linux-kernel - [PATCH V4 14/15] KVM/VMX: Change hv flush logic when ept tables are mismatched.

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Message-Id: <20181013145406.4911-15-Tianyu.Lan@microsoft.com>
Date:   Sat, 13 Oct 2018 22:54:05 +0800
From:   lantianyu1986@...il.com
To:     unlisted-recipients:; (no To-header on input)
Cc:     Lan Tianyu <Tianyu.Lan@...rosoft.com>, pbonzini@...hat.com,
        rkrcmar@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, michael.h.kelley@...rosoft.com,
        kys@...rosoft.com, vkuznets@...hat.com
Subject: [PATCH V4 14/15] KVM/VMX: Change hv flush logic when ept tables are mismatched.

From: Lan Tianyu <Tianyu.Lan@...rosoft.com>

If ept table pointers are mismatched, flushing tlb for each vcpus via
hv flush interface still helps to reduce vmexits which are triggered
by IPI and INEPT emulation.

Signed-off-by: Lan Tianyu <Tianyu.Lan@...rosoft.com>
---
 arch/x86/kvm/vmx.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6f44d3a63434..8ff13f3aed11 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1571,7 +1571,8 @@ static void check_ept_pointer_match(struct kvm *kvm)
 
 static int vmx_hv_remote_flush_tlb(struct kvm *kvm)
 {
-	int ret;
+	struct kvm_vcpu *vcpu;
+	int ret = -ENOTSUPP, i;
 
 	spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock);
 
@@ -1579,14 +1580,14 @@ static int vmx_hv_remote_flush_tlb(struct kvm *kvm)
 		check_ept_pointer_match(kvm);
 
 	if (to_kvm_vmx(kvm)->ept_pointers_match != EPT_POINTERS_MATCH) {
-		ret = -ENOTSUPP;
-		goto out;
+		kvm_for_each_vcpu(i, vcpu, kvm)
+			ret |= hyperv_flush_guest_mapping(
+				to_vmx(kvm_get_vcpu(kvm, i))->ept_pointer);
+	} else {
+		ret = hyperv_flush_guest_mapping(
+				to_vmx(kvm_get_vcpu(kvm, 0))->ept_pointer);
 	}
 
-	ret = hyperv_flush_guest_mapping(
-			to_vmx(kvm_get_vcpu(kvm, 0))->ept_pointer);
-
-out:
 	spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock);
 	return ret;
 }
-- 
2.14.4