[xen stable-4.19] x86/MCE: restore CPU vendor reporting to the outside world

[patchbot@xxxxxxx]

commit b74f88c938f928278575bb674df4daac9d6ff5a8
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Mar 10 14:45:02 2026 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Mar 10 14:45:02 2026 +0100

    x86/MCE: restore CPU vendor reporting to the outside world
    
    The records reported used to contain Linux enumerators. We first broke
    that connection when purging unused ones, and then again when switching to
    the bit mask forms.
    
    Fixes: 408413051144 ("x86/cpu: Drop unused X86_VENDOR_* values")
    Fixes: 0cd074144cbb ("x86/cpu: Renumber X86_VENDOR_* to form a bitmap")
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Jason Andryuk <jason.andryuk@xxxxxxx>
    master commit: a94c5fd8290a55461c599b8baad309df0d929f1f
    master date: 2026-02-23 08:39:58 +0100
---
 xen/arch/x86/cpu/mcheck/mce.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 5a59e79cbc..533425cf51 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -854,6 +854,22 @@ void *x86_mcinfo_reserve(struct mc_info *mi,
     return mic_index;
 }
 
+/* Linux values need using when reporting CPU vendors to the outside. */
+static unsigned int xen2linux_vendor(unsigned int vendor)
+{
+    switch ( vendor )
+    {
+    case X86_VENDOR_INTEL:    return 0;
+    case X86_VENDOR_AMD:      return 2;
+    case X86_VENDOR_CENTAUR:  return 5;
+    case X86_VENDOR_HYGON:    return 9;
+    case X86_VENDOR_SHANGHAI: return 10; /* X86_VENDOR_ZHAOXIN */
+    default: break;
+    }
+
+    return 0xff; /* X86_VENDOR_UNKNOWN */
+}
+
 static void x86_mcinfo_apei_save(
     struct mcinfo_global *mc_global, struct mcinfo_bank *mc_bank)
 {
@@ -862,7 +878,7 @@ static void x86_mcinfo_apei_save(
     memset(&m, 0, sizeof(struct mce));
 
     m.cpu = mc_global->mc_coreid;
-    m.cpuvendor = boot_cpu_data.x86_vendor;
+    m.cpuvendor = xen2linux_vendor(boot_cpu_data.x86_vendor);
     m.cpuid = cpuid_eax(1);
     m.socketid = mc_global->mc_socketid;
     m.apicid = mc_global->mc_apicid;
@@ -964,7 +980,7 @@ static void cf_check do_mc_get_cpu_info(void *v)
                         &xcp->mc_ncores_active, &xcp->mc_nthreads);
     xcp->mc_cpuid_level = c->cpuid_level;
     xcp->mc_family = c->x86;
-    xcp->mc_vendor = c->x86_vendor;
+    xcp->mc_vendor = xen2linux_vendor(c->x86_vendor);
     xcp->mc_model = c->x86_model;
     xcp->mc_step = c->x86_mask;
     xcp->mc_cache_size = c->x86_cache_size;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.19