iommu/amd: Prevent SB IOAPIC from overriding IVRS validation errors

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>
Tested-by: Yongwei Xu <xuyongwei@open-hieco.net>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

0 files changed, 0 insertions, 0 deletions