Re: [Xen-devel] [PATCH 2/4] x86/setup: Minor cleanup to host SYSCALL MSR handling

2017-02-13 Thread Jan Beulich
>>> On 13.02.17 at 16:33, wrote: > On 13/02/17 15:30, Jan Beulich wrote: > On 13.02.17 at 16:26, wrote: >>> On 13/02/17 15:19, Jan Beulich wrote: >>> On 13.02.17 at 15:32, wrote: > Xen's choice of the MSR_STAR value is constant across all pcpus. > Introduce a > new define a

Re: [Xen-devel] [PATCH 2/4] x86/setup: Minor cleanup to host SYSCALL MSR handling

2017-02-13 Thread Andrew Cooper
On 13/02/17 15:30, Jan Beulich wrote: On 13.02.17 at 16:26, wrote: >> On 13/02/17 15:19, Jan Beulich wrote: >> On 13.02.17 at 15:32, wrote: Xen's choice of the MSR_STAR value is constant across all pcpus. Introduce a new define and use it to avoid the opencoding in

Re: [Xen-devel] [PATCH 2/4] x86/setup: Minor cleanup to host SYSCALL MSR handling

2017-02-13 Thread Jan Beulich
>>> On 13.02.17 at 16:26, wrote: > On 13/02/17 15:19, Jan Beulich wrote: > On 13.02.17 at 15:32, wrote: >>> Xen's choice of the MSR_STAR value is constant across all pcpus. Introduce >>> a >>> new define and use it to avoid the opencoding in subarch_percpu_traps_init() >>> and restore_rest_

Re: [Xen-devel] [PATCH 2/4] x86/setup: Minor cleanup to host SYSCALL MSR handling

2017-02-13 Thread Andrew Cooper
On 13/02/17 15:19, Jan Beulich wrote: On 13.02.17 at 15:32, wrote: >> Xen's choice of the MSR_STAR value is constant across all pcpus. Introduce a >> new define and use it to avoid the opencoding in subarch_percpu_traps_init() >> and restore_rest_processor_state(). >> >> Despite Intel hardwa

Re: [Xen-devel] [PATCH 2/4] x86/setup: Minor cleanup to host SYSCALL MSR handling

2017-02-13 Thread Jan Beulich
>>> On 13.02.17 at 15:32, wrote: > Xen's choice of the MSR_STAR value is constant across all pcpus. Introduce a > new define and use it to avoid the opencoding in subarch_percpu_traps_init() > and restore_rest_processor_state(). > > Despite Intel hardware having an MSR_CSTAR register, nothing ac

[Xen-devel] [PATCH 2/4] x86/setup: Minor cleanup to host SYSCALL MSR handling

2017-02-13 Thread Andrew Cooper
Xen's choice of the MSR_STAR value is constant across all pcpus. Introduce a new define and use it to avoid the opencoding in subarch_percpu_traps_init() and restore_rest_processor_state(). Despite Intel hardware having an MSR_CSTAR register, nothing actually uses it as the SYSCALL instruction ra