Re: [Intel-gfx] [PATCH v4 01/29] drm/i915/gvt: Verify pfn is "valid" before dereferencing "struct page"
On 7/29/2023 4:35 AM, Sean Christopherson wrote: Check that the pfn found by gfn_to_pfn() is actually backed by "struct page" memory prior to retrieving and dereferencing the page. KVM supports backing guest memory with VM_PFNMAP, VM_IO, etc., and so there is no guarantee the pfn returned by gfn_to_pfn() has an associated "struct page". Fixes: b901b252b6cf ("drm/i915/gvt: Add 2M huge gtt support") Reviewed-by: Yan Zhao Tested-by: Yongwei Ma Signed-off-by: Sean Christopherson --- drivers/gpu/drm/i915/gvt/gtt.c | 4 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index 4ec85308379a..58b9b316ae46 100644 --- a/drivers/gpu/drm/i915/gvt/gtt.c +++ b/drivers/gpu/drm/i915/gvt/gtt.c @@ -1183,6 +1183,10 @@ static int is_2MB_gtt_possible(struct intel_vgpu *vgpu, pfn = gfn_to_pfn(vgpu->vfio_device.kvm, ops->get_pfn(entry)); if (is_error_noslot_pfn(pfn)) return -EINVAL; + + if (!pfn_valid(pfn)) + return -EINVAL; + return PageTransHuge(pfn_to_page(pfn)); } Reviewed-by: Zhi Wang
[Intel-gfx] [PATCH v4 01/29] drm/i915/gvt: Verify pfn is "valid" before dereferencing "struct page"
Check that the pfn found by gfn_to_pfn() is actually backed by "struct page" memory prior to retrieving and dereferencing the page. KVM supports backing guest memory with VM_PFNMAP, VM_IO, etc., and so there is no guarantee the pfn returned by gfn_to_pfn() has an associated "struct page". Fixes: b901b252b6cf ("drm/i915/gvt: Add 2M huge gtt support") Reviewed-by: Yan Zhao Tested-by: Yongwei Ma Signed-off-by: Sean Christopherson --- drivers/gpu/drm/i915/gvt/gtt.c | 4 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index 4ec85308379a..58b9b316ae46 100644 --- a/drivers/gpu/drm/i915/gvt/gtt.c +++ b/drivers/gpu/drm/i915/gvt/gtt.c @@ -1183,6 +1183,10 @@ static int is_2MB_gtt_possible(struct intel_vgpu *vgpu, pfn = gfn_to_pfn(vgpu->vfio_device.kvm, ops->get_pfn(entry)); if (is_error_noslot_pfn(pfn)) return -EINVAL; + + if (!pfn_valid(pfn)) + return -EINVAL; + return PageTransHuge(pfn_to_page(pfn)); } -- 2.41.0.487.g6d72f3e995-goog