[PATCH v2 34/40] ACPI/IORT: Check ATS capability in root complex nodes

Jean-Philippe Brucker
2018-05-11T19:06:35Z

Root complex node in IORT has a bit telling whether it supports ATS or
not. Store this bit in the IOMMU fwspec when setting up a device, so it
can be accessed later by an IOMMU driver.

Use the negative version (NO_ATS) at the moment because it's not clear
if/how the bit needs to be integrated in other firmware descriptions. The
SMMU has a feature bit telling if it supports ATS, which might be
sufficient in most systems for deciding whether or not we should enable
the ATS capability in endpoints.

Cc: lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org
Cc: hanjun.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org
Cc: sudeep.holla-5wv7dgnIgG8@public.gmane.org
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
---
drivers/acpi/arm64/iort.c | 11 +++++++++++
include/linux/iommu.h | 4 ++++
2 files changed, 15 insertions(+)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 7a3a541046ed..4f4907e58cc8 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -1004,6 +1004,14 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
dev_dbg(dev, "dma_pfn_offset(%#08llx)\n", offset);
}

+static bool iort_pci_rc_supports_ats(struct acpi_iort_node *node)
+{
+ struct acpi_iort_root_complex *pci_rc;
+
+ pci_rc = (struct acpi_iort_root_complex *)node->node_data;
+ return pci_rc->ats_attribute & ACPI_IORT_ATS_SUPPORTED;
+}
+
/**
* iort_iommu_configure - Set-up IOMMU configuration for a device.
*
@@ -1039,6 +1047,9 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
info.node = node;
err = pci_for_each_dma_alias(to_pci_dev(dev),
iort_pci_iommu_init, &info);
+
+ if (!err && !iort_pci_rc_supports_ats(node))
+ dev->iommu_fwspec->flags |= IOMMU_FWSPEC_PCI_NO_ATS;
} else {
int i = 0;

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index bcce44455117..d7e2f54086e4 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -655,12 +655,16 @@ struct iommu_fwspec {
const struct iommu_ops *ops;
struct fwnode_handle *iommu_fwnode;
void *iommu_priv;
+ u32 flags;
unsigned int num_ids;
unsigned int num_pasid_bits;
bool can_stall;
u32 ids[1];
};

+/* Firmware disabled ATS in the root complex */
+#define IOMMU_FWSPEC_PCI_NO_ATS (1 << 0)
+
int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
const struct iommu_ops *ops);
void iommu_fwspec_free(struct device *dev);
--
2.17.0