The introduction of acpi_dma_configure() allows to configure DMA
and related IOMMU for any device that is DMA capable. To achieve
that goal it ensures DMA masks are set-up to sane default values
before proceeding with IOMMU and DMA ops configuration.
On x86/ia64 systems, through acpi_bind_one(), acpi_dma_configure() is
called for every device that has an ACPI companion, in that every device
is considered DMA capable on x86/ia64 systems (ie acpi_get_dma_attr() API),
which has the side effect of initializing dma masks also for
pseudo-devices (eg CPUs and memory nodes) and potentially for devices
whose dma masks were not set-up before the acpi_dma_configure() API was
introduced, which may have noxious side effects.
Therefore, in preparation for IORT firmware specific DMA masks set-up,
wrap the default DMA masks set-up in acpi_dma_configure() inside an IORT
specific wrapper that reverts to a NOP on x86/ia64 systems, restoring the
default expected behaviour on x86/ia64 systems and keeping DMA default
masks set-up on IORT based (ie ARM) arch configurations.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Tomasz Nowicki <tn@xxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Sricharan R <sricharan@xxxxxxxxxxxxxx>
---
Joerg,
pending Rafael's ACK on it, given the 4.10 release timing and that the
series is queued via the IOMMU tree please consider applying this patch to
your arm/smmu branch for 4.10, it is not fixing a bug but it is modifying
the x86/ia64 code path; I prefer preventing any issue related to default
dma masks on x86/ia64 so I hope it can get merged along with the rest of
the ACPI IORT SMMU series.
Thanks a lot and apologies,
Lorenzo
drivers/acpi/arm64/iort.c | 22 ++++++++++++++++++++++
drivers/acpi/scan.c | 14 +-------------
include/linux/acpi_iort.h | 2 ++
3 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 47bace8..e0d2e6e 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -547,6 +547,28 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
}
/**
+ * iort_set_dma_mask - Set-up dma mask for a device.
+ *
+ * @dev: device to configure
+ */
+void iort_set_dma_mask(struct device *dev)
+{
+ /*
+ * Set default coherent_dma_mask to 32 bit. Drivers are expected to
+ * setup the correct supported mask.
+ */
+ if (!dev->coherent_dma_mask)
+ dev->coherent_dma_mask = DMA_BIT_MASK(32);
+
+ /*
+ * Set it to coherent_dma_mask by default if the architecture
+ * code has not set it.
+ */
+ if (!dev->dma_mask)
+ dev->dma_mask = &dev->coherent_dma_mask;
+}
+
+/**
* iort_iommu_configure - Set-up IOMMU configuration for a device.
*
* @dev: device to configure
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 80698d3..93b00cf 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1380,19 +1380,7 @@ void acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
{
const struct iommu_ops *iommu;
- /*
- * Set default coherent_dma_mask to 32 bit. Drivers are expected to
- * setup the correct supported mask.
- */
- if (!dev->coherent_dma_mask)
- dev->coherent_dma_mask = DMA_BIT_MASK(32);
-
- /*
- * Set it to coherent_dma_mask by default if the architecture
- * code has not set it.
- */
- if (!dev->dma_mask)
- dev->dma_mask = &dev->coherent_dma_mask;
+ iort_set_dma_mask(dev);
iommu = iort_iommu_configure(dev);
diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
index dcb2b60..77e0809 100644
--- a/include/linux/acpi_iort.h
+++ b/include/linux/acpi_iort.h
@@ -35,6 +35,7 @@ bool iort_node_match(u8 type);
u32 iort_msi_map_rid(struct device *dev, u32 req_id);
struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id);
/* IOMMU interface */
+void iort_set_dma_mask(struct device *dev);
const struct iommu_ops *iort_iommu_configure(struct device *dev);
#else
static inline void acpi_iort_init(void) { }
@@ -45,6 +46,7 @@ static inline struct irq_domain *iort_get_device_domain(struct device *dev,
u32 req_id)
{ return NULL; }
/* IOMMU interface */
+static inline void iort_set_dma_mask(struct device *dev) { }
static inline
const struct iommu_ops *iort_iommu_configure(struct device *dev)
{ return NULL; }
--
2.10.0
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