Re: [PATCH v4 04/11] xen/arm: introduce new helper parse_static_mem_prop and acquire_static_memory_bank

[Stefano Stabellini <sstabellini@kernel.org>]

On Mon, 20 Dec 2021, Penny Zheng wrote:
> Later, we will introduce allocate_static_memory_11 for allocating static
> memory for direct-map domains, and it will share a lot common codes with
> the existing allocate_static_memory.
> 
> In order not to bring a lot of duplicate codes, and also to make the whole
> code more readable, this commit extracts common codes into two new helpers
> parse_static_mem_prop and acquire_static_memory_bank.
> 
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> ---
> v3 changes:
> - new commit to move the split off of the code outside in a separate patch
> ---
> v4 changes:
> - use mfn_eq() instead, because it is the only value used to indicate
> there is an error and this is more lightweight than mfn_valid()
> ---
>  xen/arch/arm/domain_build.c | 100 +++++++++++++++++++++++-------------
>  1 file changed, 64 insertions(+), 36 deletions(-)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 5a106a977c..9206ec908d 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -509,12 +509,69 @@ static bool __init append_static_memory_to_bank(struct domain *d,
>      return true;
>  }
>  
> +static mfn_t __init acquire_static_memory_bank(struct domain *d,
> +                                             const __be32 **cell,
> +                                             u32 addr_cells, u32 size_cells,
> +                                             paddr_t *pbase, paddr_t *psize)

NIT: we usually align the parameters:

static mfn_t __init acquire_static_memory_bank(struct domain *d,
                                               const __be32 **cell,
                                               u32 addr_cells, u32 size_cells,
                                               paddr_t *pbase, paddr_t *psize)

with that addressed:

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>


> +{
> +    mfn_t smfn;
> +    int res;
> +
> +    device_tree_get_reg(cell, addr_cells, size_cells, pbase, psize);
> +    ASSERT(IS_ALIGNED(*pbase, PAGE_SIZE) && IS_ALIGNED(*psize, PAGE_SIZE));
> +    if ( PFN_DOWN(*psize) > UINT_MAX )
> +    {
> +        printk(XENLOG_ERR "%pd: static memory size too large: %#"PRIpaddr,
> +               d, *psize);
> +        return INVALID_MFN;
> +    }
> +
> +    smfn = maddr_to_mfn(*pbase);
> +    res = acquire_domstatic_pages(d, smfn, PFN_DOWN(*psize), 0);
> +    if ( res )
> +    {
> +        printk(XENLOG_ERR
> +               "%pd: failed to acquire static memory: %d.\n", d, res);
> +        return INVALID_MFN;
> +    }
> +
> +    return smfn;
> +}
> +
> +static int __init parse_static_mem_prop(const struct dt_device_node *node,
> +                                        u32 *addr_cells, u32 *size_cells,
> +                                        int *length, const __be32 **cell)
> +{
> +    const struct dt_property *prop;
> +
> +    prop = dt_find_property(node, "xen,static-mem", NULL);
> +    if ( !dt_property_read_u32(node, "#xen,static-mem-address-cells",
> +                               addr_cells) )
> +    {
> +        printk(XENLOG_ERR
> +               "failed to read \"#xen,static-mem-address-cells\".\n");
> +        return -EINVAL;
> +    }
> +
> +    if ( !dt_property_read_u32(node, "#xen,static-mem-size-cells",
> +                               size_cells) )
> +    {
> +        printk(XENLOG_ERR
> +               "failed to read \"#xen,static-mem-size-cells\".\n");
> +        return -EINVAL;
> +    }
> +
> +    *cell = (const __be32 *)prop->value;
> +    *length = prop->length;
> +
> +    return 0;
> +}
> +
>  /* Allocate memory from static memory as RAM for one specific domain d. */
>  static void __init allocate_static_memory(struct domain *d,
>                                            struct kernel_info *kinfo,
>                                            const struct dt_device_node *node)
>  {
> -    const struct dt_property *prop;
>      u32 addr_cells, size_cells, reg_cells;
>      unsigned int nr_banks, gbank, bank = 0;
>      const uint64_t rambase[] = GUEST_RAM_BANK_BASES;
> @@ -523,24 +580,10 @@ static void __init allocate_static_memory(struct domain *d,
>      u64 tot_size = 0;
>      paddr_t pbase, psize, gsize;
>      mfn_t smfn;
> -    int res;
> -
> -    prop = dt_find_property(node, "xen,static-mem", NULL);
> -    if ( !dt_property_read_u32(node, "#xen,static-mem-address-cells",
> -                               &addr_cells) )
> -    {
> -        printk(XENLOG_ERR
> -               "%pd: failed to read \"#xen,static-mem-address-cells\".\n", d);
> -        goto fail;
> -    }
> +    int length;
>  
> -    if ( !dt_property_read_u32(node, "#xen,static-mem-size-cells",
> -                               &size_cells) )
> -    {
> -        printk(XENLOG_ERR
> -               "%pd: failed to read \"#xen,static-mem-size-cells\".\n", d);
> +    if ( parse_static_mem_prop(node, &addr_cells, &size_cells, &length, &cell) )
>          goto fail;
> -    }
>      reg_cells = addr_cells + size_cells;
>  
>      /*
> @@ -551,29 +594,14 @@ static void __init allocate_static_memory(struct domain *d,
>      gbank = 0;
>      gsize = ramsize[gbank];
>      kinfo->mem.bank[gbank].start = rambase[gbank];
> -
> -    cell = (const __be32 *)prop->value;
> -    nr_banks = (prop->length) / (reg_cells * sizeof (u32));
> +    nr_banks = length / (reg_cells * sizeof (u32));
>  
>      for ( ; bank < nr_banks; bank++ )
>      {
> -        device_tree_get_reg(&cell, addr_cells, size_cells, &pbase, &psize);
> -        ASSERT(IS_ALIGNED(pbase, PAGE_SIZE) && IS_ALIGNED(psize, PAGE_SIZE));
> -
> -        if ( PFN_DOWN(psize) > UINT_MAX )
> -        {
> -            printk(XENLOG_ERR "%pd: static memory size too large: %#"PRIpaddr,
> -                   d, psize);
> +        smfn = acquire_static_memory_bank(d, &cell, addr_cells, size_cells,
> +                                          &pbase, &psize);
> +        if ( mfn_eq(smfn, INVALID_MFN) )
>              goto fail;
> -        }
> -        smfn = maddr_to_mfn(pbase);
> -        res = acquire_domstatic_pages(d, smfn, PFN_DOWN(psize), 0);
> -        if ( res )
> -        {
> -            printk(XENLOG_ERR
> -                   "%pd: failed to acquire static memory: %d.\n", d, res);
> -            goto fail;
> -        }
>  
>          printk(XENLOG_INFO "%pd: STATIC BANK[%u] %#"PRIpaddr"-%#"PRIpaddr"\n",
>                 d, bank, pbase, pbase + psize);
> -- 
> 2.25.1
>