Re: [Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-23 Thread Jan Beulich
>>> On 23.08.16 at 11:48, wrote: > On 23/08/16 10:41, Jan Beulich wrote: > On 23.08.16 at 11:24, wrote: >>> On 23/08/16 10:00, Jan Beulich wrote: >>> On 22.08.16 at 19:30, wrote: > On 19/08/16 19:07, Andrew Cooper wrote: >> On 19/08/16 18:09, Andrew Cooper wrote: >>> On 19/08

Re: [Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-23 Thread Andrew Cooper
On 23/08/16 10:41, Jan Beulich wrote: On 23.08.16 at 11:24, wrote: >> On 23/08/16 10:00, Jan Beulich wrote: >> On 22.08.16 at 19:30, wrote: On 19/08/16 19:07, Andrew Cooper wrote: > On 19/08/16 18:09, Andrew Cooper wrote: >> On 19/08/16 13:53, Jan Beulich wrote: >>> User

Re: [Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-23 Thread Jan Beulich
>>> On 23.08.16 at 11:24, wrote: > On 23/08/16 10:00, Jan Beulich wrote: > On 22.08.16 at 19:30, wrote: >>> On 19/08/16 19:07, Andrew Cooper wrote: On 19/08/16 18:09, Andrew Cooper wrote: > On 19/08/16 13:53, Jan Beulich wrote: >> User mode code generally cannot be expected to in

Re: [Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-23 Thread Andrew Cooper
On 23/08/16 10:00, Jan Beulich wrote: On 22.08.16 at 19:30, wrote: >> On 19/08/16 19:07, Andrew Cooper wrote: >>> On 19/08/16 18:09, Andrew Cooper wrote: On 19/08/16 13:53, Jan Beulich wrote: > User mode code generally cannot be expected to invoke the PV-enabled > CPUID Xen suppo

Re: [Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-23 Thread Jan Beulich
>>> On 22.08.16 at 19:30, wrote: > On 19/08/16 19:07, Andrew Cooper wrote: >> On 19/08/16 18:09, Andrew Cooper wrote: >>> On 19/08/16 13:53, Jan Beulich wrote: User mode code generally cannot be expected to invoke the PV-enabled CPUID Xen supports, and prior to the CPUID levelling change

Re: [Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-22 Thread Andrew Cooper
On 19/08/16 19:07, Andrew Cooper wrote: > On 19/08/16 18:09, Andrew Cooper wrote: >> On 19/08/16 13:53, Jan Beulich wrote: >>> User mode code generally cannot be expected to invoke the PV-enabled >>> CPUID Xen supports, and prior to the CPUID levelling changes for 4.7 >>> (as well as even nowadays

Re: [Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-19 Thread Andrew Cooper
On 19/08/16 18:09, Andrew Cooper wrote: > On 19/08/16 13:53, Jan Beulich wrote: >> User mode code generally cannot be expected to invoke the PV-enabled >> CPUID Xen supports, and prior to the CPUID levelling changes for 4.7 >> (as well as even nowadays on levelling incapable hardware) such CPUID >>

Re: [Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-19 Thread Andrew Cooper
On 19/08/16 13:53, Jan Beulich wrote: > User mode code generally cannot be expected to invoke the PV-enabled > CPUID Xen supports, and prior to the CPUID levelling changes for 4.7 > (as well as even nowadays on levelling incapable hardware) such CPUID > invocations actually saw the host CR4.OSXSAVE

[Xen-devel] [PATCH v2] x86/PV: don't wrongly hide/expose CPUID.OSXSAVE from/to user mode

2016-08-19 Thread Jan Beulich
User mode code generally cannot be expected to invoke the PV-enabled CPUID Xen supports, and prior to the CPUID levelling changes for 4.7 (as well as even nowadays on levelling incapable hardware) such CPUID invocations actually saw the host CR4.OSXSAVE value, whereas prior to this patch - on Intel