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 51d4dddfeb60087d259bce8627279e5e542578e2..256604c17ca7ca877043658585e5e900fcf07d93 100644 (file)
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -362,6 +362,7 @@ typedef union {
 #define MSR_EFER         0xc0000080
 #define EFER_SCE         (1u<<0)
 #define EFER_LMA         (1u<<10)
+#define EFER_SVME        (1u<<12)
 #define MSR_STAR         0xc0000081
 #define MSR_LSTAR        0xc0000082
 #define MSR_CSTAR        0xc0000083
@@ -3989,14 +3990,24 @@ x86_emulate(
 
         switch( modrm )
         {
-        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;
             goto no_writeback;
+        }
         case 0xf9: /* rdtscp */ {
             uint64_t tsc_aux;
             fail_if(ops->read_msr == NULL);