Currently, hvmloader uses SMBIOS 2.4, however, when using OVMF, the
SMBIOS is patched to 2.8, which has clarified the UUID format (as GUID).
In Linux, if the SMBIOS version is >= 2.6, the GUID format is used, else
(undefined as per SMBIOS spec), big endian is used (used by Xen). Therefore,
you have a endian mismatch causing the UUIDs to mismatch in the guest.
$ cat /sys/hypervisor/uuid
e865e63f-3d30-4f0b-83e0-8fdfc1e30eb7
$ cat /sys/devices/virtual/dmi/id/product_uuid
3fe665e8-303d-0b4f-83e0-8fdfc1e30eb7
$ cat /sys/devices/virtual/dmi/id/product_serial
e865e63f-3d30-4f0b-83e0-8fdfc1e30eb7
This patch updates the SMBIOS version from 2.4 to 2.6 and fixup the UUID
written in the table; which effectively fix this endianness mismatch with
OVMF; while the UUID displayed by Linux is still the same for SeaBIOS.
Signed-off-by: Teddy Astie <teddy.as...@vates.tech>
---
This effectively changes the UUID seen with UEFI guests as it was
actually inconsistent with SeaBIOS and SMBIOS expectations.
---
tools/firmware/hvmloader/smbios.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/tools/firmware/hvmloader/smbios.c
b/tools/firmware/hvmloader/smbios.c
index 6bcdcc233a..f4822ae6f8 100644
--- a/tools/firmware/hvmloader/smbios.c
+++ b/tools/firmware/hvmloader/smbios.c
@@ -352,7 +352,7 @@ smbios_entry_point_init(void *start,
memcpy(ep->anchor_string, "_SM_", 4);
ep->length = 0x1f;
ep->smbios_major_version = 2;
- ep->smbios_minor_version = 4;
+ ep->smbios_minor_version = 6;
ep->max_structure_size = max_structure_size;
ep->entry_point_revision = 0;
memcpy(ep->intermediate_anchor_string, "_DMI_", 5);
@@ -462,7 +462,23 @@ smbios_type_1_init(void *start, const char *xen_version,
p->version_str = 3;
p->serial_number_str = 4;
- memcpy(p->uuid, uuid, 16);
+ /*
+ * Xen uses OSF DCE UUIDs which is fully big endian, however,
+ * GUIDs (which requirement is clarified by SMBIOS >= 2.6) has the
+ * first 3 components appearing as being little endian and the rest
+ * as still being big endian.
+ */
+ /* First component */
+ for ( unsigned int i = 0; i < 4; i++ )
+ p->uuid[i] = uuid[4 - i - 1];
+ /* Second component */
+ p->uuid[4] = uuid[5];
+ p->uuid[5] = uuid[4];
+ /* Third component */
+ p->uuid[6] = uuid[7];
+ p->uuid[7] = uuid[6];
+ /* Rest */
+ memcpy(p->uuid + 8, uuid + 8, 8);
p->wake_up_type = 0x06; /* power switch */
p->sku_str = 0;
--
2.50.1
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