Re: [Xen-devel] [PATCH v2 8/9] x86/CPUID: drop INVPCID dependency on PCID

2019-09-18 Thread Andrew Cooper
On 18/09/2019 10:10, Jan Beulich wrote: > On 17.09.2019 21:59, Andrew Cooper wrote: >> On 17/09/2019 07:17, Jan Beulich wrote: >>> PCID validly depends on LM, as it can be enabled in Long Mode only. >>> INVPCID, otoh, can be used not only without PCID enabled, but also >>> outside of Long Mode alto

Re: [Xen-devel] [PATCH v2 8/9] x86/CPUID: drop INVPCID dependency on PCID

2019-09-18 Thread Jan Beulich
On 17.09.2019 21:59, Andrew Cooper wrote: > On 17/09/2019 07:17, Jan Beulich wrote: >> PCID validly depends on LM, as it can be enabled in Long Mode only. >> INVPCID, otoh, can be used not only without PCID enabled, but also >> outside of Long Mode altogether. In both cases its functionality is >>

Re: [Xen-devel] [PATCH v2 8/9] x86/CPUID: drop INVPCID dependency on PCID

2019-09-17 Thread Andrew Cooper
On 17/09/2019 07:17, Jan Beulich wrote: > PCID validly depends on LM, as it can be enabled in Long Mode only. > INVPCID, otoh, can be used not only without PCID enabled, but also > outside of Long Mode altogether. In both cases its functionality is > simply restricted to PCID 0, which is sort of ex

[Xen-devel] [PATCH v2 8/9] x86/CPUID: drop INVPCID dependency on PCID

2019-09-16 Thread Jan Beulich
PCID validly depends on LM, as it can be enabled in Long Mode only. INVPCID, otoh, can be used not only without PCID enabled, but also outside of Long Mode altogether. In both cases its functionality is simply restricted to PCID 0, which is sort of expected as no other PCID can be activated there.