Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Tianyu Lan <Tianyu.Lan@microsoft.com>
CC:     Tianyu Lan <Tianyu.Lan@microsoft.com>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "rkrcmar@redhat.com" <rkrcmar@redhat.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "hpa@zytor.com" <hpa@zytor.com>, "x86@kernel.org" <x86@kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [PATCH] KVM/MMU: Combine flushing remote tlb in mmu_set_spte()
Thread-Topic: [PATCH] KVM/MMU: Combine flushing remote tlb in mmu_set_spte()
Thread-Index: AQHUIya2sfSO0xmUGUuqak4mr618Fw==
Date:   Tue, 24 Jul 2018 08:17:07 +0000
Message-ID: <1532420205-29930-1-git-send-email-Tianyu.Lan@microsoft.com>
Accept-Language: en-US
Content-Language: en-US
received-spf: None (protection.outlook.com: microsoft.com does not designate
 permitted sender hosts)
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 31684082-bfe5-4075-6f3e-08d5f13dd932
X-MS-Exchange-CrossTenant-originalarrivaltime: 24 Jul 2018 08:17:07.7549
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SG2P15301MB0015
To:     unlisted-recipients:; (no To-header on input)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

mmu_set_spte() flushes remote tlbs for drop_parent_pte/drop_spte()
and set_spte() separately. This may introduce redundant flush. This
patch is to combine these flushes and check flush request after
calling set_spte().

Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
---
 arch/x86/kvm/mmu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 22a7984..8f21632 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2901,6 +2901,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *s=
ptep, unsigned pte_access,
 	int rmap_count;
 	int set_spte_ret;
 	int ret =3D RET_PF_RETRY;
+	bool flush =3D false;
=20
 	pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__,
 		 *sptep, write_fault, gfn);
@@ -2917,12 +2918,12 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 =
*sptep, unsigned pte_access,
=20
 			child =3D page_header(pte & PT64_BASE_ADDR_MASK);
 			drop_parent_pte(child, sptep);
-			kvm_flush_remote_tlbs(vcpu->kvm);
+			flush =3D true;
 		} else if (pfn !=3D spte_to_pfn(*sptep)) {
 			pgprintk("hfn old %llx new %llx\n",
 				 spte_to_pfn(*sptep), pfn);
 			drop_spte(vcpu->kvm, sptep);
-			kvm_flush_remote_tlbs(vcpu->kvm);
+			flush =3D true;
 		} else
 			was_rmapped =3D 1;
 	}
@@ -2934,7 +2935,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *s=
ptep, unsigned pte_access,
 			ret =3D RET_PF_EMULATE;
 		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
 	}
-	if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH)
+	if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH || flush)
 		kvm_flush_remote_tlbs(vcpu->kvm);
=20
 	if (unlikely(is_mmio_spte(*sptep)))
--=20
2.7.4