6.16-stable review patch. If anyone has any objections, please let me know.
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From: Nicolin Chen nicolinc@nvidia.com
commit 685ca577b408ffd9c5a4057a2acc0cd3e6978b36 upstream.
The arm_smmu_attach_commit() updates master->ats_enabled before calling arm_smmu_remove_master_domain() that is supposed to clean up everything in the old domain, including the old domain's nr_ats_masters. So, it is supposed to use the old ats_enabled state of the device, not an updated state.
This isn't a problem if switching between two domains where: - old ats_enabled = false; new ats_enabled = false - old ats_enabled = true; new ats_enabled = true but can fail cases where: - old ats_enabled = false; new ats_enabled = true (old domain should keep the counter but incorrectly decreased it) - old ats_enabled = true; new ats_enabled = false (old domain needed to decrease the counter but incorrectly missed it)
Update master->ats_enabled after arm_smmu_remove_master_domain() to fix this.
Fixes: 7497f4211f4f ("iommu/arm-smmu-v3: Make changing domains be hitless for ATS") Cc: stable@vger.kernel.org Signed-off-by: Nicolin Chen nicolinc@nvidia.com Acked-by: Will Deacon will@kernel.org Reviewed-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Pranjal Shrivastava praan@google.com Link: https://lore.kernel.org/r/20250801030127.2006979-1-nicolinc@nvidia.com Signed-off-by: Joerg Roedel joerg.roedel@amd.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -2997,9 +2997,9 @@ void arm_smmu_attach_commit(struct arm_s /* ATS is being switched off, invalidate the entire ATC */ arm_smmu_atc_inv_master(master, IOMMU_NO_PASID); } - master->ats_enabled = state->ats_enabled;
arm_smmu_remove_master_domain(master, state->old_domain, state->ssid); + master->ats_enabled = state->ats_enabled; }
static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)