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
