[PATCH 2/2] KVM: arm64: Actually prevent SMC64 SYSTEM_RESET2 from AArch32

[Oliver Upton]

On Mon, Mar 21, 2022 at 09:41:39PM -0700, Reiji Watanabe wrote:
> On 3/18/22 12:38 PM, Oliver Upton wrote:
> > The SMCCC does not allow the SMC64 calling convention to be used from
> > AArch32. While KVM checks to see if the calling convention is allowed in
> > PSCI_1_0_FN_PSCI_FEATURES, it does not actually prevent calls to
> > unadvertised PSCI v1.0+ functions.
> >
> > Check to see if the requested function is allowed from the guest's
> > execution state. Deny the call if it is not.
> >
> > Fixes: d43583b890e7 ("KVM: arm64: Expose PSCI SYSTEM_RESET2 call to the guest")
> > Cc: Will Deacon <will at kernel.org>
> > Signed-off-by: Oliver Upton <oupton at google.com>
> 
> Reviewed-by: Reiji Watanabe <reijiw at google.com>

Appreciated :-)

> BTW, considering the new kvm_psci_check_allowed_function()implementation
> in the patch-1, it might be better to call kvm_psci_check_allowed_function()
> from kvm_psci_call() instead?  Then, we could avoid the similar issue
> next time we support a newer PSCI version.

Good point. If Marc doesn't bite in the next day or two I'll address
this with a new spin, otherwise I'll do a separate cleanup. Just want to
avoid spamming on this topic since I already replied with yet another
patch [1].

Thanks!

[1] https://lore.kernel.org/kvmarm/20220322013310.1880100-1-oupton@google.com

--
Oliver