From aa24411b6717fd1e6ecef281bec497f6f30bbd66 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 28 Sep 2011 17:46:32 +0100 Subject: [PATCH 1/5] xen/balloon: account for pages released during memory setup In xen_memory_setup() pages that occur in gaps in the memory map are released back to Xen. This reduces the domain's current page count in the hypervisor. The Xen balloon driver does not correctly decrease its initial current_pages count to reflect this. If 'delta' pages are released and the target is adjusted the resulting reservation is always 'delta' less than the requested target. This affects dom0 if the initial allocation of pages overlaps the PCI memory region but won't affect most domU guests that have been setup with pseudo-physical memory maps that don't have gaps. Fix this by accouting for the released pages when starting the balloon driver. If the domain's targets are managed by xapi, the domain may eventually run out of memory and die because xapi currently gets its target calculations wrong and whenever it is restarted it always reduces the target by 'delta'. Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/setup.c | 7 ++++++- drivers/xen/balloon.c | 4 +++- include/xen/page.h | 2 ++ 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index 46d6d21dbdbe..c983717c018c 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -39,6 +39,9 @@ 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; +/* Number of pages released from the initial allocation. */ +unsigned long xen_released_pages; + /* * The maximum amount of extra memory compared to the base size. The * main scaling factor is the size of struct page. At extreme ratios @@ -313,7 +316,9 @@ char * __init xen_memory_setup(void) extra_pages = 0; } - extra_pages += xen_return_unused_memory(xen_start_info->nr_pages, &e820); + xen_released_pages = xen_return_unused_memory(xen_start_info->nr_pages, + &e820); + extra_pages += xen_released_pages; /* * Clamp the amount of extra memory to a EXTRA_MEM_RATIO diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 5dfd8f8ff07f..4f59fb373381 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -565,7 +565,9 @@ static int __init balloon_init(void) pr_info("xen/balloon: Initialising balloon driver.\n"); - balloon_stats.current_pages = xen_pv_domain() ? min(xen_start_info->nr_pages, max_pfn) : max_pfn; + balloon_stats.current_pages = xen_pv_domain() + ? min(xen_start_info->nr_pages - xen_released_pages, max_pfn) + : max_pfn; balloon_stats.target_pages = balloon_stats.current_pages; balloon_stats.balloon_low = 0; balloon_stats.balloon_high = 0; diff --git a/include/xen/page.h b/include/xen/page.h index 0be36b976f4b..92b61f8c772c 100644 --- a/include/xen/page.h +++ b/include/xen/page.h @@ -5,4 +5,6 @@ extern phys_addr_t xen_extra_mem_start, xen_extra_mem_size; +extern unsigned long xen_released_pages; + #endif /* _XEN_PAGE_H */ From b1cbf9b1d6af22ba262d99abcfd71d5d90dbd57a Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 28 Sep 2011 17:46:33 +0100 Subject: [PATCH 2/5] xen/balloon: simplify test for the end of usable RAM When initializing the balloon only max_pfn needs to be checked (max_pfn will always be <= e820_end_of_ram_pfn()) and improve the confusing comment. Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/balloon.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 4f59fb373381..9efb993090aa 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -586,16 +586,16 @@ static int __init balloon_init(void) #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. + * Initialize the balloon with pages from the extra memory + * region (see arch/x86/xen/setup.c). + * + * If the amount of usable memory has been limited (e.g., with + * the 'mem' command line parameter), don't add pages beyond + * this limit. */ - extra_pfn_end = min(min(max_pfn, e820_end_of_ram_pfn()), - (unsigned long)PFN_DOWN(xen_extra_mem_start + xen_extra_mem_size)); + extra_pfn_end = min(max_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++) { From 8b5d44a5ac93cd7a1b044db3ff0ba4955b4ba5ec Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 28 Sep 2011 17:46:34 +0100 Subject: [PATCH 3/5] xen: allow balloon driver to use more than one memory region 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. The maximum possible number of extra regions is 128 (== E820MAX) which is quite large so xen_extra_mem is placed in __initdata. This is safe as both xen_memory_setup() and balloon_init() are in __init. The balloon regions themselves are not altered (i.e., there is still only the one region). Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/setup.c | 20 ++++++++++---------- drivers/xen/balloon.c | 44 ++++++++++++++++++++++++++----------------- include/xen/page.h | 10 +++++++++- 3 files changed, 46 insertions(+), 28 deletions(-) diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index c983717c018c..0c8e974c738a 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] __initdata; /* Number of pages released from the initial allocation. */ unsigned long xen_released_pages; @@ -59,7 +59,7 @@ 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; if (!pages) return; @@ -69,7 +69,7 @@ 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); @@ -242,7 +242,7 @@ 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; @@ -270,8 +270,8 @@ 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) @@ -279,10 +279,10 @@ 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); /* * In domU, the ISA region is normal, usable memory, but we diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 9efb993090aa..fc43b53651d7 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -555,11 +555,32 @@ 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_region(unsigned long start_pfn, + unsigned long pages) { unsigned long pfn, extra_pfn_end; struct page *page; + /* + * If the amount of usable memory has been limited (e.g., with + * the 'mem' command line parameter), don't add pages beyond + * this limit. + */ + extra_pfn_end = min(max_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 i; + if (!xen_domain()) return -ENODEV; @@ -587,23 +608,12 @@ static int __init balloon_init(void) /* * Initialize the balloon with pages from the extra memory - * region (see arch/x86/xen/setup.c). - * - * If the amount of usable memory has been limited (e.g., with - * the 'mem' command line parameter), don't add pages beyond - * this limit. + * regions (see arch/x86/xen/setup.c). */ - extra_pfn_end = min(max_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 (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) + if (xen_extra_mem[i].size) + balloon_add_region(PFN_UP(xen_extra_mem[i].start), + PFN_DOWN(xen_extra_mem[i].size)); return 0; } diff --git a/include/xen/page.h b/include/xen/page.h index 92b61f8c772c..12765b6f9517 100644 --- a/include/xen/page.h +++ b/include/xen/page.h @@ -3,7 +3,15 @@ #include -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 128 /* == E820MAX */ + +extern __initdata +struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS]; extern unsigned long xen_released_pages; From dc91c728fddc29dfed1ae96f6807216b5f42d3a1 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Thu, 29 Sep 2011 12:26:19 +0100 Subject: [PATCH 4/5] xen: allow extra memory to be in multiple regions Allow the extra memory (used by the balloon driver) to be in multiple regions (typically two regions, one for low memory and one for high memory). This allows the balloon driver to increase the number of available low pages (if the initial number if pages is small). As a side effect, the algorithm for building the e820 memory map is simpler and more obviously correct as the map supplied by the hypervisor is (almost) used as is (in particular, all reserved regions and gaps are preserved). Only RAM regions are altered and RAM regions above max_pfn + extra_pages are marked as unused (the region is split in two if necessary). Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/setup.c | 174 ++++++++++++++++++++----------------------- 1 file changed, 82 insertions(+), 92 deletions(-) diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index 0c8e974c738a..2ad2fd53bd32 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -54,26 +54,32 @@ unsigned long xen_released_pages; */ #define EXTRA_MEM_RATIO (10) -static void __init xen_add_extra_mem(unsigned long pages) +static void __init xen_add_extra_mem(u64 start, u64 size) { unsigned long pfn; + int i; - u64 size = (u64)pages * PAGE_SIZE; - u64 extra_start = xen_extra_mem[0].start + xen_extra_mem[0].size; + for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) { + /* Add new region. */ + if (xen_extra_mem[i].size == 0) { + xen_extra_mem[i].start = start; + xen_extra_mem[i].size = size; + break; + } + /* Append to existing region. */ + if (xen_extra_mem[i].start + xen_extra_mem[i].size == start) { + xen_extra_mem[i].size += size; + break; + } + } + if (i == XEN_EXTRA_MEM_MAX_REGIONS) + printk(KERN_WARNING "Warning: not enough extra memory regions\n"); - if (!pages) - return; + memblock_x86_reserve_range(start, start + size, "XEN EXTRA"); - e820_add_region(extra_start, size, E820_RAM); - sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map); + xen_max_p2m_pfn = PFN_DOWN(start + size); - memblock_x86_reserve_range(extra_start, extra_start + size, "XEN EXTRA"); - - xen_extra_mem[0].size += size; - - xen_max_p2m_pfn = PFN_DOWN(extra_start + size); - - for (pfn = PFN_DOWN(extra_start); pfn <= xen_max_p2m_pfn; pfn++) + for (pfn = PFN_DOWN(start); pfn <= xen_max_p2m_pfn; pfn++) __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); } @@ -120,8 +126,8 @@ static unsigned long __init xen_release_chunk(phys_addr_t start_addr, return len; } -static unsigned long __init xen_return_unused_memory(unsigned long max_pfn, - const struct e820map *e820) +static unsigned long __init xen_return_unused_memory( + unsigned long max_pfn, const struct e820entry *map, int nr_map) { phys_addr_t max_addr = PFN_PHYS(max_pfn); phys_addr_t last_end = ISA_END_ADDRESS; @@ -129,13 +135,13 @@ static unsigned long __init xen_return_unused_memory(unsigned long max_pfn, int i; /* Free any unused memory above the low 1Mbyte. */ - for (i = 0; i < e820->nr_map && last_end < max_addr; i++) { - phys_addr_t end = e820->map[i].addr; + for (i = 0; i < nr_map && last_end < max_addr; i++) { + phys_addr_t end = map[i].addr; end = min(max_addr, end); if (last_end < end) released += xen_release_chunk(last_end, end); - last_end = max(last_end, e820->map[i].addr + e820->map[i].size); + last_end = max(last_end, map[i].addr + map[i].size); } if (last_end < max_addr) @@ -200,20 +206,32 @@ static unsigned long __init xen_get_max_pages(void) return min(max_pages, MAX_DOMAIN_PAGES); } +static void xen_align_and_add_e820_region(u64 start, u64 size, int type) +{ + u64 end = start + size; + + /* Align RAM regions to page boundaries. */ + if (type == E820_RAM) { + start = PAGE_ALIGN(start); + end &= ~((u64)PAGE_SIZE - 1); + } + + e820_add_region(start, end - start, type); +} + /** * machine_specific_memory_setup - Hook for machine specific memory setup. **/ char * __init xen_memory_setup(void) { static struct e820entry map[E820MAX] __initdata; - static struct e820entry map_raw[E820MAX] __initdata; unsigned long max_pfn = xen_start_info->nr_pages; unsigned long long mem_end; int rc; struct xen_memory_map memmap; + unsigned long max_pages; unsigned long extra_pages = 0; - unsigned long extra_limit; unsigned long identity_pages = 0; int i; int op; @@ -240,49 +258,55 @@ char * __init xen_memory_setup(void) } BUG_ON(rc); - memcpy(map_raw, map, sizeof(map)); - e820.nr_map = 0; - xen_extra_mem[0].start = mem_end; - for (i = 0; i < memmap.nr_entries; i++) { - unsigned long long end; + /* Make sure the Xen-supplied memory map is well-ordered. */ + sanitize_e820_map(map, memmap.nr_entries, &memmap.nr_entries); - /* Guard against non-page aligned E820 entries. */ - if (map[i].type == E820_RAM) - map[i].size -= (map[i].size + map[i].addr) % PAGE_SIZE; + max_pages = xen_get_max_pages(); + if (max_pages > max_pfn) + extra_pages += max_pages - max_pfn; - end = map[i].addr + map[i].size; - if (map[i].type == E820_RAM && end > mem_end) { - /* RAM off the end - may be partially included */ - u64 delta = min(map[i].size, end - mem_end); + xen_released_pages = xen_return_unused_memory(max_pfn, map, + memmap.nr_entries); + extra_pages += xen_released_pages; - map[i].size -= delta; - end -= delta; + /* + * Clamp the amount of extra memory to a EXTRA_MEM_RATIO + * factor the base size. On non-highmem systems, the base + * size is the full initial memory allocation; on highmem it + * is limited to the max size of lowmem, so that it doesn't + * get completely filled. + * + * In principle there could be a problem in lowmem systems if + * the initial memory is also very large with respect to + * lowmem, but we won't try to deal with that here. + */ + extra_pages = min(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)), + extra_pages); - extra_pages += PFN_DOWN(delta); - /* - * Set RAM below 4GB that is not for us to be unusable. - * This prevents "System RAM" address space from being - * used as potential resource for I/O address (happens - * when 'allocate_resource' is called). - */ - if (delta && - (xen_initial_domain() && end < 0x100000000ULL)) - e820_add_region(end, delta, E820_UNUSABLE); + i = 0; + while (i < memmap.nr_entries) { + u64 addr = map[i].addr; + u64 size = map[i].size; + u32 type = map[i].type; + + if (type == E820_RAM) { + if (addr < mem_end) { + size = min(size, mem_end - addr); + } else if (extra_pages) { + size = min(size, (u64)extra_pages * PAGE_SIZE); + extra_pages -= size / PAGE_SIZE; + xen_add_extra_mem(addr, size); + } else + type = E820_UNUSABLE; } - if (map[i].size > 0 && end > xen_extra_mem[0].start) - xen_extra_mem[0].start = end; + xen_align_and_add_e820_region(addr, size, type); - /* Add region if any remains */ - if (map[i].size > 0) - e820_add_region(map[i].addr, map[i].size, map[i].type); + map[i].addr += size; + map[i].size -= size; + if (map[i].size == 0) + i++; } - /* 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 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); /* * In domU, the ISA region is normal, usable memory, but we @@ -308,45 +332,11 @@ char * __init xen_memory_setup(void) sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map); - extra_limit = xen_get_max_pages(); - if (max_pfn + extra_pages > extra_limit) { - if (extra_limit > max_pfn) - extra_pages = extra_limit - max_pfn; - else - extra_pages = 0; - } - - xen_released_pages = xen_return_unused_memory(xen_start_info->nr_pages, - &e820); - extra_pages += xen_released_pages; - - /* - * Clamp the amount of extra memory to a EXTRA_MEM_RATIO - * factor the base size. On non-highmem systems, the base - * size is the full initial memory allocation; on highmem it - * is limited to the max size of lowmem, so that it doesn't - * get completely filled. - * - * In principle there could be a problem in lowmem systems if - * the initial memory is also very large with respect to - * lowmem, but we won't try to deal with that here. - */ - extra_limit = min(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)), - max_pfn + extra_pages); - - if (extra_limit >= max_pfn) - extra_pages = extra_limit - max_pfn; - else - extra_pages = 0; - - xen_add_extra_mem(extra_pages); - /* * Set P2M for all non-RAM pages and E820 gaps to be identity - * type PFNs. We supply it with the non-sanitized version - * of the E820. + * type PFNs. */ - identity_pages = xen_set_identity(map_raw, memmap.nr_entries); + identity_pages = xen_set_identity(e820.map, e820.nr_map); printk(KERN_INFO "Set %ld page(s) to 1-1 mapping.\n", identity_pages); return "Xen"; } From f3f436e33b925ead21e3f9b47b1e2aed965511d9 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 28 Sep 2011 17:46:36 +0100 Subject: [PATCH 5/5] xen: release all pages within 1-1 p2m mappings In xen_memory_setup() all reserved regions and gaps are set to an identity (1-1) p2m mapping. If an available page has a PFN within one of these 1-1 mappings it will become inaccessible (as it MFN is lost) so release them before setting up the mapping. This can make an additional 256 MiB or more of RAM available (depending on the size of the reserved regions in the memory map) if the initial pages overlap with reserved regions. The 1:1 p2m mappings are also extended to cover partial pages. This fixes an issue with (for example) systems with a BIOS that puts the DMI tables in a reserved region that begins on a non-page boundary. Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/setup.c | 117 ++++++++++++++++--------------------------- 1 file changed, 42 insertions(+), 75 deletions(-) diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index 2ad2fd53bd32..38d0af4fefec 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -83,25 +83,18 @@ static void __init xen_add_extra_mem(u64 start, u64 size) __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); } -static unsigned long __init xen_release_chunk(phys_addr_t start_addr, - phys_addr_t end_addr) +static unsigned long __init xen_release_chunk(unsigned long start, + unsigned long end) { struct xen_memory_reservation reservation = { .address_bits = 0, .extent_order = 0, .domid = DOMID_SELF }; - unsigned long start, end; unsigned long len = 0; unsigned long pfn; int ret; - start = PFN_UP(start_addr); - end = PFN_DOWN(end_addr); - - if (end <= start) - return 0; - for(pfn = start; pfn < end; pfn++) { unsigned long mfn = pfn_to_mfn(pfn); @@ -126,72 +119,52 @@ static unsigned long __init xen_release_chunk(phys_addr_t start_addr, return len; } -static unsigned long __init xen_return_unused_memory( - unsigned long max_pfn, const struct e820entry *map, int nr_map) +static unsigned long __init xen_set_identity_and_release( + const struct e820entry *list, size_t map_size, unsigned long nr_pages) { - phys_addr_t max_addr = PFN_PHYS(max_pfn); - phys_addr_t last_end = ISA_END_ADDRESS; + phys_addr_t start = 0; unsigned long released = 0; - int i; - - /* Free any unused memory above the low 1Mbyte. */ - for (i = 0; i < nr_map && last_end < max_addr; i++) { - phys_addr_t end = map[i].addr; - end = min(max_addr, end); - - if (last_end < end) - released += xen_release_chunk(last_end, end); - last_end = max(last_end, map[i].addr + map[i].size); - } - - if (last_end < max_addr) - released += xen_release_chunk(last_end, max_addr); - - printk(KERN_INFO "released %lu pages of unused memory\n", released); - return released; -} - -static unsigned long __init xen_set_identity(const struct e820entry *list, - ssize_t map_size) -{ - phys_addr_t last = xen_initial_domain() ? 0 : ISA_END_ADDRESS; - phys_addr_t start_pci = last; - const struct e820entry *entry; unsigned long identity = 0; + const struct e820entry *entry; int i; + /* + * Combine non-RAM regions and gaps until a RAM region (or the + * end of the map) is reached, then set the 1:1 map and + * release the pages (if available) in those non-RAM regions. + * + * The combined non-RAM regions are rounded to a whole number + * of pages so any partial pages are accessible via the 1:1 + * mapping. This is needed for some BIOSes that put (for + * example) the DMI tables in a reserved region that begins on + * a non-page boundary. + */ for (i = 0, entry = list; i < map_size; i++, entry++) { - phys_addr_t start = entry->addr; - phys_addr_t end = start + entry->size; + phys_addr_t end = entry->addr + entry->size; - if (start < last) - start = last; + if (entry->type == E820_RAM || i == map_size - 1) { + unsigned long start_pfn = PFN_DOWN(start); + unsigned long end_pfn = PFN_UP(end); - if (end <= start) - continue; + if (entry->type == E820_RAM) + end_pfn = PFN_UP(entry->addr); - /* Skip over the 1MB region. */ - if (last > end) - continue; + if (start_pfn < end_pfn) { + if (start_pfn < nr_pages) + released += xen_release_chunk( + start_pfn, min(end_pfn, nr_pages)); - if ((entry->type == E820_RAM) || (entry->type == E820_UNUSABLE)) { - if (start > start_pci) identity += set_phys_range_identity( - PFN_UP(start_pci), PFN_DOWN(start)); - - /* Without saving 'last' we would gooble RAM too - * at the end of the loop. */ - last = end; - start_pci = end; - continue; + start_pfn, end_pfn); + } + start = end; } - start_pci = min(start, start_pci); - last = end; } - if (last > start_pci) - identity += set_phys_range_identity( - PFN_UP(start_pci), PFN_DOWN(last)); - return identity; + + printk(KERN_INFO "Released %lu pages of unused memory\n", released); + printk(KERN_INFO "Set %ld page(s) to 1-1 mapping\n", identity); + + return released; } static unsigned long __init xen_get_max_pages(void) @@ -232,7 +205,6 @@ char * __init xen_memory_setup(void) struct xen_memory_map memmap; unsigned long max_pages; unsigned long extra_pages = 0; - unsigned long identity_pages = 0; int i; int op; @@ -265,8 +237,13 @@ char * __init xen_memory_setup(void) if (max_pages > max_pfn) extra_pages += max_pages - max_pfn; - xen_released_pages = xen_return_unused_memory(max_pfn, map, - memmap.nr_entries); + /* + * Set P2M for all non-RAM pages and E820 gaps to be identity + * type PFNs. Any RAM pages that would be made inaccesible by + * this are first released. + */ + xen_released_pages = xen_set_identity_and_release( + map, memmap.nr_entries, max_pfn); extra_pages += xen_released_pages; /* @@ -312,10 +289,6 @@ char * __init xen_memory_setup(void) * In domU, the ISA region is normal, usable memory, but we * reserve ISA memory anyway because too many things poke * about in there. - * - * In Dom0, the host E820 information can leave gaps in the - * ISA range, which would cause us to release those pages. To - * avoid this, we unconditionally reserve them here. */ e820_add_region(ISA_START_ADDRESS, ISA_END_ADDRESS - ISA_START_ADDRESS, E820_RESERVED); @@ -332,12 +305,6 @@ char * __init xen_memory_setup(void) sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map); - /* - * Set P2M for all non-RAM pages and E820 gaps to be identity - * type PFNs. - */ - identity_pages = xen_set_identity(e820.map, e820.nr_map); - printk(KERN_INFO "Set %ld page(s) to 1-1 mapping.\n", identity_pages); return "Xen"; }