[06/88] KVM: x86: remove vcpus CPL check in host-invoked XCR set

Steven Rostedt
2013-08-13T16:12:13Z

[-- Attachment #1: 0006-KVM-x86-remove-vcpu-s-CPL-check-in-host-invoked-XCR-.patch --]
[-- Type: text/plain, Size: 1704 bytes --]

3.6.11.7-rc1 stable review patch.
If anyone has any objections, please let me know.

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

From: "Zhanghaoyu (A)" <haoyu.zhang@huawei.com>

[ Upstream commit 764bcbc5a6d7a2f3e75c9f0e4caa984e2926e346 ]

__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.

Cc: stable@vger.kernel.org
Signed-off-by: Zhang Haoyu <haoyu.zhang@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
[Tweaks to commit message. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/x86.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f7a361f..2dcd250 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -558,8 +558,6 @@ 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))
@@ -573,7 +571,8 @@ 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;
}
--
1.7.10.4