linux-kernel - [PATCH 5.19 0031/1157] KVM: Do not incorporate page offset into gfn=>pfn cache user address

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Date:   Mon, 15 Aug 2022 19:49:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.19 0031/1157] KVM: Do not incorporate page offset into gfn=>pfn cache user address

From: Sean Christopherson <seanjc@...gle.com>

commit 3ba2c95ea180740b16281fa43a3ee5f47279c0ed upstream.

Don't adjust the userspace address in the gfn=>pfn cache by the page
offset from the gpa.  KVM should never use the user address directly, and
all KVM operations that translate a user address to something else
require the user address to be page aligned.  Ignoring the offset will
allow the cache to reuse a gfn=>hva translation in the unlikely event
that the page offset of the gpa changes, but the gfn does not.  And more
importantly, not having to (un)adjust the user address will simplify a
future bug fix.

Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Message-Id: <20220429210025.3293691-6-seanjc@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 virt/kvm/pfncache.c |    2 --
 1 file changed, 2 deletions(-)

--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -274,8 +274,6 @@ int kvm_gfn_to_pfn_cache_refresh(struct
 			ret = -EFAULT;
 			goto out;
 		}
-
-		gpc->uhva += page_offset;
 	}

 	/*