeout)
+ DRM_ERROR("Timeout waiting for sem acquire in VM flush!\n");
+ }
+
WREG32_NO_KIQ(hub->vm_inv_eng0_req + eng, tmp);
/*
@@ -253,6 +274,16 @@ static void gmc_v10_0_flush_vm_hub(struct amdgpu_device *adev, uint32_t vmid,
udelay(1);
}
+ /*
+ * add semaphore release after invalidation,
+ * write with 0 means semaphore release
+ */
+ if (vmhub == AMDGPU_MMHUB_0 ||
+ vmhub == AMDGPU_MMHUB_1)
+ WREG32_NO_KIQ(hub->vm_inv_eng0_sem + eng, 0);
+
+ spin_unlock(&adev->gmc.invalidate_lock);
+
if (i < adev->usec_timeout)
return;
@@ -338,6 +369,19 @@ static uint64_t gmc_v10_0_emit_flush_gpu_tlb(struct amdgpu_ring *ring,
uint32_t req = gmc_v10_0_get_invalidate_req(vmid, 0);
unsigned eng = ring->vm_inv_eng;
+ /*
+ * It may lose gpuvm invalidate acknowldege state across power-gating
+ * off cycle, add semaphore acquire before invalidation and semaphore
+ * release after invalidation to avoid entering power gated state
+ * to WA the Issue
+ */
+
+ /* a read return value of 1 means semaphore acuqire */
+ if (ring->funcs->vmhub == AMDGPU_MMHUB_0 ||
+ ring->funcs->vmhub == AMDGPU_MMHUB_1)
+ amdgpu_ring_emit_reg_wait(ring,
+ hub->vm_inv_eng0_sem + eng, 0x1, 0x1);
+
amdgpu_ring_emit_wreg(ring, hub->ctx0_ptb_addr_lo32 + (2 * vmid),
lower_32_bits(pd_addr));
@@ -348,6 +392,14 @@ static uint64_t gmc_v10_0_emit_flush_gpu_tlb(struct amdgpu_ring *ring,
hub->vm_inv_eng0_ack + eng,
req, 1 << vmid);
+ /*
+ * add semaphore release after invalidation,
+ * write with 0 means semaphore release
+ */
+ if (ring->funcs->vmhub == AMDGPU_MMHUB_0 ||
+ ring->funcs->vmhub == AMDGPU_MMHUB_1)
+ amdgpu_ring_emit_wreg(ring, hub->vm_inv_eng0_sem + eng, 0);
+
return pd_addr;
}
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
index b7f2b184e9b8..816fdd602c85 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
...
tmp = gmc_v9_0_get_invalidate_req(vmid, flush_type);
...
@@ -455,6 +455,27 @@ static void gmc_v9_0_flush_gpu_tlb(struct amdgpu_device *adev, uint32_t vmid,
}
spin_lock(&adev->gmc.invalidate_lock);
+
+ /*
+ * It may lose gpuvm invalidate acknowldege state across power-gating
+ * off cycle, add semaphore acquire before invalidation and semaphore
+ * release after invalidation to avoid entering power gated state
+ * to WA the Issue
+ */
+ if (vmhub == AMDGPU_MMHUB_0 ||
+ vmhub == AMDGPU_MMHUB_1) {
+ for (j = 0; j < adev->usec_timeout; j++) {
+ /* a read return value of 1 means semaphore acuqire */
+ tmp = RREG32_NO_KIQ(hub->vm_inv_eng0_sem + eng);
The tmp variable is also used for the request written to the
vm_inv_eng0_req register below. This overwrites that value.
+ if (tmp & 0x1)
+ break;
+ udelay(1);
+ }
+
+ if (j >= adev->usec_timeout)
+ DRM_ERROR("Timeout waiting for sem acquire in VM flush!\n");
+ }
+
WREG32_NO_KIQ(hub->vm_inv_eng0_req + eng, tmp);
I think this is broken if you acquired the semaphore above. You should
use a different tmp variable for acquiring the semaphore.
Regards,
Felix
/*
@@ -470,7 +491,17 @@ static void gmc_v9_0_flush_gpu_tlb(struct amdgpu_device *adev, uint32_t vmid,
break;
udelay(1);
}
+
+ /*
+ * add semaphore release after invalidation,
+ * write with 0 means semaphore release
+ */
+ if (vmhub == AMDGPU_MMHUB_0 ||
+ vmhub == AMDGPU_MMHUB_1)
+ WREG32_NO_KIQ(hub->vm_inv_eng0_sem + eng, 0);
+
spin_unlock(&adev->gmc.invalidate_lock);
+
if (j < adev->usec_timeout)
return;
@@ -485,6 +516,19 @@ static uint64_t gmc_v9_0_emit_flush_gpu_tlb(struct amdgpu_ring *ring,
uint32_t req = gmc_v9_0_get_invalidate_req(vmid, 0);
unsigned eng = ring->vm_inv_eng;
+ /*
+ * It may lose gpuvm invalidate acknowldege state across power-gating
+ * off cycle, add semaphore acquire before invalidation and semaphore
+ * release after invalidation to avoid entering power gated state
+ * to WA the Issue
+ */
+
+ /* a read return value of 1 means semaphore acuqire */
+ if (ring->funcs->vmhub == AMDGPU_MMHUB_0 ||
+ ring->funcs->vmhub == AMDGPU_MMHUB_1)
+ amdgpu_ring_emit_reg_wait(ring,
+ hub->vm_inv_eng0_sem + eng, 0x1, 0x1);
+
amdgpu_ring_emit_wreg(ring, hub->ctx0_ptb_addr_lo32 + (2 * vmid),
lower_32_bits(pd_addr));
@@ -495,6 +539,14 @@ static uint64_t gmc_v9_0_emit_flush_gpu_tlb(struct amdgpu_ring *ring,
hub->vm_inv_eng0_ack + eng,
req, 1 << vmid);
+ /*
+ * add semaphore release after invalidation,
+ * write with 0 means semaphore release
+ */
+ if (ring->funcs->vmhub == AMDGPU_MMHUB_0 ||
+ ring->funcs->vmhub == AMDGPU_MMHUB_1)
+ amdgpu_ring_emit_wreg(ring, hub->vm_inv_eng0_sem + eng, 0);
+
return pd_addr;
}
diff --git a/drivers/gpu/drm/amd/amdgpu/soc15.h b/drivers/gpu/drm/amd/amdgpu/soc15.h
index 344280b869c4..d0fb7a67c1a3 100644
--- a/drivers/gpu/drm/amd/amdgpu/soc15.h
+++ b/drivers/gpu/drm/amd/amdgpu/soc15.h
@@ -28,8 +28,8 @@
#include "nbio_v7_0.h"
#include "nbio_v7_4.h"
-#define SOC15_FLUSH_GPU_TLB_NUM_WREG 4
-#define SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT 1
+#define SOC15_FLUSH_GPU_TLB_NUM_WREG 6
+#define SOC15_FLUSH_GPU_TLB_NUM_REG_WAIT 3
extern const struct amd_ip_funcs soc15_common_ip_funcs;
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