libxc/x86/PV: don't hand through CPUID leaf 0x80000008 as is

Just like for HVM the feature set should be used for EBX output, while
EAX should be restricted to the low 16 bits and ECX/EDX should be zero.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 849cc9ac56eff8a8d575ed9f484aad72f383862c
master date: 2018-05-29 10:51:02 +0100

diff --git a/tools/libxc/xc_cpuid_x86.c b/tools/libxc/xc_cpuid_x86.c
index 978451aa55f88c7bcd03cb412d609fc03d5a555f..1e0072df95292a79615effeb51df8d63bc96d528 100644 (file)
--- a/tools/libxc/xc_cpuid_x86.c
+++ b/tools/libxc/xc_cpuid_x86.c
@@ -672,6 +672,12 @@ static void xc_cpuid_pv_policy(xc_interface *xch,
         break;
     }
 
+    case 0x80000008:
+        regs[0] &= 0x0000ffffu;
+        regs[1] = info->featureset[featureword_of(X86_FEATURE_CLZERO)];
+        regs[2] = regs[3] = 0;
+        break;
+
     case 0x00000005: /* MONITOR/MWAIT */
     case 0x0000000a: /* Architectural Performance Monitor Features */
     case 0x0000000b: /* Extended Topology Enumeration */