[IA64] libxc: make xc_ia64_copy_memmap aware of sequence lock.
Guest domain's memory map may be updated concurrently so that
it is protected sequence lock.
This patch makes xc_ia64_copy_memmap() aware of sequence lock.
Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
diff -r af0969e7e408 tools/libxc/ia64/xc_ia64_stubs.c
--- a/tools/libxc/ia64/xc_ia64_stubs.c Mon Sep 29 21:11:25 2008 +0900
+++ b/tools/libxc/ia64/xc_ia64_stubs.c Mon Sep 29 21:12:53 2008 +0900
@@ -60,46 +60,120 @@
? -1 : domctl.u.getdomaininfo.max_pages);
}
-int
-xc_ia64_copy_memmap(int xc_handle, uint32_t domid, shared_info_t *live_shinfo,
- xen_ia64_memmap_info_t **memmap_info_p,
- unsigned long *memmap_info_num_pages_p)
+/*
+ * Copy memmap info from guest domain pages into local buffers.
+ * memmap info can be updated concurrently. So
+ * - copy them into local buffers and use local copy in order to
+ * avoie inconsistent state.
+ * - protect them by seqlock. shared_info->arch.memmap_sequence.
+ * - d->arch.convmem_end (which can be got by XENMEM_maximum_gpfn) is
+ * also updated concurrently. The valuable is increased only.
+ */
+/*#define cpu_relax() ia64_hint(ia64_hint_pause)*/
+#define cpu_relax() sched_yield()
+#define unlikely(x) __builtin_expect((x),0)
+
+static unsigned long
+xc_ia64_mi_read_seqbegin(const shared_info_t *live_shinfo)
{
- unsigned int memmap_info_num_pages;
+ unsigned long ret;
+
+ repeat:
+ ret = live_shinfo->arch.memmap_sequence;
+ xen_rmb();
+ if (unlikely(ret & 1)) {
+ cpu_relax();
+ goto repeat;
+ }
+
+ return ret;
+}
+
+static int
+xc_ia64_mi_read_seqretry(const shared_info_t *live_shinfo, unsigned long start)
+{
+ xen_rmb();
+
+ return (live_shinfo->arch.memmap_sequence != start);
+}
+
+/* copy before use in case someone updating them */
+static int
+__xc_ia64_copy_memmap(int xc_handle, uint32_t domid,
+ shared_info_t *live_shinfo,
+ xen_ia64_memmap_info_t **memmap_info,
+ unsigned long *memmap_info_num_pages)
+{
unsigned long memmap_info_pfn;
unsigned long memmap_size;
+ xen_ia64_memmap_info_t *memmap_info_live;
- xen_ia64_memmap_info_t *memmap_info_live;
- xen_ia64_memmap_info_t *memmap_info;
-
- /* copy before use in case someone updating them */
- memmap_info_num_pages = live_shinfo->arch.memmap_info_num_pages;
+ *memmap_info_num_pages = live_shinfo->arch.memmap_info_num_pages;
memmap_info_pfn = live_shinfo->arch.memmap_info_pfn;
- if (memmap_info_num_pages == 0 || memmap_info_pfn == 0) {
+ if (*memmap_info_num_pages == 0 || memmap_info_pfn == 0) {
ERROR("memmap_info_num_pages 0x%x memmap_info_pfn 0x%lx",
- memmap_info_num_pages, memmap_info_pfn);
+ *memmap_info_num_pages, memmap_info_pfn);
return -1;
}
- memmap_size = memmap_info_num_pages << PAGE_SHIFT;
+ memmap_size = *memmap_info_num_pages << PAGE_SHIFT;
memmap_info_live = xc_map_foreign_range(xc_handle, domid, memmap_size,
PROT_READ, memmap_info_pfn);
if (memmap_info_live == NULL) {
PERROR("Could not map memmap info.");
return -1;
}
- memmap_info = malloc(memmap_size);
- if (memmap_info == NULL) {
+ *memmap_info = malloc(memmap_size);
+ if (*memmap_info == NULL) {
munmap(memmap_info_live, memmap_size);
return -1;
}
- memcpy(memmap_info, memmap_info_live, memmap_size); /* copy before use */
+ memcpy(*memmap_info, memmap_info_live, memmap_size); /* copy before use */
munmap(memmap_info_live, memmap_size);
+ return 0;
+}
+
+int
+xc_ia64_copy_memmap(int xc_handle, uint32_t domid, shared_info_t *live_shinfo,
+ xen_ia64_memmap_info_t **memmap_info_p,
+ unsigned long *memmap_info_num_pages_p)
+{
+ unsigned long gpfn_max_prev;
+ unsigned long gpfn_max_post;
+ unsigned long seq;
+
+ unsigned long memmap_info_num_pages;
+ xen_ia64_memmap_info_t *memmap_info;
+
+ gpfn_max_prev = xc_memory_op(xc_handle, XENMEM_maximum_gpfn, &domid);
+ if (gpfn_max_prev < 0)
+ return -1;
+
+ again:
+ do {
+ seq = xc_ia64_mi_read_seqbegin(live_shinfo);
+ if(__xc_ia64_copy_memmap(xc_handle, domid, live_shinfo,
+ &memmap_info, &memmap_info_num_pages)) {
+ return -1;
+ }
+ } while (xc_ia64_mi_read_seqretry(live_shinfo, seq));
+
+ gpfn_max_post = xc_memory_op(xc_handle, XENMEM_maximum_gpfn, &domid);
+ if (gpfn_max_prev < 0) {
+ free(memmap_info);
+ return -1;
+ }
+ if (gpfn_max_post > gpfn_max_prev) {
+ free(memmap_info);
+ gpfn_max_prev = gpfn_max_post;
+ goto again;
+ }
/* reject unknown memmap */
if (memmap_info->efi_memdesc_size != sizeof(efi_memory_desc_t) ||
(memmap_info->efi_memmap_size / memmap_info->efi_memdesc_size) == 0 ||
- memmap_info->efi_memmap_size > memmap_size - sizeof(memmap_info) ||
+ memmap_info->efi_memmap_size >
+ (memmap_info_num_pages << PAGE_SHIFT) - sizeof(memmap_info) ||
memmap_info->efi_memdesc_version != EFI_MEMORY_DESCRIPTOR_VERSION) {
PERROR("unknown memmap header. defaulting to compat mode.");
free(memmap_info);
memmap-info-tools-stack-seqlock.patch
Description: Text Data
_______________________________________________
Xen-ia64-devel mailing list
Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-ia64-devel
|
Home