[Xen-changelog] [xen-unstable] svm: decode-assists feature must depend on nextrip feature.

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1303117802 -3600
# Node ID 381ab77db71a4739b8a4f4fdad4ef3504999f998
# Parent  e324c4d1dd6eeb9417fec513640ca795bd0f5dd4
svm: decode-assists feature must depend on nextrip feature.

...since the decode-assist fast paths assume nextrip vmcb field is
valid.

Signed-off-by: Keir Fraser <keir@xxxxxxx>
---


diff -r e324c4d1dd6e -r 381ab77db71a xen/arch/x86/hvm/svm/svm.c
--- a/xen/arch/x86/hvm/svm/svm.c        Mon Apr 18 10:06:37 2011 +0100
+++ b/xen/arch/x86/hvm/svm/svm.c        Mon Apr 18 10:10:02 2011 +0100
@@ -995,6 +995,10 @@
 
     printk("SVM: Supported advanced features:\n");
 
+    /* DecodeAssists fast paths assume nextrip is valid for fast rIP update. */
+    if ( !cpu_has_svm_nrips )
+        clear_bit(SVM_FEATURE_DECODEASSISTS, &svm_feature_flags);
+
 #define P(p,s) if ( p ) { printk(" - %s\n", s); printed = 1; }
     P(cpu_has_svm_npt, "Nested Page Tables (NPT)");
     P(cpu_has_svm_lbrv, "Last Branch Record (LBR) Virtualisation");
@@ -1142,7 +1146,6 @@
 
     rc = dir ? hvm_mov_to_cr(cr, gp) : hvm_mov_from_cr(cr, gp);
 
-    ASSERT(cpu_has_svm_nrips);
     if ( rc == X86EMUL_OKAY )
         __update_guest_eip(regs, vmcb->nextrip - vmcb->rip);
 }

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