Re: [PATCH 7/9] x86/hvm: Disable MPX by default

2020-06-17 Thread Andrew Cooper
On 17/06/2020 12:41, Jan Beulich wrote: > On 17.06.2020 13:28, Andrew Cooper wrote: >> We actually have AVX512 disabled by default in XenServer.  The perf >> implications of letting 1 guest play with it is very severe. >> >> Now I think about it, I'm tempted to recommend it moves out of default >>

Re: [PATCH 7/9] x86/hvm: Disable MPX by default

2020-06-17 Thread Jan Beulich
On 17.06.2020 13:28, Andrew Cooper wrote: > We actually have AVX512 disabled by default in XenServer.  The perf > implications of letting 1 guest play with it is very severe. > > Now I think about it, I'm tempted to recommend it moves out of default > generally. Hmm, I'm tempted to ask whether yo

Re: [PATCH 7/9] x86/hvm: Disable MPX by default

2020-06-17 Thread Andrew Cooper
On 17/06/2020 12:24, Jan Beulich wrote: > On 17.06.2020 13:16, Andrew Cooper wrote: >> On 17/06/2020 11:32, Jan Beulich wrote: >>> On 16.06.2020 18:15, Andrew Cooper wrote: On 16/06/2020 10:33, Jan Beulich wrote: > On 15.06.2020 16:15, Andrew Cooper wrote: >> @@ -479,6 +497,18 @@ int x

Re: [PATCH 7/9] x86/hvm: Disable MPX by default

2020-06-17 Thread Jan Beulich
On 17.06.2020 13:16, Andrew Cooper wrote: > On 17/06/2020 11:32, Jan Beulich wrote: >> On 16.06.2020 18:15, Andrew Cooper wrote: >>> On 16/06/2020 10:33, Jan Beulich wrote: On 15.06.2020 16:15, Andrew Cooper wrote: > @@ -479,6 +497,18 @@ int xc_cpuid_apply_policy(xc_interface *xch, >

Re: [PATCH 7/9] x86/hvm: Disable MPX by default

2020-06-17 Thread Andrew Cooper
On 17/06/2020 11:32, Jan Beulich wrote: > On 16.06.2020 18:15, Andrew Cooper wrote: >> On 16/06/2020 10:33, Jan Beulich wrote: >>> On 15.06.2020 16:15, Andrew Cooper wrote: @@ -479,6 +497,18 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore, goto

Re: [PATCH 7/9] x86/hvm: Disable MPX by default

2020-06-17 Thread Jan Beulich
On 16.06.2020 18:15, Andrew Cooper wrote: > On 16/06/2020 10:33, Jan Beulich wrote: >> On 15.06.2020 16:15, Andrew Cooper wrote: >>> @@ -479,6 +497,18 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t >>> domid, bool restore, >>> goto out; >>> } >>> >>> +/* >>> + * A

Re: [PATCH 7/9] x86/hvm: Disable MPX by default

2020-06-16 Thread Andrew Cooper
On 16/06/2020 10:33, Jan Beulich wrote: > On 15.06.2020 16:15, Andrew Cooper wrote: >> @@ -479,6 +497,18 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t >> domid, bool restore, >> goto out; >> } >> >> +/* >> + * Account for feature which have been disabled by defau

Re: [PATCH 7/9] x86/hvm: Disable MPX by default

2020-06-16 Thread Jan Beulich
On 15.06.2020 16:15, Andrew Cooper wrote: > @@ -479,6 +497,18 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t > domid, bool restore, > goto out; > } > > +/* > + * Account for feature which have been disabled by default since Xen > 4.13, > + * so migrated-in VM