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From: Nicolin Chen <nicolinc@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, <joro@8bytes.org>,
	Robin Murphy <robin.murphy@arm.com>, <rafael@kernel.org>,
	Danilo Krummrich <dakr@kernel.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	<aneesh.kumar@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Gavin Shan <gshan@redhat.com>, Vikram Sethi <vsethi@nvidia.com>,
	"Anshuman Khandual" <anshuman.khandual@arm.com>,
	Shanker Donthineni <sdonthineni@nvidia.com>,
	Mostafa Saleh <smostafa@google.com>, <rppt@kernel.org>,
	Thomas Huth <thuth@redhat.com>, Marc Zyngier <maz@kernel.org>,
	Ryan Roberts <ryan.roberts@arm.com>, <kas@kernel.org>,
	Kohei Enju <enju.kohei@fujitsu.com>,
	Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	James Morse <james.morse@arm.com>,
	Steven Price <steven.price@arm.com>,
	Sang-Heon Jeon <ekffu200098@gmail.com>,
	Omar Sandoval <osandov@fb.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jinjie Ruan <ruanjinjie@huawei.com>,
	Sam Edwards <cfsworks@gmail.com>,
	Douglas Anderson <dianders@chromium.org>,
	"Florian Fainelli" <florian.fainelli@broadcom.com>,
	Chen-Yu Tsai <wenst@chromium.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Pranjal Shrivastava <praan@google.com>,
	Ashish Mhetre <amhetre@nvidia.com>,
	Shameer Kolothum <skolothumtho@nvidia.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <iommu@lists.linux.dev>,
	<driver-core@lists.linux.dev>, Sonang Patel <sonangp@nvidia.com>,
	Ankit Agrawal <ankita@nvidia.com>
Subject: Re: [PATCH v1 8/8] iommu/arm-smmu-v3: Probe a guest-level Realm VSMMU via RSI commands
Date: Wed, 9 Sep 2026 21:23:34 -0700	[thread overview]
Message-ID: <aqIwxldvOHWlNGRu@nvidia.com> (raw)
In-Reply-To: <df25452641dc126eb334a1bfbe5eee16cc8a8953.1789010941.git.nicolinc@nvidia.com>

On Wed, Sep 09, 2026 at 08:32:51PM -0700, Nicolin Chen wrote:
> @@ -5542,6 +5591,12 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
>  	}
>  	ioaddr = res->start;
>  
> +	if (is_realm_world()) {
> +		ret = arm_smmu_probe_realm_vsmmu(smmu, res);
> +		if (ret)
> +			return ret;

Sashiko pointed out a new finding (didn't appear in my local runs)
that arm_smmu_impl_probe() would allow an untrusted hypervisor to
provide a malicious ACPI/DT table specifying a vendor extension.

I think it's valid, So, we likely need a guard, until impl has RMM
level support with additional RSI validation:

-	smmu = arm_smmu_impl_probe(smmu);
-	if (IS_ERR(smmu))
-		return PTR_ERR(smmu);
+	if (!is_realm_world()) {
+		smmu = arm_smmu_impl_probe(smmu);
+		if (IS_ERR(smmu))
+			return PTR_ERR(smmu);
+	}

Nicolin


      reply	other threads:[~2026-09-10  4:24 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-10  3:32 [PATCH v1 0/8] iommu/arm-smmu-v3: Support guest-level Realm VSMMU (Part-1) Nicolin Chen
2026-09-10  3:32 ` [PATCH v1 1/8] firmware: arm_rmm: Move RSI support out of arch/arm64 Nicolin Chen
2026-09-10  3:32 ` [PATCH v1 2/8] firmware: arm_rmm: Add VSMMU commands and fields Nicolin Chen
2026-09-10  3:32 ` [PATCH v1 3/8] dma-mapping: Let a device declare that it reaches private memory Nicolin Chen
2026-09-10  3:32 ` [PATCH v1 4/8] dma-mapping: Keep DMA memory private for capable devices Nicolin Chen
2026-09-10  3:32 ` [PATCH v1 5/8] iommu: Let a driver mark an IOMMU as confidential Nicolin Chen
2026-09-10  3:32 ` [PATCH v1 6/8] iommu: Introduce TDISP T=0 state for confidential IOMMUs Nicolin Chen
2026-09-10  3:32 ` [PATCH v1 7/8] iommu: Park TDISP T=0 devices in the blocking domain Nicolin Chen
2026-09-10  3:32 ` [PATCH v1 8/8] iommu/arm-smmu-v3: Probe a guest-level Realm VSMMU via RSI commands Nicolin Chen
2026-09-10  4:23   ` Nicolin Chen [this message]

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