[PATCH 16/15] KVM: X86: Update mmu->pdptrs only when it is changed

Lai Jiangshan
2021-11-11T14:45:25Z

From: Lai Jiangshan <laijs@linux.alibaba.com>

It is unchanged in most cases.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/kvm/x86.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6ca19cac4aff..0176eaa86a35 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -828,10 +828,13 @@ int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3)
}
}

- memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs));
- kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
- /* Ensure the dirty PDPTEs to be loaded. */
- kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);
+ kvm_register_mark_available(vcpu, VCPU_EXREG_PDPTR);
+ if (memcmp(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs))) {
+ memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs));
+ kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
+ /* Ensure the dirty PDPTEs to be loaded. */
+ kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);
+ }
vcpu->arch.pdptrs_from_userspace = false;

return 1;
--
2.19.1.6.gb485710b