[PATCH v3 10/11] KVM: VMX: Skip additional Hyper-V TLB EPTP flushes if one fails

From: Sean Christopherson
Date: Tue Oct 27 2020 - 17:25:36 EST


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@xxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 5b7c5b2fd2c7..40a67dd45c8c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -528,7 +528,15 @@ static int hv_remote_flush_tlb_with_range(struct kvm *kvm,
if (++nr_unique_valid_eptps == 1)
kvm_vmx->hv_tlb_eptp = tmp_eptp;

- ret |= hv_remote_flush_eptp(tmp_eptp, range);
+ if (!ret)
+ ret = hv_remote_flush_eptp(tmp_eptp, range);
+
+ /*
+ * Stop processing EPTPs if a failure occurred and
+ * there is already a detected EPTP mismatch.
+ */
+ if (ret && nr_unique_valid_eptps > 1)
+ break;
}

/*
--
2.28.0