From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35010) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YQfDY-0001nN-5P for qemu-devel@nongnu.org; Wed, 25 Feb 2015 11:53:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YQfDT-0001Qr-11 for qemu-devel@nongnu.org; Wed, 25 Feb 2015 11:53:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55178) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YQfDS-0001Qi-P2 for qemu-devel@nongnu.org; Wed, 25 Feb 2015 11:53:42 -0500 From: "Dr. David Alan Gilbert (git)" Date: Wed, 25 Feb 2015 16:51:59 +0000 Message-Id: <1424883128-9841-37-git-send-email-dgilbert@redhat.com> In-Reply-To: <1424883128-9841-1-git-send-email-dgilbert@redhat.com> References: <1424883128-9841-1-git-send-email-dgilbert@redhat.com> Subject: [Qemu-devel] [PATCH v5 36/45] Postcopy: Use helpers to map pages during migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, quintela@redhat.com, amit.shah@redhat.com, pbonzini@redhat.com, yanghy@cn.fujitsu.com, david@gibson.dropbear.id.au From: "Dr. David Alan Gilbert" In postcopy, the destination guest is running at the same time as it's receiving pages; as we receive new pages we must put them into the guests address space atomically to avoid a running CPU accessing a partially written page. Use the helpers in postcopy-ram.c to map these pages. Note, gcc 4.9.2 is giving me false uninitialized warnings in ram_load's switch, so anything conditionally set at the start of the switch needs initializing; filed as https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64614 Signed-off-by: Dr. David Alan Gilbert --- arch_init.c | 137 ++++++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 111 insertions(+), 26 deletions(-) diff --git a/arch_init.c b/arch_init.c index acf65e1..7a1c9ea 100644 --- a/arch_init.c +++ b/arch_init.c @@ -1479,9 +1479,39 @@ static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host) return 0; } +/* + * Helper for host_from_stream_offset in the succesful case. + * Returns the host pointer for the given block and offset + * calling the postcopy hook and filling in *rb. + */ +static void *host_with_postcopy_hook(MigrationIncomingState *mis, + ram_addr_t offset, + RAMBlock *block, + RAMBlock **rb) +{ + if (rb) { + *rb = block; + } + + postcopy_hook_early_receive(mis, + (offset + block->offset) >> TARGET_PAGE_BITS); + return memory_region_get_ram_ptr(block->mr) + offset; +} + +/* + * Read a RAMBlock ID from the stream f, find the host address of the + * start of that block and add on 'offset' + * + * f: Stream to read from + * mis: MigrationIncomingState + * offset: Offset within the block + * flags: Page flags (mostly to see if it's a continuation of previous block) + * rb: Pointer to RAMBlock* that gets filled in with the RB we find + */ static inline void *host_from_stream_offset(QEMUFile *f, + MigrationIncomingState *mis, ram_addr_t offset, - int flags) + int flags, RAMBlock **rb) { static RAMBlock *block = NULL; char id[256]; @@ -1492,8 +1522,7 @@ static inline void *host_from_stream_offset(QEMUFile *f, error_report("Ack, bad migration stream!"); return NULL; } - - return memory_region_get_ram_ptr(block->mr) + offset; + return host_with_postcopy_hook(mis, offset, block, rb); } len = qemu_get_byte(f); @@ -1503,7 +1532,7 @@ static inline void *host_from_stream_offset(QEMUFile *f, QTAILQ_FOREACH(block, &ram_list.blocks, next) { if (!strncmp(id, block->idstr, sizeof(id)) && block->max_length > offset) { - return memory_region_get_ram_ptr(block->mr) + offset; + return host_with_postcopy_hook(mis, offset, block, rb); } } @@ -1537,6 +1566,15 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) { int flags = 0, ret = 0; static uint64_t seq_iter; + /* + * System is running in postcopy mode, page inserts to host memory must be + * atomic + */ + MigrationIncomingState *mis = migration_incoming_get_current(); + bool postcopy_running = postcopy_state_get(mis) >= + POSTCOPY_INCOMING_LISTENING; + void *postcopy_host_page = NULL; + bool postcopy_place_needed = false; seq_iter++; @@ -1545,14 +1583,57 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) } while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) { + RAMBlock *rb = 0; /* =0 needed to silence compiler */ ram_addr_t addr, total_ram_bytes; - void *host; + void *host = 0; + void *page_buffer = 0; uint8_t ch; + bool all_zero = false; addr = qemu_get_be64(f); flags = addr & ~TARGET_PAGE_MASK; addr &= TARGET_PAGE_MASK; + if (flags & (RAM_SAVE_FLAG_COMPRESS | RAM_SAVE_FLAG_PAGE | + RAM_SAVE_FLAG_XBZRLE)) { + host = host_from_stream_offset(f, mis, addr, flags, &rb); + if (!host) { + error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); + ret = -EINVAL; + break; + } + if (!postcopy_running) { + page_buffer = host; + } else { + /* + * Postcopy requires that we place whole host pages atomically. + * To make it atomic, the data is read into a temporary page + * that's moved into place later. + * The migration protocol uses, possibly smaller, target-pages + * however the source ensures it always sends all the components + * of a host page in order. + */ + if (!postcopy_host_page) { + postcopy_host_page = postcopy_get_tmp_page(mis); + } + page_buffer = postcopy_host_page + + ((uintptr_t)host & ~qemu_host_page_mask); + /* If all TP are zero then we can optimise the place */ + if (!((uintptr_t)host & ~qemu_host_page_mask)) { + all_zero = true; + } + + /* + * If it's the last part of a host page then we place the host + * page + */ + postcopy_place_needed = (((uintptr_t)host + TARGET_PAGE_SIZE) & + ~qemu_host_page_mask) == 0; + } + } else { + postcopy_place_needed = false; + } + switch (flags & ~RAM_SAVE_FLAG_CONTINUE) { case RAM_SAVE_FLAG_MEM_SIZE: /* Synchronize RAM block list */ @@ -1590,32 +1671,27 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) } break; case RAM_SAVE_FLAG_COMPRESS: - host = host_from_stream_offset(f, addr, flags); - if (!host) { - error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); - ret = -EINVAL; - break; - } - ch = qemu_get_byte(f); - ram_handle_compressed(host, ch, TARGET_PAGE_SIZE); - break; - case RAM_SAVE_FLAG_PAGE: - host = host_from_stream_offset(f, addr, flags); - if (!host) { - error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); - ret = -EINVAL; - break; + if (!postcopy_running) { + ram_handle_compressed(host, ch, TARGET_PAGE_SIZE); + } else { + memset(page_buffer, ch, TARGET_PAGE_SIZE); + if (ch) { + all_zero = false; + } } + break; - qemu_get_buffer(f, host, TARGET_PAGE_SIZE); + case RAM_SAVE_FLAG_PAGE: + all_zero = false; + qemu_get_buffer(f, page_buffer, TARGET_PAGE_SIZE); break; + case RAM_SAVE_FLAG_XBZRLE: - host = host_from_stream_offset(f, addr, flags); - if (!host) { - error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); - ret = -EINVAL; - break; + all_zero = false; + if (postcopy_running) { + error_report("XBZRLE RAM block in postcopy mode @%zx\n", addr); + return -EINVAL; } if (load_xbzrle(f, addr, host) < 0) { @@ -1637,6 +1713,15 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) ret = -EINVAL; } } + + if (postcopy_place_needed) { + /* This gets called at the last target page in the host page */ + ret = postcopy_place_page(mis, host + TARGET_PAGE_SIZE - + qemu_host_page_size, + postcopy_host_page, + (addr + rb->offset) >> TARGET_PAGE_BITS, + all_zero); + } if (!ret) { ret = qemu_file_get_error(f); } -- 2.1.0