Re: [PATCH] irqchip/gic-v3-its: Add early memory allocation errata

[Matthias Brugger]

Friendly reminder, if anyone has any comment on the patch :)

On 9/12/18 11:52 AM, matthias.bgg@xxxxxxxxxx wrote:
> From: Matthias Brugger <mbrugger@xxxxxxxx>
> 
> 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@xxxxxxxx>
> ---
>  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;
>

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