[PATCH 4/5] drm/amdgpu: Support snooped PTE flag

[Zeng, Oak]

Regards,
Oak

-----Original Message-----
From: Koenig, Christian <Christian.Koenig at amd.com> 
Sent: Friday, August 9, 2019 8:31 AM
To: Zeng, Oak <Oak.Zeng at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Kuehling, Felix <Felix.Kuehling at amd.com>; Keely, Sean <Sean.Keely at amd.com>
Subject: Re: [PATCH 4/5] drm/amdgpu: Support snooped PTE flag

Am 09.08.19 um 04:15 schrieb Zeng, Oak:
> 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 at amd.com>
> ---
>   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 d709902..8faead3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> @@ -599,6 +599,9 @@ 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;
> +

Still a NAK, we absolutely need a check here that this is only set when the BO is in XGMI.

[Oak]: Per discussion with upper layer stack, remote vram mapping (either over PCIe or XGMI) should always invalidate probe the cache lines of GPU who owns the memory object.

Christian.

>   	return pte_flag;
>   }
>