| Message ID | 20230321100559.341981-1-jean-philippe@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iommu/arm-smmu-v3: Explain why ATS stays disabled with bypass | expand |
On Tue, 21 Mar 2023 10:06:00 +0000, Jean-Philippe Brucker wrote: > The SMMU does not support enabling ATS for a bypass stream. Add a comment. > > Applied to will (for-joerg/arm-smmu/updates), thanks! [1/1] iommu/arm-smmu-v3: Explain why ATS stays disabled with bypass https://git.kernel.org/will/c/8c153645fa40 Cheers,
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index f2425b0f0cd6..a8410c132f1e 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -2447,6 +2447,13 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) master->domain = smmu_domain; + /* + * The SMMU does not support enabling ATS with bypass. When the STE is + * in bypass (STE.Config[2:0] == 0b100), ATS Translation Requests and + * Translated transactions are denied as though ATS is disabled for the + * stream (STE.EATS == 0b00), causing F_BAD_ATS_TREQ and + * F_TRANSL_FORBIDDEN events (IHI0070Ea 5.2 Stream Table Entry). + */ if (smmu_domain->stage != ARM_SMMU_DOMAIN_BYPASS) master->ats_enabled = arm_smmu_ats_supported(master);
The SMMU does not support enabling ATS for a bypass stream. Add a comment. Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> --- As promised here: https://lore.kernel.org/linux-iommu/Y9z3UG+wEBn4i3G2@myrica/ --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 7 +++++++ 1 file changed, 7 insertions(+)