From 42ee1471e9b879479a15debac752314a596c738e Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Mon, 30 Aug 2010 16:41:02 -0700 Subject: xen: implement "extra" memory to reserve space for pages not present at boot When using the e820 map to get the initial pseudo-physical address space, look for either Xen-provided memory which doesn't lie within an E820 region, or an E820 RAM region which extends beyond the Xen-provided memory range. Count these pages, and add them to a new "extra memory" range. This range has an E820 RAM range to describe it - so the kernel will allocate page structures for it - but it is also marked reserved so that the kernel will not attempt to use it. The balloon driver can then add this range as a set of currently ballooned-out pages, which can be used to extend the domain beyond its original size. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/xen/setup.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index dd2eb2a9303f..f9a99eaddcdc 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -34,6 +34,26 @@ extern void xen_sysenter_target(void); 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; + +static __init void xen_add_extra_mem(unsigned long pages) +{ + u64 size = (u64)pages * PAGE_SIZE; + + if (!pages) + return; + + e820_add_region(xen_extra_mem_start + xen_extra_mem_size, size, E820_RAM); + sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map); + + reserve_early(xen_extra_mem_start + xen_extra_mem_size, + xen_extra_mem_start + xen_extra_mem_size + size, + "XEN EXTRA"); + + xen_extra_mem_size += size; +} + static unsigned long __init xen_release_chunk(phys_addr_t start_addr, phys_addr_t end_addr) { @@ -105,7 +125,6 @@ static unsigned long __init xen_return_unused_memory(unsigned long max_pfn, /** * machine_specific_memory_setup - Hook for machine specific memory setup. **/ - char * __init xen_memory_setup(void) { static struct e820entry map[E820MAX] __initdata; @@ -114,6 +133,7 @@ char * __init xen_memory_setup(void) unsigned long long mem_end; int rc; struct xen_memory_map memmap; + unsigned long extra_pages = 0; int i; max_pfn = min(MAX_DOMAIN_PAGES, max_pfn); @@ -135,6 +155,7 @@ char * __init xen_memory_setup(void) BUG_ON(rc); e820.nr_map = 0; + xen_extra_mem_start = mem_end; for (i = 0; i < memmap.nr_entries; i++) { unsigned long long end = map[i].addr + map[i].size; if (map[i].type == E820_RAM) { @@ -143,6 +164,8 @@ char * __init xen_memory_setup(void) if (end > mem_end) { /* Truncate region to max_mem. */ map[i].size -= end - mem_end; + + extra_pages += PFN_DOWN(end - mem_end); } } if (map[i].size > 0) @@ -169,7 +192,9 @@ char * __init xen_memory_setup(void) sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map); - xen_return_unused_memory(xen_start_info->nr_pages, &e820); + extra_pages += xen_return_unused_memory(xen_start_info->nr_pages, &e820); + + xen_add_extra_mem(extra_pages); return "Xen"; } -- cgit v1.2.3