Re: [Xen-devel] [PATCH] x86/HVM: use single (atomic) MOV for aligned emulated writes

2020-01-14 Thread Jason Andryuk
On Tue, Jan 14, 2020 at 4:28 AM Jan Beulich wrote: > > On 13.01.2020 20:40, Jason Andryuk wrote: > > On Fri, Dec 27, 2019 at 11:09 AM Andrew Cooper > > wrote: > >> > >> On 20/12/2019 16:23, Jan Beulich wrote: > >>> On 16.09.2019 11:40, Jan Beulich wrote: > Using memcpy() may result in multip

Re: [Xen-devel] [PATCH] x86/HVM: use single (atomic) MOV for aligned emulated writes

2020-01-14 Thread Jan Beulich
On 13.01.2020 20:40, Jason Andryuk wrote: > On Fri, Dec 27, 2019 at 11:09 AM Andrew Cooper > wrote: >> >> On 20/12/2019 16:23, Jan Beulich wrote: >>> On 16.09.2019 11:40, Jan Beulich wrote: Using memcpy() may result in multiple individual byte accesses (dependening how memcpy() is implem

[Xen-devel] [PATCH] x86/HVM: use single (atomic) MOV for aligned emulated writes

2019-09-16 Thread Jan Beulich
Using memcpy() may result in multiple individual byte accesses (dependening how memcpy() is implemented and how the resulting insns, e.g. REP MOVSB, get carried out in hardware), which isn't what we want/need for carrying out guest insns as correctly as possible. Fall back to memcpy() only for acce