KVM: MMU: Avoid unnecessary remote tlb flushes when guest updates a pte (79539cec) · Commits · 戴 / test

drivers/kvm/mmu.c

+26 −1

Original line number	Diff line number	Diff line
		@@ -134,6 +134,8 @@ static int dbg = 1;
		#define PT32_DIR_BASE_ADDR_MASK \
		(PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1))

		#define PT64_PERM_MASK (PT_PRESENT_MASK \| PT_WRITABLE_MASK \| PT_USER_MASK \
		\| PT64_NX_MASK)

		#define PFERR_PRESENT_MASK (1U << 0)
		#define PFERR_WRITE_MASK (1U << 1)
		@@ -1227,7 +1229,6 @@ static void mmu_pte_write_zap_pte(struct kvm_vcpu *vcpu,
		}
		}
		set_shadow_pte(spte, shadow_trap_nonpresent_pte);
		kvm_flush_remote_tlbs(vcpu->kvm);
		}

		static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu,
		@@ -1250,6 +1251,27 @@ static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu,
		offset_in_pte);
		}

		static bool need_remote_flush(u64 old, u64 new)
		{
		if (!is_shadow_present_pte(old))
		return false;
		if (!is_shadow_present_pte(new))
		return true;
		if ((old ^ new) & PT64_BASE_ADDR_MASK)
		return true;
		old ^= PT64_NX_MASK;
		new ^= PT64_NX_MASK;
		return (old & ~new & PT64_PERM_MASK) != 0;
		}

		static void mmu_pte_write_flush_tlb(struct kvm_vcpu *vcpu, u64 old, u64 new)
		{
		if (need_remote_flush(old, new))
		kvm_flush_remote_tlbs(vcpu->kvm);
		else
		kvm_mmu_flush_tlb(vcpu);
		}

		static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu)
		{
		u64 *spte = vcpu->last_pte_updated;
		@@ -1265,6 +1287,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
		struct hlist_node node, n;
		struct hlist_head *bucket;
		unsigned index;
		u64 entry;
		u64 *spte;
		unsigned offset = offset_in_page(gpa);
		unsigned pte_size;
		@@ -1335,9 +1358,11 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
		}
		spte = &page->spt[page_offset / sizeof(*spte)];
		while (npte--) {
		entry = *spte;
		mmu_pte_write_zap_pte(vcpu, page, spte);
		mmu_pte_write_new_pte(vcpu, page, spte, new, bytes,
		page_offset & (pte_size - 1));
		mmu_pte_write_flush_tlb(vcpu, entry, *spte);
		++spte;
		}
		}

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