linux-kernel - [patch 159/164] KVM: SVM: Dont allow nested guest to VMMCALL into host

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Message-Id: <20100701173440.214873866@clark.site>
Date:	Thu, 01 Jul 2010 10:35:45 -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,
	Joerg Roedel <joerg.roedel@....com>,
	Avi Kivity <avi@...hat.com>
Subject: [patch 159/164] KVM: SVM: Dont allow nested guest to VMMCALL into host

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

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

From: Joerg Roedel <joerg.roedel@....com>

This patch disables the possibility for a l2-guest to do a
VMMCALL directly into the host. This would happen if the
l1-hypervisor doesn't intercept VMMCALL and the l2-guest
executes this instruction.

Signed-off-by: Joerg Roedel <joerg.roedel@....com>
Signed-off-by: Avi Kivity <avi@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
(cherry picked from commit 0d945bd9351199744c1e89d57a70615b6ee9f394)
---
 arch/x86/kvm/svm.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1829,8 +1829,13 @@ static bool nested_svm_vmrun(struct vcpu
 		svm->vmcb->control.intercept_cr_write &= ~INTERCEPT_CR8_MASK;
 	}
 
-	/* We don't want a nested guest to be more powerful than the guest,
-	   so all intercepts are ORed */
+	/* We don't want to see VMMCALLs from a nested guest */
+	svm->vmcb->control.intercept &= ~(1ULL << INTERCEPT_VMMCALL);
+
+	/*
+	 * We don't want a nested guest to be more powerful than the guest, so
+	 * all intercepts are ORed
+	 */
 	svm->vmcb->control.intercept_cr_read |=
 		nested_vmcb->control.intercept_cr_read;
 	svm->vmcb->control.intercept_cr_write |=


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