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authorLai Jiangshan <laijs@linux.alibaba.com>2020-09-02 21:54:21 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2020-09-11 13:16:55 -0400
commitf6f6195b888c28a0b59ceb0562daff92a2be86c3 (patch)
treea8e535e466715db50ef66bb7061a7ce4f855517f
parentc6b177a3beb9140dc0ba05b61c5142fcec5f2bf7 (diff)
downloadlinux-sh-f6f6195b888c28a0b59ceb0562daff92a2be86c3.tar.gz
kvm x86/mmu: use KVM_REQ_MMU_SYNC to sync when needed
When kvm_mmu_get_page() gets a page with unsynced children, the spt pagetable is unsynchronized with the guest pagetable. But the guest might not issue a "flush" operation on it when the pagetable entry is changed from zero or other cases. The hypervisor has the responsibility to synchronize the pagetables. KVM behaved as above for many years, But commit 8c8560b83390 ("KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes") inadvertently included a line of code to change it without giving any reason in the changelog. It is clear that the commit's intention was to change KVM_REQ_TLB_FLUSH -> KVM_REQ_TLB_FLUSH_CURRENT, so we don't needlessly flush other contexts; however, one of the hunks changed a nearby KVM_REQ_MMU_SYNC instead. This patch changes it back. Link: https://lore.kernel.org/lkml/20200320212833.3507-26-sean.j.christopherson@intel.com/ Cc: Sean Christopherson <sean.j.christopherson@intel.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> Message-Id: <20200902135421.31158-1-jiangshanlai@gmail.com> fixes: 8c8560b83390 ("KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes") Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--arch/x86/kvm/mmu/mmu.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a5d0207e7189..76c5826e29a2 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2469,7 +2469,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
}
if (sp->unsync_children)
- kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu);
+ kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
__clear_sp_write_flooding_count(sp);