hv: Implement a periodic hypervisor ptimer and use vtimer for stepping

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

proxyclient/hv.py

@@ -31,6 +31,7 @@ EvtMMIOTrace = Struct(
 
 class HV_EVENT(IntEnum):
     HOOK_VM = 1
+    VTIMER = 2
 
 VMProxyHookData = Struct(
     "flags" / RegAdapter(MMIOTraceFlags),
@@ -92,7 +93,7 @@ class HV:
         self.vbar_el1 = None
         self.want_vbar = None
         self.vectors = [None]
-        self.step = False
+        self._stepping = False
         self.sym_offset = 0
         self.symbols = []
         self.sysreg = {}
@@ -344,6 +345,9 @@ class HV:
                 code = HV_EVENT(code)
                 if code == HV_EVENT.HOOK_VM:
                     handled = self.handle_vm_hook(ctx)
+                elif code == HV_EVENT.VTIMER:
+                    print("Step")
+                    handled = True
         except Exception as e:
             print(f"Python exception while handling guest exception:")
             traceback.print_exc()
@@ -355,6 +359,9 @@ class HV:
 
             self.u.print_exception(code, ctx)
 
+        if self._stepping or not handled:
+            self._stepping = False
+
             locals = {
                 "hv": self,
                 "iface": self.iface,
@@ -376,7 +383,7 @@ class HV:
         if new_info != info_data:
             self.iface.writemem(info, new_info)
 
-        if ret == EXC_RET.HANDLED and self.step:
+        if ret == EXC_RET.HANDLED and self._stepping:
             ret = EXC_RET.STEP
         self.p.exit(ret)
 
@@ -387,6 +394,10 @@ class HV:
     def cont(self):
         raise shell.ExitConsole(EXC_RET.HANDLED)
 
+    def step(self):
+        self._stepping = True
+        raise shell.ExitConsole(EXC_RET.STEP)
+
     def exit(self):
         raise shell.ExitConsole(EXC_RET.EXIT_GUEST)
 
@@ -490,7 +501,9 @@ class HV:
         self.iface.set_handler(START.EXCEPTION_LOWER, EXC.IRQ, self.handle_exception)
         self.iface.set_handler(START.EXCEPTION_LOWER, EXC.FIQ, self.handle_exception)
         self.iface.set_handler(START.EXCEPTION_LOWER, EXC.SERROR, self.handle_exception)
+        self.iface.set_handler(START.EXCEPTION, EXC.FIQ, self.handle_exception)
         self.iface.set_handler(START.HV, HV_EVENT.HOOK_VM, self.handle_exception)
+        self.iface.set_handler(START.HV, HV_EVENT.VTIMER, self.handle_exception)
         self.iface.set_event_handler(EVENT.MMIOTRACE, self.handle_mmiotrace)
 
         self.map_hw(0x2_00000000, 0x2_00000000, 0x5_00000000)

src/hv.c

@@ -5,10 +5,14 @@
 #include "cpu_regs.h"
 #include "utils.h"
 
+#define HV_TICK_RATE 1000
+
 void hv_enter_guest(u64 x0, u64 x1, u64 x2, u64 x3, void *entry);
 
 extern char _hv_vectors_start[0];
 
+u64 hv_tick_interval;
+
 void hv_init(void)
 {
     // Enable physical timer for EL1
@@ -28,6 +32,9 @@ void hv_init(void)
     // No guest vectors initially
     msr(VBAR_EL12, 0);
 
+    // Compute tick interval
+    hv_tick_interval = mrs(CNTFRQ_EL0) / HV_TICK_RATE;
+
     sysop("dsb ishst");
     sysop("tlbi alle1is");
     sysop("dsb ish");
@@ -38,7 +45,19 @@ void hv_start(void *entry, u64 regs[4])
 {
     msr(VBAR_EL1, _hv_vectors_start);
 
+    hv_arm_tick();
     hv_enter_guest(regs[0], regs[1], regs[2], regs[3], entry);
 
     printf("Exiting hypervisor.\n");
 }
+
+void hv_arm_tick(void)
+{
+    msr(CNTP_TVAL_EL0, hv_tick_interval);
+    msr(CNTP_CTL_EL0, CNTx_CTL_ENABLE);
+}
+
+void hv_tick(void)
+{
+    //     printf("HV tick!\n");
+}

src/hv.h

@@ -29,6 +29,7 @@ struct hv_vm_proxy_hook_data {
 
 typedef enum _hv_entry_type {
     HV_HOOK_VM = 1,
+    HV_VTIMER,
 } hv_entry_type;
 
 /* VM */
@@ -53,5 +54,7 @@ void hv_exc_proxy(u64 *regs, uartproxy_boot_reason_t reason, uartproxy_exc_code_
 /* HV main */
 void hv_init(void);
 void hv_start(void *entry, u64 regs[4]);
+void hv_arm_tick(void);
+void hv_tick(void);
 
 #endif

src/hv_exc.c

@@ -82,7 +82,30 @@ void hv_exc_irq(u64 *regs)
 
 void hv_exc_fiq(u64 *regs)
 {
-    hv_exc_proxy(regs, START_EXCEPTION_LOWER, EXC_FIQ, NULL);
+    if (mrs(CNTP_CTL_EL0) == (CNTx_CTL_ISTATUS | CNTx_CTL_ENABLE)) {
+        msr(CNTP_CTL_EL0, CNTx_CTL_ISTATUS | CNTx_CTL_IMASK | CNTx_CTL_ENABLE);
+        hv_tick();
+        hv_arm_tick();
+    }
+
+    if (mrs(CNTV_CTL_EL0) == (CNTx_CTL_ISTATUS | CNTx_CTL_ENABLE)) {
+        msr(CNTV_CTL_EL0, CNTx_CTL_ISTATUS | CNTx_CTL_IMASK | CNTx_CTL_ENABLE);
+        hv_exc_proxy(regs, START_HV, HV_VTIMER, NULL);
+    }
+
+    u64 reg = mrs(SYS_IMP_APL_PMCR0);
+    if ((reg & (PMCR0_IMODE_MASK | PMCR0_IACT)) == (PMCR0_IMODE_FIQ | PMCR0_IACT)) {
+        printf("[FIQ] PMC IRQ, masking");
+        reg_clr(SYS_IMP_APL_PMCR0, PMCR0_IACT | PMCR0_IMODE_MASK);
+        hv_exc_proxy(regs, START_EXCEPTION_LOWER, EXC_FIQ, NULL);
+    }
+
+    reg = mrs(SYS_IMP_APL_UPMCR0);
+    if ((reg & UPMCR0_IMODE_MASK) == UPMCR0_IMODE_FIQ && (mrs(SYS_IMP_APL_UPMSR) & UPMSR_IACT)) {
+        printf("[FIQ] UPMC IRQ, masking");
+        reg_clr(SYS_IMP_APL_UPMCR0, UPMCR0_IMODE_MASK);
+        hv_exc_proxy(regs, START_EXCEPTION_LOWER, EXC_FIQ, NULL);
+    }
 }
 
 void hv_exc_serr(u64 *regs)