[Qemu-devel] [PULL 49/49] kvm: Allow the Hyper-V vendor ID to be specified

[Paolo Bonzini <pbonzini@redhat.com>]

From: Alex Williamson <alex.williamson@redhat.com>

According to Microsoft documentation, the signature in the standard
hypervisor CPUID leaf at 0x40000000 identifies the Vendor ID and is
for reporting and diagnostic purposes only.  We can therefore allow
the user to change it to whatever they want, within the 12 character
limit.  Add a new hyperv-vendor-id option to the -cpu flag to allow
for this, ex:

 -cpu host,hv_time,hv_vendor_id=KeenlyKVM

Link: http://msdn.microsoft.com/library/windows/hardware/hh975392
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Message-Id: <20151015221556.31645.81905.stgit@gimli.home>
[Do not abort. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target-i386/cpu-qom.h |  1 +
 target-i386/cpu.c     |  1 +
 target-i386/kvm.c     | 13 ++++++++++++-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/target-i386/cpu-qom.h b/target-i386/cpu-qom.h
index 9eab41b..e3bfe9d 100644
--- a/target-i386/cpu-qom.h
+++ b/target-i386/cpu-qom.h
@@ -88,6 +88,7 @@ typedef struct X86CPU {
     bool hyperv_vapic;
     bool hyperv_relaxed_timing;
     int hyperv_spinlock_attempts;
+    char *hyperv_vendor_id;
     bool hyperv_time;
     bool hyperv_crash;
     bool hyperv_reset;
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index d2b0619..5f53af2 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -3149,6 +3149,7 @@ static Property x86_cpu_properties[] = {
     DEFINE_PROP_UINT32("level", X86CPU, env.cpuid_level, 0),
     DEFINE_PROP_UINT32("xlevel", X86CPU, env.cpuid_xlevel, 0),
     DEFINE_PROP_UINT32("xlevel2", X86CPU, env.cpuid_xlevel2, 0),
+    DEFINE_PROP_STRING("hv-vendor-id", X86CPU, hyperv_vendor_id),
     DEFINE_PROP_END_OF_LIST()
 };
 
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 010ac51..e9f1779 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -505,7 +505,18 @@ int kvm_arch_init_vcpu(CPUState *cs)
     if (hyperv_enabled(cpu)) {
         c = &cpuid_data.entries[cpuid_i++];
         c->function = HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
-        memcpy(signature, "Microsoft Hv", 12);
+        if (!cpu->hyperv_vendor_id) {
+            memcpy(signature, "Microsoft Hv", 12);
+        } else {
+            size_t len = strlen(cpu->hyperv_vendor_id);
+
+            if (len > 12) {
+                fprintf(stderr,
+                        "hyperv-vendor-id too long, limited to 12 charaters");
+            }
+            memset(signature, 0, 12);
+            memcpy(signature, cpu->hyperv_vendor_id, len);
+        }
         c->eax = HYPERV_CPUID_MIN;
         c->ebx = signature[0];
         c->ecx = signature[1];
-- 
2.5.0