[2/2] VMX/cpu-policy: disable RDTSCP and INVPCID insns as needed

Commit Message

Jan Beulich April 26, 2023, 12:58 p.m. UTC

When either feature is available in hardware, but disabled for a guest,
the respective insn would better cause #UD if attempted to be used.

Signed-off-by: Jan Beulich <[e-mail]>

Comments

Tian, Kevin May 26, 2023, 4:54 a.m. UTC | #1

> From: Jan Beulich <[e-mail]>
> Sent: Wednesday, April 26, 2023 8:58 PM
> 
> When either feature is available in hardware, but disabled for a guest,
> the respective insn would better cause #UD if attempted to be used.
> 
> Signed-off-by: Jan Beulich <[e-mail]>
> 

Reviewed-by: Kevin Tian <[e-mail]>

Patch

--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -785,6 +785,30 @@  static void cf_check vmx_cpuid_policy_ch
     vmx_vmcs_enter(v);
     vmx_update_exception_bitmap(v);
 
+    if ( cp->extd.rdtscp )
+    {
+        v->arch.hvm.vmx.secondary_exec_control |= SECONDARY_EXEC_ENABLE_RDTSCP;
+        vmx_update_secondary_exec_control(v);
+    }
+    else if ( v->arch.hvm.vmx.secondary_exec_control &
+              SECONDARY_EXEC_ENABLE_RDTSCP )
+    {
+        v->arch.hvm.vmx.secondary_exec_control &= ~SECONDARY_EXEC_ENABLE_RDTSCP;
+        vmx_update_secondary_exec_control(v);
+    }
+
+    if ( cp->feat.invpcid )
+    {
+        v->arch.hvm.vmx.secondary_exec_control |= SECONDARY_EXEC_ENABLE_INVPCID;
+        vmx_update_secondary_exec_control(v);
+    }
+    else if ( v->arch.hvm.vmx.secondary_exec_control &
+              SECONDARY_EXEC_ENABLE_INVPCID )
+    {
+        v->arch.hvm.vmx.secondary_exec_control &= ~SECONDARY_EXEC_ENABLE_INVPCID;
+        vmx_update_secondary_exec_control(v);
+    }
+
     /*
      * We can safely pass MSR_SPEC_CTRL through to the guest, even if STIBP
      * isn't enumerated in hardware, as SPEC_CTRL_STIBP is ignored.