Re: [PATCH v03 1/5] powerpc/drmem: Export 'dynamic-memory' loader

[Tyrel Datwyler <tyreld@linux.vnet.ibm.com>]

On 10/01/2018 05:59 AM, Michael Bringmann wrote:
> powerpc/drmem: Export many of the functions of DRMEM to parse
> "ibm,dynamic-memory" and "ibm,dynamic-memory-v2" during hotplug
> operations and for Post Migration events.
> 
> Also modify the DRMEM initialization code to allow it to,
> 
> * Be called after system initialization
> * Provide a separate user copy of the LMB array that is produces
> * Free the user copy upon request
> 
> In addition, a couple of changes were made to make the creation
> of additional copies of the LMB array more useful including,
> 
> * Add new iterator to work through a pair of drmem_info arrays.
> * Modify DRMEM code to replace usages of dt_root_addr_cells, and
>   dt_mem_next_cell, as these are only available at first boot.
> 
> Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/drmem.h |   15 ++++++++
>  arch/powerpc/mm/drmem.c          |   75 ++++++++++++++++++++++++++++----------
>  2 files changed, 70 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/drmem.h b/arch/powerpc/include/asm/drmem.h
> index ce242b9..b0e70fd 100644
> --- a/arch/powerpc/include/asm/drmem.h
> +++ b/arch/powerpc/include/asm/drmem.h
> @@ -35,6 +35,18 @@ struct drmem_lmb_info {
>  		&drmem_info->lmbs[0],				\
>  		&drmem_info->lmbs[drmem_info->n_lmbs - 1])
> 
> +#define for_each_dinfo_lmb(dinfo, lmb)				\
> +	for_each_drmem_lmb_in_range((lmb),			\
> +		&dinfo->lmbs[0],				\
> +		&dinfo->lmbs[dinfo->n_lmbs - 1])
> +
> +#define for_each_pair_dinfo_lmb(dinfo1, lmb1, dinfo2, lmb2)	\
> +	for ((lmb1) = (&dinfo1->lmbs[0]),			\
> +	     (lmb2) = (&dinfo2->lmbs[0]);			\
> +	     ((lmb1) <= (&dinfo1->lmbs[dinfo1->n_lmbs - 1])) &&	\
> +	     ((lmb2) <= (&dinfo2->lmbs[dinfo2->n_lmbs - 1]));	\
> +	     (lmb1)++, (lmb2)++)
> +
>  /*
>   * The of_drconf_cell_v1 struct defines the layout of the LMB data
>   * specified in the ibm,dynamic-memory device tree property.
> @@ -94,6 +106,9 @@ void __init walk_drmem_lmbs(struct device_node *dn,
>  			void (*func)(struct drmem_lmb *, const __be32 **));
>  int drmem_update_dt(void);
> 
> +struct drmem_lmb_info *drmem_lmbs_init(struct property *prop);
> +void drmem_lmbs_free(struct drmem_lmb_info *dinfo);
> +
>  #ifdef CONFIG_PPC_PSERIES
>  void __init walk_drmem_lmbs_early(unsigned long node,
>  			void (*func)(struct drmem_lmb *, const __be32 **));
> diff --git a/arch/powerpc/mm/drmem.c b/arch/powerpc/mm/drmem.c
> index 3f18036..13d2abb 100644
> --- a/arch/powerpc/mm/drmem.c
> +++ b/arch/powerpc/mm/drmem.c
> @@ -20,6 +20,7 @@
> 
>  static struct drmem_lmb_info __drmem_info;
>  struct drmem_lmb_info *drmem_info = &__drmem_info;
> +static int n_root_addr_cells;

What is the point of this new global? I see two places were it gets initialized if it is null, and both those initializers simply set it to "dt_root_addr_cells". I also checked the rest of the patches in the series and none of those even reference this variable.

> 
>  u64 drmem_lmb_memory_max(void)
>  {
> @@ -193,12 +194,13 @@ int drmem_update_dt(void)
>  	return rc;
>  }
> 
> -static void __init read_drconf_v1_cell(struct drmem_lmb *lmb,
> +static void read_drconf_v1_cell(struct drmem_lmb *lmb,
>  				       const __be32 **prop)
>  {
>  	const __be32 *p = *prop;
> 
> -	lmb->base_addr = dt_mem_next_cell(dt_root_addr_cells, &p);
> +	lmb->base_addr = of_read_number(p, n_root_addr_cells);
> +	p += n_root_addr_cells;

Unnecessary code churn do to the introduction of "n_root_addr_cells".

>  	lmb->drc_index = of_read_number(p++, 1);
> 
>  	p++; /* skip reserved field */
> @@ -209,7 +211,7 @@ static void __init read_drconf_v1_cell(struct drmem_lmb *lmb,
>  	*prop = p;
>  }
> 
> -static void __init __walk_drmem_v1_lmbs(const __be32 *prop, const __be32 *usm,
> +static void __walk_drmem_v1_lmbs(const __be32 *prop, const __be32 *usm,
>  			void (*func)(struct drmem_lmb *, const __be32 **))
>  {
>  	struct drmem_lmb lmb;
> @@ -225,13 +227,14 @@ static void __init __walk_drmem_v1_lmbs(const __be32 *prop, const __be32 *usm,
>  	}
>  }
> 
> -static void __init read_drconf_v2_cell(struct of_drconf_cell_v2 *dr_cell,
> +static void read_drconf_v2_cell(struct of_drconf_cell_v2 *dr_cell,
>  				       const __be32 **prop)
>  {
>  	const __be32 *p = *prop;
> 
>  	dr_cell->seq_lmbs = of_read_number(p++, 1);
> -	dr_cell->base_addr = dt_mem_next_cell(dt_root_addr_cells, &p);
> +	dr_cell->base_addr = of_read_number(p, n_root_addr_cells);
> +	p += n_root_addr_cells;

Same comment as above.

>  	dr_cell->drc_index = of_read_number(p++, 1);
>  	dr_cell->aa_index = of_read_number(p++, 1);
>  	dr_cell->flags = of_read_number(p++, 1);
> @@ -239,7 +242,7 @@ static void __init read_drconf_v2_cell(struct of_drconf_cell_v2 *dr_cell,
>  	*prop = p;
>  }
> 
> -static void __init __walk_drmem_v2_lmbs(const __be32 *prop, const __be32 *usm,
> +static void __walk_drmem_v2_lmbs(const __be32 *prop, const __be32 *usm,
>  			void (*func)(struct drmem_lmb *, const __be32 **))
>  {
>  	struct of_drconf_cell_v2 dr_cell;
> @@ -275,6 +278,9 @@ void __init walk_drmem_lmbs_early(unsigned long node,
>  	const __be32 *prop, *usm;
>  	int len;
> 
> +	if (n_root_addr_cells == 0)
> +		n_root_addr_cells = dt_root_addr_cells;
> +

As I mentioned initially whats the point? Why not just use "dt_root_addr_cells"?

>  	prop = of_get_flat_dt_prop(node, "ibm,lmb-size", &len);
>  	if (!prop || len < dt_root_size_cells * sizeof(__be32))
>  		return;
> @@ -353,24 +359,26 @@ void __init walk_drmem_lmbs(struct device_node *dn,
>  	}
>  }
> 
> -static void __init init_drmem_v1_lmbs(const __be32 *prop)
> +static void init_drmem_v1_lmbs(const __be32 *prop,
> +				struct drmem_lmb_info *dinfo)
>  {
>  	struct drmem_lmb *lmb;
> 
> -	drmem_info->n_lmbs = of_read_number(prop++, 1);
> -	if (drmem_info->n_lmbs == 0)
> +	dinfo->n_lmbs = of_read_number(prop++, 1);
> +	if (dinfo->n_lmbs == 0)
>  		return;
> 
> -	drmem_info->lmbs = kcalloc(drmem_info->n_lmbs, sizeof(*lmb),
> +	dinfo->lmbs = kcalloc(dinfo->n_lmbs, sizeof(*lmb),
>  				   GFP_KERNEL);
> -	if (!drmem_info->lmbs)
> +	if (!dinfo->lmbs)
>  		return;
> 
> -	for_each_drmem_lmb(lmb)
> +	for_each_dinfo_lmb(dinfo, lmb)
>  		read_drconf_v1_cell(lmb, &prop);
>  }
> 
> -static void __init init_drmem_v2_lmbs(const __be32 *prop)
> +static void init_drmem_v2_lmbs(const __be32 *prop,
> +				struct drmem_lmb_info *dinfo)
>  {
>  	struct drmem_lmb *lmb;
>  	struct of_drconf_cell_v2 dr_cell;
> @@ -386,12 +394,12 @@ static void __init init_drmem_v2_lmbs(const __be32 *prop)
>  	p = prop;
>  	for (i = 0; i < lmb_sets; i++) {
>  		read_drconf_v2_cell(&dr_cell, &p);
> -		drmem_info->n_lmbs += dr_cell.seq_lmbs;
> +		dinfo->n_lmbs += dr_cell.seq_lmbs;
>  	}
> 
> -	drmem_info->lmbs = kcalloc(drmem_info->n_lmbs, sizeof(*lmb),
> +	dinfo->lmbs = kcalloc(dinfo->n_lmbs, sizeof(*lmb),
>  				   GFP_KERNEL);
> -	if (!drmem_info->lmbs)
> +	if (!dinfo->lmbs)
>  		return;
> 
>  	/* second pass, read in the LMB information */
> @@ -402,10 +410,10 @@ static void __init init_drmem_v2_lmbs(const __be32 *prop)
>  		read_drconf_v2_cell(&dr_cell, &p);
> 
>  		for (j = 0; j < dr_cell.seq_lmbs; j++) {
> -			lmb = &drmem_info->lmbs[lmb_index++];
> +			lmb = &dinfo->lmbs[lmb_index++];
> 
>  			lmb->base_addr = dr_cell.base_addr;
> -			dr_cell.base_addr += drmem_info->lmb_size;
> +			dr_cell.base_addr += dinfo->lmb_size;
> 
>  			lmb->drc_index = dr_cell.drc_index;
>  			dr_cell.drc_index++;
> @@ -416,11 +424,38 @@ static void __init init_drmem_v2_lmbs(const __be32 *prop)
>  	}
>  }
> 
> +void drmem_lmbs_free(struct drmem_lmb_info *dinfo)
> +{
> +	if (dinfo) {
> +		kfree(dinfo->lmbs);
> +		kfree(dinfo);
> +	}
> +}
> +
> +struct drmem_lmb_info *drmem_lmbs_init(struct property *prop)
> +{
> +	struct drmem_lmb_info *dinfo;
> +
> +	dinfo = kzalloc(sizeof(*dinfo), GFP_KERNEL);
> +	if (!dinfo)
> +		return NULL;
> +
> +	if (!strcmp("ibm,dynamic-memory", prop->name))
> +		init_drmem_v1_lmbs(prop->value, dinfo);
> +	else if (!strcmp("ibm,dynamic-memory-v2", prop->name))
> +		init_drmem_v2_lmbs(prop->value, dinfo);
> +
> +	return dinfo;
> +}
> +
>  static int __init drmem_init(void)
>  {
>  	struct device_node *dn;
>  	const __be32 *prop;
> 
> +	if (n_root_addr_cells == 0)
> +		n_root_addr_cells = dt_root_addr_cells;
> +

See previous comment.

-Tyrel

>  	dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
>  	if (!dn) {
>  		pr_info("No dynamic reconfiguration memory found\n");
> @@ -434,11 +469,11 @@ static int __init drmem_init(void)
> 
>  	prop = of_get_property(dn, "ibm,dynamic-memory", NULL);
>  	if (prop) {
> -		init_drmem_v1_lmbs(prop);
> +		init_drmem_v1_lmbs(prop, drmem_info);
>  	} else {
>  		prop = of_get_property(dn, "ibm,dynamic-memory-v2", NULL);
>  		if (prop)
> -			init_drmem_v2_lmbs(prop);
> +			init_drmem_v2_lmbs(prop, drmem_info);
>  	}
> 
>  	of_node_put(dn);
>