[Xen-devel] [PATCH] x86/emul: Fix the emulation of invlpga

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Brian Woods <brian.woods@xxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index f22f821..9f18567 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -5121,8 +5121,15 @@ x86_emulate(
             break;
 
         case 0xdf: /* invlpga */
-            generate_exception_if(!in_protmode(ctxt, ops), EXC_UD);
+            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);
             generate_exception_if(!mode_ring0(), EXC_GP, 0);
+            generate_exception_if(regs->ecx, EXC_UD); /* TODO: Support ASIDs. 
*/
             fail_if(ops->invlpg == NULL);
             if ( (rc = ops->invlpg(x86_seg_none, truncate_ea(_regs.r(ax)),
                                    ctxt)) )
-- 
2.1.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel