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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: [PATCH 1/3] xen: allow balloon driver to use more than one memory region
On Tue, Aug 16, 2011 at 11:00:36AM +0100, David Vrabel wrote:
> Allow the xen balloon driver to populate its list of extra pages from
> more than one region of memory. This will allow platforms to provide
> (for example) a region of low memory and a region of high memory.
What does this solve? Is this a requirement for another patch? If so
please specify the name of it.
>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> ---
> Is there a better way of passing the memory information to the balloon
> driver?
I think the way you have it is OK.
> ---
> arch/x86/xen/setup.c | 20 ++++++++++----------
> drivers/xen/balloon.c | 48 ++++++++++++++++++++++++++++--------------------
> include/xen/page.h | 9 ++++++++-
> 3 files changed, 46 insertions(+), 31 deletions(-)
>
> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> index df118a8..30d0015 100644
> --- a/arch/x86/xen/setup.c
> +++ b/arch/x86/xen/setup.c
> @@ -37,7 +37,7 @@ extern void xen_syscall_target(void);
> extern void xen_syscall32_target(void);
>
> /* Amount of extra memory space we add to the e820 ranges */
> -phys_addr_t xen_extra_mem_start, xen_extra_mem_size;
> +struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS];
>
> /*
> * The maximum amount of extra memory compared to the base size. The
> @@ -56,7 +56,7 @@ static void __init xen_add_extra_mem(unsigned long pages)
> unsigned long pfn;
>
> u64 size = (u64)pages * PAGE_SIZE;
> - u64 extra_start = xen_extra_mem_start + xen_extra_mem_size;
> + u64 extra_start = xen_extra_mem[0].start + xen_extra_mem[0].size;
Wouldn't this be for [1]?
>
> if (!pages)
> return;
> @@ -66,7 +66,7 @@ static void __init xen_add_extra_mem(unsigned long pages)
>
> memblock_x86_reserve_range(extra_start, extra_start + size, "XEN
> EXTRA");
>
> - xen_extra_mem_size += size;
> + xen_extra_mem[0].size += size;
>
> xen_max_p2m_pfn = PFN_DOWN(extra_start + size);
>
> @@ -226,7 +226,7 @@ char * __init xen_memory_setup(void)
>
> memcpy(map_raw, map, sizeof(map));
> e820.nr_map = 0;
> - xen_extra_mem_start = mem_end;
> + xen_extra_mem[0].start = mem_end;
> for (i = 0; i < memmap.nr_entries; i++) {
> unsigned long long end;
>
> @@ -254,8 +254,8 @@ char * __init xen_memory_setup(void)
> e820_add_region(end, delta, E820_UNUSABLE);
> }
>
> - if (map[i].size > 0 && end > xen_extra_mem_start)
> - xen_extra_mem_start = end;
> + if (map[i].size > 0 && end > xen_extra_mem[0].start)
> + xen_extra_mem[0].start = end;
>
> /* Add region if any remains */
> if (map[i].size > 0)
> @@ -263,10 +263,10 @@ char * __init xen_memory_setup(void)
> }
> /* Align the balloon area so that max_low_pfn does not get set
> * to be at the _end_ of the PCI gap at the far end (fee01000).
> - * Note that xen_extra_mem_start gets set in the loop above to be
> - * past the last E820 region. */
> - if (xen_initial_domain() && (xen_extra_mem_start < (1ULL<<32)))
> - xen_extra_mem_start = (1ULL<<32);
> + * Note that the start of balloon area gets set in the loop above
> + * to be past the last E820 region. */
> + if (xen_initial_domain() && (xen_extra_mem[0].start < (1ULL<<32)))
> + xen_extra_mem[0].start = (1ULL<<32);
So what about the highmem memory? Should there a be a check to move
the lowmem to highmem count?
>
> /*
> * In domU, the ISA region is normal, usable memory, but we
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 5dfd8f8..de7278a 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -555,11 +555,35 @@ void free_xenballooned_pages(int nr_pages, struct
> page** pages)
> }
> EXPORT_SYMBOL(free_xenballooned_pages);
>
> -static int __init balloon_init(void)
> +static void __init balloon_add_memory_region(unsigned long start_pfn,
> unsigned long pages)
> {
> unsigned long pfn, extra_pfn_end;
> struct page *page;
>
> + /*
> + * Initialise the balloon with excess memory space. We need
> + * to make sure we don't add memory which doesn't exist or
> + * logically exist. The E820 map can be trimmed to be smaller
> + * than the amount of physical memory due to the mem= command
> + * line parameter. And if this is a 32-bit non-HIGHMEM kernel
> + * on a system with memory which requires highmem to access,
> + * don't try to use it.
> + */
> + extra_pfn_end = min(min(max_pfn, e820_end_of_ram_pfn()),
> + start_pfn + pages);
> + for (pfn = start_pfn; pfn < extra_pfn_end; pfn++) {
> + page = pfn_to_page(pfn);
> + /* totalram_pages and totalhigh_pages do not
> + include the boot-time balloon extension, so
> + don't subtract from it. */
> + __balloon_append(page);
> + }
> +}
> +
> +static int __init balloon_init(void)
> +{
> + int r;
> +
> if (!xen_domain())
> return -ENODEV;
>
> @@ -583,25 +607,9 @@ static int __init balloon_init(void)
> register_memory_notifier(&xen_memory_nb);
> #endif
>
> - /*
> - * Initialise the balloon with excess memory space. We need
> - * to make sure we don't add memory which doesn't exist or
> - * logically exist. The E820 map can be trimmed to be smaller
> - * than the amount of physical memory due to the mem= command
> - * line parameter. And if this is a 32-bit non-HIGHMEM kernel
> - * on a system with memory which requires highmem to access,
> - * don't try to use it.
> - */
> - extra_pfn_end = min(min(max_pfn, e820_end_of_ram_pfn()),
> - (unsigned long)PFN_DOWN(xen_extra_mem_start +
> xen_extra_mem_size));
> - for (pfn = PFN_UP(xen_extra_mem_start);
> - pfn < extra_pfn_end;
> - pfn++) {
> - page = pfn_to_page(pfn);
> - /* totalram_pages and totalhigh_pages do not include the
> boot-time
> - balloon extension, so don't subtract from it. */
> - __balloon_append(page);
> - }
> + for (r = 0; r < XEN_EXTRA_MEM_MAX_REGIONS; r++)
You probably should also check to make sure that the values are actually valid.
Like
if (!xedn_extra_mem[r].start)
continue;
> + balloon_add_memory_region(PFN_UP(xen_extra_mem[r].start),
> + PFN_DOWN(xen_extra_mem[r].size));
>
> return 0;
> }
> diff --git a/include/xen/page.h b/include/xen/page.h
> index 0be36b9..b01f6ac 100644
> --- a/include/xen/page.h
> +++ b/include/xen/page.h
> @@ -3,6 +3,13 @@
>
> #include <asm/xen/page.h>
>
> -extern phys_addr_t xen_extra_mem_start, xen_extra_mem_size;
> +struct xen_memory_region {
> + phys_addr_t start;
> + phys_addr_t size;
> +};
> +
> +#define XEN_EXTRA_MEM_MAX_REGIONS 1
> +
> +extern struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS];
>
> #endif /* _XEN_PAGE_H */
> --
> 1.7.4.1
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