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| author | Joe Damato <joe@dama.to> | 2026-03-10 02:52:33 +0300 |
|---|---|---|
| committer | Joerg Roedel <joerg.roedel@amd.com> | 2026-03-17 16:02:02 +0300 |
| commit | ba17de98545d07285d15ce4fe2afe98283338fb0 (patch) | |
| tree | 4ad0b0b84066deb0240f8f4613c0647eb7d094e8 | |
| parent | 06e14c36e20b48171df13d51b89fe67c594ed07a (diff) | |
| download | linux-ba17de98545d07285d15ce4fe2afe98283338fb0.tar.xz | |
iommu/amd: Block identity domain when SNP enabled
Previously, commit 8388f7df936b ("iommu/amd: Do not support
IOMMU_DOMAIN_IDENTITY after SNP is enabled") prevented users from
changing the IOMMU domain to identity if SNP was enabled.
This resulted in an error when writing to sysfs:
# echo "identity" > /sys/kernel/iommu_groups/50/type
-bash: echo: write error: Cannot allocate memory
However, commit 4402f2627d30 ("iommu/amd: Implement global identity
domain") changed the flow of the code, skipping the SNP guard and
allowing users to change the IOMMU domain to identity after a machine
has booted.
Once the user does that, they will probably try to bind and the
device/driver will start to do DMA which will trigger errors:
iommu ivhd3: AMD-Vi: Event logged [ILLEGAL_DEV_TABLE_ENTRY device=0000:43:00.0 pasid=0x00000 address=0x3737b01000 flags=0x0020]
iommu ivhd3: AMD-Vi: Control Reg : 0xc22000142148d
AMD-Vi: DTE[0]: 6000000000000003
AMD-Vi: DTE[1]: 0000000000000001
AMD-Vi: DTE[2]: 2000003088b3e013
AMD-Vi: DTE[3]: 0000000000000000
bnxt_en 0000:43:00.0 (unnamed net_device) (uninitialized): Error (timeout: 500015) msg {0x0 0x0} len:0
iommu ivhd3: AMD-Vi: Event logged [ILLEGAL_DEV_TABLE_ENTRY device=0000:43:00.0 pasid=0x00000 address=0x3737b01000 flags=0x0020]
iommu ivhd3: AMD-Vi: Control Reg : 0xc22000142148d
AMD-Vi: DTE[0]: 6000000000000003
AMD-Vi: DTE[1]: 0000000000000001
AMD-Vi: DTE[2]: 2000003088b3e013
AMD-Vi: DTE[3]: 0000000000000000
bnxt_en 0000:43:00.0: probe with driver bnxt_en failed with error -16
To prevent this from happening, create an attach wrapper for
identity_domain_ops which returns EINVAL if amd_iommu_snp_en is true.
With this commit applied:
# echo "identity" > /sys/kernel/iommu_groups/62/type
-bash: echo: write error: Invalid argument
Fixes: 4402f2627d30 ("iommu/amd: Implement global identity domain")
Signed-off-by: Joe Damato <joe@dama.to>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
| -rw-r--r-- | drivers/iommu/amd/iommu.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index 81c4d7733872..760d5f4623b5 100644 --- a/drivers/iommu/amd/iommu.c +++ b/drivers/iommu/amd/iommu.c @@ -2909,8 +2909,21 @@ static struct iommu_domain blocked_domain = { static struct protection_domain identity_domain; +static int amd_iommu_identity_attach(struct iommu_domain *dom, struct device *dev, + struct iommu_domain *old) +{ + /* + * Don't allow attaching a device to the identity domain if SNP is + * enabled. + */ + if (amd_iommu_snp_en) + return -EINVAL; + + return amd_iommu_attach_device(dom, dev, old); +} + static const struct iommu_domain_ops identity_domain_ops = { - .attach_dev = amd_iommu_attach_device, + .attach_dev = amd_iommu_identity_attach, }; void amd_iommu_init_identity_domain(void) |