4.19-stable review patch. If anyone has any objections, please let me know.
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From: Sean Christopherson sean.j.christopherson@intel.com
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: 4bd518f1598d ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/mmu.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -5776,11 +5776,28 @@ static bool kvm_has_zapped_obsolete_page
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); }