[PATCH V2 10/10] KVM: X86: Don't check unsync if the original spte is writible

Lai Jiangshan
2021-09-18T00:57:44Z

If the original spte is writable, the target gfn should not be the
gfn of synchronized shadowpage and can continue to be writable.

When !can_unsync, speculative must be false. So when the check of
"!can_unsync" is removed, we need to move the label of "out" up.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/kvm/mmu/spte.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index b68a580f3510..a33c581aabd6 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -150,7 +150,7 @@ int make_spte(struct kvm_vcpu *vcpu, unsigned int pte_access, int level,
* is responsibility of kvm_mmu_get_page / kvm_mmu_sync_roots.
* Same reasoning can be applied to dirty page accounting.
*/
- if (!can_unsync && is_writable_pte(old_spte))
+ if (is_writable_pte(old_spte))
goto out;

/*
@@ -171,10 +171,10 @@ int make_spte(struct kvm_vcpu *vcpu, unsigned int pte_access, int level,
if (pte_access & ACC_WRITE_MASK)
spte |= spte_shadow_dirty_mask(spte);

+out:
if (speculative)
spte = mark_spte_for_access_track(spte);

-out:
WARN_ONCE(is_rsvd_spte(&vcpu->arch.mmu->shadow_zero_check, spte, level),
"spte = 0x%llx, level = %d, rsvd bits = 0x%llx", spte, level,
get_rsvd_bits(&vcpu->arch.mmu->shadow_zero_check, spte, level));
--
2.19.1.6.gb485710b