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Subject[PATCH] irqchip/gic-v3-its: Add early memory allocation errata
Date
From: Matthias Brugger <mbrugger@suse.com>

Some hardware does not implement two-level page tables so that
the amount of contigious memory needed by the baser is bigger
then the zone order. This is a known problem on Cavium Thunderx
with 4K page size.

We fix this by adding an errata which allocates the memory early
in the boot cycle, using the memblock allocator.

Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
arch/arm64/Kconfig | 12 ++++++++
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/kernel/cpu_errata.c | 33 +++++++++++++++++++++
drivers/irqchip/irq-gic-v3-its.c | 50 ++++++++++++++++++++------------
4 files changed, 79 insertions(+), 19 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1b1a0e95c751..dfd9fe08f0b2 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -597,6 +597,18 @@ config QCOM_FALKOR_ERRATUM_E1041

If unsure, say Y.

+config CAVIUM_ALLOC_ITS_TABLE_EARLY
+ bool "Cavium Thunderx: Allocate the its table early"
+ default y
+ depends on ARM64_4K_PAGES && FORCE_MAX_ZONEORDER < 13
+ depends on ARM_GIC_V3_ITS
+ help
+ Cavium Thunderx needs to allocate 16MB of ITS translation table.
+ This can be bigger as MAX_ZONE_ORDER and need therefore be done
+ via the memblock allocator.
+
+ If unsure, say Y.
+
endmenu


diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index ae1f70450fb2..c98be4809b7f 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -51,7 +51,8 @@
#define ARM64_SSBD 30
#define ARM64_MISMATCHED_CACHE_TYPE 31
#define ARM64_HAS_STAGE2_FWB 32
+#define ARM64_WORKAROUND_CAVIUM_ITS_TABLE 33

-#define ARM64_NCAPS 33
+#define ARM64_NCAPS 34

#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index dec10898d688..7908f8fa3ba8 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -411,6 +411,29 @@ static bool has_ssbd_mitigation(const struct arm64_cpu_capabilities *entry,
}
#endif /* CONFIG_ARM64_SSBD */

+#ifdef CONFIG_CAVIUM_ALLOC_ITS_TABLE_EARLY
+#include <linux/bootmem.h>
+extern void *its_base;
+
+/*
+ * Hardware that doesn't use two-level page table and exceedes
+ * the maximum order of pages that can be allocated by the buddy
+ * allocator. Try to use the memblock allocator instead.
+ * This has been observed on Cavium Thunderx machines with 4K
+ * page size.
+ */
+static bool __init its_early_alloc(const struct arm64_cpu_capabilities *cap,
+ int scope)
+{
+ /* We need to allocate the table only once */
+ if (scope & ARM64_CPUCAP_SCOPE_BOOT_CPU && !its_base)
+ its_base = (void *)memblock_virt_alloc_nopanic(16 * SZ_1M,
+ 64 * SZ_1K);
+
+ return true;
+}
+#endif /* CONFIG_CAVIUM_ALLOC_ITS_TABLE_EARLY */
+
#define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max) \
.matches = is_affected_midr_range, \
.midr_range = MIDR_RANGE(model, v_min, r_min, v_max, r_max)
@@ -679,6 +702,16 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
.matches = has_ssbd_mitigation,
},
+#endif
+#ifdef CONFIG_CAVIUM_ALLOC_ITS_TABLE_EARLY
+ {
+ /* Cavium ThunderX, pass 1.x - 2.1 */
+ .desc = "Cavium alloc ITS table early",
+ .capability = ARM64_WORKAROUND_CAVIUM_ITS_TABLE,
+ .type = ARM64_CPUCAP_SCOPE_BOOT_CPU,
+ .matches = its_early_alloc,
+ .midr_range = MIDR_RANGE(MIDR_THUNDERX, 0, 0, 1, 1),
+ },
#endif
{
}
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index c2df341ff6fa..b78546740a0d 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -87,6 +87,8 @@ struct its_baser {
u32 psz;
};

+void *its_base;
+
struct its_device;

/*
@@ -1666,7 +1668,7 @@ static void its_write_baser(struct its_node *its, struct its_baser *baser,
baser->val = its_read_baser(its, baser);
}

-static int its_setup_baser(struct its_node *its, struct its_baser *baser,
+static int __init its_setup_baser(struct its_node *its, struct its_baser *baser,
u64 cache, u64 shr, u32 psz, u32 order,
bool indirect)
{
@@ -1675,7 +1677,6 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
u64 type = GITS_BASER_TYPE(val);
u64 baser_phys, tmp;
u32 alloc_pages;
- void *base;

retry_alloc_baser:
alloc_pages = (PAGE_ORDER_TO_SIZE(order) / psz);
@@ -1687,11 +1688,22 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
order = get_order(GITS_BASER_PAGES_MAX * psz);
}

- base = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
- if (!base)
- return -ENOMEM;
+ if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_ITS_TABLE)) {
+ if (!its_base) {
+ pr_warn("ITS@%pa: %s Allocation using memblock failed %pS\n",
+ &its->phys_base, its_base_type_string[type],
+ its_base);
+ return -ENOMEM;
+ }
+
+ } else {
+ its_base = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+ order);
+ if (!its_base)
+ return -ENOMEM;
+ }

- baser_phys = virt_to_phys(base);
+ baser_phys = virt_to_phys(its_base);

/* Check if the physical address of the memory is above 48bits */
if (IS_ENABLED(CONFIG_ARM64_64K_PAGES) && (baser_phys >> 48)) {
@@ -1699,7 +1711,7 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
/* 52bit PA is supported only when PageSize=64K */
if (psz != SZ_64K) {
pr_err("ITS: no 52bit PA support when psz=%d\n", psz);
- free_pages((unsigned long)base, order);
+ free_pages((unsigned long)its_base, order);
return -ENXIO;
}

@@ -1744,7 +1756,7 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
shr = tmp & GITS_BASER_SHAREABILITY_MASK;
if (!shr) {
cache = GITS_BASER_nC;
- gic_flush_dcache_to_poc(base, PAGE_ORDER_TO_SIZE(order));
+ gic_flush_dcache_to_poc(its_base, PAGE_ORDER_TO_SIZE(order));
}
goto retry_baser;
}
@@ -1755,7 +1767,7 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
* size and retry. If we reach 4K, then
* something is horribly wrong...
*/
- free_pages((unsigned long)base, order);
+ free_pages((unsigned long)its_base, order);
baser->base = NULL;

switch (psz) {
@@ -1772,19 +1784,19 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
pr_err("ITS@%pa: %s doesn't stick: %llx %llx\n",
&its->phys_base, its_base_type_string[type],
val, tmp);
- free_pages((unsigned long)base, order);
+ free_pages((unsigned long)its_base, order);
return -ENXIO;
}

baser->order = order;
- baser->base = base;
+ baser->base = its_base;
baser->psz = psz;
tmp = indirect ? GITS_LVL1_ENTRY_SIZE : esz;

pr_info("ITS@%pa: allocated %d %s @%lx (%s, esz %d, psz %dK, shr %d)\n",
&its->phys_base, (int)(PAGE_ORDER_TO_SIZE(order) / (int)tmp),
its_base_type_string[type],
- (unsigned long)virt_to_phys(base),
+ (unsigned long)virt_to_phys(its_base),
indirect ? "indirect" : "flat", (int)esz,
psz / SZ_1K, (int)shr >> GITS_BASER_SHAREABILITY_SHIFT);

@@ -1832,12 +1844,14 @@ static bool its_parse_indirect_baser(struct its_node *its,
* feature is not supported by hardware.
*/
new_order = max_t(u32, get_order(esz << ids), new_order);
- if (new_order >= MAX_ORDER) {
- new_order = MAX_ORDER - 1;
- ids = ilog2(PAGE_ORDER_TO_SIZE(new_order) / (int)esz);
- pr_warn("ITS@%pa: %s Table too large, reduce ids %u->%u\n",
- &its->phys_base, its_base_type_string[type],
- its->device_ids, ids);
+ if (!cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_ITS_TABLE)) {
+ if (new_order >= MAX_ORDER) {
+ new_order = MAX_ORDER - 1;
+ ids = ilog2(PAGE_ORDER_TO_SIZE(new_order) / (int)esz);
+ pr_warn("ITS@%pa: %s Table too large, reduce ids %u->%u\n",
+ &its->phys_base, its_base_type_string[type],
+ its->device_ids, ids);
+ }
}

*order = new_order;
--
2.18.0
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