Hi Wentao, well the problem is you don't seem to understand how the hardware works. See the engines see an MC address space with a hole in the middle, similar to the how x86 64bit CPU address space works. But the page tables are programmed linearly. So the calculation in amdgpu_driver_open_kms() is correct because it takes the MC address and mages a linear page table index from it again. The only thing we might need to fix here is shifting max_pfn before the subtraction and I doubt that even that is necessary. Regards, Christian. Am 16.01.19 um 10:34 schrieb Lou, Wentao: Hi Christian, Now vm_size was set to 0x4 0000 GB by below commit: 1bf621c42137926ac249af761c0190a9258aa0db drm/amdgpu: Remove unnecessary VM size calculations So that max_pfn would be 0x10 0000 0000. amdgpu_csa_vaddr would make max_pfn << 12 to get 0x1 0000 0000 0000, and then minus AMDGPU_VA_RESERVED_SIZE, to get 0xFFFF FFF0 0000 unfortunately this number was between AMDGPU_GMC_HOLE_START and AMDGPU_GMC_HOLE_END, so that amdgpu_gmc_sign_extend was called to make it 0xFFFF FFFF FFF0 0000 in amdgpu_driver_open_kms, extended csa_addr cannot be passed into amdgpu_map_static_csa directly, it would be above the limit of max_pfn. So that csa_addr was restricted by AMDGPU_GMC_HOLE_MASK to make it possible for amdgpu_vm_alloc_pts. But this restriction by AMDGPU_GMC_HOLE_MASK would make the address fall back into AMDGPU_GMC_HOLE again, which causing GPU reset. We just put amdgpu_csa_vaddr back to AMDGPU_GMC_HOLE_START, to avoid the address touching AMDGPU_GMC_HOLE. By the way, if max_pfn was shift much to the left, it would always get zero, with or without min(*,*). BR, Wentao -----Original Message----- From: Koenig, Christian Sent: Tuesday, January 15, 2019 4:02 PM To: Liu, Monk ; Lou, Wentao ; amd-gfx@lists.freedesktop.org; Zhu, Rex Subject: Re: [PATCH] drm/amdgpu: csa_vaddr should not larger than AMDGPU_GMC_HOLE_START Am 15.01.19 um 07:19 schrieb Liu, Monk: > The max_pfn is now 1'0000'0000'0000'0000 (bytes) which is above 48 bit now, and it with AMDGPU_GMC_HOLE_MASK make it to zero .... > > And in code "amdgpu_driver_open_kms()" I saw @Zhu, Rex write the code as : > > "csa_addr = amdgpu_csa_vadr(adev) & AMDGPU_GMC_HOLE_MASK", I think this is wrong since you intentionally place the csa above GMC hole, right ? The fix is just completely incorrect since min(adev->vm_manager.max_pfn << AMDGPU_GPU_PAGE_SHIFT, AMDGPU_GMC_HOLE_START) still gives you 0 when we shift max_pfn to much to the left. The correct solution is to substract the reserved size first and then shift. E.g.: addr = (max_pfn - (AMDGPU_VA_RESERVED_SIZE >> AMDGPU_PAGE_SHIFT)) << AMDGPU_PAGE_SHIFT; Regards, Christian. > > Looks like we should modify this place > > /Monk > > -----Original Message----- > From: amd-gfx > On Behalf Of > Christian K?nig > Sent: Monday, January 14, 2019 9:05 PM > To: Lou, Wentao >; amd-gfx@lists.freedesktop.org > Subject: Re: [PATCH] drm/amdgpu: csa_vaddr should not larger than > AMDGPU_GMC_HOLE_START > > Am 14.01.19 um 09:40 schrieb wentalou: >> After removing unnecessary VM size calculations, vm_manager.max_pfn >> would reach 0x10,0000,0000 max_pfn << AMDGPU_GPU_PAGE_SHIFT exceeding >> AMDGPU_GMC_HOLE_START would caused GPU reset. >> >> Change-Id: I47ad0be2b0bd9fb7490c4e1d7bb7bdacf71132cb >> Signed-off-by: wentalou > > NAK, that is incorrect. We intentionally place the csa above the GMC hole. > > Regards, > Christian. > >> --- >> drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c >> b/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c >> index 7e22be7..dd3bd01 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c >> @@ -26,7 +26,8 @@ >> >> uint64_t amdgpu_csa_vaddr(struct amdgpu_device *adev) >> { >> - uint64_t addr = adev->vm_manager.max_pfn << AMDGPU_GPU_PAGE_SHIFT; >> + uint64_t addr = min(adev->vm_manager.max_pfn << AMDGPU_GPU_PAGE_SHIFT, >> + AMDGPU_GMC_HOLE_START); >> >> addr -= AMDGPU_VA_RESERVED_SIZE; >> addr = amdgpu_gmc_sign_extend(addr); > _______________________________________________ > amd-gfx mailing list > amd-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx