[Xen-devel] [PATCH v3 2/4] hvm/svm: Enable Breakpoint events

[Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>]

This commit implements the breakpoint events for svm.
At the moment, the Breakpoint vmexit is not forwarded to the monitor layer.
This patch adds the hvm_monitor_debug call to the VMEXIT_EXCEPTION_BP.
Also, the Software Breakpoint cap is moved from the Intel arch to the
common part of the code.

Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>

---
Changes since V2:
        - Moved the comment from vmx_vmexit_handler to
          hvm_monitor_debug
        - Moved the AMD comment up.
---
 xen/arch/x86/hvm/monitor.c    |  5 +++++
 xen/arch/x86/hvm/svm/svm.c    | 48 +++++++++++++++++++++++++++++++++++--------
 xen/arch/x86/hvm/vmx/vmx.c    |  5 -----
 xen/include/asm-x86/monitor.h |  4 ++--
 4 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/xen/arch/x86/hvm/monitor.c b/xen/arch/x86/hvm/monitor.c
index 131b852..60cb68d 100644
--- a/xen/arch/x86/hvm/monitor.c
+++ b/xen/arch/x86/hvm/monitor.c
@@ -133,6 +133,11 @@ static inline unsigned long gfn_of_rip(unsigned long rip)
 int hvm_monitor_debug(unsigned long rip, enum hvm_monitor_debug_type type,
                       unsigned long trap_type, unsigned long insn_length)
 {
+    /*
+     * rc < 0 error in monitor/vm_event, crash
+     * !rc    continue normally
+     * rc > 0 paused waiting for response, work here is done
+     */
     struct vcpu *curr = current;
     struct arch_domain *ad = &curr->domain->arch;
     vm_event_request_t req = {};
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index dcbd550..0d9baf8 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -59,6 +59,7 @@
 #include <asm/hap.h>
 #include <asm/apic.h>
 #include <asm/debugger.h>
+#include <asm/hvm/monitor.h>
 #include <asm/xstate.h>
 
 void svm_asm_do_resume(void);
@@ -1079,7 +1080,8 @@ static void svm_ctxt_switch_to(struct vcpu *v)
 static void noreturn svm_do_resume(struct vcpu *v)
 {
     struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
-    bool_t debug_state = v->domain->debugger_attached;
+    bool debug_state = v->domain->debugger_attached
+                || v->domain->arch.monitor.software_breakpoint_enabled;
     bool_t vcpu_guestmode = 0;
     struct vlapic *vlapic = vcpu_vlapic(v);
 
@@ -2407,6 +2409,19 @@ static bool svm_get_pending_event(struct vcpu *v, struct 
x86_event *info)
     return true;
 }
 
+static void svm_propagate_intr(struct vcpu *v, unsigned long insn_len)
+{
+    struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
+    struct x86_event event = {
+        .vector = vmcb->eventinj.fields.type,
+        .type = vmcb->eventinj.fields.type,
+        .error_code = vmcb->exitinfo1,
+    };
+
+    event.insn_len = insn_len;
+    hvm_inject_event(&event);
+}
+
 static struct hvm_function_table __initdata svm_function_table = {
     .name                 = "SVM",
     .cpu_up_prepare       = svm_cpu_up_prepare,
@@ -2619,14 +2634,31 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
         break;
 
     case VMEXIT_EXCEPTION_BP:
-        if ( !v->domain->debugger_attached )
-            goto unexpected_exit_type;
-        /* AMD Vol2, 15.11: INT3, INTO, BOUND intercepts do not update RIP. */
-        if ( (inst_len = __get_instruction_length(v, INSTR_INT3)) == 0 )
+        inst_len = __get_instruction_length(v, INSTR_INT3);
+
+        if ( inst_len == 0 )
             break;
-        __update_guest_eip(regs, inst_len);
-        current->arch.gdbsx_vcpu_event = TRAP_int3;
-        domain_pause_for_debugger();
+
+        if ( v->domain->debugger_attached )
+        {
+            /* AMD Vol2, 15.11: INT3, INTO, BOUND intercepts do not update 
RIP. */
+            __update_guest_eip(regs, inst_len);
+            current->arch.gdbsx_vcpu_event = TRAP_int3;
+            domain_pause_for_debugger();
+        }
+        else
+        {
+           int rc;
+
+           rc = hvm_monitor_debug(regs->rip,
+                                  HVM_MONITOR_SOFTWARE_BREAKPOINT,
+                                  X86_EVENTTYPE_SW_EXCEPTION,
+                                  inst_len);
+           if ( rc < 0 )
+               goto unexpected_exit_type;
+           if ( !rc )
+               svm_propagate_intr(v, inst_len);
+        }
         break;
 
     case VMEXIT_EXCEPTION_NM:
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 3dc6a6d..c89b4b6 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -3709,11 +3709,6 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
                                        HVM_MONITOR_DEBUG_EXCEPTION,
                                        trap_type, insn_len);
 
-                /*
-                 * rc < 0 error in monitor/vm_event, crash
-                 * !rc    continue normally
-                 * rc > 0 paused waiting for response, work here is done
-                 */
                 if ( rc < 0 )
                     goto exit_and_crash;
                 if ( !rc )
diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
index c339324..11a0cae 100644
--- a/xen/include/asm-x86/monitor.h
+++ b/xen/include/asm-x86/monitor.h
@@ -77,13 +77,13 @@ static inline uint32_t arch_monitor_get_capabilities(struct 
domain *d)
     if ( !is_hvm_domain(d) )
         return capabilities;
 
-    capabilities = (1U << XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST);
+    capabilities = ((1U << XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST) |
+                   (1U << XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT));
 
     if( cpu_has_vmx )
     {
         capabilities |= (1U << XEN_DOMCTL_MONITOR_EVENT_WRITE_CTRLREG) |
                        (1U << XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR) |
-                       (1U << XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT) |
                        (1U << XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION) |
                        (1U << XEN_DOMCTL_MONITOR_EVENT_CPUID) |
                        (1U << XEN_DOMCTL_MONITOR_EVENT_INTERRUPT) |
-- 
2.7.4


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