[Xen-changelog] [xen-unstable] x86, vmx: Fix single step on debugger

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1230559526 0
# Node ID e0301796fce82b65411fb543d1d08342755d1efb
# Parent  d0751463539a47ab617856791a1b1283fa0d3373
x86, vmx: Fix single step on debugger

Signed-off-by: Kouya Shimura <kouya@xxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmx.c |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+)

diff -r d0751463539a -r e0301796fce8 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Mon Dec 29 14:03:26 2008 +0000
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Mon Dec 29 14:05:26 2008 +0000
@@ -1314,8 +1314,29 @@ static void vmx_set_uc_mode(struct vcpu 
 
 static void vmx_set_info_guest(struct vcpu *v)
 {
+    unsigned long intr_shadow;
+
     vmx_vmcs_enter(v);
+
     __vmwrite(GUEST_DR7, v->arch.guest_context.debugreg[7]);
+
+    /* 
+     * If the interruptibility-state field indicates blocking by STI,
+     * setting the TF flag in the EFLAGS may cause VM entry to fail
+     * and crash the guest. See SDM 3B 22.3.1.5.
+     * Resetting the VMX_INTR_SHADOW_STI flag looks hackish but
+     * to set the GUEST_PENDING_DBG_EXCEPTIONS.BS here incurs
+     * immediately vmexit and hence make no progress.
+     */
+    intr_shadow = __vmread(GUEST_INTERRUPTIBILITY_INFO);
+    if ( v->domain->debugger_attached &&
+         (v->arch.guest_context.user_regs.eflags & X86_EFLAGS_TF) &&
+         (intr_shadow & VMX_INTR_SHADOW_STI) )
+    {
+        intr_shadow &= ~VMX_INTR_SHADOW_STI;
+        __vmwrite(GUEST_INTERRUPTIBILITY_INFO, intr_shadow);
+    }
+
     vmx_vmcs_exit(v);
 }
 

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