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[3.5.y.z,extended,stable] Patch "KVM: x86: remove vcpu's CPL check in host-invoked XCR set" has been added to staging queue

Message ID 1372152647-7571-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques June 25, 2013, 9:30 a.m. UTC 
This is a note to let you know that I have just added a patch titled

    KVM: x86: remove vcpu's CPL check in host-invoked XCR set

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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From cbe60f0f98e8500844de4f8f351a12b11a8cd8e3 Mon Sep 17 00:00:00 2001
From: "Zhanghaoyu (A)" <haoyu.zhang@huawei.com>
Date: Fri, 14 Jun 2013 07:36:13 +0000
Subject: [PATCH] KVM: x86: remove vcpu's CPL check in host-invoked XCR set

commit 764bcbc5a6d7a2f3e75c9f0e4caa984e2926e346 upstream.

__kvm_set_xcr function does the CPL check when set xcr. __kvm_set_xcr is
called in two flows, one is invoked by guest, call stack shown as below,

  handle_xsetbv(or xsetbv_interception)
    kvm_set_xcr
      __kvm_set_xcr

the other one is invoked by host, for example during system reset:

  kvm_arch_vcpu_ioctl
    kvm_vcpu_ioctl_x86_set_xcrs
      __kvm_set_xcr

The former does need the CPL check, but the latter does not.

Signed-off-by: Zhang Haoyu <haoyu.zhang@huawei.com>
[Tweaks to commit message. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 arch/x86/kvm/x86.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--
1.8.1.2
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Patch

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a7c8796..671e5df 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -555,8 +555,6 @@  int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 	if (index != XCR_XFEATURE_ENABLED_MASK)
 		return 1;
 	xcr0 = xcr;
-	if (kvm_x86_ops->get_cpl(vcpu) != 0)
-		return 1;
 	if (!(xcr0 & XSTATE_FP))
 		return 1;
 	if ((xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE))
@@ -570,7 +568,8 @@  int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)

 int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 {
-	if (__kvm_set_xcr(vcpu, index, xcr)) {
+	if (kvm_x86_ops->get_cpl(vcpu) != 0 ||
+	    __kvm_set_xcr(vcpu, index, xcr)) {
 		kvm_inject_gp(vcpu, 0);
 		return 1;
 	}