x86: Enable MTF for HVM guest single step in gdb

Signed-off-by: Edwin Zhai <edwin.zhai@intel.com>
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

3 files changed, 49 insertions, 12 deletions

diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c
index e1bf86ee6a..afffd68d1a 100644
--- a/tools/libxc/xc_domain.c
+++ b/tools/libxc/xc_domain.c
@@ -1061,6 +1061,20 @@ int xc_domain_suppress_spurious_page_faults(int xc, uint32_t domid)
 
 }
 
+int xc_domain_debug_control(int xc, uint32_t domid, uint32_t sop, uint32_t vcpu)
+{
+    DECLARE_DOMCTL;
+
+    memset(&domctl, 0, sizeof(domctl));
+    domctl.domain = (domid_t)domid;
+    domctl.cmd = XEN_DOMCTL_debug_op;
+    domctl.u.debug_op.op     = sop;
+    domctl.u.debug_op.vcpu   = vcpu;
+
+    return do_domctl(xc, &domctl);
+}
+
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxc/xc_ptrace.c b/tools/libxc/xc_ptrace.c
index fa6c3a0ad1..094bf165df 100644
--- a/tools/libxc/xc_ptrace.c
+++ b/tools/libxc/xc_ptrace.c
@@ -524,10 +524,20 @@ xc_ptrace(
         /*  XXX we can still have problems if the user switches threads
          *  during single-stepping - but that just seems retarded
          */
-        ctxt[cpu].c.user_regs.eflags |= PSL_T;
-        if ((retval = xc_vcpu_setcontext(xc_handle, current_domid, cpu,
-                                &ctxt[cpu])))
-            goto out_error_domctl;
+        /* Try to enalbe Monitor Trap Flag for HVM, and fall back to TF
+         * if no MTF support
+         */
+        if ( !current_is_hvm ||
+             xc_domain_debug_control(xc_handle,
+                                     current_domid,
+                                     XEN_DOMCTL_DEBUG_OP_SINGLE_STEP_ON,
+                                     cpu) )
+        {
+            ctxt[cpu].c.user_regs.eflags |= PSL_T;
+            if ((retval = xc_vcpu_setcontext(xc_handle, current_domid, cpu,
+                                    &ctxt[cpu])))
+                goto out_error_domctl;
+        }
         /* FALLTHROUGH */
 
     case PTRACE_CONT:
@@ -538,15 +548,22 @@ xc_ptrace(
         {
             FOREACH_CPU(cpumap, index) {
                 cpu = index - 1;
-                if (fetch_regs(xc_handle, cpu, NULL))
-                    goto out_error;
-                /* Clear trace flag */
-                if ( ctxt[cpu].c.user_regs.eflags & PSL_T )
+                if ( !current_is_hvm ||
+                      xc_domain_debug_control(xc_handle,
+                                              current_domid,
+                                              XEN_DOMCTL_DEBUG_OP_SINGLE_STEP_OFF,
+                                              cpu) )
                 {
-                    ctxt[cpu].c.user_regs.eflags &= ~PSL_T;
-                    if ((retval = xc_vcpu_setcontext(xc_handle, current_domid,
-                                                cpu, &ctxt[cpu])))
-                        goto out_error_domctl;
+                    if (fetch_regs(xc_handle, cpu, NULL))
+                        goto out_error;
+                    /* Clear trace flag */
+                    if ( ctxt[cpu].c.user_regs.eflags & PSL_T )
+                    {
+                        ctxt[cpu].c.user_regs.eflags &= ~PSL_T;
+                        if ((retval = xc_vcpu_setcontext(xc_handle, current_domid,
+                                        cpu, &ctxt[cpu])))
+                            goto out_error_domctl;
+                    }
                 }
             }
         }
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 18d2f5f4d1..b915ccaff2 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -1111,6 +1111,12 @@ int xc_domain_set_target(int xc_handle,
                          uint32_t domid,
                          uint32_t target);
 
+/* Control the domain for debug */
+int xc_domain_debug_control(int xc_handle,
+                            uint32_t domid,
+                            uint32_t sop,
+                            uint32_t vcpu);
+
 #if defined(__i386__) || defined(__x86_64__)
 int xc_cpuid_check(int xc,
                    const unsigned int *input,