From 1e557c1cd0549b30fa4bc3e9aa46c5eeadaa63f5 Mon Sep 17 00:00:00 2001 From: Yan Zhao Date: Fri, 28 Jul 2023 18:35:08 -0700 Subject: [PATCH] drm/i915/gvt: remove interface intel_gvt_is_valid_gfn Currently intel_gvt_is_valid_gfn() is called in two places: (1) shadowing guest GGTT entry (2) shadowing guest PPGTT leaf entry, which was introduced in commit cc753fbe1ac4 ("drm/i915/gvt: validate gfn before set shadow page entry"). However, now it's not necessary to call this interface any more, because a. GGTT partial write issue has been fixed by commit bc0686ff5fad ("drm/i915/gvt: support inconsecutive partial gtt entry write") commit 510fe10b6180 ("drm/i915/gvt: fix a bug of partially write ggtt enties") b. PPGTT resides in normal guest RAM and we only treat 8-byte writes as valid page table writes. Any invalid GPA found is regarded as an error, either due to guest misbehavior/attack or bug in host shadow code. So,rather than do GFN pre-checking and replace invalid GFNs with scratch GFN and continue silently, just remove the pre-checking and abort PPGTT shadowing on error detected. c. GFN validity check is still performed in intel_gvt_dma_map_guest_page() --> gvt_pin_guest_page(). It's more desirable to call VFIO interface to do both validity check and mapping. Calling intel_gvt_is_valid_gfn() to do GFN validity check from KVM side while later mapping the GFN through VFIO interface is unnecessarily fragile and confusing for unaware readers. Signed-off-by: Yan Zhao [sean: remove now-unused local variables] Acked-by: Zhi Wang Tested-by: Yongwei Ma Link: https://lore.kernel.org/r/20230729013535.1070024-3-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- drivers/gpu/drm/i915/gvt/gtt.c | 36 +----------------------------------- 1 file changed, 1 insertion(+), 35 deletions(-) diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index 58b9b31..f30922c55 100644 --- a/drivers/gpu/drm/i915/gvt/gtt.c +++ b/drivers/gpu/drm/i915/gvt/gtt.c @@ -49,22 +49,6 @@ static bool enable_out_of_sync = false; static int preallocated_oos_pages = 8192; -static bool intel_gvt_is_valid_gfn(struct intel_vgpu *vgpu, unsigned long gfn) -{ - struct kvm *kvm = vgpu->vfio_device.kvm; - int idx; - bool ret; - - if (!test_bit(INTEL_VGPU_STATUS_ATTACHED, vgpu->status)) - return false; - - idx = srcu_read_lock(&kvm->srcu); - ret = kvm_is_visible_gfn(kvm, gfn); - srcu_read_unlock(&kvm->srcu, idx); - - return ret; -} - /* * validate a gm address and related range size, * translate it to host gm address @@ -1333,11 +1317,9 @@ static int ppgtt_populate_shadow_entry(struct intel_vgpu *vgpu, static int ppgtt_populate_spt(struct intel_vgpu_ppgtt_spt *spt) { struct intel_vgpu *vgpu = spt->vgpu; - struct intel_gvt *gvt = vgpu->gvt; - const struct intel_gvt_gtt_pte_ops *ops = gvt->gtt.pte_ops; struct intel_vgpu_ppgtt_spt *s; struct intel_gvt_gtt_entry se, ge; - unsigned long gfn, i; + unsigned long i; int ret; trace_spt_change(spt->vgpu->id, "born", spt, @@ -1354,13 +1336,6 @@ static int ppgtt_populate_spt(struct intel_vgpu_ppgtt_spt *spt) ppgtt_generate_shadow_entry(&se, s, &ge); ppgtt_set_shadow_entry(spt, &se, i); } else { - gfn = ops->get_pfn(&ge); - if (!intel_gvt_is_valid_gfn(vgpu, gfn)) { - ops->set_pfn(&se, gvt->gtt.scratch_mfn); - ppgtt_set_shadow_entry(spt, &se, i); - continue; - } - ret = ppgtt_populate_shadow_entry(vgpu, spt, i, &ge); if (ret) goto fail; @@ -2335,14 +2310,6 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off, m.val64 = e.val64; m.type = e.type; - /* one PTE update may be issued in multiple writes and the - * first write may not construct a valid gfn - */ - if (!intel_gvt_is_valid_gfn(vgpu, gfn)) { - ops->set_pfn(&m, gvt->gtt.scratch_mfn); - goto out; - } - ret = intel_gvt_dma_map_guest_page(vgpu, gfn, PAGE_SIZE, &dma_addr); if (ret) { @@ -2359,7 +2326,6 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off, ops->clear_present(&m); } -out: ggtt_set_guest_entry(ggtt_mm, &e, g_gtt_index); ggtt_get_host_entry(ggtt_mm, &e, g_gtt_index); -- 2.7.4