RE: 'repz' instruction not supported.
Thanks. Will share the code sometime this week with you. Regards Ashutosh > Date: Fri, 21 Nov 2014 11:22:06 -0800 > Subject: Re: 'repz' instruction not supported. > From: neeln...@gmail.com > To: mrashut...@hotmail.com > CC: freebsd-virtualization@freebsd.org > > Hi Ashutosh, > > On Fri, Nov 21, 2014 at 2:07 AM, Ashutosh Kumar > wrote: > > Yes you are right 'repz' prefixes is added to the ‘cmps’ and 'scas' > > instructions. > > > > The actual opcode is “F3 A5” which is ‘rep movs’ (disassembly is showing > > ‘repz’). > > > > > > > > Yes the guest is emitting these instructions to access MMIO (local apic) > > > > Bummer. > > I was hoping that it was a prefix stuck by the compiler for > optimization (that could be ignored): > http://repzret.org/p/repzret/ > > In any case, the primitives you will need to emulate MOVS exist in > vmm_instruction_emul.c. I don't have any plans to work on this but > would be happy to review/submit the patch that does the emulation. > > best > Neel > > > > > > > Regards > > Ashutosh > > > > > >> Date: Fri, 21 Nov 2014 00:08:15 -0800 > >> Subject: Re: 'repz' instruction not supported. > >> From: neeln...@gmail.com > >> To: mrashut...@hotmail.com > >> CC: freebsd-virtualization@freebsd.org > > > >> > >> Hi Ashutosh, > >> > >> On Wed, Nov 19, 2014 at 10:30 PM, Ashutosh Kumar > >> wrote: > >> > Hi > >> > We have found that emulation of 'repz' instruction is not supported in > >> > bhyve. This is causing VM_EXIT for Guest OS. Do we have plans to add > >> > support > >> > for instructions like 'repz'. > >> > > >> > >> 'repz' is actually an instruction prefix. The two instructions with > >> which 'repz' is allowed are 'cmps' and 'scas'. Both these instructions > >> typically don't need to be emulated since they operate on strings in > >> "regular" guest memory. > >> > >> Is your guest emitting these instructions to access MMIO? Can you > >> share an objdump with the offending instructions? > >> > >> best > >> Neel > >> > >> > RegardsAshutosh > >> > ___ > >> > freebsd-virtualization@freebsd.org mailing list > >> > http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > >> > To unsubscribe, send any mail to > >> > "freebsd-virtualization-unsubscr...@freebsd.org" ___ freebsd-virtualization@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"
Re: 'repz' instruction not supported.
Hi Ashutosh, On Fri, Nov 21, 2014 at 2:07 AM, Ashutosh Kumar wrote: > Yes you are right 'repz' prefixes is added to the ‘cmps’ and 'scas' > instructions. > > The actual opcode is “F3 A5” which is ‘rep movs’ (disassembly is showing > ‘repz’). > > > > Yes the guest is emitting these instructions to access MMIO (local apic) > Bummer. I was hoping that it was a prefix stuck by the compiler for optimization (that could be ignored): http://repzret.org/p/repzret/ In any case, the primitives you will need to emulate MOVS exist in vmm_instruction_emul.c. I don't have any plans to work on this but would be happy to review/submit the patch that does the emulation. best Neel > > > Regards > Ashutosh > > >> Date: Fri, 21 Nov 2014 00:08:15 -0800 >> Subject: Re: 'repz' instruction not supported. >> From: neeln...@gmail.com >> To: mrashut...@hotmail.com >> CC: freebsd-virtualization@freebsd.org > >> >> Hi Ashutosh, >> >> On Wed, Nov 19, 2014 at 10:30 PM, Ashutosh Kumar >> wrote: >> > Hi >> > We have found that emulation of 'repz' instruction is not supported in >> > bhyve. This is causing VM_EXIT for Guest OS. Do we have plans to add >> > support >> > for instructions like 'repz'. >> > >> >> 'repz' is actually an instruction prefix. The two instructions with >> which 'repz' is allowed are 'cmps' and 'scas'. Both these instructions >> typically don't need to be emulated since they operate on strings in >> "regular" guest memory. >> >> Is your guest emitting these instructions to access MMIO? Can you >> share an objdump with the offending instructions? >> >> best >> Neel >> >> > RegardsAshutosh >> > ___ >> > freebsd-virtualization@freebsd.org mailing list >> > http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization >> > To unsubscribe, send any mail to >> > "freebsd-virtualization-unsubscr...@freebsd.org" ___ freebsd-virtualization@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"
RE: 'repz' instruction not supported.
Yes you are right 'repz' prefixes is added to the ‘cmps’ and 'scas' instructions. The actual opcode is “F3 A5” which is ‘rep movs’ (disassembly is showing ‘repz’). Yes the guest is emitting these instructions to access MMIO (local apic) RegardsAshutosh > Date: Fri, 21 Nov 2014 00:08:15 -0800 > Subject: Re: 'repz' instruction not supported. > From: neeln...@gmail.com > To: mrashut...@hotmail.com > CC: freebsd-virtualization@freebsd.org > > Hi Ashutosh, > > On Wed, Nov 19, 2014 at 10:30 PM, Ashutosh Kumar > wrote: > > Hi > > We have found that emulation of 'repz' instruction is not supported in > > bhyve. This is causing VM_EXIT for Guest OS. Do we have plans to add > > support for instructions like 'repz'. > > > > 'repz' is actually an instruction prefix. The two instructions with > which 'repz' is allowed are 'cmps' and 'scas'. Both these instructions > typically don't need to be emulated since they operate on strings in > "regular" guest memory. > > Is your guest emitting these instructions to access MMIO? Can you > share an objdump with the offending instructions? > > best > Neel > > > RegardsAshutosh > > ___ > > freebsd-virtualization@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > > To unsubscribe, send any mail to > > "freebsd-virtualization-unsubscr...@freebsd.org" ___ freebsd-virtualization@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"
Re: 'repz' instruction not supported.
Hi Ashutosh, On Wed, Nov 19, 2014 at 10:30 PM, Ashutosh Kumar wrote: > Hi > We have found that emulation of 'repz' instruction is not supported in bhyve. > This is causing VM_EXIT for Guest OS. Do we have plans to add support for > instructions like 'repz'. > 'repz' is actually an instruction prefix. The two instructions with which 'repz' is allowed are 'cmps' and 'scas'. Both these instructions typically don't need to be emulated since they operate on strings in "regular" guest memory. Is your guest emitting these instructions to access MMIO? Can you share an objdump with the offending instructions? best Neel > RegardsAshutosh > ___ > freebsd-virtualization@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > To unsubscribe, send any mail to > "freebsd-virtualization-unsubscr...@freebsd.org" ___ freebsd-virtualization@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"
Re: 'repz' instruction not supported.
On Thursday, November 20, 2014 1:30:41 am Ashutosh Kumar wrote: > Hi > We have found that emulation of 'repz' instruction is not supported in bhyve. This is causing VM_EXIT for Guest OS. Do we have plans to add support for instructions like 'repz'. What are you using repz for? Is it memory access to some device? -- John Baldwin ___ freebsd-virtualization@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"
'repz' instruction not supported.
Hi We have found that emulation of 'repz' instruction is not supported in bhyve. This is causing VM_EXIT for Guest OS. Do we have plans to add support for instructions like 'repz'. RegardsAshutosh ___ freebsd-virtualization@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"
