linux-kernel - [PATCH 12/15] KVM: x86: Defer MMU sync on PCID invalidation

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Message-Id: <20210609234235.1244004-13-seanjc@google.com>
Date:   Wed,  9 Jun 2021 16:42:32 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Junaid Shahid <junaids@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Lai Jiangshan <laijs@...ux.alibaba.com>
Subject: [PATCH 12/15] KVM: x86: Defer MMU sync on PCID invalidation

Defer the MMU sync on PCID invalidation so that multiple sync requests in
a single VM-Exit are batched.  This is a very minor optimization as
checking for unsync'd children is quite cheap.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9620d8936dc4..d3a2a3375541 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1096,7 +1096,7 @@ static void kvm_invalidate_pcid(struct kvm_vcpu *vcpu, unsigned long pcid)
 	 * happen anyway before switching to any other CR3.
 	 */
 	if (kvm_get_active_pcid(vcpu) == pcid) {
-		kvm_mmu_sync_roots(vcpu);
+		kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
 		kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu);
 	}
 
-- 
2.32.0.rc1.229.g3e70b5a671-goog