[PATCH v2 3/8] x86/msr: explicitly handle AMD DE_CFG

[Roger Pau Monne <roger.pau@citrix.com>]

Report the hardware value of DE_CFG on AMD hardware and silently drop
writes.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Changes since v1:
 - New in this version.
---
 xen/arch/x86/msr.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index ca4307e19f..a890cb9976 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -274,6 +274,14 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val)
         *val = msrs->tsc_aux;
         break;
 
+    case MSR_AMD64_DE_CFG:
+        if ( !(cp->x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON)) ||
+             !(boot_cpu_data.x86_vendor & (X86_VENDOR_AMD |
+                                           X86_VENDOR_HYGON)) ||
+             rdmsr_safe(MSR_AMD64_DE_CFG, *val) )
+            goto gp_fault;
+        break;
+
     case MSR_AMD64_DR0_ADDRESS_MASK:
     case MSR_AMD64_DR1_ADDRESS_MASK ... MSR_AMD64_DR3_ADDRESS_MASK:
         if ( !cp->extd.dbext )
@@ -499,6 +507,12 @@ int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t val)
             wrmsr_tsc_aux(val);
         break;
 
+    case MSR_AMD64_DE_CFG:
+        if ( !(cp->x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON)) ||
+             !(boot_cpu_data.x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON)) )
+            goto gp_fault;
+        break;
+
     case MSR_AMD64_DR0_ADDRESS_MASK:
     case MSR_AMD64_DR1_ADDRESS_MASK ... MSR_AMD64_DR3_ADDRESS_MASK:
         if ( !cp->extd.dbext || val != (uint32_t)val )
-- 
2.28.0