On Wed, Jun 29 2022, Eric Auger <eauger@xxxxxxxxxx> wrote: > Hi Connie, > > On 6/13/22 18:02, Cornelia Huck wrote: >> On Fri, Jun 10 2022, Eric Auger <eauger@xxxxxxxxxx> wrote: >> >>> Hi Connie, >>> >>> On 5/12/22 15:11, Cornelia Huck wrote: >>>> This series enables MTE for kvm guests, if the kernel supports it. >>>> Lightly tested while running under the simulator (the arm64/mte/ >>>> kselftests pass... if you wait patiently :) >>>> >>>> A new cpu property "mte" (defaulting to on if possible) is introduced; >>>> for tcg, you still need to enable mte at the machine as well. >>> isn't the property set to off by default when kvm is enabled (because of >>> the migration blocker). >> >> Oh, I had changed that around several times, and it seems I ended up >> being confused when I wrote this cover letter... I wonder what the best >> state would be (assuming that I don't manage to implement it soonish, >> but it seems we still would need kernel changes as by the discussion in >> that other patch series.) > Having mte=off by default along with KVM, until the migration gets > supported, looks OK to me. Does it prevent you from having it set to > another value by default with TCG (depending on the virt machine > tag_memory option)? > > tag_memory=on tag_memory=off > KVM CPU mte=off invalid mte=off > KVM CPU mte=on invalid mte=on > TCG CPU mte=off invalid mte=off > TCG CPU mte=on mte=on invalid > > default value: > KVM mte = off until migration gets supported > TCG mte = machine.tag_memory With OnOffAuto, I currently have: valid for tcg: cpu.mte=on, tag_memory=on (result: mte on) cpu.mte=off, tag_memory either on or off (result: mte off) cpu.mte unspecified, tag_memory either on or off (result: mte==tag_memory) valid for kvm: tag_memory always off cpu.mte=off (result: mte off) cpu.mte=on if mte supported in kvm (result: mte on) cpu.mte unspecified (result: mte on if kvm supports it; this I can flip) all other combinations: error