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Subject[PATCH v9 7/8] genirq/msi: map/unmap the MSI doorbells on msi_domain_alloc/free_irqs
Date
This patch handles the iommu mapping of MSI doorbells that require to
be mapped in an iommu domain. This happens on msi_domain_alloc/free_irqs
since this is called in code that can sleep (pci_enable/disable_msi):
iommu_map/unmap is not stated as atomic. On msi_domain_(de)activate and
msi_domain_set_affinity, which must be atomic, we just lookup for this
pre-allocated/mapped IOVA.

Signed-off-by: Eric Auger <eric.auger@linaro.org>

---
v8 -> v9:
- decouple irq_data parsing from the actual mapping/unmapping

v7 -> v8:
- new percpu pointer type
- exit from the irq domain hierarchy parsing on first map/unmap success
- reset desc->irq to 0 on mapping failure

v7: creation
---
kernel/irq/msi.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 100 insertions(+), 8 deletions(-)

diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 72bf4d6..d654524 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -14,6 +14,8 @@
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/msi.h>
+#include <linux/msi-iommu.h>
+#include <linux/iommu.h>

/* Temparory solution for building, will be removed later */
#include <linux/pci.h>
@@ -322,6 +324,74 @@ int msi_domain_populate_irqs(struct irq_domain *domain, struct device *dev,
}

/**
+ * msi_handle_doorbell_mappings: in case the irq data corresponds to an
+ * MSI that requires iommu mapping, traverse the irq domain hierarchy
+ * to retrieve the doorbells to handle and iommu_map/unmap them according
+ * to @map boolean.
+ *
+ * @data: irq data handle
+ * @map: mapping if true, unmapping if false
+ */
+static int msi_handle_doorbell_mappings(struct irq_data *data, bool map)
+{
+ const struct irq_chip_msi_doorbell_info *dbinfo;
+ struct iommu_domain *domain;
+ struct irq_chip *chip;
+ struct device *dev;
+ dma_addr_t iova;
+ int ret = 0, cpu;
+
+ while (data) {
+ dev = msi_desc_to_dev(irq_data_get_msi_desc(data));
+ domain = iommu_msi_domain(dev);
+ if (domain) {
+ chip = irq_data_get_irq_chip(data);
+ if (chip->msi_doorbell_info)
+ break;
+ }
+ data = data->parent_data;
+ }
+
+ if (!data)
+ return 0;
+
+ dbinfo = chip->msi_doorbell_info(data);
+ if (!dbinfo)
+ return -EINVAL;
+
+ if (!dbinfo->doorbell_is_percpu) {
+ if (!map) {
+ iommu_msi_put_doorbell_iova(domain,
+ dbinfo->global_doorbell);
+ return 0;
+ }
+ return iommu_msi_get_doorbell_iova(domain,
+ dbinfo->global_doorbell,
+ dbinfo->size, dbinfo->prot,
+ &iova);
+ }
+
+ /* percpu doorbells */
+ for_each_possible_cpu(cpu) {
+ phys_addr_t __percpu *db_addr =
+ per_cpu_ptr(dbinfo->percpu_doorbells, cpu);
+
+ if (!map) {
+ iommu_msi_put_doorbell_iova(domain, *db_addr);
+ } else {
+
+ ret = iommu_msi_get_doorbell_iova(domain, *db_addr,
+ dbinfo->size,
+ dbinfo->prot, &iova);
+ if (ret)
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+/**
* msi_domain_alloc_irqs - Allocate interrupts from a MSI interrupt domain
* @domain: The domain to allocate from
* @dev: Pointer to device struct of the device for which the interrupts
@@ -352,17 +422,29 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,

virq = __irq_domain_alloc_irqs(domain, virq, desc->nvec_used,
dev_to_node(dev), &arg, false);
- if (virq < 0) {
- ret = -ENOSPC;
- if (ops->handle_error)
- ret = ops->handle_error(domain, desc, ret);
- if (ops->msi_finish)
- ops->msi_finish(&arg, ret);
- return ret;
- }
+ if (virq < 0)
+ goto error;

for (i = 0; i < desc->nvec_used; i++)
irq_set_msi_desc_off(virq, i, desc);
+
+ for (i = 0; i < desc->nvec_used; i++) {
+ struct irq_data *d = irq_get_irq_data(virq + i);
+
+ ret = msi_handle_doorbell_mappings(d, true);
+ if (ret)
+ break;
+ }
+ if (ret) {
+ for (; i >= 0; i--) {
+ struct irq_data *d = irq_get_irq_data(virq + i);
+
+ msi_handle_doorbell_mappings(d, false);
+ }
+ irq_domain_free_irqs(virq, desc->nvec_used);
+ desc->irq = 0;
+ goto error;
+ }
}

if (ops->msi_finish)
@@ -377,6 +459,13 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
}

return 0;
+error:
+ ret = -ENOSPC;
+ if (ops->handle_error)
+ ret = ops->handle_error(domain, desc, ret);
+ if (ops->msi_finish)
+ ops->msi_finish(&arg, ret);
+ return ret;
}

/**
@@ -396,6 +485,9 @@ void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev)
* entry. If that's the case, don't do anything.
*/
if (desc->irq) {
+ msi_handle_doorbell_mappings(
+ irq_get_irq_data(desc->irq),
+ false);
irq_domain_free_irqs(desc->irq, desc->nvec_used);
desc->irq = 0;
}
--
1.9.1
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