hv_wdt: Make HV WDT CPU configurable and WDT optional

Signed-off-by: Hector Martin <marcan@marcan.st>

proxyclient/m1n1/hv.py

@@ -132,6 +132,7 @@ class HV(Reloadable):
         self.shell_locals = {}
         self.xnu_mode = False
         self._update_shell_locals()
+        self.wdt_cpu = None
 
     def _reloadme(self):
         super()._reloadme()
@@ -1041,14 +1042,9 @@ class HV(Reloadable):
                     del self.adt[name]
                 except KeyError:
                     pass
-        for name in ("/cpus/cpu1",
-                     "/cpus/cpu2",
-                     "/cpus/cpu3",
-                     "/cpus/cpu4",
-                     "/cpus/cpu5",
-                     "/cpus/cpu6",
-                     "/cpus/cpu7",
-                    ):
+
+        if self.wdt_cpu is not None:
+            name = f"/cpus/cpu{self.wdt_cpu}"
             print(f"Removing ADT node {name}")
             try:
                 del self.adt[name]
@@ -1239,6 +1235,8 @@ class HV(Reloadable):
         self.iface.dev.timeout = None
         self.default_sigint = signal.signal(signal.SIGINT, self._handle_sigint)
 
+        if self.wdt_cpu is not None:
+            self.p.hv_wdt_start(self.wdt_cpu)
         # Does not return
         self.p.hv_start(self.entry, self.guest_base + self.bootargs_off)
 

proxyclient/m1n1/proxy.py

@@ -561,6 +561,7 @@ class M1N1Proxy(Reloadable):
     P_HV_PT_WALK = 0xc04
     P_HV_MAP_VUART = 0xc05
     P_HV_TRACE_IRQ = 0xc06
+    P_HV_WDT_START = 0xc07
 
     P_FB_INIT = 0xd00
     P_FB_SHUTDOWN = 0xd01
@@ -955,6 +956,8 @@ class M1N1Proxy(Reloadable):
         return self.request(self.P_HV_MAP_VUART, base, irq, iodev)
     def hv_trace_irq(self, evt_type, num, count, flags):
         return self.request(self.P_HV_TRACE_IRQ, evt_type, num, count, flags)
+    def hv_wdt_start(self, cpu):
+        return self.request(self.P_HV_WDT_START, cpu)
 
     def fb_init(self):
         return self.request(self.P_FB_INIT)

src/hv.c

@@ -65,7 +65,6 @@ void hv_start(void *entry, u64 regs[4])
     if (gxf_enabled())
         gl2_call(hv_set_gxf_vbar, 0, 0, 0, 0);
 
-    hv_wdt_start();
     hv_arm_tick();
     hv_enter_guest(regs[0], regs[1], regs[2], regs[3], entry);
     hv_wdt_stop();

src/hv.h

@@ -71,7 +71,7 @@ void hv_wdt_pet(void);
 void hv_wdt_suspend(void);
 void hv_wdt_resume(void);
 void hv_wdt_init(void);
-void hv_wdt_start(void);
+void hv_wdt_start(int cpu);
 void hv_wdt_stop(void);
 void hv_wdt_breadcrumb(char c);
 

src/hv_wdt.c

@@ -6,7 +6,6 @@
 #include "uart.h"
 #include "utils.h"
 
-#define WDT_CPU     1
 #define WDT_TIMEOUT 1
 
 static bool hv_wdt_active = false;
@@ -15,6 +14,8 @@ static volatile u64 hv_wdt_timestamp = 0;
 static u64 hv_wdt_timeout = 0;
 static volatile u64 hv_wdt_breadcrumbs;
 
+static int hv_wdt_cpu;
+
 static u64 cpu_dbg_base = 0;
 
 void hv_wdt_bark(void)
@@ -105,18 +106,25 @@ void hv_wdt_init(void)
     cpu_dbg_base = reg[0];
 }
 
-void hv_wdt_start(void)
+void hv_wdt_start(int cpu)
 {
+    if (hv_wdt_active)
+        return;
+
+    hv_wdt_cpu = cpu;
     hv_wdt_breadcrumbs = 0;
     hv_wdt_timeout = mrs(CNTFRQ_EL0) * WDT_TIMEOUT;
     hv_wdt_pet();
     hv_wdt_active = true;
     hv_wdt_enabled = true;
-    smp_call4(WDT_CPU, hv_wdt_main, 0, 0, 0, 0);
+    smp_call4(hv_wdt_cpu, hv_wdt_main, 0, 0, 0, 0);
 }
 
 void hv_wdt_stop(void)
 {
+    if (!hv_wdt_active)
+        return;
+
     hv_wdt_active = false;
-    smp_wait(WDT_CPU);
+    smp_wait(hv_wdt_cpu);
 }

src/proxy.c

@@ -436,6 +436,9 @@ int proxy_process(ProxyRequest *request, ProxyReply *reply)
             reply->retval = hv_trace_irq(request->args[0], request->args[1], request->args[2],
                                          request->args[3]);
             break;
+        case P_HV_WDT_START:
+            hv_wdt_start(request->args[0]);
+            break;
 
         case P_FB_INIT:
             fb_init();

src/proxy.h

@@ -119,6 +119,7 @@ typedef enum {
     P_HV_PT_WALK,
     P_HV_MAP_VUART,
     P_HV_TRACE_IRQ,
+    P_HV_WDT_START,
 
     P_FB_INIT = 0xd00,
     P_FB_SHUTDOWN,