Re: [PATCH v6 4/7] xen/arm: static memory initialization

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 8 Sep 2021, Penny Zheng wrote:
> This patch introduces static memory initialization, during system boot-up.
> 
> The new function init_staticmem_pages is responsible for static memory
> initialization.
> 
> Helper free_staticmem_pages is the equivalent of free_heap_pages, to free
> nr_mfns pages of static memory.
> 
> This commit also introduces a new CONFIG_STATIC_MEMORY option to wrap all
> static-allocation-related code.
> 
> Put asynchronously scrubbing pages of static memory in TODO list.
> 
> Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  xen/arch/arm/setup.c    | 27 +++++++++++++++++++++++++++
>  xen/common/Kconfig      | 13 +++++++++++++
>  xen/common/page_alloc.c | 21 +++++++++++++++++++++
>  xen/include/xen/mm.h    |  6 ++++++
>  4 files changed, 67 insertions(+)
> 
> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> index 63a908e325..5be7f2b0c2 100644
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -609,6 +609,29 @@ static void __init init_pdx(void)
>      }
>  }
>  
> +/* Static memory initialization */
> +static void __init init_staticmem_pages(void)
> +{
> +#ifdef CONFIG_STATIC_MEMORY
> +    unsigned int bank;
> +
> +    for ( bank = 0 ; bank < bootinfo.reserved_mem.nr_banks; bank++ )
> +    {
> +        if ( bootinfo.reserved_mem.bank[bank].xen_domain )
> +        {
> +            mfn_t bank_start = 
> _mfn(PFN_UP(bootinfo.reserved_mem.bank[bank].start));
> +            unsigned long bank_pages = 
> PFN_DOWN(bootinfo.reserved_mem.bank[bank].size);
> +            mfn_t bank_end = mfn_add(bank_start, bank_pages);
> +
> +            if ( mfn_x(bank_end) <= mfn_x(bank_start) )
> +                return;
> +
> +            free_staticmem_pages(mfn_to_page(bank_start), bank_pages, false);
> +        }
> +    }
> +#endif
> +}
> +
>  #ifdef CONFIG_ARM_32
>  static void __init setup_mm(void)
>  {
> @@ -736,6 +759,8 @@ static void __init setup_mm(void)
>      /* Add xenheap memory that was not already added to the boot allocator. 
> */
>      init_xenheap_pages(mfn_to_maddr(xenheap_mfn_start),
>                         mfn_to_maddr(xenheap_mfn_end));
> +
> +    init_staticmem_pages();
>  }
>  #else /* CONFIG_ARM_64 */
>  static void __init setup_mm(void)
> @@ -789,6 +814,8 @@ static void __init setup_mm(void)
>  
>      setup_frametable_mappings(ram_start, ram_end);
>      max_page = PFN_DOWN(ram_end);
> +
> +    init_staticmem_pages();
>  }
>  #endif
>  
> diff --git a/xen/common/Kconfig b/xen/common/Kconfig
> index 0ddd18e11a..3558be0dbc 100644
> --- a/xen/common/Kconfig
> +++ b/xen/common/Kconfig
> @@ -67,6 +67,19 @@ config MEM_ACCESS
>  config NEEDS_LIBELF
>       bool
>  
> +config STATIC_MEMORY
> +     bool "Static Allocation Support (UNSUPPORTED)" if UNSUPPORTED
> +     depends on ARM
> +     help
> +       Static Allocation refers to system or sub-system(domains) for
> +       which memory areas are pre-defined by configuration using physical
> +       address ranges.
> +
> +       When enabled, memory can be statically allocated to a domain using
> +       the property "xen,static-mem" defined in the domain configuration.
> +
> +       If unsure, say N.
> +
>  menu "Speculative hardening"
>  
>  config SPECULATIVE_HARDEN_ARRAY
> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
> index a3ee5eca9e..ba7adc80db 100644
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -2604,6 +2604,27 @@ struct domain *get_pg_owner(domid_t domid)
>      return pg_owner;
>  }
>  
> +#ifdef CONFIG_STATIC_MEMORY
> +/* Equivalent of free_heap_pages to free nr_mfns pages of static memory. */
> +void __init free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
> +                                 bool need_scrub)
> +{
> +    mfn_t mfn = page_to_mfn(pg);
> +    unsigned long i;
> +
> +    for ( i = 0; i < nr_mfns; i++ )
> +    {
> +        mark_page_free(&pg[i], mfn_add(mfn, i));
> +
> +        if ( need_scrub )
> +        {
> +            /* TODO: asynchronous scrubbing for pages of static memory. */
> +            scrub_one_page(pg);
> +        }
> +    }
> +}
> +#endif
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
> index 667f9dac83..8e8fb5a615 100644
> --- a/xen/include/xen/mm.h
> +++ b/xen/include/xen/mm.h
> @@ -85,6 +85,12 @@ bool scrub_free_pages(void);
>  } while ( false )
>  #define FREE_XENHEAP_PAGE(p) FREE_XENHEAP_PAGES(p, 0)
>  
> +#ifdef CONFIG_STATIC_MEMORY
> +/* These functions are for static memory */
> +void free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
> +                          bool need_scrub);
> +#endif
> +
>  /* Map machine page range in Xen virtual address space. */
>  int map_pages_to_xen(
>      unsigned long virt,
> -- 
> 2.25.1
>