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Subject[PATCH 4.9 38/44] irqchip/gic-v3-its: Align PCI Multi-MSI allocation on their size
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@arm.com>

commit 8208d1708b88b412ca97f50a6d951242c88cbbac upstream.

The way we allocate events works fine in most cases, except
when multiple PCI devices share an ITS-visible DevID, and that
one of them is trying to use MultiMSI allocation.

In that case, our allocation is not guaranteed to be zero-based
anymore, and we have to make sure we allocate it on a boundary
that is compatible with the PCI Multi-MSI constraints.

Fix this by allocating the full region upfront instead of iterating
over the number of MSIs. MSI-X are always allocated one by one,
so this shouldn't change anything on that front.

Fixes: b48ac83d6bbc2 ("irqchip: GICv3: ITS: MSI support")
Cc: stable@vger.kernel.org
Reported-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
[ardb: rebased onto v4.9.153, should apply cleanly onto v4.4.y as well]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
drivers/irqchip/irq-gic-v3-its.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)

--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1372,13 +1372,14 @@ static void its_free_device(struct its_d
kfree(its_dev);
}

-static int its_alloc_device_irq(struct its_device *dev, irq_hw_number_t *hwirq)
+static int its_alloc_device_irq(struct its_device *dev, int nvecs, irq_hw_number_t *hwirq)
{
int idx;

- idx = find_first_zero_bit(dev->event_map.lpi_map,
- dev->event_map.nr_lpis);
- if (idx == dev->event_map.nr_lpis)
+ idx = bitmap_find_free_region(dev->event_map.lpi_map,
+ dev->event_map.nr_lpis,
+ get_count_order(nvecs));
+ if (idx < 0)
return -ENOSPC;

*hwirq = dev->event_map.lpi_base + idx;
@@ -1464,20 +1465,20 @@ static int its_irq_domain_alloc(struct i
int err;
int i;

- for (i = 0; i < nr_irqs; i++) {
- err = its_alloc_device_irq(its_dev, &hwirq);
- if (err)
- return err;
+ err = its_alloc_device_irq(its_dev, nr_irqs, &hwirq);
+ if (err)
+ return err;

- err = its_irq_gic_domain_alloc(domain, virq + i, hwirq);
+ for (i = 0; i < nr_irqs; i++) {
+ err = its_irq_gic_domain_alloc(domain, virq + i, hwirq + i);
if (err)
return err;

irq_domain_set_hwirq_and_chip(domain, virq + i,
- hwirq, &its_irq_chip, its_dev);
+ hwirq + i, &its_irq_chip, its_dev);
pr_debug("ID:%d pID:%d vID:%d\n",
- (int)(hwirq - its_dev->event_map.lpi_base),
- (int) hwirq, virq + i);
+ (int)(hwirq + i - its_dev->event_map.lpi_base),
+ (int)(hwirq + i), virq + i);
}

return 0;

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