linux-kernel - [PATCH V3 12/13] KVM/VMX: Change hv flush logic when ept tables are mismatched.

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Date:   Thu, 27 Sep 2018 03:50:00 +0000
From:   Tianyu Lan <Tianyu.Lan@...rosoft.com>
To:     unlisted-recipients:; (no To-header on input)
CC:     Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>,
        KY Srinivasan <kys@...rosoft.com>,
        vkuznets <vkuznets@...hat.com>,
        Jork Loeser <Jork.Loeser@...rosoft.com>
Subject: [PATCH V3 12/13] KVM/VMX: Change hv flush logic when ept tables are
 mismatched.

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 533a327372c8..2869c3e78168 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1557,7 +1557,8 @@ 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);
 
@@ -1565,14 +1566,14 @@ 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