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![Leonardo Bras](/assets/img/avatar_default.png)
Implement zero copy send on nocomp_send_write(), by making use of QIOChannel writev + flags & flush interface. Change multifd_send_sync_main() so flush_zero_copy() can be called after each iteration in order to make sure all dirty pages are sent before a new iteration is started. It will also flush at the beginning and at the end of migration. Also make it return -1 if flush_zero_copy() fails, in order to cancel the migration process, and avoid resuming the guest in the target host without receiving all current RAM. This will work fine on RAM migration because the RAM pages are not usually freed, and there is no problem on changing the pages content between writev_zero_copy() and the actual sending of the buffer, because this change will dirty the page and cause it to be re-sent on a next iteration anyway. A lot of locked memory may be needed in order to use multifd migration with zero-copy enabled, so disabling the feature should be necessary for low-privileged users trying to perform multifd migrations. Signed-off-by: Leonardo Bras <leobras@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20220513062836.965425-9-leobras@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
186 lines
5.5 KiB
C
186 lines
5.5 KiB
C
/*
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* Multifd common functions
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*
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* Copyright (c) 2019-2020 Red Hat Inc
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*
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* Authors:
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* Juan Quintela <quintela@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#ifndef QEMU_MIGRATION_MULTIFD_H
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#define QEMU_MIGRATION_MULTIFD_H
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int multifd_save_setup(Error **errp);
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void multifd_save_cleanup(void);
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int multifd_load_setup(Error **errp);
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int multifd_load_cleanup(Error **errp);
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bool multifd_recv_all_channels_created(void);
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bool multifd_recv_new_channel(QIOChannel *ioc, Error **errp);
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void multifd_recv_sync_main(void);
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int multifd_send_sync_main(QEMUFile *f);
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int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset);
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/* Multifd Compression flags */
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#define MULTIFD_FLAG_SYNC (1 << 0)
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/* We reserve 3 bits for compression methods */
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#define MULTIFD_FLAG_COMPRESSION_MASK (7 << 1)
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/* we need to be compatible. Before compression value was 0 */
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#define MULTIFD_FLAG_NOCOMP (0 << 1)
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#define MULTIFD_FLAG_ZLIB (1 << 1)
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#define MULTIFD_FLAG_ZSTD (2 << 1)
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/* This value needs to be a multiple of qemu_target_page_size() */
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#define MULTIFD_PACKET_SIZE (512 * 1024)
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typedef struct {
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uint32_t magic;
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uint32_t version;
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uint32_t flags;
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/* maximum number of allocated pages */
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uint32_t pages_alloc;
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/* non zero pages */
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uint32_t normal_pages;
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/* size of the next packet that contains pages */
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uint32_t next_packet_size;
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uint64_t packet_num;
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uint64_t unused[4]; /* Reserved for future use */
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char ramblock[256];
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uint64_t offset[];
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} __attribute__((packed)) MultiFDPacket_t;
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typedef struct {
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/* number of used pages */
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uint32_t num;
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/* number of allocated pages */
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uint32_t allocated;
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/* global number of generated multifd packets */
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uint64_t packet_num;
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/* offset of each page */
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ram_addr_t *offset;
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RAMBlock *block;
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} MultiFDPages_t;
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typedef struct {
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/* this fields are not changed once the thread is created */
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/* channel number */
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uint8_t id;
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/* channel thread name */
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char *name;
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/* channel thread id */
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QemuThread thread;
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/* communication channel */
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QIOChannel *c;
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/* sem where to wait for more work */
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QemuSemaphore sem;
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/* this mutex protects the following parameters */
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QemuMutex mutex;
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/* is this channel thread running */
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bool running;
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/* should this thread finish */
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bool quit;
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/* is the yank function registered */
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bool registered_yank;
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/* thread has work to do */
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int pending_job;
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/* array of pages to sent */
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MultiFDPages_t *pages;
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/* packet allocated len */
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uint32_t packet_len;
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/* pointer to the packet */
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MultiFDPacket_t *packet;
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/* multifd flags for sending ram */
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int write_flags;
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/* multifd flags for each packet */
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uint32_t flags;
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/* size of the next packet that contains pages */
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uint32_t next_packet_size;
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/* global number of generated multifd packets */
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uint64_t packet_num;
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/* thread local variables */
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/* packets sent through this channel */
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uint64_t num_packets;
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/* non zero pages sent through this channel */
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uint64_t total_normal_pages;
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/* syncs main thread and channels */
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QemuSemaphore sem_sync;
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/* buffers to send */
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struct iovec *iov;
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/* number of iovs used */
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uint32_t iovs_num;
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/* Pages that are not zero */
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ram_addr_t *normal;
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/* num of non zero pages */
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uint32_t normal_num;
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/* used for compression methods */
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void *data;
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} MultiFDSendParams;
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typedef struct {
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/* this fields are not changed once the thread is created */
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/* channel number */
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uint8_t id;
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/* channel thread name */
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char *name;
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/* channel thread id */
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QemuThread thread;
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/* communication channel */
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QIOChannel *c;
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/* this mutex protects the following parameters */
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QemuMutex mutex;
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/* is this channel thread running */
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bool running;
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/* should this thread finish */
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bool quit;
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/* ramblock host address */
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uint8_t *host;
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/* packet allocated len */
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uint32_t packet_len;
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/* pointer to the packet */
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MultiFDPacket_t *packet;
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/* multifd flags for each packet */
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uint32_t flags;
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/* global number of generated multifd packets */
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uint64_t packet_num;
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/* thread local variables */
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/* size of the next packet that contains pages */
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uint32_t next_packet_size;
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/* packets sent through this channel */
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uint64_t num_packets;
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/* non zero pages recv through this channel */
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uint64_t total_normal_pages;
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/* syncs main thread and channels */
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QemuSemaphore sem_sync;
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/* buffers to recv */
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struct iovec *iov;
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/* Pages that are not zero */
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ram_addr_t *normal;
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/* num of non zero pages */
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uint32_t normal_num;
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/* used for de-compression methods */
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void *data;
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} MultiFDRecvParams;
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typedef struct {
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/* Setup for sending side */
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int (*send_setup)(MultiFDSendParams *p, Error **errp);
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/* Cleanup for sending side */
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void (*send_cleanup)(MultiFDSendParams *p, Error **errp);
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/* Prepare the send packet */
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int (*send_prepare)(MultiFDSendParams *p, Error **errp);
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/* Setup for receiving side */
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int (*recv_setup)(MultiFDRecvParams *p, Error **errp);
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/* Cleanup for receiving side */
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void (*recv_cleanup)(MultiFDRecvParams *p);
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/* Read all pages */
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int (*recv_pages)(MultiFDRecvParams *p, Error **errp);
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} MultiFDMethods;
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void multifd_register_ops(int method, MultiFDMethods *ops);
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#endif
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