From: Sebastian Ene <sebastianene@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: catalin.marinas@arm.com, james.morse@arm.com,
jean-philippe@linaro.org, maz@kernel.org, qperret@google.com,
qwandor@google.com, suzuki.poulose@arm.com, tabba@google.com,
will@kernel.org, yuzenghui@huawei.com, kvmarm@lists.linux.dev,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kernel-team@android.com
Subject: Re: [PATCH 2/2] KVM: arm64: Allow only the specified FF-A calls to be forwarded to TZ
Date: Thu, 28 Mar 2024 13:59:00 +0000 [thread overview]
Message-ID: <ZgV3pGvUhaK5otUL@google.com> (raw)
In-Reply-To: <ZgKKcurtndJaIwAV@linux.dev>
On Tue, Mar 26, 2024 at 01:42:26AM -0700, Oliver Upton wrote:
> On Mon, Mar 25, 2024 at 11:29:39AM +0000, Sebastian Ene wrote:
> > On Fri, Mar 22, 2024 at 07:07:52PM -0700, Oliver Upton wrote:
> > > On Fri, Mar 22, 2024 at 12:43:03PM +0000, Sebastian Ene wrote:
> > > > The previous logic used a deny list to filter the FF-A calls. Because of
> > > > this, some of the calls escaped the check and they were forwarded by
> > > > default to Trustzone. (eg. FFA_MSG_SEND_DIRECT_REQ was denied but the 64
> > > > bit version of the call was not).
> > > > Modify the logic to use an allowlist and allow only the calls specified in
> > > > the filter function to be proxied to TZ from the hypervisor.
> >
> > Hi Oliver,
> >
> > >
> > > I had discussed this with Will back when the feature was upstreamed and
> > > he said there's a lot of off-label calls that necessitate a denylist
> > > implementation. Has anything changed to give us confidence that we can
> > > be restrictive, at least on the FF-A range?
> > >
> >
> > I remember your proposal for having an allowlist instead. The current change makes
> > sense if we have https://lore.kernel.org/kvmarm/20240322124303.309423-1-sebastianene@google.com/
> > which opens the window for more FF-A calls to be forwarded to TZ.
>
> Got it. Last time I didn't catch the level of abuse we expect to endure
> from vendors, but now it seems we will not support non-conforming calls
> that appear in standardized SMC ranges.
>
> Adding mention of this to the changelog might be a good idea then.
>
That's a good point. I didn't create a changelog for this but I should
add one and specify this.
> --
> Thanks,
> Oliver
Thanks,
Sebastian
prev parent reply other threads:[~2024-03-28 13:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-22 12:43 [PATCH 1/2] KVM: arm64: Fix the identification range for the FF-A smcs Sebastian Ene
2024-03-22 12:43 ` [PATCH 2/2] KVM: arm64: Allow only the specified FF-A calls to be forwarded to TZ Sebastian Ene
2024-03-23 2:07 ` Oliver Upton
2024-03-25 11:29 ` Sebastian Ene
2024-03-26 8:42 ` Oliver Upton
2024-03-28 13:59 ` Sebastian Ene [this message]
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