From: Vasant Hegde <vasant.hegde@amd.com>
To: Wei Wang <wei.w.wang@hotmail.com>,
joro@8bytes.org, suravee.suthikulpanit@amd.com, will@kernel.org,
robin.murphy@arm.com, thomas.lendacky@amd.com, aik@amd.com,
jgg@nvidia.com, kevin.tian@intel.com, xuyongwei@open-hieco.net
Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 1/3] iommu/amd: Prevent SB IOAPIC from overriding IVRS validation errors
Date: Fri, 29 May 2026 09:43:34 +0530 [thread overview]
Message-ID: <b9721658-874c-4135-b1f1-a302e4aa6a31@amd.com> (raw)
In-Reply-To: <SI2PR01MB4393E6509A349AD67BD79BF7DC5DA@SI2PR01MB4393.apcprd01.prod.exchangelabs.com>
On 4/6/2026 9:10 PM, Wei Wang wrote:
> The check_ioapic_information() function validates IOAPICs against the
> IVRS table to safely disable Interrupt Remapping (IR) if the BIOS provides
> a broken topology.
>
> Currently, the validation loop contains a bug: If an unmapped secondary
> IOAPIC is encountered, 'ret' is set to false. But if the Southbridge (SB)
> IOAPIC is enumerated after it in the MADT, the loop overwrites 'ret' to
> true.
>
> This bypasses the validation failure and leaves IR enabled. When devices
> attached to the unmapped secondary IOAPIC fire interrupts, the IOMMU drops
> them due to the missing Requestor ID, leading to localized device hangs.
>
> Fix this by initializing 'ret' to true and only toggling it to false
> upon encountering a validation error, ensuring failures are never erased.
>
> Fixes: c2ff5cf5294b ("iommu/amd: Work around wrong IOAPIC device-id in IVRS table")
> Signed-off-by: Wei Wang <wei.w.wang@hotmail.com>
Thanks for the fix.
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
-Vasant
next prev parent reply other threads:[~2026-05-29 4:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-06 15:40 [PATCH v1 0/3] iommu/amd: Fix and improve SB IOAPIC IVRS validation Wei Wang
2026-04-06 15:40 ` [PATCH v1 1/3] iommu/amd: Prevent SB IOAPIC from overriding IVRS validation errors Wei Wang
2026-05-29 4:13 ` Vasant Hegde [this message]
2026-04-06 15:40 ` [PATCH v1 2/3] iommu/amd: Fix false positive in SB IOAPIC IVRS validation Wei Wang
2026-05-29 4:30 ` Vasant Hegde
2026-04-06 15:40 ` [PATCH v1 3/3] iommu/amd: Dynamically verify Southbridge IOAPIC via PCI config space Wei Wang
2026-05-29 4:30 ` Vasant Hegde
2026-05-11 7:40 ` [PATCH v1 0/3] iommu/amd: Fix and improve SB IOAPIC IVRS validation Jörg Rödel
2026-05-17 17:55 ` Vasant Hegde
2026-05-26 13:40 ` 徐勇伟
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