diff options
| author | Christian Bruel <christian.bruel@foss.st.com> | 2025-09-02 11:10:45 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2025-09-04 14:52:47 +0200 |
| commit | 2ef3886ce626dcdab0cbc452dbbebc19f57133d8 (patch) | |
| tree | ae2833ef5500057f7768cb0efbe59f545a92996f | |
| parent | d36bf356068cdb5499b9bc458db9149c0fd938a2 (diff) | |
irqchip/gic-v2m: Handle Multiple MSI base IRQ Alignment
The PCI Local Bus Specification 3.0 (section 6.8.1.6) allows modifying the
low-order bits of the MSI Message DATA register to encode nr_irqs interrupt
numbers in the log2(nr_irqs) bits for the domain.
The problem arises if the base vector (GICV2m base spi) is not aligned with
nr_irqs; in this case, the low-order log2(nr_irqs) bits from the base
vector conflict with the nr_irqs masking, causing the wrong MSI interrupt
to be identified.
To fix this, use bitmap_find_next_zero_area_off() instead of
bitmap_find_free_region() to align the initial base vector with nr_irqs.
Signed-off-by: Christian Bruel <christian.bruel@foss.st.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/all/20250902091045.220847-1-christian.bruel@foss.st.com
| -rw-r--r-- | drivers/irqchip/irq-gic-v2m.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c index 24ef5af569fe..8a3410c2b7b5 100644 --- a/drivers/irqchip/irq-gic-v2m.c +++ b/drivers/irqchip/irq-gic-v2m.c @@ -153,14 +153,19 @@ static int gicv2m_irq_domain_alloc(struct irq_domain *domain, unsigned int virq, { msi_alloc_info_t *info = args; struct v2m_data *v2m = NULL, *tmp; - int hwirq, offset, i, err = 0; + int hwirq, i, err = 0; + unsigned long offset; + unsigned long align_mask = nr_irqs - 1; spin_lock(&v2m_lock); list_for_each_entry(tmp, &v2m_nodes, entry) { - offset = bitmap_find_free_region(tmp->bm, tmp->nr_spis, - get_count_order(nr_irqs)); - if (offset >= 0) { + unsigned long align_off = tmp->spi_start - (tmp->spi_start & ~align_mask); + + offset = bitmap_find_next_zero_area_off(tmp->bm, tmp->nr_spis, 0, + nr_irqs, align_mask, align_off); + if (offset < tmp->nr_spis) { v2m = tmp; + bitmap_set(v2m->bm, offset, nr_irqs); break; } } |