linux-kernel - [PATCH v2 14/16] KVM: Skip unnecessary "unmap" if gpc is already valid during refresh

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Message-ID: <20221013211234.1318131-15-seanjc@google.com>
Date:   Thu, 13 Oct 2022 21:12:32 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michal Luczaj <mhal@...x.co>,
        David Woodhouse <dwmw2@...radead.org>
Subject: [PATCH v2 14/16] KVM: Skip unnecessary "unmap" if gpc is already
 valid during refresh

When refreshing a gfn=>pfn cache, skip straight to unlocking if the cache
already valid instead of stuffing the "old" variables to turn the
unmapping outro into a nop.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 virt/kvm/pfncache.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index f211c878788b..57d47f06637d 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -293,9 +293,8 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa)
 		ret = hva_to_pfn_retry(gpc);
 	} else {
 		/* If the HVA→PFN mapping was already valid, don't unmap it. */
-		old_pfn = KVM_PFN_ERR_FAULT;
-		old_khva = NULL;
 		ret = 0;
+		goto out_unlock;
 	}
 
  out:
-- 
2.38.0.413.g74048e4d9e-goog