--- /dev/null
+/******************************************************************************
+ * balloon.c
+ *
+ * Xen balloon driver - enables returning/claiming memory to/from Xen.
+ *
+ * Copyright (c) 2003, B Dragovic
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <asm/xen_proc.h>
+
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/smp_lock.h>
+#include <linux/pagemap.h>
+#include <linux/bootmem.h>
+#include <linux/highmem.h>
+#include <linux/vmalloc.h>
+
+#include <asm/hypervisor.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/uaccess.h>
+#include <asm/tlb.h>
+
+/* USER DEFINES -- THESE SHOULD BE COPIED TO USER-SPACE TOOLS */
+#define USER_INFLATE_BALLOON 1 /* return mem to hypervisor */
+#define USER_DEFLATE_BALLOON 2 /* claim mem from hypervisor */
+typedef struct user_balloon_op {
+ unsigned int op;
+ unsigned long size;
+} user_balloon_op_t;
+/* END OF USER DEFINE */
+
+static struct proc_dir_entry *balloon_pde;
+unsigned long credit;
+static unsigned long current_pages, most_seen_pages;
+
+/*
+ * Dead entry written into balloon-owned entries in the PMT.
+ * It is deliberately different to INVALID_P2M_ENTRY.
+ */
+#define DEAD 0xdead1234
+
+static inline pte_t *get_ptep(unsigned long addr)
+{
+ pgd_t *pgd; pmd_t *pmd; pte_t *ptep;
+ pgd = pgd_offset_k(addr);
+
+ if ( pgd_none(*pgd) || pgd_bad(*pgd) ) BUG();
+
+ pmd = pmd_offset(pgd, addr);
+ if ( pmd_none(*pmd) || pmd_bad(*pmd) ) BUG();
+
+ ptep = pte_offset(pmd, addr);
+
+ return ptep;
+}
+
+/* Main function for relinquishing memory. */
+static unsigned long inflate_balloon(unsigned long num_pages)
+{
+ unsigned long *parray;
+ unsigned long *currp;
+ unsigned long curraddr;
+ unsigned long ret = 0;
+ unsigned long i, j;
+
+ parray = (unsigned long *)vmalloc(num_pages * sizeof(unsigned long));
+ if ( parray == NULL )
+ {
+ printk(KERN_ERR "inflate_balloon: Unable to vmalloc parray\n");
+ return -EFAULT;
+ }
+
+ currp = parray;
+
+ for ( i = 0; i < num_pages; i++, currp++ )
+ {
+ struct page *page = alloc_page(GFP_HIGHUSER);
+ unsigned long pfn = page - mem_map;
+
+ /* If allocation fails then free all reserved pages. */
+ if ( page == NULL )
+ {
+ printk(KERN_ERR "Unable to inflate balloon by %ld, only"
+ " %ld pages free.", num_pages, i);
+ currp = parray;
+ for ( j = 0; j < i; j++, currp++ )
+ __free_page((struct page *) (mem_map + *currp));
+ ret = -EFAULT;
+ goto cleanup;
+ }
+
+ *currp = pfn;
+ }
+
+
+ for ( i = 0, currp = parray; i < num_pages; i++, currp++ )
+ {
+ unsigned long mfn = phys_to_machine_mapping[*currp];
+ curraddr = (unsigned long)page_address(mem_map + *currp);
+ /* Blow away page contents for security, and also p.t. ref if any. */
+ if ( curraddr != 0 )
+ {
+ scrub_pages(curraddr, 1);
+ queue_l1_entry_update(get_ptep(curraddr), 0);
+ }
+#ifdef CONFIG_XEN_SCRUB_PAGES
+ else
+ {
+ void *p = kmap(&mem_map[*currp]);
+ scrub_pages(p, 1);
+ kunmap(&mem_map[*currp]);
+ }
+#endif
+ phys_to_machine_mapping[*currp] = DEAD;
+ *currp = mfn;
+ }
+
+ /* Flush updates through and flush the TLB. */
+ xen_tlb_flush();
+
+ ret = HYPERVISOR_dom_mem_op(MEMOP_decrease_reservation,
+ parray, num_pages, 0);
+ if ( unlikely(ret != num_pages) )
+ {
+ printk(KERN_ERR "Unable to inflate balloon, error %lx\n", ret);
+ goto cleanup;
+ }
+
+ credit += num_pages;
+ ret = num_pages;
+
+ cleanup:
+ vfree(parray);
+
+ return ret;
+}
+
+/*
+ * Install new mem pages obtained by deflate_balloon. function walks
+ * phys->machine mapping table looking for DEAD entries and populates
+ * them.
+ */
+static unsigned long process_returned_pages(unsigned long * parray,
+ unsigned long num)
+{
+ /* currently, this function is rather simplistic as
+ * it is assumed that domain reclaims only number of
+ * pages previously released. this is to change soon
+ * and the code to extend page tables etc. will be
+ * incorporated here.
+ */
+
+ unsigned long tot_pages = most_seen_pages;
+ unsigned long * curr = parray;
+ unsigned long num_installed;
+ unsigned long i;
+
+ num_installed = 0;
+ for ( i = 0; (i < tot_pages) && (num_installed < num); i++ )
+ {
+ if ( phys_to_machine_mapping[i] == DEAD )
+ {
+ phys_to_machine_mapping[i] = *curr;
+ queue_machphys_update(*curr, i);
+ if (i<max_low_pfn)
+ queue_l1_entry_update(
+ get_ptep((unsigned long)__va(i << PAGE_SHIFT)),
+ ((*curr) << PAGE_SHIFT) | pgprot_val(PAGE_KERNEL));
+
+ __free_page(mem_map + i);
+
+ curr++;
+ num_installed++;
+ }
+ }
+
+ return num_installed;
+}
+
+unsigned long deflate_balloon(unsigned long num_pages)
+{
+ unsigned long ret;
+ unsigned long * parray;
+
+ if ( num_pages > credit )
+ {
+ printk(KERN_ERR "deflate_balloon: %lu pages > %lu credit.\n",
+ num_pages, credit);
+ return -EAGAIN;
+ }
+
+ parray = (unsigned long *)vmalloc(num_pages * sizeof(unsigned long));
+ if ( parray == NULL )
+ {
+ printk(KERN_ERR "deflate_balloon: Unable to vmalloc parray\n");
+ return 0;
+ }
+
+ ret = HYPERVISOR_dom_mem_op(MEMOP_increase_reservation,
+ parray, num_pages, 0);
+ if ( unlikely(ret != num_pages) )
+ {
+ printk(KERN_ERR "deflate_balloon: xen increase_reservation err %lx\n",
+ ret);
+ goto cleanup;
+ }
+
+ if ( (ret = process_returned_pages(parray, num_pages)) < num_pages )
+ {
+ printk(KERN_WARNING
+ "deflate_balloon: restored only %lx of %lx pages.\n",
+ ret, num_pages);
+ goto cleanup;
+ }
+
+ ret = num_pages;
+ credit -= num_pages;
+
+ cleanup:
+ vfree(parray);
+
+ return ret;
+}
+
+#define PAGE_TO_MB_SHIFT 8
+
+/*
+ * pagetable_extend() mimics pagetable_init() from arch/xen/mm/init.c
+ * The loops do go through all of low memory (ZONE_NORMAL). The
+ * old pages have _PAGE_PRESENT set and so get skipped.
+ * If low memory is not full, the new pages are used to fill it, going
+ * from cur_low_pfn to low_pfn. high memory is not direct mapped so
+ * no extension is needed for new high memory.
+ */
+
+static void pagetable_extend (int cur_low_pfn, int newpages)
+{
+ unsigned long vaddr, end;
+ pgd_t *kpgd, *pgd, *pgd_base;
+ int i, j, k;
+ pmd_t *kpmd, *pmd;
+ pte_t *kpte, *pte, *pte_base;
+ int low_pfn = min(cur_low_pfn+newpages,(int)max_low_pfn);
+
+ /*
+ * This can be zero as well - no problem, in that case we exit
+ * the loops anyway due to the PTRS_PER_* conditions.
+ */
+ end = (unsigned long)__va(low_pfn*PAGE_SIZE);
+
+ pgd_base = init_mm.pgd;
+ i = __pgd_offset(PAGE_OFFSET);
+ pgd = pgd_base + i;
+
+ for (; i < PTRS_PER_PGD; pgd++, i++) {
+ vaddr = i*PGDIR_SIZE;
+ if (end && (vaddr >= end))
+ break;
+ pmd = (pmd_t *)pgd;
+ for (j = 0; j < PTRS_PER_PMD; pmd++, j++) {
+ vaddr = i*PGDIR_SIZE + j*PMD_SIZE;
+ if (end && (vaddr >= end))
+ break;
+
+ /* Filled in for us already? */
+ if ( pmd_val(*pmd) & _PAGE_PRESENT )
+ continue;
+
+ pte_base = pte = (pte_t *) __get_free_page(GFP_KERNEL);
+
+ for (k = 0; k < PTRS_PER_PTE; pte++, k++) {
+ vaddr = i*PGDIR_SIZE + j*PMD_SIZE + k*PAGE_SIZE;
+ if (end && (vaddr >= end))
+ break;
+ *pte = mk_pte_phys(__pa(vaddr), PAGE_KERNEL);
+ }
+ kpgd = pgd_offset_k((unsigned long)pte_base);
+ kpmd = pmd_offset(kpgd, (unsigned long)pte_base);
+ kpte = pte_offset(kpmd, (unsigned long)pte_base);
+ queue_l1_entry_update(kpte,
+ (*(unsigned long *)kpte)&~_PAGE_RW);
+ set_pmd(pmd, __pmd(_KERNPG_TABLE + __pa(pte_base)));
+ XEN_flush_page_update_queue();
+ }
+ }
+}
+
+/*
+ * claim_new_pages() asks xen to increase this domain's memory reservation
+ * and return a list of the new pages of memory. This new pages are
+ * added to the free list of the memory manager.
+ *
+ * Available RAM does not normally change while Linux runs. To make this work,
+ * the linux mem= boottime command line param must say how big memory could
+ * possibly grow. Then setup_arch() in arch/xen/kernel/setup.c
+ * sets max_pfn, max_low_pfn and the zones according to
+ * this max memory size. The page tables themselves can only be
+ * extended after xen has assigned new pages to this domain.
+ */
+
+static unsigned long
+claim_new_pages(unsigned long num_pages)
+{
+ unsigned long new_page_cnt, pfn;
+ unsigned long * parray, *curr;
+
+ if (most_seen_pages+num_pages> max_pfn)
+ num_pages = max_pfn-most_seen_pages;
+ if (num_pages==0) return 0;
+
+ parray = (unsigned long *)vmalloc(num_pages * sizeof(unsigned long));
+ if ( parray == NULL )
+ {
+ printk(KERN_ERR "claim_new_pages: Unable to vmalloc parray\n");
+ return 0;
+ }
+
+ new_page_cnt = HYPERVISOR_dom_mem_op(MEMOP_increase_reservation,
+ parray, num_pages, 0);
+ if ( new_page_cnt != num_pages )
+ {
+ printk(KERN_WARNING
+ "claim_new_pages: xen granted only %lu of %lu requested pages\n",
+ new_page_cnt, num_pages);
+
+ /*
+ * Avoid xen lockup when user forgot to setdomainmaxmem. Xen
+ * usually can dribble out a few pages and then hangs.
+ */
+ if ( new_page_cnt < 1000 )
+ {
+ printk(KERN_WARNING "Remember to use setdomainmaxmem\n");
+ HYPERVISOR_dom_mem_op(MEMOP_decrease_reservation,
+ parray, new_page_cnt, 0);
+ return -EFAULT;
+ }
+ }
+ memcpy(phys_to_machine_mapping+most_seen_pages, parray,
+ new_page_cnt * sizeof(unsigned long));
+
+ pagetable_extend(most_seen_pages,new_page_cnt);
+
+ for ( pfn = most_seen_pages, curr = parray;
+ pfn < most_seen_pages+new_page_cnt;
+ pfn++, curr++ )
+ {
+ struct page *page = mem_map + pfn;
+
+#ifndef CONFIG_HIGHMEM
+ if ( pfn>=max_low_pfn )
+ {
+ printk(KERN_WARNING "Warning only %ldMB will be used.\n",
+ pfn>>PAGE_TO_MB_SHIFT);
+ printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
+ break;
+ }
+#endif
+ queue_machphys_update(*curr, pfn);
+ if ( pfn < max_low_pfn )
+ queue_l1_entry_update(
+ get_ptep((unsigned long)__va(pfn << PAGE_SHIFT)),
+ ((*curr) << PAGE_SHIFT) | pgprot_val(PAGE_KERNEL));
+
+ XEN_flush_page_update_queue();
+
+ /* this next bit mimics arch/xen/mm/init.c:one_highpage_init() */
+ ClearPageReserved(page);
+ if ( pfn >= max_low_pfn )
+ set_bit(PG_highmem, &page->flags);
+ set_page_count(page, 1);
+ __free_page(page);
+ }
+
+ vfree(parray);
+
+ return new_page_cnt;
+}
+
+static int balloon_write(struct file *file, const char *buffer,
+ u_long count, void *data)
+{
+ char memstring[64], *endchar;
+ int len, i;
+ unsigned long target;
+ unsigned long long targetbytes;
+
+ /* Only admin can play with the balloon :) */
+ if ( !capable(CAP_SYS_ADMIN) )
+ return -EPERM;
+
+ if ( count > sizeof(memstring) )
+ return -EFBIG;
+
+ len = strnlen_user(buffer, count);
+ if ( len == 0 ) return -EBADMSG;
+ if ( len == 1 ) return 1; /* input starts with a NUL char */
+ if ( strncpy_from_user(memstring, buffer, len) < 0 )
+ return -EFAULT;
+
+ endchar = memstring;
+ for ( i = 0; i < len; ++i, ++endchar )
+ if ( (memstring[i] < '0') || (memstring[i] > '9') )
+ break;
+ if ( i == 0 )
+ return -EBADMSG;
+
+ targetbytes = memparse(memstring,&endchar);
+ target = targetbytes >> PAGE_SHIFT;
+
+ if ( target < current_pages )
+ {
+ int change = inflate_balloon(current_pages-target);
+ if ( change <= 0 )
+ return change;
+
+ current_pages -= change;
+ printk(KERN_INFO "Relinquish %dMB to xen. Domain now has %luMB\n",
+ change>>PAGE_TO_MB_SHIFT, current_pages>>PAGE_TO_MB_SHIFT);
+ }
+ else if ( target > current_pages )
+ {
+ int change, reclaim = min(target,most_seen_pages) - current_pages;
+
+ if ( reclaim )
+ {
+ change = deflate_balloon( reclaim);
+ if ( change <= 0 )
+ return change;
+ current_pages += change;
+ printk(KERN_INFO "Reclaim %dMB from xen. Domain now has %luMB\n",
+ change>>PAGE_TO_MB_SHIFT, current_pages>>PAGE_TO_MB_SHIFT);
+ }
+
+ if ( most_seen_pages < target )
+ {
+ int growth = claim_new_pages(target-most_seen_pages);
+ if ( growth <= 0 )
+ return growth;
+ most_seen_pages += growth;
+ current_pages += growth;
+ printk(KERN_INFO "Granted %dMB new mem. Dom now has %luMB\n",
+ growth>>PAGE_TO_MB_SHIFT, current_pages>>PAGE_TO_MB_SHIFT);
+ }
+ }
+
+
+ return len;
+}
+
+
+static int balloon_read(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int len;
+ len = sprintf(page,"%lu\n",current_pages<<PAGE_SHIFT);
+
+ if (len <= off+count) *eof = 1;
+ *start = page + off;
+ len -= off;
+ if (len>count) len = count;
+ if (len<0) len = 0;
+ return len;
+}
+
+static int __init init_module(void)
+{
+ printk(KERN_ALERT "Starting Xen Balloon driver\n");
+
+ most_seen_pages = current_pages = min(xen_start_info.nr_pages,max_pfn);
+ if ( (balloon_pde = create_xen_proc_entry("memory_target", 0644)) == NULL )
+ {
+ printk(KERN_ALERT "Unable to create balloon driver proc entry!");
+ return -1;
+ }
+
+ balloon_pde->write_proc = balloon_write;
+ balloon_pde->read_proc = balloon_read;
+
+ /*
+ * make a new phys map if mem= says xen can give us memory to grow
+ */
+ if ( max_pfn > xen_start_info.nr_pages )
+ {
+ extern unsigned long *phys_to_machine_mapping;
+ unsigned long *newmap;
+ newmap = (unsigned long *)vmalloc(max_pfn * sizeof(unsigned long));
+ memset(newmap, ~0, max_pfn * sizeof(unsigned long));
+ memcpy(newmap, phys_to_machine_mapping,
+ xen_start_info.nr_pages * sizeof(unsigned long));
+ phys_to_machine_mapping = newmap;
+ }
+
+ return 0;
+}
+
+static void __exit cleanup_module(void)
+{
+ if ( balloon_pde != NULL )
+ {
+ remove_xen_proc_entry("balloon");
+ balloon_pde = NULL;
+ }
+}
+
+module_init(init_module);
+module_exit(cleanup_module);
projects / xen.git / commitdiff