From 6bcb05fc4211d2bd88fe73c65e93602428c51e5b Mon Sep 17 00:00:00 2001 From: Wei Wang Date: Tue, 11 Dec 2018 16:24:50 +0800 Subject: [PATCH] migration: API to clear bits of guest free pages from the dirty bitmap This patch adds an API to clear bits corresponding to guest free pages from the dirty bitmap. Spilt the free page block if it crosses the QEMU RAMBlock boundary. Signed-off-by: Wei Wang CC: Dr. David Alan Gilbert CC: Juan Quintela CC: Michael S. Tsirkin CC: Peter Xu Reviewed-by: Peter Xu Message-Id: <1544516693-5395-5-git-send-email-wei.w.wang@intel.com> Signed-off-by: Dr. David Alan Gilbert --- include/migration/misc.h | 2 ++ migration/ram.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/include/migration/misc.h b/include/migration/misc.h index 6f9df74436..81ee347e35 100644 --- a/include/migration/misc.h +++ b/include/migration/misc.h @@ -14,12 +14,14 @@ #ifndef MIGRATION_MISC_H #define MIGRATION_MISC_H +#include "exec/cpu-common.h" #include "qemu/notify.h" #include "qapi/qapi-types-net.h" /* migration/ram.c */ void ram_mig_init(void); +void qemu_guest_free_page_hint(void *addr, size_t len); /* migration/block.c */ diff --git a/migration/ram.c b/migration/ram.c index 0747873ca9..32c0dbb98a 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -3182,6 +3182,53 @@ static void ram_state_resume_prepare(RAMState *rs, QEMUFile *out) } /* + * This function clears bits of the free pages reported by the caller from the + * migration dirty bitmap. @addr is the host address corresponding to the + * start of the continuous guest free pages, and @len is the total bytes of + * those pages. + */ +void qemu_guest_free_page_hint(void *addr, size_t len) +{ + RAMBlock *block; + ram_addr_t offset; + size_t used_len, start, npages; + MigrationState *s = migrate_get_current(); + + /* This function is currently expected to be used during live migration */ + if (!migration_is_setup_or_active(s->state)) { + return; + } + + for (; len > 0; len -= used_len, addr += used_len) { + block = qemu_ram_block_from_host(addr, false, &offset); + if (unlikely(!block || offset >= block->used_length)) { + /* + * The implementation might not support RAMBlock resize during + * live migration, but it could happen in theory with future + * updates. So we add a check here to capture that case. + */ + error_report_once("%s unexpected error", __func__); + return; + } + + if (len <= block->used_length - offset) { + used_len = len; + } else { + used_len = block->used_length - offset; + } + + start = offset >> TARGET_PAGE_BITS; + npages = used_len >> TARGET_PAGE_BITS; + + qemu_mutex_lock(&ram_state->bitmap_mutex); + ram_state->migration_dirty_pages -= + bitmap_count_one_with_offset(block->bmap, start, npages); + bitmap_clear(block->bmap, start, npages); + qemu_mutex_unlock(&ram_state->bitmap_mutex); + } +} + +/* * Each of ram_save_setup, ram_save_iterate and ram_save_complete has * long-running RCU critical section. When rcu-reclaims in the code * start to become numerous it will be necessary to reduce the -- 2.11.4.GIT