As PCIe is non-coherent link, do not allow direct memory access across
PCIe link. Handle CPU fault by migrating pages back to host memory.
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Jon Bloomfield <jon.bloomfield@xxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Sudeep Dutt <sudeep.dutt@xxxxxxxxx>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_svm_devmem.c | 70 +++++++++++++++++++++++++-
1 file changed, 69 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_svm_devmem.c b/drivers/gpu/drm/i915/i915_svm_devmem.c
index 0a1f1394f196..98ab27879041 100644
--- a/drivers/gpu/drm/i915/i915_svm_devmem.c
+++ b/drivers/gpu/drm/i915/i915_svm_devmem.c
@@ -286,9 +286,77 @@ int i915_devmem_migrate_vma(struct intel_memory_region *mem,
return ret;
}
+static vm_fault_t
+i915_devmem_fault_alloc_and_copy(struct i915_devmem_migrate *migrate)
+{
+ struct device *dev = migrate->i915->drm.dev;
+ struct migrate_vma *args = migrate->args;
+ struct page *dpage, *spage;
+
+ DRM_DEBUG_DRIVER("start 0x%lx\n", args->start);
+ /* Allocate host page */
+ spage = migrate_pfn_to_page(args->src[0]);
+ if (unlikely(!spage || !(args->src[0] & MIGRATE_PFN_MIGRATE)))
+ return 0;
+
+ dpage = alloc_page_vma(GFP_HIGHUSER, args->vma, args->start);
+ if (unlikely(!dpage))
+ return VM_FAULT_SIGBUS;
+ lock_page(dpage);
+
+ args->dst[0] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+
+ /* Copy the pages */
+ migrate->npages = 1;
+
+ return 0;
+}
+
+void i915_devmem_fault_finalize_and_map(struct i915_devmem_migrate *migrate)
+{
+ DRM_DEBUG_DRIVER("\n");
+}
+
+static inline struct i915_devmem *page_to_devmem(struct page *page)
+{
+ return container_of(page->pgmap, struct i915_devmem, pagemap);
+}
+
static vm_fault_t i915_devmem_migrate_to_ram(struct vm_fault *vmf)
{
- return VM_FAULT_SIGBUS;
+ struct i915_devmem *devmem = page_to_devmem(vmf->page);
+ struct drm_i915_private *i915 = devmem->i915;
+ struct i915_devmem_migrate migrate = {0};
+ unsigned long src = 0, dst = 0;
+ vm_fault_t ret;
+ struct migrate_vma args = {
+ .vma = vmf->vma,
+ .start = vmf->address,
+ .end = vmf->address + PAGE_SIZE,
+ .src = &src,
+ .dst = &dst,
+ };
+
+ /* XXX: Opportunistically migrate more pages? */
+ DRM_DEBUG_DRIVER("addr 0x%lx\n", args.start);
+ migrate.i915 = i915;
+ migrate.args = &args;
+ migrate.src_id = INTEL_REGION_LMEM;
+ migrate.dst_id = INTEL_REGION_SMEM;
+ if (migrate_vma_setup(&args) < 0)
+ return VM_FAULT_SIGBUS;
+ if (!args.cpages)
+ return 0;
+
+ ret = i915_devmem_fault_alloc_and_copy(&migrate);
+ if (ret || dst == 0)
+ goto done;
+
+ migrate_vma_pages(&args);
+ i915_devmem_fault_finalize_and_map(&migrate);
+done:
+ migrate_vma_finalize(&args);
+ return ret;
}
static void i915_devmem_page_free(struct page *page)
--
2.21.0.rc0.32.g243a4c7e27
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