From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44422) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZuP1y-0000XE-VO for qemu-devel@nongnu.org; Thu, 05 Nov 2015 13:13:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZuP1x-00043A-Oq for qemu-devel@nongnu.org; Thu, 05 Nov 2015 13:13:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43462) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZuP1x-000433-II for qemu-devel@nongnu.org; Thu, 05 Nov 2015 13:13:01 -0500 From: "Dr. David Alan Gilbert (git)" Date: Thu, 5 Nov 2015 18:11:04 +0000 Message-Id: <1446747083-18205-38-git-send-email-dgilbert@redhat.com> In-Reply-To: <1446747083-18205-1-git-send-email-dgilbert@redhat.com> References: <1446747083-18205-1-git-send-email-dgilbert@redhat.com> Subject: [Qemu-devel] [PATCH v9 37/56] postcopy: ram_enable_notify to switch on userfault 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, liang.z.li@intel.com, luis@cs.umu.se, bharata@linux.vnet.ibm.com, amit.shah@redhat.com, pbonzini@redhat.com, david@gibson.dropbear.id.au From: "Dr. David Alan Gilbert" Mark the area of RAM as 'userfault' Start up a fault-thread to handle any userfaults we might receive from it (to be filled in later) Signed-off-by: Dr. David Alan Gilbert Reviewed-by: David Gibson Reviewed-by: Juan Quintela Reviewed-by: Amit Shah --- include/migration/migration.h | 3 ++ include/migration/postcopy-ram.h | 6 ++++ migration/postcopy-ram.c | 68 ++++++++++++++++++++++++++++++++++++++++ migration/savevm.c | 9 ++++++ 4 files changed, 86 insertions(+) diff --git a/include/migration/migration.h b/include/migration/migration.h index 6e42b58..2ad0d2b 100644 --- a/include/migration/migration.h +++ b/include/migration/migration.h @@ -86,6 +86,9 @@ struct MigrationIncomingState { */ QemuEvent main_thread_load_event; + QemuThread fault_thread; + QemuSemaphore fault_thread_sem; + /* For the kernel to send us notifications */ int userfault_fd; QEMUFile *to_src_file; diff --git a/include/migration/postcopy-ram.h b/include/migration/postcopy-ram.h index f87020c..b10c03d 100644 --- a/include/migration/postcopy-ram.h +++ b/include/migration/postcopy-ram.h @@ -17,6 +17,12 @@ bool postcopy_ram_supported_by_host(void); /* + * Make all of RAM sensitive to accesses to areas that haven't yet been written + * and wire up anything necessary to deal with it. + */ +int postcopy_ram_enable_notify(MigrationIncomingState *mis); + +/* * Initialise postcopy-ram, setting the RAM to a state where we can go into * postcopy later; must be called prior to any precopy. * called from ram.c's similarly named ram_postcopy_incoming_init diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 2e72d35..a7d6c9f 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -275,6 +275,69 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) return 0; } +/* + * Mark the given area of RAM as requiring notification to unwritten areas + * Used as a callback on qemu_ram_foreach_block. + * host_addr: Base of area to mark + * offset: Offset in the whole ram arena + * length: Length of the section + * opaque: MigrationIncomingState pointer + * Returns 0 on success + */ +static int ram_block_enable_notify(const char *block_name, void *host_addr, + ram_addr_t offset, ram_addr_t length, + void *opaque) +{ + MigrationIncomingState *mis = opaque; + struct uffdio_register reg_struct; + + reg_struct.range.start = (uintptr_t)host_addr; + reg_struct.range.len = length; + reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING; + + /* Now tell our userfault_fd that it's responsible for this area */ + if (ioctl(mis->userfault_fd, UFFDIO_REGISTER, ®_struct)) { + error_report("%s userfault register: %s", __func__, strerror(errno)); + return -1; + } + + return 0; +} + +/* + * Handle faults detected by the USERFAULT markings + */ +static void *postcopy_ram_fault_thread(void *opaque) +{ + MigrationIncomingState *mis = opaque; + + fprintf(stderr, "postcopy_ram_fault_thread\n"); + /* TODO: In later patch */ + qemu_sem_post(&mis->fault_thread_sem); + while (1) { + /* TODO: In later patch */ + } + + return NULL; +} + +int postcopy_ram_enable_notify(MigrationIncomingState *mis) +{ + /* Create the fault handler thread and wait for it to be ready */ + qemu_sem_init(&mis->fault_thread_sem, 0); + qemu_thread_create(&mis->fault_thread, "postcopy/fault", + postcopy_ram_fault_thread, mis, QEMU_THREAD_JOINABLE); + qemu_sem_wait(&mis->fault_thread_sem); + qemu_sem_destroy(&mis->fault_thread_sem); + + /* Mark so that we get notified of accesses to unwritten areas */ + if (qemu_ram_foreach_block(ram_block_enable_notify, mis)) { + return -1; + } + + return 0; +} + #else /* No target OS support, stubs just fail */ bool postcopy_ram_supported_by_host(void) @@ -299,6 +362,11 @@ int postcopy_ram_discard_range(MigrationIncomingState *mis, uint8_t *start, { assert(0); } + +int postcopy_ram_enable_notify(MigrationIncomingState *mis) +{ + assert(0); +} #endif /* ------------------------------------------------------------------------- */ diff --git a/migration/savevm.c b/migration/savevm.c index 8cf4c53..9fd276e 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1381,6 +1381,15 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis) return -1; } + /* + * Sensitise RAM - can now generate requests for blocks that don't exist + * However, at this point the CPU shouldn't be running, and the IO + * shouldn't be doing anything yet so don't actually expect requests + */ + if (postcopy_ram_enable_notify(mis)) { + return -1; + } + /* TODO start up the postcopy listening thread */ return 0; } -- 2.5.0