linux-kernel - [PATCH 02/10] KVM: Drop bogus "pfn != 0" guard from kvm_release

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Date:   Fri, 29 Apr 2022 01:04:08 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.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 02/10] KVM: Drop bogus "pfn != 0" guard from kvm_release_pfn()

Remove a check from kvm_release_pfn() to bail if the provided @pfn is
zero.  Zero is a perfectly valid pfn on most architectures, and should
not be used to indicate an error or an invalid pfn.  The bogus check was
added by commit 917248144db5 ("x86/kvm: Cache gfn to pfn translation"),
which also did the bad thing of zeroing the pfn and gfn to mark a cache
invalid.  Thankfully, that bad behavior was axed by commit 357a18ad230f
("KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache").

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

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 04ed4334473c..154c3dda7010 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2723,9 +2723,6 @@ EXPORT_SYMBOL_GPL(gfn_to_page);

 void kvm_release_pfn(kvm_pfn_t pfn, bool dirty)
 {
-	if (pfn == 0)
-		return;
-
 	if (dirty)
 		kvm_release_pfn_dirty(pfn);
 	else
-- 
2.36.0.464.gb9c8b46e94-goog