From 7fb9ce40e75e06fe6d25c835830832e7c3940d03 Mon Sep 17 00:00:00 2001 From: Yuan Liu Date: Wed, 18 Dec 2024 17:14:11 +0800 Subject: [PATCH] multifd: bugfix for migration using compression methods When compression is enabled on the migration channel and the pages processed are all zero pages, these pages will not be sent and updated on the target side, resulting in incorrect memory data on the source and target sides. The root cause is that all compression methods call multifd_send_prepare_common to determine whether to compress dirty pages, but multifd_send_prepare_common does not update the IOV of MultiFDPacket_t when all dirty pages are zero pages. The solution is to always update the IOV of MultiFDPacket_t regardless of whether the dirty pages are all zero pages. Fixes: 303e6f54f9 ("migration/multifd: Implement zero page transmission on the multifd thread.") Cc: qemu-stable@nongnu.org #9.0+ Signed-off-by: Yuan Liu Reviewed-by: Jason Zeng Reviewed-by: Peter Xu Message-Id: <20241218091413.140396-2-yuan1.liu@intel.com> Signed-off-by: Fabiano Rosas (cherry picked from commit cdc3970f8597ebdc1a4c2090cfb4d11e297329ed) Signed-off-by: Michael Tokarev --- migration/multifd-nocomp.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/migration/multifd-nocomp.c b/migration/multifd-nocomp.c index 55191152f9..2e4aaac285 100644 --- a/migration/multifd-nocomp.c +++ b/migration/multifd-nocomp.c @@ -362,6 +362,7 @@ int multifd_ram_flush_and_sync(void) bool multifd_send_prepare_common(MultiFDSendParams *p) { MultiFDPages_t *pages = &p->data->u.ram; + multifd_send_prepare_header(p); multifd_send_zero_page_detect(p); if (!pages->normal_num) { @@ -369,8 +370,6 @@ bool multifd_send_prepare_common(MultiFDSendParams *p) return false; } - multifd_send_prepare_header(p); - return true; } -- 2.39.5