Re: [Xen-devel] [PATCH v2 4/5] xen/domain: Allocate d->vcpu[] earlier during domain_create()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 12.11.18 at 17:16, <andrew.cooper3@xxxxxxxxxx> wrote:
> The ARM code has a chicken-and-egg problem.  One of the vGIC_v3 emulations
> wants to know d->max_vcpus to be able to size itself appropriately, but the
> current order of initialisation requires the vGIC to be set up before the
> requested number of vcpus can be checked.
> 
> Move the range checking of config->max_vcpus into sanitise_domain_config()
> path, which allows for the allocation of d->vcpu[] and d->max_vcpus to happen
> earlier during create, and in particular, before the call to
> arch_domain_create().
> 
> The x86 side is fairly easy, and implements the logical equivalent of
> domain_max_vcpus() but using XEN_DOMCTL_CDF_hvm_guest rather than
> is_hvm_domain().
> 
> For the ARM side, re-purpose vgic_max_vcpus() to take a domctl vGIC version,
> and return the maximum number of supported vCPUs, reusing 0 for "version not
> supported".  To avoid exporting the vgic_ops structures (which are in the
> process of being replaced), hard code the upper limits.
> 
> This allows for the removal of the domain_max_vcpus() infrastructure, which is
> done to prevent it being reused incorrectly in the future.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Non-Arm bits
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>



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