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Message-Id: <1422327961-19733-1-git-send-email-baozich@gmail.com>
Date: Tue, 27 Jan 2015 03:06:01 +0000
From: Chen Baozi <baozich@...il.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
Chen Baozi <chenbaozi@...inos.com.cn>
Subject: [PATCH] irqchip: GICv3: ITS: Allocate enough memory for the full range of DeviceID
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 <marc.zyngier@....com>
Signed-off-by: Chen Baozi <chenbaozi@...inos.com.cn>
---
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
--
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