[PATCH v2 1/3] xen: Define xen_domain_handle_t encoding and formatting

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

xen_domain_handle_t is defined as a opaque 16-bytes blob, but is
commonly used by toolstack and guest as a big-endian encoded and
formatted UUID (alike RFC 9562).

Clarify the definition of the type to ensure the guest and toolstack
interprets this value correctly in a way consistent with existing users
(at least with XAPI, xl, libvirt, hvmloader and Linux).

Fixes: 30ce2a9295a5 ("Store an opaque handle (tools uuid) in the domain 
structure")
Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
---
v2:
 - introduced
---
 CHANGELOG.md             | 1 +
 xen/include/public/xen.h | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cd34ea87b8..8c4435c181 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ The format is based on [Keep a 
Changelog](https://keepachangelog.com/en/1.0.0/)
    - For x86, GCC 5.1 and Binutils 2.25, or Clang/LLVM 11
    - For ARM32 and ARM64, GCC 5.1 and Binutils 2.25
  - Linux based device model stubdomains are now fully supported.
+ - Clarify guest UUIDs as being big-endian encoded.
 
  - On x86:
    - Restrict the cache flushing done as a result of guest physical memory map
diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index 82b9c05a76..a219ef870f 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -973,6 +973,13 @@ typedef struct dom0_vga_console_info {
 #define xen_vga_console_info dom0_vga_console_info
 #define xen_vga_console_info_t dom0_vga_console_info_t
 
+/*
+ * The domain handle is chosen by the toolstack, and intended to hold a UUID
+ * conforming to RFC 9562 (i.e. big endian).
+ *
+ * Certain cases (e.g. SMBios) transform it to a Microsoft GUID (little
+ * endian) for presentation to the guest.
+ */
 typedef uint8_t xen_domain_handle_t[16];
 
 __DEFINE_XEN_GUEST_HANDLE(uint8,  uint8_t);
-- 
2.50.1



Teddy Astie | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

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