On 20/03/2024 1:57 pm, Roger Pau Monne wrote: > There's no reason to force HVM guests to have a valid vcpu_info area when > initializing a vCPU, as the vCPU can also be brought online using the local > APIC, and on that path there's no requirement for vcpu_info to be setup ahead > of the bring up. Note an HVM vCPU can operate normally without making use of > vcpu_info. > > Restrict the check against dummy_vcpu_info to only apply to PV guests. > > Fixes: 192df6f9122d ('x86: allow HVM guests to use hypercalls to bring up > vCPUs') > Signed-off-by: Roger Pau Monné <roger....@citrix.com>
Thanks for looking into this. But, do we actually need to force this on PV either? The only interesting user of dummy_vcpu_info now is vcpu_info_populate() which can cope with any arbitrary vCPU. I have a suspicion that we can (now) delete these two checks, delete the dummy_vcpu_info object, and use a regular NULL pointer in vcpu_info_{populate,reset}(), and in doing so, remove one of the bigger pieces of PV-absurdity from Xen. I can entirely believe that this is only safe to do with Jan's physical registration changes in place. ~Andrew