linux-kernel - [189/200] KVM: Dont allow lmsw to clear cr0.pe

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Message-Id: <20100701174302.487936206@clark.site>
Date:	Thu, 01 Jul 2010 10:44:39 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>
Subject: [189/200] KVM: Dont allow lmsw to clear cr0.pe

2.6.34-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Avi Kivity <avi@...hat.com>

The current lmsw implementation allows the guest to clear cr0.pe, contrary
to the manual, which breaks EMM386.EXE.

Fix by ORing the old cr0.pe with lmsw's operand.

Signed-off-by: Avi Kivity <avi@...hat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

(Cherry-picked from commit f78e917688edbf1f14c318d2e50dc8e7dad20445)
---
 arch/x86/kvm/x86.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -484,7 +484,7 @@ EXPORT_SYMBOL_GPL(kvm_set_cr0);
 
 void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw)
 {
-	kvm_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~0x0ful) | (msw & 0x0f));
+	kvm_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~0x0eul) | (msw & 0x0f));
 }
 EXPORT_SYMBOL_GPL(kvm_lmsw);
 


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