Re: [Xen-devel] [PATCH 1/2] x86: report if PCID and INVPCID are supported

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.03.18 at 12:43, <jgross@xxxxxxxx> wrote:
> On 05/03/18 12:20, Jan Beulich wrote:
>>>>> On 05.03.18 at 10:50, <wei.liu2@xxxxxxxxxx> wrote:
>>> --- a/xen/arch/x86/setup.c
>>> +++ b/xen/arch/x86/setup.c
>>> @@ -1701,6 +1701,13 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>>>             cpu_has_nx ? XENLOG_INFO : XENLOG_WARNING "Warning: ",
>>>             cpu_has_nx ? "" : "not ");
>>>  
>>> +
>>> +    printk(XENLOG_INFO
>>> +           "PCID (Process-Context IDentifier) %ssupported\n",
>>> +           cpu_has_pcid ? "" : "not ");
>>> +
>>> +    printk(XENLOG_INFO "INVPCID %ssupported\n", cpu_has_invpcid ? "" : 
>>> "not ");
>> 
>> Do we really need this? We log a message for NX as an exception,
>> we don't do so for other features (and things would get pretty
>> unwieldy if we did).
> 
> I'd rather keep this message. As we are hiding PCID and INPCID from dom0
> this is the only indicator of those features being supported. In case of
> an error related to TLB consistency this information is important IMO.

Well, this argument would hold for almost every other advanced
feature we use.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel