KVM: x86/mmu: Detect MMIO generation wrap in any address space (e1359e2b) · Commits · 戴 / test

The check to detect a wrap of the MMIO generation explicitly looks for a generation number of zero. Now that unique memslots generation numbers are assigned to each address space, only address space 0 will get a generation number of exactly zero when wrapping. E.g. when address space 1 goes from 0x7fffe to 0x80002, the MMIO generation number will wrap to 0x2. Adjust the MMIO generation to strip the address space modifier prior to checking for a wrap. Fixes: ("KVM: use separate generations for each address space") Cc: <stable@vger.kernel.org> Signed-off-by:

Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

+19 −2

Original line number	Diff line number	Diff line
		@@ -5895,11 +5895,28 @@ static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)

		void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen)
		{
		gen &= MMIO_GEN_MASK;

		/*
		* Shift to eliminate the "update in-progress" flag, which isn't
		* included in the spte's generation number.
		*/
		gen >>= 1;

		/*
		* Generation numbers are incremented in multiples of the number of
		* address spaces in order to provide unique generations across all
		* address spaces. Strip what is effectively the address space
		* modifier prior to checking for a wrap of the MMIO generation so
		* that a wrap in any address space is detected.
		*/
		gen &= ~((u64)KVM_ADDRESS_SPACE_NUM - 1);

		/*
		* The very rare case: if the generation-number is round,
		* The very rare case: if the MMIO generation number has wrapped,
		* zap all shadow pages.
		*/
		if (unlikely((gen & MMIO_GEN_MASK) == 0)) {
		if (unlikely(gen == 0)) {
		kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n");
		kvm_mmu_invalidate_zap_all_pages(kvm);
		}

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