[PATCH v3 3/7] irqchip/gicv2m: Don't map the MSI page in gicv2m_compose_msi_msg()

Julien Grall
2019-05-01T13:58:20Z

gicv2m_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 GICv2m 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:
- Add Eric's reviewed-by

Changes in v2:
- Rework the commit message to use imperative mood
---
drivers/irqchip/irq-gic-v2m.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
index f5fe0100f9ff..4359f0583377 100644
--- a/drivers/irqchip/irq-gic-v2m.c
+++ b/drivers/irqchip/irq-gic-v2m.c
@@ -110,7 +110,7 @@ static void gicv2m_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
if (v2m->flags & GICV2M_NEEDS_SPI_OFFSET)
msg->data -= v2m->spi_offset;

- iommu_dma_map_msi_msg(data->irq, msg);
+ iommu_dma_compose_msi_msg(irq_data_get_msi_desc(data), msg);
}

static struct irq_chip gicv2m_irq_chip = {
@@ -167,6 +167,7 @@ static void gicv2m_unalloc_msi(struct v2m_data *v2m, unsigned int hwirq,
static int gicv2m_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
unsigned int nr_irqs, void *args)
{
+ msi_alloc_info_t *info = args;
struct v2m_data *v2m = NULL, *tmp;
int hwirq, offset, i, err = 0;

@@ -186,6 +187,11 @@ static int gicv2m_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,

hwirq = v2m->spi_start + offset;

+ err = iommu_dma_prepare_msi(info->desc,
+ v2m->res.start + V2M_MSI_SETSPI_NS);
+ if (err)
+ return err;
+
for (i = 0; i < nr_irqs; i++) {
err = gicv2m_irq_gic_domain_alloc(domain, virq + i, hwirq + i);
if (err)
--
2.11.0