Re: [Xen-devel] [PATCH v3 4/5] x86emul: make write and cmpxchg hooks optional

2016-12-07 Thread Jan Beulich
>>> On 07.12.16 at 14:36, wrote: > On 07/12/16 08:32, Jan Beulich wrote: >> And I don't see why the ->cpuid() hook would be required all of the >> sudden - all its uses are guarded by a NULL check. > > You made it convincing argument in c/s 043ad80 "x86: always supply > .cpuid() handler to x86_em

Re: [Xen-devel] [PATCH v3 4/5] x86emul: make write and cmpxchg hooks optional

2016-12-07 Thread Andrew Cooper
On 07/12/16 08:32, Jan Beulich wrote: On 06.12.16 at 18:34, wrote: >> On 06/12/16 11:15, Jan Beulich wrote: >>> While the read and fetch hooks are basically unavoidable, write and >>> cmpxchg aren't really needed by that many insns. >>> >>> Signed-off-by: Jan Beulich >> As a corollary, pleas

Re: [Xen-devel] [PATCH v3 4/5] x86emul: make write and cmpxchg hooks optional

2016-12-07 Thread Jan Beulich
>>> On 06.12.16 at 18:34, wrote: > On 06/12/16 11:15, Jan Beulich wrote: >> While the read and fetch hooks are basically unavoidable, write and >> cmpxchg aren't really needed by that many insns. >> >> Signed-off-by: Jan Beulich > > As a corollary, please can we gain > > ASSERT(ops->read && ops

Re: [Xen-devel] [PATCH v3 4/5] x86emul: make write and cmpxchg hooks optional

2016-12-06 Thread Andrew Cooper
On 06/12/16 11:15, Jan Beulich wrote: > While the read and fetch hooks are basically unavoidable, write and > cmpxchg aren't really needed by that many insns. > > Signed-off-by: Jan Beulich As a corollary, please can we gain ASSERT(ops->read && ops->fetch && ops->cpuid) at the start of x86_emul

[Xen-devel] [PATCH v3 4/5] x86emul: make write and cmpxchg hooks optional

2016-12-06 Thread Jan Beulich
While the read and fetch hooks are basically unavoidable, write and cmpxchg aren't really needed by that many insns. Signed-off-by: Jan Beulich --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -1492,6 +1492,8 @@ protmode_load_seg( { uint3