On 02/03/18 16:47, Jan Beulich wrote:
>>>> On 02.03.18 at 17:23, <wei.l...@citrix.com> wrote:
>> +static inline void invpcid(unsigned int pcid, unsigned long addr,
>> + unsigned int type)
>> +{
>> + struct {
>> + uint64_t pcid:12;
>> + uint64_t reserved:52;
>> + uint64_t addr;
>> + } desc = { .pcid = pcid, .addr = addr };
>> +
>> + asm volatile (
>> +#ifdef HAVE_AS_INVPCID
>> + "invpcid %[desc], %q[type]"
>> + : /* No output */
>> + : [desc] "m" (desc), [type] "r" (type)
>> +#else
>> + INVPCID_OPCODE MODRM_ECX_01
>> + : /* No output */
>> + : "a" (type), "c" (&desc)
>> +#endif
>> + : "memory" );
> I can see why you need the memory clobber in the #else case
> (albeit even there it could be avoided by also properly specifying
> the input), but what is this good for in the #if case?
This is a tlb flush operation. I don't think anything good will come
from having other operations reordered around it.
~Andrew
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
