x86/emul: Fix the emulation of invlpga

The instruction requires EFER.SVME set to be usable in the first place.

Furthermore, the emulation doesn't handle ASIDs, so avoid giving the
impression that they work.  Permit ASID 0 which is reserved for non-root
mode (in which case the instruction is identical to invlpg), but raise #UD for
any other ASID.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: a91b2ec337a45d5d98e5a4387aa6563bc5cdc4c9
master date: 2018-02-05 18:17:22 +0000

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index bfabec06ba1012ed2d5761508c88badcadc43b43..5340d5c5d57901531d2e75931c0746f3e6ee6daa 100644 (file)
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4419,14 +4419,24 @@ x86_emulate(
             _regs.eflags |= EFLG_ZF;
             break;
 
-        case 0xdf: /* invlpga */
-            generate_exception_if(!in_protmode(ctxt, ops), EXC_UD, -1);
+        case 0xdf: /* invlpga */ {
+            uint64_t msr_val;
+
+            fail_if(!ops->read_msr);
+            if ( (rc = ops->read_msr(MSR_EFER,
+                                     &msr_val, ctxt)) != X86EMUL_OKAY )
+                goto done;
+            /* Finding SVME set implies vcpu_has_svm(). */
+            generate_exception_if(!(msr_val & EFER_SVME) ||
+                                  !in_protmode(ctxt, ops), EXC_UD, -1);
             generate_exception_if(!mode_ring0(), EXC_GP, 0);
+            generate_exception_if((uint32_t)_regs.ecx, EXC_UD, -1); /* TODO: Support ASIDs. */
             fail_if(ops->invlpg == NULL);
             if ( (rc = ops->invlpg(x86_seg_none, truncate_ea(_regs.eax),
                                    ctxt)) )
                 goto done;
             break;
+        }
 
         case 0xf9: /* rdtscp */
         {