Merge tag 'migration-20240311-pull-request' of https://gitlab.com/peterx/qemu into staging

Migration pull request

- Avihai's fix to allow vmstate iterators to not starve for VFIO
- Maksim's fix on additional check on precopy load error
- Fabiano's fix on fdatasync() hang in mapped-ram
- Jonathan's fix on vring cached access over MMIO regions
- Cedric's cleanup patches 1-4 out of his error report series
- Yu's fix for RDMA migration (which used to be broken even for 8.2)
- Anthony's small cleanup/fix on err message
- Steve's patches on privatize migration.h
- Xiang's patchset to enable zero page detections in multifd threads

# -----BEGIN PGP SIGNATURE-----
#
# iIgEABYKADAWIQS5GE3CDMRX2s990ak7X8zN86vXBgUCZe9+uBIccGV0ZXJ4QHJl
# ZGhhdC5jb20ACgkQO1/MzfOr1wamaQD/SvmpMEcuRndT9LPSxzXowAGDZTBpYUfv
# 5XAbx80dS9IBAO8PJJgQJIBHBeacyLBjHP9CsdVtgw5/VW+wCsbfV4AB
# =xavb
# -----END PGP SIGNATURE-----
# gpg: Signature made Mon 11 Mar 2024 21:59:20 GMT
# gpg:                using EDDSA key B9184DC20CC457DACF7DD1A93B5FCCCDF3ABD706
# gpg:                issuer "peterx@redhat.com"
# gpg: Good signature from "Peter Xu <xzpeter@gmail.com>" [marginal]
# gpg:                 aka "Peter Xu <peterx@redhat.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: B918 4DC2 0CC4 57DA CF7D  D1A9 3B5F CCCD F3AB D706

* tag 'migration-20240311-pull-request' of https://gitlab.com/peterx/qemu: (34 commits)
  migration/multifd: Add new migration test cases for legacy zero page checking.
  migration/multifd: Enable multifd zero page checking by default.
  migration/multifd: Implement ram_save_target_page_multifd to handle multifd version of MigrationOps::ram_save_target_page.
  migration/multifd: Implement zero page transmission on the multifd thread.
  migration/multifd: Add new migration option zero-page-detection.
  migration/multifd: Allow clearing of the file_bmap from multifd
  migration/multifd: Allow zero pages in file migration
  migration: purge MigrationState from public interface
  migration: delete unused accessors
  migration: privatize colo interfaces
  migration: migration_file_set_error
  migration: migration_is_device
  migration: migration_thread_is_self
  migration: export vcpu_dirty_limit_period
  migration: export migration_is_running
  migration: export migration_is_active
  migration: export migration_is_setup_or_active
  migration: remove migration.h references
  migration: export fewer options
  migration: Fix format in error message
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 87 insertions, 0 deletions

diff --git a/migration/multifd-zero-page.c b/migration/multifd-zero-page.c
new file mode 100644
index 0000000000..1ba38be636
--- /dev/null
+++ b/migration/multifd-zero-page.c
@@ -0,0 +1,87 @@
+/*
+ * Multifd zero page detection implementation.
+ *
+ * Copyright (c) 2024 Bytedance Inc
+ *
+ * Authors:
+ *  Hao Xiang <hao.xiang@bytedance.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/cutils.h"
+#include "exec/ramblock.h"
+#include "migration.h"
+#include "multifd.h"
+#include "options.h"
+#include "ram.h"
+
+static bool multifd_zero_page_enabled(void)
+{
+    return migrate_zero_page_detection() == ZERO_PAGE_DETECTION_MULTIFD;
+}
+
+static void swap_page_offset(ram_addr_t *pages_offset, int a, int b)
+{
+    ram_addr_t temp;
+
+    if (a == b) {
+        return;
+    }
+
+    temp = pages_offset[a];
+    pages_offset[a] = pages_offset[b];
+    pages_offset[b] = temp;
+}
+
+/**
+ * multifd_send_zero_page_detect: Perform zero page detection on all pages.
+ *
+ * Sorts normal pages before zero pages in p->pages->offset and updates
+ * p->pages->normal_num.
+ *
+ * @param p A pointer to the send params.
+ */
+void multifd_send_zero_page_detect(MultiFDSendParams *p)
+{
+    MultiFDPages_t *pages = p->pages;
+    RAMBlock *rb = pages->block;
+    int i = 0;
+    int j = pages->num - 1;
+
+    if (!multifd_zero_page_enabled()) {
+        pages->normal_num = pages->num;
+        return;
+    }
+
+    /*
+     * Sort the page offset array by moving all normal pages to
+     * the left and all zero pages to the right of the array.
+     */
+    while (i <= j) {
+        uint64_t offset = pages->offset[i];
+
+        if (!buffer_is_zero(rb->host + offset, p->page_size)) {
+            i++;
+            continue;
+        }
+
+        swap_page_offset(pages->offset, i, j);
+        ram_release_page(rb->idstr, offset);
+        j--;
+    }
+
+    pages->normal_num = i;
+}
+
+void multifd_recv_zero_page_process(MultiFDRecvParams *p)
+{
+    for (int i = 0; i < p->zero_num; i++) {
+        void *page = p->host + p->zero[i];
+        if (!buffer_is_zero(page, p->page_size)) {
+            memset(page, 0, p->page_size);
+        }
+    }
+}