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    Subject[PATCH 4/7] irqchip/gic-v3-its: Don't map the MSI page in its_irq_compose_msi_msg
    Date
    The function 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 patch split the function iommu_dma_map_msi_msg in 2 functions:
    one that should be called in preemptible context, the other does
    not have any requirement.

    This patch reworks the GICv3 ITS driver to avoid executing preemptible
    code in non-preemptible context by preparing the MSI mapping when
    allocating the MSI interrupt.

    Signed-off-by: Julien Grall <julien.grall@arm.com>
    ---
    drivers/irqchip/irq-gic-v3-its.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
    index 7577755bdcf4..1e8e01797d9b 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(d->irq, 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 +2575,8 @@ 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));
    +
    for (i = 0; i < nr_irqs; i++) {
    err = its_irq_gic_domain_alloc(domain, virq + i, hwirq + i);
    if (err)
    --
    2.11.0
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