Re: [PATCH 03/12] KVM: arm64: Block unsafe FF-A calls from the host

[Will Deacon]

On Wed, Nov 16, 2022 at 05:40:48PM +0000, Oliver Upton wrote:
> On Wed, Nov 16, 2022 at 05:03:26PM +0000, Quentin Perret wrote:
> > From: Will Deacon <will@xxxxxxxxxx>
> > 
> > When KVM is initialised in protected mode, we must take care to filter
> > certain FFA calls from the host kernel so that the integrity of guest
> > and hypervisor memory is maintained and is not made available to the
> > secure world.
> > 
> > As a first step, intercept and block all memory-related FF-A SMC calls
> > from the host to EL3. This puts the framework in place for handling them
> > properly.
> 
> Shouldn't FFA_FEATURES interception actually precede this patch? At this
> point in the series we're outright lying about the supported features to
> the host.

FF-A is in a pretty sorry state after this patch as we block all the memory
transactions, but I take your point that we should be consistent and not
advertise the features that we're blocking.

I'll return FFA_RET_NOT_SUPPORTED for all FFA_FEATURES calls until the
interception patch comes in later and does something smarter.

Will