rjmcmahon
/
umber-kernel
1
0
Fork 0
Code Issues 1 Pull Requests Packages Projects Releases Wiki Activity

iommu/arm-smmu-v3: Do not set disable_ats unless vSTE is Translate 

[ Upstream commit a45dd34663025c75652b27e384e91c9c05ba1d80 ]

A vSTE may have three configuration types: Abort, Bypass, and Translate.

An Abort vSTE wouldn't enable ATS, but the other two might.

It makes sense for a Transalte vSTE to rely on the guest vSTE.EATS field.

For a Bypass vSTE, it would end up with an S2-only physical STE, similar
to an attachment to a regular S2 domain. However, the nested case always
disables ATS following the Bypass vSTE, while the regular S2 case always
enables ATS so long as arm_smmu_ats_supported(master) == true.

Note that ATS is needed for certain VM centric workloads and historically
non-vSMMU cases have relied on this automatic enablement. So, having the
nested case behave differently causes problems.

To fix that, add a condition to disable_ats, so that it might enable ATS
for a Bypass vSTE, aligning with the regular S2 case.

Fixes: f27298a82b ("iommu/arm-smmu-v3: Allow ATS for IOMMU_DOMAIN_NESTED")
Cc: stable@vger.kernel.org
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Nicolin Chen 2026-01-14 17:12:43 -08:00 committed by Sasha Levin
parent 779e0c250a
commit a50006e7ba
1 changed files with 3 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
View File

@ -165,7 +165,9 @@ static int arm_smmu_attach_dev_nested(struct iommu_domain *domain,
* config bit here base this off the EATS value in the STE. If the EATS
* is set then the VM must generate ATC flushes.
*/
state.disable_ats = !nested_domain->enable_ats;
if (FIELD_GET(STRTAB_STE_0_CFG, le64_to_cpu(nested_domain->ste[0])) ==
STRTAB_STE_0_CFG_S1_TRANS)
state.disable_ats = !nested_domain->enable_ats;
ret = arm_smmu_attach_prepare(&state, domain);
if (ret) {
mutex_unlock(&arm_smmu_asid_lock);