linux-kernel - [PATCH v3 05/28] drm/i915/gvt: Explicitly check that vGPU is attached before shadowing

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Message-ID: <20230513003600.818142-6-seanjc@google.com>
Date:   Fri, 12 May 2023 17:35:37 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Zhi Wang <zhi.a.wang@...el.com>
Cc:     kvm@...r.kernel.org, intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Yan Zhao <yan.y.zhao@...el.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH v3 05/28] drm/i915/gvt: Explicitly check that vGPU is attached
 before shadowing

Move the check that a vGPU is attacked from is_2MB_gtt_possible() to its
sole caller, ppgtt_populate_shadow_entry().  All of the paths in
ppgtt_populate_shadow_entry() eventually check for attachment by way of
intel_gvt_dma_map_guest_page(), but explicitly checking can avoid
unnecessary work and will make it more obvious that a future cleanup of
is_2MB_gtt_possible() isn't introducing a bug.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 drivers/gpu/drm/i915/gvt/gtt.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index 5426a27c1b71..2aed31b497c9 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -1163,8 +1163,6 @@ static int is_2MB_gtt_possible(struct intel_vgpu *vgpu,
 	if (!HAS_PAGE_SIZES(vgpu->gvt->gt->i915, I915_GTT_PAGE_SIZE_2M))
 		return 0;
 
-	if (!test_bit(INTEL_VGPU_STATUS_ATTACHED, vgpu->status))
-		return -EINVAL;
 	pfn = gfn_to_pfn(vgpu->vfio_device.kvm, ops->get_pfn(entry));
 	if (is_error_noslot_pfn(pfn))
 		return -EINVAL;
@@ -1277,6 +1275,9 @@ static int ppgtt_populate_shadow_entry(struct intel_vgpu *vgpu,
 	if (!pte_ops->test_present(ge))
 		return 0;
 
+	if (!test_bit(INTEL_VGPU_STATUS_ATTACHED, vgpu->status))
+		return -EINVAL;
+
 	gfn = pte_ops->get_pfn(ge);
 
 	switch (ge->type) {
-- 
2.40.1.606.ga4b1b128d6-goog