Am 24.08.19 um 18:24 schrieb Kuehling, Felix:
On 2019-08-24 7:13, Christian König wrote:
Am 23.08.19 um 23:33 schrieb Kuehling, Felix:
From: Oak Zeng <Oak.Zeng@xxxxxxx>
Set snooped PTE flag according to mapping flag. Write request to a
page with snooped bit set, will send out invalidate probe request
to TCC of the remote GPU where the vram page resides.
Change-Id: I799f68ec7a5a1abf32075f5ef31051641a0b3736
Signed-off-by: Oak Zeng <Oak.Zeng@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
index 9aafcda6c488..8a7c4ec69ae8 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -604,6 +604,9 @@ static uint64_t gmc_v9_0_get_vm_pte_flags(struct
amdgpu_device *adev,
if (flags & AMDGPU_VM_PAGE_PRT)
pte_flag |= AMDGPU_PTE_PRT;
+ if (flags & AMDGPU_VM_PAGE_INVALIDATE_PROBE)
+ pte_flag |= AMDGPU_PTE_SNOOPED;
+
That is still a NAK without further checks. We need to make absolutely
sure that we don't set this when PCIe routing is in use.
The only place where AMDGPU_VM_... flags are accepted from user mode
seems to be amdgpu_gem_va_ioctl. It has an explicit set of valid_flags
it accepts. The new INVALIDATE_PROBE flag is not part of it. That means
user mode will not be able to set it directly. If we added it to the
set of valid_flags in amdgpu_gem_va_ioctl, we'd need to add appropriate
checks at the same time.
KFD does not expose AMDGPU_VM_... flags directly to user mode. It only
sets the INVALIDATE_PROBE flag in kernel mode for mappings in the same
XGMI hive on Arturus (in patch 4).
If there is something I'm missing, please point it out. But AFAICT the
checking that is currently done should satisfy your requirements.
The hardware behavior depends on the placement of the buffer, so at bare
minimum we need to check if it's pointing to PCIe or local (check the
system bit).
But even if it's local what is the behavior for local memory? E.g. not
accessed through XGMI?
As far as I can see what we need to check here is that this is a remote
access over XGMI and then (and only then!) we are allowed to set the
snoop bit on the PTE.
Regards,
Christian.
Regards,
Felix
Christian.
return pte_flag;
}
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