kvm-qemu: Fix monitor and gdbstub deadlocks v2

PATCH New Jan Kiszka 1 participant 1 message May 12, 2008 KVM

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Jan Kiszka

author

2008-05-12 10:51 UTC #0 lore raw

PATCH 1/1 kvm-qemu: Fix monitor and gdbstub deadlocks v2

Refreshed version of the earlier posted patch, now also adding a safety check about the correct vm state to kvm_load_registers.

Some monitor commands as well as the vm_stop() issued by the gdbstub on external interruption so far deadlock on vcpu locks in the kernel. Patch below resolves the issue by temporarily or permanently stopping all vcpu threads before issuing the related KVM IOCTLs. At this chance the patch also removes redundant checks for kvm_enabled.

Among other things, the patch now allows to break into the BIOS or other guest code spinning in the vcpu and to use things like "info cpus" in the monitor.

Signed-off-by Jan Kiszka <[email protected]>

---
 qemu/gdbstub.c  |   12 ++++--------
 qemu/monitor.c  |    3 +--
 qemu/qemu-kvm.c |   41 +++++++++++++++++++++++++++--------------
 qemu/vl.c       |    2 +-
 4 files changed, 33 insertions(+), 25 deletions(-)

qemu/monitor.c +1 -2

Index: b/qemu/monitor.c
===================================================================
@@ -286,8 +286,7 @@ static CPUState *mon_get_cpu(void)
         mon_set_cpu(0);
     }
 
-    if (kvm_enabled())
-	kvm_save_registers(mon_cpu);
+    kvm_save_registers(mon_cpu);
 
     return mon_cpu;
 }

qemu/qemu-kvm.c +27 ~~-14~~

65 lines not on this page · raw message

qemu/vl.c +1 -1

Index: b/qemu/vl.c
===================================================================
@@ -7225,12 +7225,12 @@ void vm_stop(int reason)
 {
     if (vm_running) {
         cpu_disable_ticks();
-        vm_running = 0;
         if (reason != 0) {
             if (vm_stop_cb) {
                 vm_stop_cb(vm_stop_opaque, reason);
             }
         }
+        vm_running = 0;
         vm_state_notify(0);
     }
 }

qemu/gdbstub.c +4 -8

Index: b/qemu/gdbstub.c
===================================================================
@@ -904,8 +904,7 @@ static int gdb_handle_packet(GDBState *s
             addr = strtoull(p, (char **)&p, 16);
 #if defined(TARGET_I386)
             env->eip = addr;
-	    if (kvm_enabled())
-		kvm_load_registers(env);
+            kvm_load_registers(env);
 #elif defined (TARGET_PPC)
             env->nip = addr;
 #elif defined (TARGET_SPARC)

@@ -928,8 +927,7 @@ static int gdb_handle_packet(GDBState *s
             addr = strtoull(p, (char **)&p, 16);
 #if defined(TARGET_I386)
             env->eip = addr;
-	    if (kvm_enabled())
-		kvm_load_registers(env);
+            kvm_load_registers(env);
 #elif defined (TARGET_PPC)
             env->nip = addr;
 #elif defined (TARGET_SPARC)

@@ -973,8 +971,7 @@ static int gdb_handle_packet(GDBState *s
         }
         break;
     case 'g':
-	if (kvm_enabled())
-	    kvm_save_registers(env);
+        kvm_save_registers(env);
         reg_size = cpu_gdb_read_registers(env, mem_buf);
         memtohex(buf, mem_buf, reg_size);
         put_packet(s, buf);

@@ -984,8 +981,7 @@ static int gdb_handle_packet(GDBState *s
         len = strlen(p) / 2;
         hextomem((uint8_t *)registers, p, len);
         cpu_gdb_write_registers(env, mem_buf, len);
-	if (kvm_enabled())
-	    kvm_load_registers(env);
+        kvm_load_registers(env);
         put_packet(s, "OK");
         break;
     case 'm':

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