Subject: Re: [PATCH 2/8] powerpc/memory: Parse new memory property to register blocks.

From: Tyrel Datwyler <[email-masked]>
Date: Mon, 25 Jul 2016 16:54:22 -0700

On 07/25/2016 03:21 PM, Michael Bringmann wrote:
> powerpc/memory: Add parallel routines to parse the new property
> "ibm,dynamic-memory-v2" property when it is present, and then to
> register the relevant memory blocks with the operating system.
> This property format is intended to provide a more compact
> representation of memory when communicating with the front end
> processor, especially when describing vast amounts of RAM.
> 
> Signed-off-by: Michael Bringmann <[email-masked]>
> ---
> diff --git a/arch/powerpc/include/asm/prom.h b/arch/powerpc/include/asm/prom.h
> index 7f436ba..b9a1534 100644
> --- a/arch/powerpc/include/asm/prom.h
> +++ b/arch/powerpc/include/asm/prom.h
> @@ -69,6 +69,8 @@ struct boot_param_header {
>   * OF address retreival & translation
>   */
>  
> +extern int n_mem_addr_cells;
> +
>  /* Parse the ibm,dma-window property of an OF node into the busno, phys and
>   * size parameters.
>   */
> @@ -81,8 +83,9 @@ extern void of_instantiate_rtc(void);
>  extern int of_get_ibm_chip_id(struct device_node *np);
>  
>  /* The of_drconf_cell struct defines the layout of the LMB array
> - * specified in the device tree property
> - * ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory
> + * specified in the device tree properties,
> + *     ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory
> + *     ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory-v2
>   */
>  struct of_drconf_cell {
>  	u64	base_addr;
> @@ -92,9 +95,39 @@ struct of_drconf_cell {
>  	u32	flags;
>  };
>  
> -#define DRCONF_MEM_ASSIGNED	0x00000008
> -#define DRCONF_MEM_AI_INVALID	0x00000040
> -#define DRCONF_MEM_RESERVED	0x00000080
> +#define DRCONF_MEM_ASSIGNED		0x00000008
> +#define DRCONF_MEM_AI_INVALID		0x00000040
> +#define DRCONF_MEM_RESERVED		0x00000080
> +
> +	/* It is important to note that this structure can not
> +	 * be safely mapped onto the memory containing the
> +	 * 'ibm,dynamic-memory-v2'.  This structure represents
> +	 * the order of the fields stored, but compiler alignment
> +	 * may insert extra bytes of padding between the fields
> +	 * 'num_seq_lmbs' and 'base_addr'.
> +	 */

The "packed" attribute should prevent the struct from being padded.

struct of_drconf_cell_v2 {
...
} __attribute__((packed));

or, simply

struct of_drconf_cell_v2 {
...
} __packed;

-Tyrel

> +struct of_drconf_cell_v2 {
> +	u32	num_seq_lmbs;
> +	u64	base_addr;
> +	u32	drc_index;
> +	u32	aa_index;
> +	u32	flags;
> +};
> +
> +
> +static inline int dyn_mem_v2_len(int entries)
> +{
> +	int drconf_v2_cells = (n_mem_addr_cells + 4);
> +	int drconf_v2_cells_len = (drconf_v2_cells * sizeof(unsigned int));
> +	return (((entries) * drconf_v2_cells_len) +
> +                (1 * sizeof(unsigned int)));
> +}
> +
> +extern void read_drconf_cell_v2(struct of_drconf_cell_v2 *drmem,
> +				const __be32 **cellp);
> +extern void read_one_drc_info(int **info, char **drc_type, char **drc_name,
> +			unsigned long int *fdi_p, unsigned long int *nsl_p,
> +			unsigned long int *si_p, unsigned long int *ldi_p);
>  
>  /*
>   * There are two methods for telling firmware what our capabilities are.
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 669a15e..ad294ce 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -405,6 +405,24 @@ static void read_drconf_cell(struct of_drconf_cell *drmem, const __be32 **cellp)
>  
>  	*cellp = cp + 4;
>  }
> + 
> + /*
> + * Retrieve and validate the ibm,dynamic-memory property of the device tree.
> + * Read the next memory block set entry from the ibm,dynamic-memory-v2 property
> + * and return the information in the provided of_drconf_cell_v2 structure.
> + */
> +void read_drconf_cell_v2(struct of_drconf_cell_v2 *drmem, const __be32 **cellp)
> +{
> +	const __be32 *cp = (const __be32 *)*cellp;
> +	drmem->num_seq_lmbs = be32_to_cpu(*cp++);
> +	drmem->base_addr = read_n_cells(n_mem_addr_cells, &cp);
> +	drmem->drc_index = be32_to_cpu(*cp++);
> +	drmem->aa_index = be32_to_cpu(*cp++);
> +	drmem->flags = be32_to_cpu(*cp++);
> +
> +	*cellp = cp;
> +}
> +EXPORT_SYMBOL(read_drconf_cell_v2);
>  
>  /*
>   * Retrieve and validate the ibm,dynamic-memory property of the device tree.
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index 946e34f..a55bc1e 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -56,6 +56,7 @@
>  #include <asm/opal.h>
>  #include <asm/fadump.h>
>  #include <asm/debug.h>
> +#include <asm/firmware.h>
>  
>  #include <mm/mmu_decl.h>
>  
> @@ -441,12 +442,12 @@ static int __init early_init_dt_scan_chosen_ppc(unsigned long node,
>  
>  #ifdef CONFIG_PPC_PSERIES
>  /*
> - * Interpret the ibm,dynamic-memory property in the
> - * /ibm,dynamic-reconfiguration-memory node.
> + * Interpret the ibm,dynamic-memory property/ibm,dynamic-memory-v2
> + * in the /ibm,dynamic-reconfiguration-memory node.
>   * This contains a list of memory blocks along with NUMA affinity
>   * information.
>   */
> -static int __init early_init_dt_scan_drconf_memory(unsigned long node)
> +static int __init early_init_dt_scan_drconf_memory_v1(unsigned long node)
>  {
>  	const __be32 *dm, *ls, *usm;
>  	int l;
> @@ -516,6 +517,105 @@ static int __init early_init_dt_scan_drconf_memory(unsigned long node)
>  	memblock_dump_all();
>  	return 0;
>  }
> +
> +static int __init early_init_dt_scan_drconf_memory_v2(unsigned long node)
> +{
> +	const __be32 *dm, *ls, *usm;
> +	int l;
> +	unsigned long num_sets;
> +	u64 size, base, memblock_size;
> +	unsigned int is_kexec_kdump = 0, rngs;
> +
> +	ls = of_get_flat_dt_prop(node, "ibm,lmb-size", &l);
> +	if (ls == NULL || l < dt_root_size_cells * sizeof(__be32))
> +		return 0;
> +	memblock_size = dt_mem_next_cell(dt_root_size_cells, &ls);
> +
> +	dm = of_get_flat_dt_prop(node, "ibm,dynamic-memory-v2", &l);
> +	if (dm == NULL || l < sizeof(__be32))
> +		return 0;
> +
> +	num_sets = of_read_number(dm++, 1);
> +	if (l < (num_sets * (dt_root_addr_cells + 4) + 1) * sizeof(__be32))
> +		return 0;
> +
> +	/* check if this is a kexec/kdump kernel. */
> +	usm = of_get_flat_dt_prop(node, "linux,drconf-usable-memory", &l);
> +	if (usm != NULL)
> +		is_kexec_kdump = 1;
> +
> +	if (n_mem_addr_cells == 0)
> +		n_mem_addr_cells = dt_root_addr_cells;
> +
> +	for (; num_sets != 0; --num_sets) {
> +		struct of_drconf_cell_v2 drmem;
> +		unsigned long nsl;
> +
> +		read_drconf_cell_v2(&drmem, &dm);
> +		base = drmem.base_addr;
> +		nsl = drmem.num_seq_lmbs;
> +		size = memblock_size;
> +
> +		/* SKip this block if the reserved bit is set in flags
> +		 * or if the block is not assigned to this partition
> +		 */
> +		if ((drmem.flags & DRCONF_MEM_RESERVED) ||
> +		    !(drmem.flags & DRCONF_MEM_ASSIGNED))
> +			continue;
> +
> +		for (; nsl != 0; nsl--) {
> +			size = memblock_size;
> +			rngs = 1;
> +			if (is_kexec_kdump)
> +				/*
> +				 * For each memblock in ibm,dynamic-memory,
> +				 * a corresponding entry in
> +				 * linux,drconf-usable-memory property
> +				 * contains a counter 'p' followed by 'p'
> +				 * (base, size) duple.  Now read the counter
> +				 * from linux,drconf-usable-memory property
> +				 */
> +				rngs = dt_mem_next_cell(dt_root_size_cells,
> +							&usm);
> +
> +			if (rngs) {
> +				do {
> +					if (is_kexec_kdump) {
> +						base = dt_mem_next_cell(
> +							dt_root_addr_cells,
> +							&usm);
> +						size = dt_mem_next_cell(
> +							dt_root_size_cells,
> +							&usm);
> +					}
> +					if (iommu_is_off) {
> +						if (base >= 0x80000000ul)
> +							continue;
> +						if ((base + size) >
> +								0x80000000ul)
> +							size = 0x80000000ul -
> +								base;
> +					}
> +					memblock_add(base, size);
> +				} while (--rngs);
> +			}
> +
> +			base += size;
> +		}
> +	}
> +
> +	memblock_dump_all();
> +	return 0;
> +}
> +
> +static int __init early_init_dt_scan_drconf_memory(unsigned long node)
> +{
> +	if (firmware_has_feature(FW_FEATURE_RPS_DM2))
> +		return early_init_dt_scan_drconf_memory_v2(node);
> +	else
> +		return early_init_dt_scan_drconf_memory_v1(node);
> +}
> +
>  #else
>  #define early_init_dt_scan_drconf_memory(node)	0
>  #endif /* CONFIG_PPC_PSERIES */
> 
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