On 11/15/19 11:27 AM, Thomas Huth wrote: > On 15/11/2019 11.20, Janosch Frank wrote: >> On 11/15/19 11:04 AM, Thomas Huth wrote: >>> On 24/10/2019 13.40, Janosch Frank wrote: >>>> If the host initialized the Ultravisor, we can set stfle bit 161 >>>> (protected virtual IPL enhancements facility), which indicates, that >>>> the IPL subcodes 8, 9 and are valid. These subcodes are used by a >>>> normal guest to set/retrieve a IPIB of type 5 and transition into >>>> protected mode. >>>> >>>> Once in protected mode, the VM will loose the facility bit, as each >>> >>> So should the bit be cleared in the host code again? ... I don't see >>> this happening in this patch? >>> >>> Thomas >> >> No, KVM doesn't report stfle facilities in protected mode and we would >> need to add it again in normal mode so just clearing it would be >> pointless. In protected mode 8-10 do not intercept, so there's nothing >> we need to do. > > Ah, ok, that's what I've missed. Maybe replace "the VM will loose the > facility bit" with "the ultravisor will conceal the facility bit" ? > > Thomas > Sure
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