Re: [PATCH] x86/hvm: simplify hvm_physdev_op allowance control

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 04/05/2020 17:31, Roger Pau Monne wrote:
> PVHv1 dom0 was given access to all PHYSDEVOP hypercalls, and such
> restriction was not removed when PVHv1 code was removed. As a result
> the switch in hvm_physdev_op was more complicated than required, and
> relied on PVHv2 dom0 not having PIRQ support in order to prevent
> access to some PV specific PHYSDEVOPs.
>
> Fix this by moving the default case to the bottom of the switch, since
> there's no need for any fall through now. Also remove the hardware
> domain check, as all the not explicitly listed PHYSDEVOPs are
> forbidden for HVM domains.
>
> Finally tighten the condition to allow usage of
> PHYSDEVOP_pci_mmcfg_reserved: apart from having vPCI enabled it should
> only be used by the hardware domain. Note that the code in
> do_physdev_op is already restricting the call to privileged domains
> only, but it can be further restricted to the hardware domain only, as
> other privileged domains don't have access to MMCFG regions anyway.
>
> Overall no functional change should arise from this change.
>
> Reported-by: Julien Grall <jgrall@xxxxxxxxxx>
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>