drm/i915/gvt: Put the page reference obtained by KVM's gfn_to_pfn()

Put the struct page reference acquired by gfn_to_pfn(), KVM's API is that
the caller is ultimately responsible for dropping any reference.

Note, kvm_release_pfn_clean() ensures the pfn is actually a refcounted
struct page before trying to put any references.

Fixes: b901b252b6cf ("drm/i915/gvt: Add 2M huge gtt support")
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index f30922c..5426a27 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -1158,6 +1158,7 @@ static int is_2MB_gtt_possible(struct intel_vgpu *vgpu,
 {
        const struct intel_gvt_gtt_pte_ops *ops = vgpu->gvt->gtt.pte_ops;
        kvm_pfn_t pfn;
+       int ret;
 
        if (!HAS_PAGE_SIZES(vgpu->gvt->gt->i915, I915_GTT_PAGE_SIZE_2M))
                return 0;
@@ -1171,7 +1172,9 @@ static int is_2MB_gtt_possible(struct intel_vgpu *vgpu,
        if (!pfn_valid(pfn))
                return -EINVAL;
 
-       return PageTransHuge(pfn_to_page(pfn));
+       ret = PageTransHuge(pfn_to_page(pfn));
+       kvm_release_pfn_clean(pfn);
+       return ret;
 }
 
 static int split_2MB_gtt_entry(struct intel_vgpu *vgpu,