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@linux.intel.com Cc: Jon Bloomfield jon.bloomfield@intel.com Cc: Daniel Vetter daniel.vetter@intel.com Cc: Sudeep Dutt sudeep.dutt@intel.com Signed-off-by: Niranjana Vishwanathapura niranjana.vishwanathapura@intel.com --- 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 40c2f79ff614..37a205d3a82f 100644 --- a/drivers/gpu/drm/i915/i915_svm_devmem.c +++ b/drivers/gpu/drm/i915/i915_svm_devmem.c @@ -280,9 +280,77 @@ 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)