Re: [Xen-devel] [PATCH 04/17] x86emul: complete decoding of two-byte instructions

2016-09-27 Thread Jan Beulich
>>> On 27.09.16 at 15:28, wrote: > On 26/09/16 08:34, Jan Beulich wrote: >> >>> 0F6F was previously ImplicitOps|ModRM, but looks like it should be ModRM >>> like the rest of 0F6x. 0F7F, 0FC7 and 0FE7 similarly. >> Why? As mentioned elsewhere I think the (otherwise benign) >> ImplicitOps (as well

Re: [Xen-devel] [PATCH 04/17] x86emul: complete decoding of two-byte instructions

2016-09-27 Thread Andrew Cooper
On 26/09/16 08:34, Jan Beulich wrote: > >> 0F6F was previously ImplicitOps|ModRM, but looks like it should be ModRM >> like the rest of 0F6x. 0F7F, 0FC7 and 0FE7 similarly. > Why? As mentioned elsewhere I think the (otherwise benign) > ImplicitOps (as well as the individual DstImplicit and SrcImp

Re: [Xen-devel] [PATCH 04/17] x86emul: complete decoding of two-byte instructions

2016-09-26 Thread Jan Beulich
>>> On 23.09.16 at 18:34, wrote: > It would be helpful if you listed all of the decoding modified. > > From the looks of things, the instructions changed are: I don't see the point: If any of them got proper emulation added, I'd agree. But with the purpose of the patch being to simply add corre

Re: [Xen-devel] [PATCH 04/17] x86emul: complete decoding of two-byte instructions

2016-09-23 Thread Andrew Cooper
On 14/09/16 16:05, Jan Beulich wrote: On 14.09.16 at 16:22, wrote: On 08/09/16 14:10, Jan Beulich wrote: This way we can at least size (and e.g. skip) them if needed, and we also won't raise the wrong fault due to not having read all relevant bytes. What faults are you referring to? #UD vs #

Re: [Xen-devel] [PATCH 04/17] x86emul: complete decoding of two-byte instructions

2016-09-14 Thread Jan Beulich
>>> On 14.09.16 at 16:22, wrote: > On 08/09/16 14:10, Jan Beulich wrote: >> This way we can at least size (and e.g. skip) them if needed, and we >> also won't raise the wrong fault due to not having read all relevant >> bytes. > > What faults are you referring to? #UD vs #GP from hitting the %cs

Re: [Xen-devel] [PATCH 04/17] x86emul: complete decoding of two-byte instructions

2016-09-14 Thread Andrew Cooper
On 08/09/16 14:10, Jan Beulich wrote: > This way we can at least size (and e.g. skip) them if needed, and we > also won't raise the wrong fault due to not having read all relevant > bytes. What faults are you referring to? #UD vs #GP from hitting the %cs limit? > > This at once adds correct rais

[Xen-devel] [PATCH 04/17] x86emul: complete decoding of two-byte instructions

2016-09-08 Thread Jan Beulich
This way we can at least size (and e.g. skip) them if needed, and we also won't raise the wrong fault due to not having read all relevant bytes. This at once adds correct raising of #UD for the three "ud" flavors (Intel names only "ud2", but AMD names all three of them in their opcode maps), as th