From 093d7b4639951ea3021a6f70d376c3ff31f4740c Mon Sep 17 00:00:00 2001 From: Miroslav Rezanina Date: Wed, 16 Sep 2009 03:56:17 -0400 Subject: [PATCH] xen: release unused free memory Scan an e820 table and release any memory which lies between e820 entries, as it won't be used and would just be wasted. At present this is just to release any memory beyond the end of the e820 map, but it will also deal with holes being punched in the map. Derived from patch by Miroslav Rezanina Signed-off-by: Jeremy Fitzhardinge --- arch/x86/xen/enlighten.c | 1 - arch/x86/xen/setup.c | 53 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 53 insertions(+), 1 deletion(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 65d8d79b46a8..399bed2de881 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -731,7 +731,6 @@ static void set_xen_basic_apic_ops(void) #endif - static void xen_clts(void) { struct multicall_space mcs; diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index ad0047f47cd4..e0942630d47a 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include "xen-ops.h" @@ -32,6 +33,56 @@ extern void xen_sysenter_target(void); extern void xen_syscall_target(void); extern void xen_syscall32_target(void); +static unsigned long __init xen_release_chunk(phys_addr_t start_addr, phys_addr_t end_addr) +{ + struct xen_memory_reservation reservation = { + .address_bits = 0, + .extent_order = 0, + .domid = DOMID_SELF + }; + unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list; + unsigned long start, end; + unsigned long len; + unsigned long pfn; + int ret; + + start = PFN_UP(start_addr); + end = PFN_UP(end_addr); + + if (end <= start) + return 0; + + len = end - start; + + set_xen_guest_handle(reservation.extent_start, &mfn_list[start]); + reservation.nr_extents = len; + + ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); + WARN(ret != (end - start), "Failed to release memory %lx-%lx err=%d\n", + start, end, ret); + + for(pfn = start; pfn < end; pfn++) + set_phys_to_machine(pfn, INVALID_P2M_ENTRY); + + return len; +} + +static unsigned long __init xen_return_unused_memory(const struct e820map *e820) +{ + unsigned long last_end = 0; + unsigned long released = 0; + int i; + + for (i = 0; i < e820->nr_map; i++) { + released += xen_release_chunk(last_end, e820->map[i].addr); + last_end = e820->map[i].addr + e820->map[i].size; + } + + released += xen_release_chunk(last_end, PFN_PHYS(xen_start_info->nr_pages)); + + printk(KERN_INFO "released %ld pages of unused memory\n", released); + return released; +} /** * machine_specific_memory_setup - Hook for machine specific memory setup. @@ -67,6 +118,8 @@ char * __init xen_memory_setup(void) sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map); + xen_return_unused_memory(&e820); + return "Xen"; } -- 2.39.2