KVM: x86: Zap the oldest MMU pages, not the newest
Walk the list of MMU pages in reverse in kvm_mmu_zap_oldest_mmu_pages(). The list is FIFO, meaning new pages are inserted at the head and thus the oldest pages are at the tail. Using a "forward" iterator causes KVM to zap MMU pages that were just added, which obliterates guest performance once the max number of shadow MMU pages is reached. Fixes: 6b82ef2c ("KVM: x86/mmu: Batch zap MMU pages when recycling oldest pages") Reported-by:Zdenek Kaspar <zkaspar82@gmail.com> Cc: stable@vger.kernel.org Signed-off-by:
Sean Christopherson <seanjc@google.com> Message-Id: <20210113205030.3481307-1-seanjc@google.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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