On 25/04/2019 14:21, Jan Beulich wrote:
>>>> On 19.04.19 at 10:50, <fionali...@zhaoxin.com> wrote:
>> When executing SYSEXIT or SYSENTRY in Zhaoxin CPU, CPU needs to
> SYSENTER
>
>> --- a/xen/arch/x86/x86_64/traps.c
>> +++ b/xen/arch/x86/x86_64/traps.c
>> @@ -334,7 +334,8 @@ void subarch_percpu_traps_init(void)
>> (unsigned long)lstar_enter);
>> stub_va += offset;
>>
>> - if ( boot_cpu_data.x86_vendor & (X86_VENDOR_INTEL | X86_VENDOR_CENTAUR)
>> )
>> + if ( boot_cpu_data.x86_vendor &
>> + (X86_VENDOR_INTEL | X86_VENDOR_CENTAUR | X86_VENDOR_SHANGHAI) )
>> {
>> /* SYSENTER entry. */
>> wrmsrl(MSR_IA32_SYSENTER_ESP, stack_bottom);
> How is this hunk related to the title of the change? I think the
> title wants to be adjusted.
>
> Furthermore for all of the changes done, wouldn't we better
> switch to use cpu_has_sep? init_amd() as well as default_init()
> already clear this flag. Andrew, thoughts?
I wondered exactly that after queuing this patch, but didn't get around
to experimenting.
We have to be a little careful with the ordering of operations.
cpu_has_sep is visible in CPUID but needs clobbering in AMD/Hygon before
cpu_has_sep is safe to use (although for the MSRs, it should be safe).
~Andrew
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