From: Jason Gunthorpe <jgg@nvidia.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: linux-coco@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Greg KH <gregkh@linuxfoundation.org>,
Jeremy Linton <jeremy.linton@arm.com>,
Jonathan Cameron <jic23@kernel.org>,
Lorenzo Pieralisi <lpieralisi@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Will Deacon <will@kernel.org>,
Steven Price <steven.price@arm.com>,
Suzuki K Poulose <Suzuki.Poulose@arm.com>,
Andre Przywara <andre.przywara@arm.com>
Subject: Re: [PATCH v10 6/7] firmware: smccc: arm-cca-guest: Bind the TSM provider to an SMCCC device
Date: Wed, 9 Sep 2026 09:05:34 -0300 [thread overview]
Message-ID: <20260909120534.GE2779763@nvidia.com> (raw)
In-Reply-To: <yq5atsnyeuz5.fsf@kernel.org>
On Wed, Sep 09, 2026 at 01:07:18PM +0530, Aneesh Kumar K.V wrote:
> > Could this also leak kernel register state to EL2?
> >
>
> Should we instead do
>
> arm_smccc_1_1_invoke(smccc_dev->func_id,
> 0, 0, 0, 0, 0, 0, 0, &res);
> ret = res.a0;
>
> There is no standard defining how the various SMCCC VERSION calls are
> expected to work. For example, ARM_SMCCC_TRNG_VERSION does not use x1,
> while SMC_RSI_ABI_VERSION does. Another VERSION call could use both x1
> and x2. The only consistent behavior is to return
> SMCCC_RET_NOT_SUPPORTED when the SMCCC function ID is not supported.
That seems safer to me at least. I'm less worried about "garbage"
leaking out but it maybe could cause something weird to happen in the
FW.. It might get confused and return the wrong error code and not get
discovered.
Jason
next prev parent reply other threads:[~2026-09-09 12:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-04 9:49 [PATCH v10 0/7] Switch Arm SMCCC firmware services to an SMCCC bus Aneesh Kumar K.V (Arm)
2026-09-04 9:49 ` [PATCH v10 1/7] firmware: smccc: Add an Arm " Aneesh Kumar K.V (Arm)
2026-09-04 19:39 ` Jason Gunthorpe
2026-09-04 9:49 ` [PATCH v10 2/7] firmware: hwrng: arm_smccc_trng: Register as an SMCCC device Aneesh Kumar K.V (Arm)
2026-09-04 19:39 ` Jason Gunthorpe
2026-09-04 9:49 ` [PATCH v10 3/7] firmware: arm_rmm: Move RSI support out of arch/arm64 Aneesh Kumar K.V (Arm)
2026-09-04 19:39 ` Jason Gunthorpe
2026-09-04 9:49 ` [PATCH v10 4/7] arm64: realm: Move Realm memory encryption ops to RSI code Aneesh Kumar K.V (Arm)
2026-09-04 19:39 ` Jason Gunthorpe
2026-09-04 9:49 ` [PATCH v10 5/7] virt: coco: arm-cca-guest: Rename TSM report source file Aneesh Kumar K.V (Arm)
2026-09-04 19:39 ` Jason Gunthorpe
2026-09-04 9:49 ` [PATCH v10 6/7] firmware: smccc: arm-cca-guest: Bind the TSM provider to an SMCCC device Aneesh Kumar K.V (Arm)
2026-09-04 19:39 ` Jason Gunthorpe
2026-09-09 7:37 ` Aneesh Kumar K.V
2026-09-09 12:05 ` Jason Gunthorpe [this message]
2026-09-04 9:50 ` [PATCH v10 7/7] coco: guest: arm64: Replace dummy CCA device with sysfs ABI Aneesh Kumar K.V (Arm)
2026-09-04 19:39 ` Jason Gunthorpe
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