From: "Denis V. Lunev" <[email protected]> memsave and pmemsave read guest memory and write it to a file, with no guard at all. They run on the main thread with the BQL held, so on a postcopy destination touching a not-yet-received page deadlocks: the thread blocks on the userfault while the postcopy incoming path waits for the BQL to install that page. During precopy the read returns incomplete state instead.
Refuse both while guest RAM is still being received, using the same migration_guest_ram_loading() check as dump-guest-memory. Signed-off-by: Denis V. Lunev <[email protected]> Reviewed-by: Marc-André Lureau <[email protected]> Message-Id: <[email protected]> --- system/cpus.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/system/cpus.c b/system/cpus.c index 49f6daec3cd..b31c825b464 100644 --- a/system/cpus.c +++ b/system/cpus.c @@ -43,6 +43,7 @@ #include "system/physmem.h" #include "system/replay.h" #include "system/runstate.h" +#include "migration/misc.h" #include "system/cpu-timers.h" #include "system/whpx.h" #include "hw/core/boards.h" @@ -843,6 +844,11 @@ void qmp_memsave(uint64_t addr, uint64_t size, const char *filename, uint8_t buf[1024]; uint64_t orig_addr = addr, orig_size = size; + if (migration_guest_ram_loading()) { + error_setg(errp, "Guest memory access not allowed during migration"); + return; + } + if (!has_cpu) { cpu_index = 0; } @@ -889,6 +895,11 @@ void qmp_pmemsave(uint64_t addr, uint64_t size, const char *filename, uint64_t l; uint8_t buf[1024]; + if (migration_guest_ram_loading()) { + error_setg(errp, "Guest memory access not allowed during migration"); + return; + } + f = fopen(filename, "wb"); if (!f) { error_setg_file_open(errp, errno, filename); -- 2.54.0
