[PATCH 1/2] drm/amdgpu: Moved fault hash table to amdgpu vm
Zeng, Oak
Oak.Zeng at amd.com
Fri Sep 7 15:30:46 UTC 2018
Without a VM, how can you get the physical address of the faulty virtual address? Where this information should be hold?
Thanks,
Oak
From: Koenig, Christian
Sent: Monday, September 10, 2018 7:20 AM
To: Zeng, Oak <Oak.Zeng at amd.com>; Oak Zeng <zengshanjun at gmail.com>; amd-gfx at lists.freedesktop.org; Yang, Philip <Philip.Yang at amd.com>
Subject: Re: [PATCH 1/2] drm/amdgpu: Moved fault hash table to amdgpu vm
Am I right that the handling of page fault need a valid VM?
No, exactly that view is incorrect.
The VM is meant to be a memory management structure of page tables and is completely pointless fault processing because it represent the future state of the page tables and not the current one.
What we need for fault processing is a new structure build around PASIDs which is feed by the with addresses when page tables are moved around.
Alternatively I hope that we can use the SDMA to walk the page tables and update the required entries by just using the address.
Regards,
Christian.
Am 07.09.2018 um 16:55 schrieb Zeng, Oak:
Hi Christian,
What is the value of delay the destroy of hash to after vm is destroyed? Since vm is destroyed, you basically don’t have enough information to paging in the correct page to gpuvm. Am I right that the handling of page fault need a valid VM? For example, you need the VM to get the corresponding physical address of the faulty page.
After vm is destroyed, the retry interrupt can be directly discard as you can’t find vm through pasid. You can think this is also one kind of prescreen.
So I am stand for the point that, there is no need to delay the destroy of hash to after vm is destroyed. Prescreening hash can be destroyed at the time of vm_fini.
Thanks,
Oak
From: Christian König <ckoenig.leichtzumerken at gmail.com><mailto:ckoenig.leichtzumerken at gmail.com>
Sent: Friday, September 07, 2018 4:39 AM
To: Zeng, Oak <Oak.Zeng at amd.com><mailto:Oak.Zeng at amd.com>; Oak Zeng <zengshanjun at gmail.com><mailto:zengshanjun at gmail.com>; amd-gfx at lists.freedesktop.org<mailto:amd-gfx at lists.freedesktop.org>
Cc: Zeng, Oak <Oak.Zeng at amd.com><mailto:Oak.Zeng at amd.com>
Subject: Re: [PATCH 1/2] drm/amdgpu: Moved fault hash table to amdgpu vm
Hi Oak,
yeah, but this is still a NAK. Making the hash per PASID was not a suggestion but rather a must have.
The VM structures must be destroyed while the processing is still ongoing, or otherwise we would not have a clean OOM handling.
The IDR for PASID lockup can be put into amdgpu_ids.c, you can just replace the IDA already used there with an IDR.
Since the PASID is already freed up delayed we should have the grace period for interrupt processing included. If that still isn't sufficient we can still add some delayed work for this.
Regards,
Christian.
Am 07.09.2018 um 06:16 schrieb ozeng:
Hi Christian,
In this implementation, fault hash is made per vm, not per pasid as suggested, based on below considerations:
* Delay the destroy of hash introduces more effort like how to set the proper grace period after which no retry interrupt will be generated. We want to avoid those complication if we can.
* The problem of the per vm implementation is that it is hard to delay the destroy of fault hash, because when vm is destroyed, prescreen function won't be able to retrieve the fault hash. But in this case, the prescreen function can either let the interrupt go through (to gmc) or ignore it. From this perspective, it is not very necessary to delay the destroy of hash table.
* On the other hand, since ASICs after vega10 have the HW CAM feature. So the SW IV prescreen is only useful for vega10. For all the HW implemented CAM, we can consider the delayed CAM acknowledgment.
* Making it per pasid need to introduce another idr to correlate pasid and hash table - where to put the idr? You will have to make it a global variable which is not very desirable.
The main purpose of this patch is to solve the inter-process lock issue (when hash table is full), while still keep codes simple.
Also with this patch, the faults kfifo is not necessary any more. See patch 2.
Regards,
Oak
On 09/06/2018 11:28 PM, Oak Zeng wrote:
In stead of share one fault hash table per device, make it
per vm. This can avoid inter-process lock issue when fault
hash table is full.
Change-Id: I5d1281b7c41eddc8e26113e010516557588d3708
Signed-off-by: Oak Zeng <Oak.Zeng at amd.com><mailto:Oak.Zeng at amd.com>
Suggested-by: Christian Konig <Christian.Koenig at amd.com><mailto:Christian.Koenig at amd.com>
Suggested-by: Felix Kuehling <Felix.Kuehling at amd.com><mailto:Felix.Kuehling at amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c | 75 ------------------------
drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h | 10 ----
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 102 ++++++++++++++++++++++++++++++++-
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 12 ++++
drivers/gpu/drm/amd/amdgpu/vega10_ih.c | 38 +++++-------
5 files changed, 127 insertions(+), 110 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c
index 06373d4..4ed8621 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c
@@ -197,78 +197,3 @@ int amdgpu_ih_process(struct amdgpu_device *adev)
return IRQ_HANDLED;
}
-/**
- * amdgpu_ih_add_fault - Add a page fault record
- *
- * @adev: amdgpu device pointer
- * @key: 64-bit encoding of PASID and address
- *
- * This should be called when a retry page fault interrupt is
- * received. If this is a new page fault, it will be added to a hash
- * table. The return value indicates whether this is a new fault, or
- * a fault that was already known and is already being handled.
- *
- * If there are too many pending page faults, this will fail. Retry
- * interrupts should be ignored in this case until there is enough
- * free space.
- *
- * Returns 0 if the fault was added, 1 if the fault was already known,
- * -ENOSPC if there are too many pending faults.
- */
-int amdgpu_ih_add_fault(struct amdgpu_device *adev, u64 key)
-{
- unsigned long flags;
- int r = -ENOSPC;
-
- if (WARN_ON_ONCE(!adev->irq.ih.faults))
- /* Should be allocated in <IP>_ih_sw_init on GPUs that
- * support retry faults and require retry filtering.
- */
- return r;
-
- spin_lock_irqsave(&adev->irq.ih.faults->lock, flags);
-
- /* Only let the hash table fill up to 50% for best performance */
- if (adev->irq.ih.faults->count >= (1 << (AMDGPU_PAGEFAULT_HASH_BITS-1)))
- goto unlock_out;
-
- r = chash_table_copy_in(&adev->irq.ih.faults->hash, key, NULL);
- if (!r)
- adev->irq.ih.faults->count++;
-
- /* chash_table_copy_in should never fail unless we're losing count */
- WARN_ON_ONCE(r < 0);
-
-unlock_out:
- spin_unlock_irqrestore(&adev->irq.ih.faults->lock, flags);
- return r;
-}
-
-/**
- * amdgpu_ih_clear_fault - Remove a page fault record
- *
- * @adev: amdgpu device pointer
- * @key: 64-bit encoding of PASID and address
- *
- * This should be called when a page fault has been handled. Any
- * future interrupt with this key will be processed as a new
- * page fault.
- */
-void amdgpu_ih_clear_fault(struct amdgpu_device *adev, u64 key)
-{
- unsigned long flags;
- int r;
-
- if (!adev->irq.ih.faults)
- return;
-
- spin_lock_irqsave(&adev->irq.ih.faults->lock, flags);
-
- r = chash_table_remove(&adev->irq.ih.faults->hash, key, NULL);
- if (!WARN_ON_ONCE(r < 0)) {
- adev->irq.ih.faults->count--;
- WARN_ON_ONCE(adev->irq.ih.faults->count < 0);
- }
-
- spin_unlock_irqrestore(&adev->irq.ih.faults->lock, flags);
-}
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h
index a23e1c0..f411ffb 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h
@@ -32,13 +32,6 @@ struct amdgpu_device;
#define AMDGPU_IH_CLIENTID_LEGACY 0
#define AMDGPU_IH_CLIENTID_MAX SOC15_IH_CLIENTID_MAX
-#define AMDGPU_PAGEFAULT_HASH_BITS 8
-struct amdgpu_retryfault_hashtable {
- DECLARE_CHASH_TABLE(hash, AMDGPU_PAGEFAULT_HASH_BITS, 8, 0);
- spinlock_t lock;
- int count;
-};
-
/*
* R6xx+ IH ring
*/
@@ -57,7 +50,6 @@ struct amdgpu_ih_ring {
bool use_doorbell;
bool use_bus_addr;
dma_addr_t rb_dma_addr; /* only used when use_bus_addr = true */
- struct amdgpu_retryfault_hashtable *faults;
};
#define AMDGPU_IH_SRC_DATA_MAX_SIZE_DW 4
@@ -95,7 +87,5 @@ int amdgpu_ih_ring_init(struct amdgpu_device *adev, unsigned ring_size,
bool use_bus_addr);
void amdgpu_ih_ring_fini(struct amdgpu_device *adev);
int amdgpu_ih_process(struct amdgpu_device *adev);
-int amdgpu_ih_add_fault(struct amdgpu_device *adev, u64 key);
-void amdgpu_ih_clear_fault(struct amdgpu_device *adev, u64 key);
#endif
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 1d7e3c1..8b220e9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2692,6 +2692,22 @@ void amdgpu_vm_adjust_size(struct amdgpu_device *adev, uint32_t min_vm_size,
adev->vm_manager.fragment_size);
}
+static struct amdgpu_retryfault_hashtable *init_fault_hash(void)
+{
+ struct amdgpu_retryfault_hashtable *fault_hash;
+
+ fault_hash = kmalloc(sizeof(*fault_hash), GFP_KERNEL);
+ if (!fault_hash)
+ return fault_hash;
+
+ INIT_CHASH_TABLE(fault_hash->hash,
+ AMDGPU_PAGEFAULT_HASH_BITS, 8, 0);
+ spin_lock_init(&fault_hash->lock);
+ fault_hash->count = 0;
+
+ return fault_hash;
+}
+
/**
* amdgpu_vm_init - initialize a vm instance
*
@@ -2780,6 +2796,12 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
vm->pasid = pasid;
}
+ vm->fault_hash = init_fault_hash();
+ if (!vm->fault_hash) {
+ r = -ENOMEM;
+ goto error_free_root;
+ }
+
INIT_KFIFO(vm->faults);
vm->fault_credit = 16;
@@ -2973,7 +2995,7 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
/* Clear pending page faults from IH when the VM is destroyed */
while (kfifo_get(&vm->faults, &fault))
- amdgpu_ih_clear_fault(adev, fault);
+ amdgpu_vm_clear_fault(vm->fault_hash, fault);
if (vm->pasid) {
unsigned long flags;
@@ -2983,6 +3005,9 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
spin_unlock_irqrestore(&adev->vm_manager.pasid_lock, flags);
}
+ kfree(vm->fault_hash);
+ vm->fault_hash = NULL;
+
drm_sched_entity_destroy(&vm->entity);
if (!RB_EMPTY_ROOT(&vm->va.rb_root)) {
@@ -3183,3 +3208,78 @@ void amdgpu_vm_set_task_info(struct amdgpu_vm *vm)
}
}
}
+
+/**
+ * amdgpu_vm_add_fault - Add a page fault record to fault hash table
+ *
+ * @fault_hash: fault hash table
+ * @key: 64-bit encoding of PASID and address
+ *
+ * This should be called when a retry page fault interrupt is
+ * received. If this is a new page fault, it will be added to a hash
+ * table. The return value indicates whether this is a new fault, or
+ * a fault that was already known and is already being handled.
+ *
+ * If there are too many pending page faults, this will fail. Retry
+ * interrupts should be ignored in this case until there is enough
+ * free space.
+ *
+ * Returns 0 if the fault was added, 1 if the fault was already known,
+ * -ENOSPC if there are too many pending faults.
+ */
+int amdgpu_vm_add_fault(struct amdgpu_retryfault_hashtable *fault_hash, u64 key)
+{
+ unsigned long flags;
+ int r = -ENOSPC;
+
+ if (WARN_ON_ONCE(!fault_hash))
+ /* Should be allocated in amdgpu_vm_init
+ */
+ return r;
+
+ spin_lock_irqsave(&fault_hash->lock, flags);
+
+ /* Only let the hash table fill up to 50% for best performance */
+ if (fault_hash->count >= (1 << (AMDGPU_PAGEFAULT_HASH_BITS-1)))
+ goto unlock_out;
+
+ r = chash_table_copy_in(&fault_hash->hash, key, NULL);
+ if (!r)
+ fault_hash->count++;
+
+ /* chash_table_copy_in should never fail unless we're losing count */
+ WARN_ON_ONCE(r < 0);
+
+unlock_out:
+ spin_unlock_irqrestore(&fault_hash->lock, flags);
+ return r;
+}
+
+/**
+ * amdgpu_vm_clear_fault - Remove a page fault record
+ *
+ * @fault_hash: fault hash table
+ * @key: 64-bit encoding of PASID and address
+ *
+ * This should be called when a page fault has been handled. Any
+ * future interrupt with this key will be processed as a new
+ * page fault.
+ */
+void amdgpu_vm_clear_fault(struct amdgpu_retryfault_hashtable *fault_hash, u64 key)
+{
+ unsigned long flags;
+ int r;
+
+ if (!fault_hash)
+ return;
+
+ spin_lock_irqsave(&fault_hash->lock, flags);
+
+ r = chash_table_remove(&fault_hash->hash, key, NULL);
+ if (!WARN_ON_ONCE(r < 0)) {
+ fault_hash->count--;
+ WARN_ON_ONCE(fault_hash->count < 0);
+ }
+
+ spin_unlock_irqrestore(&fault_hash->lock, flags);
+}
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
index e275ee7..6eb1da1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
@@ -178,6 +178,13 @@ struct amdgpu_task_info {
pid_t tgid;
};
+#define AMDGPU_PAGEFAULT_HASH_BITS 8
+struct amdgpu_retryfault_hashtable {
+ DECLARE_CHASH_TABLE(hash, AMDGPU_PAGEFAULT_HASH_BITS, 8, 0);
+ spinlock_t lock;
+ int count;
+};
+
struct amdgpu_vm {
/* tree of virtual addresses mapped */
struct rb_root_cached va;
@@ -240,6 +247,7 @@ struct amdgpu_vm {
struct ttm_lru_bulk_move lru_bulk_move;
/* mark whether can do the bulk move */
bool bulk_moveable;
+ struct amdgpu_retryfault_hashtable *fault_hash;
};
struct amdgpu_vm_manager {
@@ -355,4 +363,8 @@ void amdgpu_vm_set_task_info(struct amdgpu_vm *vm);
void amdgpu_vm_move_to_lru_tail(struct amdgpu_device *adev,
struct amdgpu_vm *vm);
+int amdgpu_vm_add_fault(struct amdgpu_retryfault_hashtable *fault_hash, u64 key);
+
+void amdgpu_vm_clear_fault(struct amdgpu_retryfault_hashtable *fault_hash, u64 key);
+
#endif
diff --git a/drivers/gpu/drm/amd/amdgpu/vega10_ih.c b/drivers/gpu/drm/amd/amdgpu/vega10_ih.c
index 5ae5ed2..acbe5a7 100644
--- a/drivers/gpu/drm/amd/amdgpu/vega10_ih.c
+++ b/drivers/gpu/drm/amd/amdgpu/vega10_ih.c
@@ -265,35 +265,36 @@ static bool vega10_ih_prescreen_iv(struct amdgpu_device *adev)
return true;
}
- addr = ((u64)(dw5 & 0xf) << 44) | ((u64)dw4 << 12);
- key = AMDGPU_VM_FAULT(pasid, addr);
- r = amdgpu_ih_add_fault(adev, key);
-
- /* Hash table is full or the fault is already being processed,
- * ignore further page faults
- */
- if (r != 0)
- goto ignore_iv;
-
/* Track retry faults in per-VM fault FIFO. */
spin_lock(&adev->vm_manager.pasid_lock);
vm = idr_find(&adev->vm_manager.pasid_idr, pasid);
+ addr = ((u64)(dw5 & 0xf) << 44) | ((u64)dw4 << 12);
+ key = AMDGPU_VM_FAULT(pasid, addr);
if (!vm) {
/* VM not found, process it normally */
spin_unlock(&adev->vm_manager.pasid_lock);
- amdgpu_ih_clear_fault(adev, key);
return true;
+ } else {
+ r = amdgpu_vm_add_fault(vm->fault_hash, key);
+
+ /* Hash table is full or the fault is already being processed,
+ * ignore further page faults
+ */
+ if (r != 0) {
+ spin_unlock(&adev->vm_manager.pasid_lock);
+ goto ignore_iv;
+ }
}
/* No locking required with single writer and single reader */
r = kfifo_put(&vm->faults, key);
if (!r) {
/* FIFO is full. Ignore it until there is space */
+ amdgpu_vm_clear_fault(vm->fault_hash, key);
spin_unlock(&adev->vm_manager.pasid_lock);
- amdgpu_ih_clear_fault(adev, key);
goto ignore_iv;
}
- spin_unlock(&adev->vm_manager.pasid_lock);
+ spin_unlock(&adev->vm_manager.pasid_lock);
/* It's the first fault for this address, process it normally */
return true;
@@ -386,14 +387,6 @@ static int vega10_ih_sw_init(void *handle)
adev->irq.ih.use_doorbell = true;
adev->irq.ih.doorbell_index = AMDGPU_DOORBELL64_IH << 1;
- adev->irq.ih.faults = kmalloc(sizeof(*adev->irq.ih.faults), GFP_KERNEL);
- if (!adev->irq.ih.faults)
- return -ENOMEM;
- INIT_CHASH_TABLE(adev->irq.ih.faults->hash,
- AMDGPU_PAGEFAULT_HASH_BITS, 8, 0);
- spin_lock_init(&adev->irq.ih.faults->lock);
- adev->irq.ih.faults->count = 0;
-
r = amdgpu_irq_init(adev);
return r;
@@ -406,9 +399,6 @@ static int vega10_ih_sw_fini(void *handle)
amdgpu_irq_fini(adev);
amdgpu_ih_ring_fini(adev);
- kfree(adev->irq.ih.faults);
- adev->irq.ih.faults = NULL;
-
return 0;
}
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