Messages in this thread | | | Subject | Re: [RESEND PATCH 2/3] nouveau: fix mixed normal and device private page migration | From | Ralph Campbell <> | Date | Mon, 22 Jun 2020 18:42:00 -0700 |
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On 6/22/20 5:30 PM, John Hubbard wrote: > On 2020-06-22 16:38, Ralph Campbell wrote: >> The OpenCL function clEnqueueSVMMigrateMem(), without any flags, will >> migrate memory in the given address range to device private memory. The >> source pages might already have been migrated to device private memory. >> In that case, the source struct page is not checked to see if it is >> a device private page and incorrectly computes the GPU's physical >> address of local memory leading to data corruption. >> Fix this by checking the source struct page and computing the correct >> physical address. >> >> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> >> --- >> drivers/gpu/drm/nouveau/nouveau_dmem.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c >> index cc9993837508..f6a806ba3caa 100644 >> --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c >> +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c >> @@ -540,6 +540,12 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm, >> if (!(src & MIGRATE_PFN_MIGRATE)) >> goto out; >> + if (spage && is_device_private_page(spage)) { >> + paddr = nouveau_dmem_page_addr(spage); >> + *dma_addr = DMA_MAPPING_ERROR; >> + goto done; >> + } >> + >> dpage = nouveau_dmem_page_alloc_locked(drm); >> if (!dpage) >> goto out; >> @@ -560,6 +566,7 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct nouveau_drm *drm, >> goto out_free_page; >> } >> +done: >> *pfn = NVIF_VMM_PFNMAP_V0_V | NVIF_VMM_PFNMAP_V0_VRAM | >> ((paddr >> PAGE_SHIFT) << NVIF_VMM_PFNMAP_V0_ADDR_SHIFT); >> if (src & MIGRATE_PFN_WRITE) >> @@ -615,6 +622,7 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm, >> struct migrate_vma args = { >> .vma = vma, >> .start = start, >> + .src_owner = drm->dev, > > Hi Ralph, > > This .src_owner setting does look like a required fix, but it seems like > a completely separate fix from what is listed in this patch's commit > description, right? (It feels like a casualty of rearranging the patches.) > > > thanks,
It's a bit more complex. There is a catch-22 here with the change to mm/migrate.c. Without this patch or mm/migrate.c, a second call to clEnqueueSVMMigrateMem() for the same address range will invalidate the GPU mapping to device private memory created by the first call. With this patch but not mm/migrate.c, the first call to clEnqueueSVMMigrateMem() will fail to migrate normal anonymous memory to device private memory. Without this patch but including the change to mm/migrate.c, a second call to clEnqueueSVMMigrateMem() will crash the kernel because dma_map_page() will be called with the device private PFN which is not a valid CPU physical address. With both changes, a range of anonymous and device private pages can be migrated to the GPU and the GPU page tables updated properly.
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