mem_event: Revert pointless, unrelated, and broken (on i386) change in 23434:ef410f262299

vcpu_pause() is nestable in the hypervisor, hence checking for
already-paused is not required.

Signed-off-by: Keir Fraser <keir@xen.org>
xen-unstable changeset:   23435:c15f06b99bbe
xen-unstable date:        Sat May 28 08:33:54 2011 +0100

mem_event: Allow memory access listener to perform single step execution.

Add a new memory event that handles single step. This allows the
memory access listener to handle instructions that modify data within
the execution page.  This can be enabled in the listener by doing:
xc_set_hvm_param(xch, domain_id, HVM_PARAM_MEMORY_EVENT_SINGLE_STEP,
HVMPME_mode_sync)

Now the listener can start single stepping by:
xc_domain_debug_control(xch, domain_id,
XEN_DOMCTL_DEBUG_OP_SINGLE_STEP_ON, vcpu_id)

And stop single stepping by: xc_domain_debug_control(xch, domain_id,
XEN_DOMCTL_DEBUG_OP_SINGLE_STEP_OFF, vcpu_id)

Signed-off-by: Aravindh Puthiyaparambil <aravindh@virtuata.com>
Acked-by: Tim Deegan <Tim.Deegan@citrix.com>
xen-unstable changeset:   23434:ef410f262299
xen-unstable date:        Fri May 27 18:44:26 2011 +0100

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index ce3caa4fcbca02682eadfaa802f365a3361831bb..bb086bcb228d3edaac41f2f1d5c40148bc17c205 100644 (file)
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3257,7 +3257,8 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE(void) arg)
                     rc = -EPERM;
                 break;
             case HVM_PARAM_MEMORY_EVENT_INT3:
-                if ( d == current->domain ) 
+            case HVM_PARAM_MEMORY_EVENT_SINGLE_STEP:
+                if ( d == current->domain )
                 {
                     rc = -EPERM;
                     break;
@@ -3274,6 +3275,7 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE(void) arg)
                 switch( a.index )
                 {
                 case HVM_PARAM_MEMORY_EVENT_INT3:
+                case HVM_PARAM_MEMORY_EVENT_SINGLE_STEP:
                 {
                     domain_pause(d);
                     domain_unpause(d); /* Causes guest to latch new status */
@@ -3885,6 +3887,18 @@ int hvm_memory_event_int3(unsigned long gla)
                                   MEM_EVENT_REASON_INT3,
                                   gfn, 0, 1, gla);
 }
+
+int hvm_memory_event_single_step(unsigned long gla)
+{
+    uint32_t pfec = PFEC_page_present;
+    unsigned long gfn;
+    gfn = paging_gva_to_gfn(current, gla, &pfec);
+
+    return hvm_memory_event_traps(current->domain->arch.hvm_domain
+            .params[HVM_PARAM_MEMORY_EVENT_SINGLE_STEP],
+            MEM_EVENT_REASON_SINGLESTEP,
+            gfn, 0, 1, gla);
+}
 #endif /* __x86_64__ */
 
 /*

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 18e7055157021eb3962c2220c867df804d618005..e51dcdaf1183ed6f0126c6bcd4a5585a6c23361e 100644 (file)
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -1083,8 +1083,9 @@ void vmx_do_resume(struct vcpu *v)
         hvm_asid_flush_vcpu(v);
     }
 
-    debug_state = v->domain->debugger_attached 
-                  || v->domain->arch.hvm_domain.params[HVM_PARAM_MEMORY_EVENT_INT3];
+    debug_state = v->domain->debugger_attached
+                  || v->domain->arch.hvm_domain.params[HVM_PARAM_MEMORY_EVENT_INT3]
+                  || v->domain->arch.hvm_domain.params[HVM_PARAM_MEMORY_EVENT_SINGLE_STEP];
 
     if ( unlikely(v->arch.hvm_vcpu.debug_state_latch != debug_state) )
     {

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index cd5545b3687c02ca7fa37ec7760b855fe640b9c8..ab903a354bc145dd525e225e7fc5d94dadcdf91b 100644 (file)
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2626,8 +2626,12 @@ asmlinkage void vmx_vmexit_handler(struct cpu_user_regs *regs)
     case EXIT_REASON_MONITOR_TRAP_FLAG:
         v->arch.hvm_vmx.exec_control &= ~CPU_BASED_MONITOR_TRAP_FLAG;
         vmx_update_cpu_exec_control(v);
-        if ( v->domain->debugger_attached && v->arch.hvm_vcpu.single_step )
-            domain_pause_for_debugger();
+        if ( v->arch.hvm_vcpu.single_step ) {
+          hvm_memory_event_single_step(regs->eip);
+          if ( v->domain->debugger_attached )
+              domain_pause_for_debugger();
+        }
+
         break;
 
     case EXIT_REASON_PAUSE_INSTRUCTION:

diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 46baf2c8942153cc09f8bb3ad3f3eef2608b680b..fd79ba2032272fb7cff701059b16c823a2e6b7ad 100644 (file)
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -380,6 +380,10 @@ void hvm_memory_event_cr4(unsigned long value, unsigned long old);
 
 /* Called for current VCPU on int3: returns -1 if no listener */
 int hvm_memory_event_int3(unsigned long gla);
+
+/* Called for current VCPU on single step: returns -1 if no listener */
+int hvm_memory_event_single_step(unsigned long gla);
+
 #else
 static inline void hvm_memory_event_cr0(unsigned long value, unsigned long old)
 { }
@@ -389,6 +393,8 @@ static inline void hvm_memory_event_cr4(unsigned long value, unsigned long old)
 { }
 static inline int hvm_memory_event_int3(unsigned long gla)
 { return 0; }
+static inline int hvm_memory_event_single_step(unsigned long gla)
+{ return 0; }
 #endif
 
 #endif /* __ASM_X86_HVM_HVM_H__ */

diff --git a/xen/include/public/hvm/params.h b/xen/include/public/hvm/params.h
index 45b9a639807c6340f58be2be815288990b548cfb..1c98277d781f86a3eed761642052f75a2fc549c2 100644 (file)
--- a/xen/include/public/hvm/params.h
+++ b/xen/include/public/hvm/params.h
@@ -126,10 +126,11 @@
 
 /* Enable blocking memory events, async or sync (pause vcpu until response) 
  * onchangeonly indicates messages only on a change of value */
-#define HVM_PARAM_MEMORY_EVENT_CR0   20
-#define HVM_PARAM_MEMORY_EVENT_CR3   21
-#define HVM_PARAM_MEMORY_EVENT_CR4   22
-#define HVM_PARAM_MEMORY_EVENT_INT3  23
+#define HVM_PARAM_MEMORY_EVENT_CR0          20
+#define HVM_PARAM_MEMORY_EVENT_CR3          21
+#define HVM_PARAM_MEMORY_EVENT_CR4          22
+#define HVM_PARAM_MEMORY_EVENT_INT3         23
+#define HVM_PARAM_MEMORY_EVENT_SINGLE_STEP  25
 
 #define HVMPME_MODE_MASK       (3 << 0)
 #define HVMPME_mode_disabled   0
@@ -137,6 +138,6 @@
 #define HVMPME_mode_sync       2
 #define HVMPME_onchangeonly    (1 << 2)
 
-#define HVM_NR_PARAMS          24
+#define HVM_NR_PARAMS          26
 
 #endif /* __XEN_PUBLIC_HVM_PARAMS_H__ */

diff --git a/xen/include/public/mem_event.h b/xen/include/public/mem_event.h
index 93c824b86759b198d51920aa64fc6466d0fc43ac..45c15d3ef233940ea7ad738b91e9edae4af54728 100644 (file)
--- a/xen/include/public/mem_event.h
+++ b/xen/include/public/mem_event.h
@@ -46,6 +46,7 @@
 #define MEM_EVENT_REASON_CR3         3    /* CR3 was hit: gfn is CR3 value */
 #define MEM_EVENT_REASON_CR4         4    /* CR4 was hit: gfn is CR4 value */
 #define MEM_EVENT_REASON_INT3        5    /* int3 was hit: gla/gfn are RIP */
+#define MEM_EVENT_REASON_SINGLESTEP  6    /* single step was invoked: gla/gfn are RIP */
 
 typedef struct mem_event_shared_page {
     uint32_t port;