Commit 61b67d47 authored by Daniel P. Berrangé's avatar Daniel P. Berrangé Committed by Amit Shah
Browse files

migration: convert post-copy to use QIOChannelBuffer 



The post-copy code does some I/O to/from an intermediate
in-memory buffer rather than direct to the underlying
I/O channel. Switch this code to use QIOChannelBuffer
instead of QEMUSizedBuffer.

Reviewed-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Message-Id: <1461751518-12128-12-git-send-email-berrange@redhat.com>
Signed-off-by: default avatarAmit Shah <amit.shah@redhat.com>
parent d59ce6f3

docs/migration.txt

+2 −2
Original line number Diff line number Diff line
@@ -403,8 +403,8 @@ listen thread: --- page -- page -- page -- page -- page -- 


On receipt of CMD_PACKAGED (1)

   All the data associated with the package - the ( ... ) section in the

diagram - is read into memory (into a QEMUSizedBuffer), and the main thread

recurses into qemu_loadvm_state_main to process the contents of the package (2)

diagram - is read into memory, and the main thread recurses into

qemu_loadvm_state_main to process the contents of the package (2)

which contains commands (3,6) and devices (4...)



On receipt of 'postcopy listen' - 3 -(i.e. the 1st command in the package)

include/sysemu/sysemu.h

+1 −1
Original line number Diff line number Diff line
@@ -119,7 +119,7 @@ void qemu_savevm_command_send(QEMUFile *f, enum qemu_vm_cmd command, 
                              uint16_t len, uint8_t *data);

void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);

void qemu_savevm_send_open_return_path(QEMUFile *f);

int qemu_savevm_send_packaged(QEMUFile *f, const QEMUSizedBuffer *qsb);

int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len);

void qemu_savevm_send_postcopy_advise(QEMUFile *f);

void qemu_savevm_send_postcopy_listen(QEMUFile *f);

void qemu_savevm_send_postcopy_run(QEMUFile *f);

migration/migration.c

+7 −8
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include "qom/cpu.h"

#include "exec/memory.h"

#include "exec/address-spaces.h"

#include "io/channel-buffer.h"



#define MAX_THROTTLE  (32 << 20)      /* Migration transfer speed throttling */
@@ -1457,7 +1458,8 @@ static int await_return_path_close_on_source(MigrationState *ms) 
static int postcopy_start(MigrationState *ms, bool *old_vm_running)

{

    int ret;

    const QEMUSizedBuffer *qsb;

    QIOChannelBuffer *bioc;

    QEMUFile *fb;

    int64_t time_at_stop = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);

    migrate_set_state(&ms->state, MIGRATION_STATUS_ACTIVE,

                      MIGRATION_STATUS_POSTCOPY_ACTIVE);
@@ -1516,11 +1518,9 @@ static int postcopy_start(MigrationState *ms, bool *old_vm_running) 
     * So we wrap the device state up in a package with a length at the start;

     * to do this we use a qemu_buf to hold the whole of the device state.

     */

    QEMUFile *fb = qemu_bufopen("w", NULL);

    if (!fb) {

        error_report("Failed to create buffered file");

        goto fail;

    }

    bioc = qio_channel_buffer_new(4096);

    fb = qemu_fopen_channel_output(QIO_CHANNEL(bioc));

    object_unref(OBJECT(bioc));



    /*

     * Make sure the receiver can get incoming pages before we send the rest
@@ -1534,10 +1534,9 @@ static int postcopy_start(MigrationState *ms, bool *old_vm_running) 
    qemu_savevm_send_postcopy_run(fb);



    /* <><> end of stuff going into the package */

    qsb = qemu_buf_get(fb);



    /* Now send that blob */

    if (qemu_savevm_send_packaged(ms->to_dst_file, qsb)) {

    if (qemu_savevm_send_packaged(ms->to_dst_file, bioc->data, bioc->usage)) {

        goto fail_closefb;

    }

    qemu_fclose(fb);

migration/savevm.c

+16 −31
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ 
#include "block/snapshot.h"

#include "block/qapi.h"

#include "qemu/cutils.h"

#include "io/channel-buffer.h"



#ifndef ETH_P_RARP

#define ETH_P_RARP 0x8035
@@ -760,10 +761,8 @@ void qemu_savevm_send_open_return_path(QEMUFile *f) 
 *    0 on success

 *    -ve on error

 */

int qemu_savevm_send_packaged(QEMUFile *f, const QEMUSizedBuffer *qsb)

int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len)

{

    size_t cur_iov;

    size_t len = qsb_get_length(qsb);

    uint32_t tmp;



    if (len > MAX_VM_CMD_PACKAGED_SIZE) {
@@ -777,18 +776,7 @@ int qemu_savevm_send_packaged(QEMUFile *f, const QEMUSizedBuffer *qsb) 
    trace_qemu_savevm_send_packaged();

    qemu_savevm_command_send(f, MIG_CMD_PACKAGED, 4, (uint8_t *)&tmp);



    /* all the data follows (concatinating the iov's) */

    for (cur_iov = 0; cur_iov < qsb->n_iov; cur_iov++) {

        /* The iov entries are partially filled */

        size_t towrite = MIN(qsb->iov[cur_iov].iov_len, len);

        len -= towrite;



        if (!towrite) {

            break;

        }



        qemu_put_buffer(f, qsb->iov[cur_iov].iov_base, towrite);

    }

    qemu_put_buffer(f, buf, len);



    return 0;

}
@@ -1578,39 +1566,36 @@ static int loadvm_postcopy_handle_run(MigrationIncomingState *mis) 
static int loadvm_handle_cmd_packaged(MigrationIncomingState *mis)

{

    int ret;

    uint8_t *buffer;

    uint32_t length;

    QEMUSizedBuffer *qsb;

    size_t length;

    QIOChannelBuffer *bioc;



    length = qemu_get_be32(mis->from_src_file);

    trace_loadvm_handle_cmd_packaged(length);



    if (length > MAX_VM_CMD_PACKAGED_SIZE) {

        error_report("Unreasonably large packaged state: %u", length);

        error_report("Unreasonably large packaged state: %zu", length);

        return -1;

    }

    buffer = g_malloc0(length);

    ret = qemu_get_buffer(mis->from_src_file, buffer, (int)length);



    bioc = qio_channel_buffer_new(length);

    ret = qemu_get_buffer(mis->from_src_file,

                          bioc->data,

                          length);

    if (ret != length) {

        g_free(buffer);

        error_report("CMD_PACKAGED: Buffer receive fail ret=%d length=%d",

        object_unref(OBJECT(bioc));

        error_report("CMD_PACKAGED: Buffer receive fail ret=%d length=%zu",

                     ret, length);

        return (ret < 0) ? ret : -EAGAIN;

    }

    bioc->usage += length;

    trace_loadvm_handle_cmd_packaged_received(ret);



    /* Setup a dummy QEMUFile that actually reads from the buffer */

    qsb = qsb_create(buffer, length);

    g_free(buffer); /* Because qsb_create copies */

    if (!qsb) {

        error_report("Unable to create qsb");

    }

    QEMUFile *packf = qemu_bufopen("r", qsb);

    QEMUFile *packf = qemu_fopen_channel_input(QIO_CHANNEL(bioc));



    ret = qemu_loadvm_state_main(packf, mis);

    trace_loadvm_handle_cmd_packaged_main(ret);

    qemu_fclose(packf);

    qsb_free(qsb);

    object_unref(OBJECT(bioc));



    return ret;

}