irqchip/gic-v3-its: Don't map the MSI page in its_irq_compose_msi_msg()

its_irq_compose_msi_msg() may be called from non-preemptible context.
However, on RT, iommu_dma_map_msi_msg requires to be called from a
preemptible context.

A recent change split iommu_dma_map_msi_msg() in two new functions:
one that should be called in preemptible context, the other does
not have any requirement.

The GICv3 ITS driver is reworked to avoid executing preemptible code in
non-preemptible context. This can be achieved by preparing the MSI
mapping when allocating the MSI interrupt.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 75d396b9b666..1e364d3ad9c5 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1178,7 +1178,7 @@ static void its_irq_compose_msi_msg(struct irq_data *d, struct msi_msg *msg)
         msg->address_hi         = upper_32_bits(addr);
         msg->data               = its_get_event_id(d);
 
-        iommu_dma_map_msi_msg(d->irq, msg);
+        iommu_dma_compose_msi_msg(irq_data_get_msi_desc(d), msg);
 }
 
 static int its_irq_set_irqchip_state(struct irq_data *d,
@@ -2563,6 +2563,7 @@ static int its_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 {
         msi_alloc_info_t *info = args;
         struct its_device *its_dev = info->scratchpad[0].ptr;
+        struct its_node *its = its_dev->its;
         irq_hw_number_t hwirq;
         int err;
         int i;
@@ -2571,6 +2572,10 @@ static int its_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
         if (err)
                 return err;
 
+        err = iommu_dma_prepare_msi(info->desc, its->get_msi_base(its_dev));
+        if (err)
+                return err;
+
         for (i = 0; i < nr_irqs; i++) {
                 err = its_irq_gic_domain_alloc(domain, virq + i, hwirq + i);
                 if (err)