In case the msi is emitted by a device attached to an iommu domain
and this iommu domain requires MSI mapping, the msi address (aka
doorbell) must be mapped in the IOMMU. Else MSI write transaction
will cause a fault.
We handle the iommu mapping/unmapping anytime the msi address is
updated.
In case the mapping fails we just WARN_ON.
Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
---
v6:
- check the domain type to detect bypass situation (rebase on
new default domain modality)
- fix the msi_domain_set_affinity sequence:
unmap the address once the PCI device has been given the new address
- use new proto for iommu_put_reserved_iova. New function names
v5:
- use macros to increase the readability
- add comments
- fix a typo that caused a compilation error if CONFIG_IOMMU_API
is not set
---
include/linux/msi.h | 15 +++++++
kernel/irq/msi.c | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 138 insertions(+)
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 08441b1..1dc41db 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -10,6 +10,21 @@ struct msi_msg {
u32 data; /* 16 bits of msi message data */
};
+/* Helpers to convert the msi message address to a an iova/physical address */
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+#define msg_to_dma_addr(msg) \
+ (((dma_addr_t)((msg)->address_hi) << 32) | (msg)->address_lo)
+#else
+#define msg_to_dma_addr(msg) ((msg)->address_lo)
+#endif
+
+#ifdef CONFIG_PHYS_ADDR_T_64BIT
+#define msg_to_phys_addr(msg) \
+ (((phys_addr_t)((msg)->address_hi) << 32) | (msg)->address_lo)
+#else
+#define msg_to_phys_addr(msg) ((msg)->address_lo)
+#endif
+
extern int pci_msi_ignore_mask;
/* Helper functions */
struct irq_data;
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 9b0ba4a..7440653 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -17,6 +17,8 @@
/* Temparory solution for building, will be removed later */
#include <linux/pci.h>
+#include <linux/iommu.h>
+#include <linux/dma-reserved-iommu.h>
struct msi_desc *alloc_msi_entry(struct device *dev)
{
@@ -56,6 +58,94 @@ static inline void irq_chip_write_msi_msg(struct irq_data *data,
}
/**
+ * msi_map_doorbell: make sure an IOMMU mapping exists on domain @d
+ * for the message physical address (aka. doorbell)
+ *
+ * Either allocate an IOVA and create a mapping or simply increment
+ * a reference count on the existing IOMMU mapping
+ * @d: iommu domain handle the mapping belongs to
+ * @msg: msi message handle
+ */
+static int msi_map_doorbell(struct iommu_domain *d, struct msi_msg *msg)
+{
+#ifdef CONFIG_IOMMU_DMA_RESERVED
+ phys_addr_t addr;
+ dma_addr_t iova;
+ int ret;
+
+ addr = msg_to_phys_addr(msg);
+ ret = iommu_get_reserved_iova(d, addr, sizeof(addr), IOMMU_WRITE, &iova);
+ if (!ret) {
+ msg->address_lo = lower_32_bits(iova);
+ msg->address_hi = upper_32_bits(iova);
+ }
+ return ret;
+#else
+ return -ENODEV;
+#endif
+}
+
+/**
+ * msi_unmap_doorbell: decrements the reference count on an existing
+ * doorbell IOMMU mapping
+ *
+ * @d: iommu domain the mapping is attached to
+ * @msg: msi message containing the doorbell IOVA to unbind
+ */
+static void msi_unmap_doorbell(struct iommu_domain *d, struct msi_msg *msg)
+{
+#ifdef CONFIG_IOMMU_DMA_RESERVED
+ dma_addr_t iova;
+
+ iova = msg_to_dma_addr(msg);
+ iommu_put_reserved_iova(d, iova);
+#endif
+}
+
+#ifdef CONFIG_IOMMU_API
+/**
+ * irq_data_to_msi_mapping_domain: checks if an irq corresponds to
+ * an MSI whose write address must be mapped in an IOMMU domain
+ *
+ * determine whether the irq corresponds to an MSI emitted by a device,
+ * upstream to an IOMMU, and if this IOMMU requires a binding of the
+ * MSI address
+ *
+ * @irq_data: irq data handle
+ */
+static struct iommu_domain *
+irq_data_to_msi_mapping_domain(struct irq_data *irq_data)
+{
+ struct iommu_domain *d;
+ struct msi_desc *desc;
+ struct device *dev;
+ int ret;
+
+ desc = irq_data_get_msi_desc(irq_data);
+ if (!desc)
+ return NULL;
+
+ dev = msi_desc_to_dev(desc);
+
+ d = iommu_get_domain_for_dev(dev);
+ if (!d || (d->type == IOMMU_DOMAIN_DMA))
+ return NULL;
+
+ ret = iommu_domain_get_attr(d, DOMAIN_ATTR_MSI_MAPPING, NULL);
+ if (!ret)
+ return d;
+ else
+ return NULL;
+}
+#else
+static inline struct iommu_domain *
+irq_data_to_msi_mapping_domain(struct irq_data *irq_data)
+{
+ return NULL;
+}
+#endif /* CONFIG_IOMMU_API */
+
+/**
* msi_domain_set_affinity - Generic affinity setter function for MSI domains
* @irq_data: The irq data associated to the interrupt
* @mask: The affinity mask to set
@@ -73,8 +163,27 @@ int msi_domain_set_affinity(struct irq_data *irq_data,
ret = parent->chip->irq_set_affinity(parent, mask, force);
if (ret >= 0 && ret != IRQ_SET_MASK_OK_DONE) {
+ bool doorbell_change = false;
+ struct iommu_domain *d;
+ struct msi_msg old_msg;
+
+ d = irq_data_to_msi_mapping_domain(irq_data);
+ if (unlikely(d)) {
+ get_cached_msi_msg(irq_data->irq, &old_msg);
+ doorbell_change =
+ (old_msg.address_lo != msg.address_lo) ||
+ (old_msg.address_hi != msg.address_hi);
+ }
+
BUG_ON(irq_chip_compose_msi_msg(irq_data, &msg));
+
+ if (unlikely(doorbell_change))
+ WARN_ON(msi_map_doorbell(d, &msg));
+
irq_chip_write_msi_msg(irq_data, &msg);
+
+ if (unlikely(doorbell_change))
+ msi_unmap_doorbell(d, &old_msg);
}
return ret;
@@ -83,19 +192,33 @@ int msi_domain_set_affinity(struct irq_data *irq_data,
static void msi_domain_activate(struct irq_domain *domain,
struct irq_data *irq_data)
{
+ struct iommu_domain *d;
struct msi_msg msg;
+ d = irq_data_to_msi_mapping_domain(irq_data);
+
BUG_ON(irq_chip_compose_msi_msg(irq_data, &msg));
+ if (unlikely(d))
+ WARN_ON(msi_map_doorbell(d, &msg));
irq_chip_write_msi_msg(irq_data, &msg);
}
static void msi_domain_deactivate(struct irq_domain *domain,
struct irq_data *irq_data)
{
+ struct iommu_domain *d;
+ struct msi_msg old_msg;
struct msi_msg msg;
+ d = irq_data_to_msi_mapping_domain(irq_data);
+ if (unlikely(d))
+ get_cached_msi_msg(irq_data->irq, &old_msg);
+
memset(&msg, 0, sizeof(msg));
irq_chip_write_msi_msg(irq_data, &msg);
+
+ if (unlikely(d))
+ msi_unmap_doorbell(d, &old_msg);
}
static int msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
--
1.9.1
--
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