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| author | Alexey Kardashevskiy <aik@ozlabs.ru> | 2018-12-19 19:52:29 +1100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2018-12-21 16:20:46 +1100 |
| commit | 58629c0dc34904d135af944d120eb23165ec3b61 (patch) | |
| tree | c6e96ae78213fc95c6f7181047ee68210d6440d1 /arch/powerpc | |
| parent | 135ef954051b102870a8d47a8eb822af1f1b1ec1 (diff) | |
| download | linux-58629c0dc34904d135af944d120eb23165ec3b61.tar.bz2 | |
powerpc/powernv/npu: Fault user page into the hypervisor's pagetable
When a page fault happens in a GPU, the GPU signals the OS and the GPU
driver calls the fault handler which populated a page table; this allows
the GPU to complete an ATS request.
On the bare metal get_user_pages() is enough as it adds a pte to
the kernel page table but under KVM the partition scope tree does not get
updated so ATS will still fail.
This reads a byte from an effective address which causes HV storage
interrupt and KVM updates the partition scope tree.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/platforms/powernv/npu-dma.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c index b713727663e2..d7f742ed48ba 100644 --- a/arch/powerpc/platforms/powernv/npu-dma.c +++ b/arch/powerpc/platforms/powernv/npu-dma.c @@ -1132,6 +1132,8 @@ int pnv_npu2_handle_fault(struct npu_context *context, uintptr_t *ea, u64 rc = 0, result = 0; int i, is_write; struct page *page[1]; + const char __user *u; + char c; /* mmap_sem should be held so the struct_mm must be present */ struct mm_struct *mm = context->mm; @@ -1144,18 +1146,17 @@ int pnv_npu2_handle_fault(struct npu_context *context, uintptr_t *ea, is_write ? FOLL_WRITE : 0, page, NULL, NULL); - /* - * To support virtualised environments we will have to do an - * access to the page to ensure it gets faulted into the - * hypervisor. For the moment virtualisation is not supported in - * other areas so leave the access out. - */ if (rc != 1) { status[i] = rc; result = -EFAULT; continue; } + /* Make sure partition scoped tree gets a pte */ + u = page_address(page[0]); + if (__get_user(c, u)) + result = -EFAULT; + status[i] = 0; put_page(page[0]); } |