linux-kernel - [PATCH v2 09/10] KVM: VMX: Skip additional Hyper-V TLB EPTP flushes if one fails

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Message-Id: <20201020215613.8972-10-sean.j.christopherson@intel.com>
Date:   Tue, 20 Oct 2020 14:56:12 -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
Subject: [PATCH v2 09/10] KVM: VMX: Skip additional Hyper-V TLB EPTP flushes if one fails

Skip additional EPTP flushes if one fails when processing EPTPs for
Hyper-V's paravirt TLB flushing.  If _any_ flush fails, KVM falls back
to a full global flush, i.e. additional flushes are unnecessary (and
will likely fail anyways).

Continue processing the loop unless a mismatch was already detected,
e.g. to handle the case where the first flush fails and there is a
yet-to-be-detected mismatch.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/vmx/vmx.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a45a90d44d24..e0fea09a6e42 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -517,7 +517,11 @@ static int hv_remote_flush_tlb_with_range(struct kvm *kvm,
 			else
 				mismatch = true;
 
-			ret |= hv_remote_flush_eptp(tmp_eptp, range);
+			if (!ret)
+				ret = hv_remote_flush_eptp(tmp_eptp, range);
+
+			if (ret && mismatch)
+				break;
 		}
 		if (mismatch)
 			kvm_vmx->hv_tlb_eptp = INVALID_PAGE;
-- 
2.28.0