Re: [PATCH 07/20] qemu: QEMU_SAVE_VERSION: Bump to version 3

QEMU's new mapped-ram stream format [1] is incompatible with the existing sequential stream format. An older libvirt+QEMU that does not support mapped-ram must not attempt to restore a mapped-ram saved image. Currently the only way to achieve this is to bump QEMU_SAVE_VERSION. To avoid future version bumps, add a new 'features' element to the saved image header. The element is used now to indicate the use of mapped-ram feature, and provides a mechanism to support future save image features. [1] https://gitlab.com/qemu-project/qemu/-/blob/master/docs/devel/migration/m... Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; --- src/qemu/qemu_saveimage.c | 7 +++++++ src/qemu/qemu_saveimage.h | 9 +++++++-- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/src/qemu/qemu_saveimage.c b/src/qemu/qemu_saveimage.c index 018ab5a222..50fec33f54 100644 --- a/src/qemu/qemu_saveimage.c +++ b/src/qemu/qemu_saveimage.c @@ -74,6 +74,7 @@ qemuSaveImageBswapHeader(virQEMUSaveHeader *hdr) hdr->was_running = GUINT32_SWAP_LE_BE(hdr->was_running); hdr->compressed = GUINT32_SWAP_LE_BE(hdr->compressed); hdr->cookieOffset = GUINT32_SWAP_LE_BE(hdr->cookieOffset); + hdr->features = GUINT32_SWAP_LE_BE(hdr->features); } @@ -637,6 +638,12 @@ qemuSaveImageOpen(virQEMUDriver *driver, return -1; } + if (header->features && header->features != QEMU_SAVE_FEATURE_MAPPED_RAM) {

+ virReportError(VIR_ERR_OPERATION_FAILED, "%s", + _("image contains unsupported features)")); + return -1; + } + if (header->cookieOffset) xml_len = header->cookieOffset; else diff --git a/src/qemu/qemu_saveimage.h b/src/qemu/qemu_saveimage.h index e541792153..9dd7de292d 100644 --- a/src/qemu/qemu_saveimage.h +++ b/src/qemu/qemu_saveimage.h @@ -28,10 +28,14 @@ */ #define QEMU_SAVE_MAGIC "LibvirtQemudSave" #define QEMU_SAVE_PARTIAL "LibvirtQemudPart" -#define QEMU_SAVE_VERSION 2 +#define QEMU_SAVE_VERSION 3

G_STATIC_ASSERT(sizeof(QEMU_SAVE_MAGIC) == sizeof(QEMU_SAVE_PARTIAL)); +typedef enum { + QEMU_SAVE_FEATURE_MAPPED_RAM = 1 << 0, +} qemuSaveFeatures; + typedef struct _virQEMUSaveHeader virQEMUSaveHeader; struct _virQEMUSaveHeader { char magic[sizeof(QEMU_SAVE_MAGIC)-1]; @@ -40,7 +44,8 @@ struct _virQEMUSaveHeader { uint32_t was_running; uint32_t compressed; uint32_t cookieOffset; - uint32_t unused[14]; + uint32_t features;

+ uint32_t unused[13]; }; -- 2.35.3