x86/svm: Intercept and terminate RDPRU with #UD

The RDPRU instruction isn't supported at all (and it is unclear how this can
ever be offered safely to guests).  However, a guest which ignores CPUID and
blindly executes RDPRU will find that it functions.

Use the intercept and terminate with #UD.  While at it, fold SKINIT into the
same "unconditionally disabled" path.

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

xen/arch/x86/hvm/svm/svm.c

@@ -2945,6 +2945,8 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
 
     case VMEXIT_MONITOR:
     case VMEXIT_MWAIT:
+    case VMEXIT_SKINIT:
+    case VMEXIT_RDPRU:
         hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
         break;
 
@@ -2963,9 +2965,6 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
     case VMEXIT_CLGI:
         svm_vmexit_do_clgi(regs, v);
         break;
-    case VMEXIT_SKINIT:
-        hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
-        break;
 
     case VMEXIT_XSETBV:
         if ( vmcb_get_cpl(vmcb) )

xen/arch/x86/hvm/svm/vmcb.c

@@ -70,7 +70,8 @@ static int construct_vmcb(struct vcpu *v)
         GENERAL2_INTERCEPT_STGI        | GENERAL2_INTERCEPT_CLGI        |
         GENERAL2_INTERCEPT_SKINIT      | GENERAL2_INTERCEPT_MWAIT       |
         GENERAL2_INTERCEPT_WBINVD      | GENERAL2_INTERCEPT_MONITOR     |
-        GENERAL2_INTERCEPT_XSETBV      | GENERAL2_INTERCEPT_ICEBP;
+        GENERAL2_INTERCEPT_XSETBV      | GENERAL2_INTERCEPT_ICEBP       |
+        GENERAL2_INTERCEPT_RDPRU;
 
     /* Intercept all debug-register writes. */
     vmcb->_dr_intercepts = ~0u;

xen/include/asm-x86/hvm/svm/vmcb.h

@@ -74,7 +74,8 @@ enum GenericIntercept2bits
     GENERAL2_INTERCEPT_MONITOR = 1 << 10,
     GENERAL2_INTERCEPT_MWAIT   = 1 << 11,
     GENERAL2_INTERCEPT_MWAIT_CONDITIONAL = 1 << 12,
-    GENERAL2_INTERCEPT_XSETBV  = 1 << 13
+    GENERAL2_INTERCEPT_XSETBV  = 1 << 13,
+    GENERAL2_INTERCEPT_RDPRU   = 1 << 14,
 };
 
 
@@ -300,6 +301,7 @@ enum VMEXIT_EXITCODE
     VMEXIT_MWAIT            = 139, /* 0x8b */
     VMEXIT_MWAIT_CONDITIONAL= 140, /* 0x8c */
     VMEXIT_XSETBV           = 141, /* 0x8d */
+    VMEXIT_RDPRU            = 142, /* 0x8e */
     VMEXIT_NPF              = 1024, /* 0x400, nested paging fault */
     VMEXIT_INVALID          =  -1
 };