[PATCH v4 4/5] drm/amdgpu: address remove from fault filter

[Philip Yang]

Add interface to remove address from fault filter ring by resetting
fault ring entry key, then future vm fault on the address will be
processed to recover.

Define fault key as atomic64_t type to use atomic read/set/cmpxchg key
to protect fault ring access by interrupt handler and interrupt deferred
work for vg20. Change fault->timestamp to 56-bit to share same uint64_t
with 8-bit fault->next, it is big enough for 48bit IH timestamp.

Signed-off-by: Philip Yang <Philip.Yang at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 54 +++++++++++++++++++++++--
 drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h |  6 ++-
 2 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
index c39ed9eb0987..888b749bd75e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
@@ -332,6 +332,17 @@ void amdgpu_gmc_agp_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
 			mc->agp_size >> 20, mc->agp_start, mc->agp_end);
 }
 
+/**
+ * amdgpu_gmc_fault_key - get hask key from vm fault address and pasid
+ *
+ * @addr: 48bit physical address
+ * @pasid: 4 bit
+ */
+static inline uint64_t amdgpu_gmc_fault_key(uint64_t addr, uint16_t pasid)
+{
+	return addr << 4 | pasid;
+}
+
 /**
  * amdgpu_gmc_filter_faults - filter VM faults
  *
@@ -349,13 +360,14 @@ bool amdgpu_gmc_filter_faults(struct amdgpu_device *adev, uint64_t addr,
 {
 	struct amdgpu_gmc *gmc = &adev->gmc;
 
-	uint64_t stamp, key = addr << 4 | pasid;
+	uint64_t stamp, key = amdgpu_gmc_fault_key(addr, pasid);
 	struct amdgpu_gmc_fault *fault;
 	uint32_t hash;
 
 	/* If we don't have space left in the ring buffer return immediately */
 	stamp = max(timestamp, AMDGPU_GMC_FAULT_TIMEOUT + 1) -
 		AMDGPU_GMC_FAULT_TIMEOUT;
+
 	if (gmc->fault_ring[gmc->last_fault].timestamp >= stamp)
 		return true;
 
@@ -365,7 +377,7 @@ bool amdgpu_gmc_filter_faults(struct amdgpu_device *adev, uint64_t addr,
 	while (fault->timestamp >= stamp) {
 		uint64_t tmp;
 
-		if (fault->key == key)
+		if (atomic64_read(&fault->key) == key)
 			return true;
 
 		tmp = fault->timestamp;
@@ -378,7 +390,7 @@ bool amdgpu_gmc_filter_faults(struct amdgpu_device *adev, uint64_t addr,
 
 	/* Add the fault to the ring */
 	fault = &gmc->fault_ring[gmc->last_fault];
-	fault->key = key;
+	atomic64_set(&fault->key, key);
 	fault->timestamp = timestamp;
 
 	/* And update the hash */
@@ -387,6 +399,42 @@ bool amdgpu_gmc_filter_faults(struct amdgpu_device *adev, uint64_t addr,
 	return false;
 }
 
+/**
+ * amdgpu_gmc_filter_faults_remove - remove address from VM faults filter
+ *
+ * @adev: amdgpu device structure
+ * @addr: address of the VM fault
+ * @pasid: PASID of the process causing the fault
+ *
+ * Remove the address from fault filter, then future vm fault on this address
+ * will pass to retry fault handler to recover.
+ */
+void amdgpu_gmc_filter_faults_remove(struct amdgpu_device *adev, uint64_t addr,
+				     uint16_t pasid)
+{
+	struct amdgpu_gmc *gmc = &adev->gmc;
+
+	uint64_t key = amdgpu_gmc_fault_key(addr, pasid);
+	struct amdgpu_gmc_fault *fault;
+	uint32_t hash;
+
+	hash = hash_64(key, AMDGPU_GMC_FAULT_HASH_ORDER);
+	fault = &gmc->fault_ring[gmc->fault_hash[hash].idx];
+	while (true) {
+		uint64_t tmp;
+
+		if (atomic64_cmpxchg(&fault->key, key, 0) == key)
+			break;
+
+		tmp = fault->timestamp;
+		fault = &gmc->fault_ring[fault->next];
+
+		/* Check if the entry was reused */
+		if (fault->timestamp >= tmp)
+			break;
+	}
+}
+
 int amdgpu_gmc_ras_late_init(struct amdgpu_device *adev)
 {
 	int r;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
index 9d11c02a3938..95e18ef83aec 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
@@ -66,9 +66,9 @@ struct firmware;
  * GMC page fault information
  */
 struct amdgpu_gmc_fault {
-	uint64_t	timestamp;
+	uint64_t	timestamp:56;
 	uint64_t	next:AMDGPU_GMC_FAULT_RING_ORDER;
-	uint64_t	key:52;
+	atomic64_t	key;
 };
 
 /*
@@ -318,6 +318,8 @@ void amdgpu_gmc_agp_location(struct amdgpu_device *adev,
 			     struct amdgpu_gmc *mc);
 bool amdgpu_gmc_filter_faults(struct amdgpu_device *adev, uint64_t addr,
 			      uint16_t pasid, uint64_t timestamp);
+void amdgpu_gmc_filter_faults_remove(struct amdgpu_device *adev, uint64_t addr,
+				     uint16_t pasid);
 int amdgpu_gmc_ras_late_init(struct amdgpu_device *adev);
 void amdgpu_gmc_ras_fini(struct amdgpu_device *adev);
 int amdgpu_gmc_allocate_vm_inv_eng(struct amdgpu_device *adev);
-- 
2.17.1