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

[Juergen Gross <jgross@xxxxxxxx>]

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.


Juergen

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