linux-kernel - [PATCH v3 08/37] KVM: VMX: Skip global INVVPID fallback if vpid==0 in vpid_sync

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Message-Id: <20200320212833.3507-9-sean.j.christopherson@intel.com>
Date:   Fri, 20 Mar 2020 14:28:04 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.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, Ben Gardon <bgardon@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Liran Alon <liran.alon@...cle.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        John Haxby <john.haxby@...cle.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: [PATCH v3 08/37] KVM: VMX: Skip global INVVPID fallback if vpid==0 in vpid_sync_context()

Skip the global INVVPID in the unlikely scenario that vpid==0 and the
SINGLE_CONTEXT variant of INVVPID is unsupported.  If vpid==0, there's
no need to INVVPID as it's impossible to do VM-Enter with VPID enabled
and vmcs.VPID==0, i.e. there can't be any TLB entries for the vCPU with
vpid==0.  The fact that the SINGLE_CONTEXT variant isn't supported is
irrelevant.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/vmx/ops.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/ops.h b/arch/x86/kvm/vmx/ops.h
index 45eaedee2ac0..33645a8e5463 100644
--- a/arch/x86/kvm/vmx/ops.h
+++ b/arch/x86/kvm/vmx/ops.h
@@ -285,7 +285,7 @@ static inline void vpid_sync_context(int vpid)
 {
 	if (cpu_has_vmx_invvpid_single())
 		vpid_sync_vcpu_single(vpid);
-	else
+	else if (vpid != 0)
 		vpid_sync_vcpu_global();
 }
 
-- 
2.24.1