[PATCH v3 4/7] irqchip/gic-v3-its: Don't map the MSI page in its_irq_compose_msi_msg()

Julien Grall
2019-05-01T13:59:37Z

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>

---
Changes in v3:
- Fix typo in the commit message
- Check the return of iommu_dma_prepare_msi
- Add Eric's reviewed-by

Changes in v2:
- Rework the commit message to use imperative mood
---
drivers/irqchip/irq-gic-v3-its.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 7577755bdcf4..9cddf336c09d 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1179,7 +1179,7 @@ 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,
@@ -2566,6 +2566,7 @@ 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;
@@ -2574,6 +2575,10 @@ 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)