x86/msr: Virtualise MSR_PLATFORM_ID properly

This is an Intel-only, read-only MSR related to microcode loading.  Expose it
in similar circumstances as the PATCHLEVEL MSR.

This should have been alongside c/s 013896cb8b2 "x86/msr: Fix handling of
MSR_AMD_PATCHLEVEL/MSR_IA32_UCODE_REV"

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index 785574de675027a4d82d0276fbe944838567a14c..1cea77768003781f60036862b1a38d4e87e87daa 100644 (file)
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -143,6 +143,13 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val)
         /* Not offered to guests. */
         goto gp_fault;
 
+    case MSR_IA32_PLATFORM_ID:
+        if ( !(cp->x86_vendor & X86_VENDOR_INTEL) ||
+             !(boot_cpu_data.x86_vendor & X86_VENDOR_INTEL) )
+            goto gp_fault;
+        rdmsrl(MSR_IA32_PLATFORM_ID, *val);
+        break;
+
     case MSR_AMD_PATCHLEVEL:
         BUILD_BUG_ON(MSR_IA32_UCODE_REV != MSR_AMD_PATCHLEVEL);
         /*
@@ -275,6 +282,7 @@ int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t val)
     {
         uint64_t rsvd;
 
+    case MSR_IA32_PLATFORM_ID:
     case MSR_INTEL_CORE_THREAD_COUNT:
     case MSR_INTEL_PLATFORM_INFO:
     case MSR_ARCH_CAPABILITIES: