From: Jan Beulich <jbeulich@suse.com>
Date: Tue, 3 Sep 2019 12:49:20 +0000 (+0200)
Subject: x86/HVM: ignore guest INVD uses
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=4d4fec207b472a7483483b99c3d94537b06cddad;p=people%2Flarsk%2Fxen.git

x86/HVM: ignore guest INVD uses

The only place we'd expect the insn to be sensibly used is in
(virtualization unaware) firmware.

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

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index b61faf704b..7cd727ab97 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2210,11 +2210,18 @@ static int hvmemul_cache_op(
 
         hvmemul_unmap_linear_addr(mapping, addr, 0, hvmemul_ctxt);
         /* fall through */
-    case x86emul_invd:
     case x86emul_wbinvd:
     case x86emul_wbnoinvd:
         alternative_vcall(hvm_funcs.wbinvd_intercept);
         break;
+
+    case x86emul_invd:
+        /*
+         * Deliberately ignored: We mustn't issue INVD, and issuing WBINVD
+         * wouldn't match the request. And the only place we'd expect the insn
+         * to be sensibly used is in (virtualization unaware) firmware.
+         */
+        break;
     }
 
     return X86EMUL_OKAY;