From 9083348a260991ca19844b2dad2ec82c5e6426aa Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Mon, 29 Jun 2009 11:15:01 -0300
Subject: [PATCH 1/2] KVM: SVM: Remove port 80 passthrough (upstream backport)
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KVM: SVM: Remove port 80 passthrough

KVM optimizes guest port 80 accesses by passthing them through to the host.
Some AMD machines die on port 80 writes, allowing the guest to hard-lock
the host.

Remove the port passthrough to avoid the problem.

Reported-by: Piotr Jaroszyński <p.jaroszynski@gmail.com>
Tested-by: Piotr Jaroszyński <p.jaroszynski@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Bugzilla: 507730
Message-ID: <20090629141501.GA15118@amt.cnet>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
RH-Upstream-status: backported-from-upstream
Acked-by: john cooper <john.cooper@redhat.com>
Acked-by: Glauber Costa <glommer@redhat.com>
Acked-by: Dor Laor <dlaor@redhat.com>
---
 arch/x86/kvm/svm.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index dd68dcc..3e8d840 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -411,7 +411,6 @@ static __init int svm_hardware_setup(void)
 
 	iopm_va = page_address(iopm_pages);
 	memset(iopm_va, 0xff, PAGE_SIZE * (1 << IOPM_ALLOC_ORDER));
-	clear_bit(0x80, iopm_va); /* allow direct access to PC debug port */
 	iopm_base = page_to_pfn(iopm_pages) << PAGE_SHIFT;
 
 	if (boot_cpu_has(X86_FEATURE_NX))
-- 
1.6.3.rc4.29.g8146