[Qemu-ppc] [PATCH 3/3] Enable kvm emulated watchdog

[Bharat Bhushan]

Enable the KVM emulated watchdog if KVM supports (use the
capability enablement in watchdog handler). Also watchdog exit
(KVM_EXIT_WATCHDOG) handling is added.
Watchdog state machine is cleared whenever VM state changes to running.
This is to handle the cases like return from debug halt etc.

Signed-off-by: Bharat Bhushan <address@hidden>
---
 hw/ppc.h         |    2 +
 hw/ppc_booke.c   |   71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 target-ppc/kvm.c |   13 +++++++++-
 3 files changed, 85 insertions(+), 1 deletions(-)

diff --git a/hw/ppc.h b/hw/ppc.h
index 2f3ea27..3672fe8 100644
--- a/hw/ppc.h
+++ b/hw/ppc.h
@@ -44,6 +44,8 @@ struct ppc_tb_t {
 
 uint64_t cpu_ppc_get_tb(ppc_tb_t *tb_env, uint64_t vmclk, int64_t tb_offset);
 clk_setup_cb cpu_ppc_tb_init (CPUPPCState *env, uint32_t freq);
+extern int cap_ppc_watchdog;
+extern int cap_booke_sregs;
 /* Embedded PowerPC DCR management */
 typedef uint32_t (*dcr_read_cb)(void *opaque, int dcrn);
 typedef void (*dcr_write_cb)(void *opaque, int dcrn, uint32_t val);
diff --git a/hw/ppc_booke.c b/hw/ppc_booke.c
index 837a5b6..f18df74 100644
--- a/hw/ppc_booke.c
+++ b/hw/ppc_booke.c
@@ -21,6 +21,8 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+#include "sysemu.h"
+#include "kvm.h"
 #include "hw.h"
 #include "ppc.h"
 #include "qemu-timer.h"
@@ -203,6 +205,11 @@ static void booke_wdt_cb(void *opaque)
                              booke_timer->wdt_timer);
 }
 
+static void ppc_booke_watchdog_clear_tsr(CPUPPCState *env, target_ulong tsr)
+{
+    env->spr[SPR_BOOKE_TSR] = tsr & ~(TSR_ENW | TSR_WIS | TSR_WRS_MASK);
+}
+
 void store_booke_tsr(CPUPPCState *env, target_ulong val)
 {
     env->spr[SPR_BOOKE_TSR] &= ~val;
@@ -241,6 +248,64 @@ static void ppc_booke_timer_reset_handle(void *opaque)
     booke_update_irq(env);
 }
 
+static void cpu_state_change_handler(void *opaque, int running, RunState state)
+{
+    CPUPPCState *env = opaque;
+
+    struct kvm_sregs sregs;
+
+    if (!running) {
+        return;
+    }
+
+    /*
+     * Clear watchdog interrupt condition by clearing TSR.
+     * Similar logic needed to be implemented for watchdog
+     * emulation in qemu.
+     */
+
+    if (!kvm_enabled()) {
+        /* FIXME: add handling for qemu emulated case */
+        return;
+    }
+
+    if (cap_booke_sregs && cap_ppc_watchdog) {
+        kvm_vcpu_ioctl(env, KVM_GET_SREGS, &sregs);
+
+        /* Clear TSR.ENW, TSR.WIS and TSR.WRS */
+        ppc_booke_watchdog_clear_tsr(env, sregs.u.e.tsr);
+        sregs.u.e.tsr = env->spr[SPR_BOOKE_TSR];
+        sregs.u.e.update_special = KVM_SREGS_E_UPDATE_TSR;
+
+        kvm_vcpu_ioctl(env, KVM_SET_SREGS, &sregs);
+    }
+}
+
+static int kvm_booke_watchdog_enable(CPUPPCState *env)
+{
+    int ret;
+    struct kvm_enable_cap encap = {};
+
+    if (!kvm_enabled()) {
+        return 0;
+    }
+
+    if (!cap_ppc_watchdog) {
+        printf("warning: KVM does not support watchdog");
+        return 0;
+    }
+
+    encap.cap = KVM_CAP_PPC_BOOKE_WATCHDOG;
+    ret = kvm_vcpu_ioctl(env, KVM_ENABLE_CAP, &encap);
+    if (ret < 0) {
+        fprintf(stderr, "%s: couldn't enable KVM_CAP_PPC_BOOKE_WATCHDOG: %s\n",
+                __func__, strerror(-ret));
+        return ret;
+    }
+
+    return ret;
+}
+
 void ppc_booke_timers_init(CPUPPCState *env, uint32_t freq, uint32_t flags)
 {
     ppc_tb_t *tb_env;
@@ -262,5 +327,11 @@ void ppc_booke_timers_init(CPUPPCState *env, uint32_t 
freq, uint32_t flags)
     booke_timer->wdt_timer =
         qemu_new_timer_ns(vm_clock, &booke_wdt_cb, env);
 
+    if (kvm_enabled()) {
+        kvm_booke_watchdog_enable(env);
+    }
+
+    qemu_add_vm_change_state_handler(cpu_state_change_handler, env);
+
     qemu_register_reset(ppc_booke_timer_reset_handle, env);
 }
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 3f5df57..3d5f86a 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -32,6 +32,7 @@
 #include "device_tree.h"
 #include "hw/sysbus.h"
 #include "hw/spapr.h"
+#include "hw/watchdog.h"
 
 #include "hw/sysbus.h"
 #include "hw/spapr.h"
@@ -56,11 +57,12 @@ const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
 static int cap_interrupt_unset = false;
 static int cap_interrupt_level = false;
 static int cap_segstate;
-static int cap_booke_sregs;
+int cap_booke_sregs;
 static int cap_ppc_smt;
 static int cap_ppc_rma;
 static int cap_spapr_tce;
 static int cap_hior;
+int cap_ppc_watchdog;
 
 /* XXX We have a race condition where we actually have a level triggered
  *     interrupt, but the infrastructure can't expose that yet, so the guest
@@ -90,6 +92,7 @@ int kvm_arch_init(KVMState *s)
     cap_ppc_rma = kvm_check_extension(s, KVM_CAP_PPC_RMA);
     cap_spapr_tce = kvm_check_extension(s, KVM_CAP_SPAPR_TCE);
     cap_hior = kvm_check_extension(s, KVM_CAP_PPC_HIOR);
+    cap_ppc_watchdog = kvm_check_extension(s, KVM_CAP_PPC_BOOKE_WATCHDOG);
 
     if (!cap_interrupt_level) {
         fprintf(stderr, "KVM: Couldn't find level irq capability. Expect the "
@@ -823,6 +826,14 @@ int kvm_arch_handle_exit(CPUPPCState *env, struct kvm_run 
*run)
         ret = 0;
         break;
 #endif
+#ifdef KVM_EXIT_WATCHDOG
+    case KVM_EXIT_WATCHDOG:
+        dprintf("handle watchdog expiry\n");
+        watchdog_perform_action();
+        ret = 0;
+        break;
+#endif
+
     default:
         fprintf(stderr, "KVM: unknown exit reason %d\n", run->exit_reason);
         ret = -1;
-- 
1.7.0.4