KVM: nVMX: postpone VMCS changes on MSR_IA32_APICBASE write
authorRadim Krčmář <rkrcmar@redhat.com>
Mon, 8 Aug 2016 18:16:23 +0000 (20:16 +0200)
committerPaolo Bonzini <pbonzini@redhat.com>
Thu, 18 Aug 2016 10:19:08 +0000 (12:19 +0200)
commitdccbfcf52cebb8963246eba5b177b77f26b34da0
tree6b1f29cc3abda66cde275bd0296f119ef849ea59
parentd048c098218e91ed0e10dfa1f0f80e2567fe4ef7
KVM: nVMX: postpone VMCS changes on MSR_IA32_APICBASE write

If vmcs12 does not intercept APIC_BASE writes, then KVM will handle the
write with vmcs02 as the current VMCS.
This will incorrectly apply modifications intended for vmcs01 to vmcs02
and L2 can use it to gain access to L0's x2APIC registers by disabling
virtualized x2APIC while using msr bitmap that assumes enabled.

Postpone execution of vmx_set_virtual_x2apic_mode until vmcs01 is the
current VMCS.  An alternative solution would temporarily make vmcs01 the
current VMCS, but it requires more care.

Fixes: 8d14695f9542 ("x86, apicv: add virtual x2apic support")
Reported-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
arch/x86/kvm/vmx.c