The ITS table allocator is only allocating a single page per table. This works fine for most things, but leads to silent lack of interrupt delivery if we end-up with a device that has an ID that is out of the range defined by a single page of memory. Even worse, depending on the page size, behaviour changes, which is not a very good experience.
A solution is actually to allocate memory for the full range of ID that the ITS supports. A massive waste memory wise, but at least a safe bet. This patch has been tested on the Phytium SoC. Signed-off-by: Marc Zyngier <[email protected]> Signed-off-by: Chen Baozi <[email protected]> --- drivers/irqchip/irq-gic-v3-its.c | 25 +++++++++++++++++++++---- include/linux/irqchip/arm-gic-v3.h | 2 ++ 2 files changed, 23 insertions(+), 4 deletions(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 86e4684..d7a3d36 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -806,14 +806,31 @@ static int its_alloc_tables(struct its_node *its) u64 val = readq_relaxed(its->base + GITS_BASER + i * 8); u64 type = GITS_BASER_TYPE(val); u64 entry_size = GITS_BASER_ENTRY_SIZE(val); + int order = 0; + int alloc_size; u64 tmp; void *base; if (type == GITS_BASER_TYPE_NONE) continue; - /* We're lazy and only allocate a single page for now */ - base = (void *)get_zeroed_page(GFP_KERNEL); + /* + * Allocate as many entries as required to fit the + * range of device IDs that the ITS can grok... The ID + * space being incredibly sparse, this results in a + * massive waste of memory. + * + * For other tables, only allocate a single page. + */ + if (type == GITS_BASER_TYPE_DEVICE) { + u64 typer = readq_relaxed(its->base + GITS_TYPER); + u32 ids = GITS_TYPER_DEVBITS(typer); + + order = get_order((1UL << ids) * entry_size); + } + + alloc_size = (1 << order) * PAGE_SIZE; + base = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order); if (!base) { err = -ENOMEM; goto out_free; @@ -841,7 +858,7 @@ retry_baser: break; } - val |= (PAGE_SIZE / psz) - 1; + val |= (alloc_size / psz) - 1; writeq_relaxed(val, its->base + GITS_BASER + i * 8); tmp = readq_relaxed(its->base + GITS_BASER + i * 8); @@ -882,7 +899,7 @@ retry_baser: } pr_info("ITS: allocated %d %s @%lx (psz %dK, shr %d)\n", - (int)(PAGE_SIZE / entry_size), + (int)(alloc_size / entry_size), its_base_type_string[type], (unsigned long)virt_to_phys(base), psz / SZ_1K, (int)shr >> GITS_BASER_SHAREABILITY_SHIFT); diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h index 1e8b0cf..7cf8d40 100644 --- a/include/linux/irqchip/arm-gic-v3.h +++ b/include/linux/irqchip/arm-gic-v3.h @@ -132,6 +132,8 @@ #define GITS_BASER 0x0100 #define GITS_PIDR2 GICR_PIDR2 +#define GITS_TYPER_DEVBITS_SHIFT 13 +#define GITS_TYPER_DEVBITS(r) ((((r) >> GITS_TYPER_DEVBITS_SHIFT) & 0x1f) + 1) #define GITS_TRANSLATER 0x10040 #define GITS_TYPER_PTA (1UL << 19) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
