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iommu/amd: Skip non-IVMD entries when parsing IVRS memory definitions

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init_memory_definitions() walks every top-level subtable including the
IVHD blocks (type 0x10/0x11/0x40) in the IVRS ACPI table. It interprets
each one as a 'struct ivmd_header', solely on m->flags, without first
checking that the subtable's type actually is one of the IVMD types
(ACPI_IVMD_TYPE, ACPI_IVMD_TYPE_ALL, ACPI_IVMD_TYPE_RANGE).

    if (m->flags & (IVMD_FLAG_UNITY_MAP | IVMD_FLAG_EXCL_RANGE))
            init_unity_map_range(m, table);

IVMD_FLAG_UNITY_MAP (0x01) occupies the same bit position as the IVHD
flags field's HtTunEn bit. Unlike real hardware, QEMU's AMD IOMMU
emulation sets HtTunEn unconditionally (flags=0xD1 for type 0x10,
0x11 for type 0x11), so every QEMU-emitted IVHD block is misidentified
as a unity-map/exclusion-range IVMD entry, which subsequently results
in the creation of a bogus pci segment. Eg:

    AMD-Vi: PCI segment : 0x4000, last bdf : 0x0000

Fix by checking the subtable's type before treating it as IVMD.

Fixes: be2a022c0d ("x86, AMD IOMMU: add functions to parse IOMMU memory mapping requirements for devices")
Cc: stable@vger.kernel.org
Signed-off-by: Akshay Jindal <Akshay.Jindal@amd.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Akshay Jindal 2026-11-05 16:32:17 +00:00 committed by Joerg Roedel
parent ec91bb159d
commit e62df37e0e
1 changed files with 12 additions and 2 deletions
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14
drivers/iommu/amd/init.c
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@ -2776,6 +2776,15 @@ static int __init init_unity_map_range(struct ivmd_header *m,
return 0;
}
static bool ivrs_block_type_ivmd(u8 type)
{
if (type == ACPI_IVMD_TYPE ||
type == ACPI_IVMD_TYPE_ALL ||
type == ACPI_IVMD_TYPE_RANGE)
return true;
return false;
}
/* iterates over all memory definitions we find in the ACPI table */
static int __init init_memory_definitions(struct acpi_table_header *table)
{
@ -2787,10 +2796,11 @@ static int __init init_memory_definitions(struct acpi_table_header *table)
while (p < end) {
m = (struct ivmd_header *)p;
p += m->length;
if (!ivrs_block_type_ivmd(m->type))
continue;
if (m->flags & (IVMD_FLAG_UNITY_MAP | IVMD_FLAG_EXCL_RANGE))
init_unity_map_range(m, table);
p += m->length;
}
return 0;