Re: [Xen-devel] [PATCH v2] vlapic: fix two flaws in emulating MSR_IA32_APICBASE

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 31.05.17 at 14:41, <chao.gao@xxxxxxxxx> wrote:
> According to SDM Chapter ADVANCED PROGRAMMABLE INTERRUPT CONTROLLER (APIC)
> -> Extended XAPIC (x2APIC) -> x2APIC State Transitions, The existing code to
> handle guest's writing MSR_IA32_APICBASE has two flaws:
> 1. Transition from x2APIC Mode to Disabled Mode is allowed but wrongly
> disabled currently. Fix it by removing the related check.
> 2. Transition from x2APIC Mode to xAPIC Mode is illegal but wrongly allowed
> currently. Considering changing ENABLE bit of the MSR has been handled,
> it can be fixed by only allowing transition from xAPIC Mode to x2APIC Mode
> (the other two transitions: from x2APIC mode to xAPIC Mode, from disabled 
> mode
> to invalid state (EN=0, EXTD=1) are disabled).
> 
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel