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Commit 656e9e5d authored by Sean Christopherson's avatar Sean Christopherson Committed by Greg Kroah-Hartman
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KVM: x86/mmu: Detect MMIO generation wrap in any address space 



commit e1359e2beb8b0a1188abc997273acbaedc8ee791 upstream.

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: 4bd518f1 ("KVM: use separate generations for each address space")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 23ad135a

arch/x86/kvm/mmu.c

+19 −2
Original line number Diff line number Diff line
@@ -5776,11 +5776,28 @@ 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);

	}