[Qemu-devel] [PATCH v7 11/11] target-arm: Add support for VIRQ and VFIQ

["Edgar E. Iglesias" <edgar.iglesias@gmail.com>]

From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>

This only implements the external delivery method via the GIC.

Acked-by: Greg Bellows <greg.bellows@linaro.org>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
---
 cpu-exec.c              | 12 ++++++++++++
 target-arm/cpu.c        | 35 ++++++++++++++++++++++++-----------
 target-arm/cpu.h        | 35 ++++++++++++++++++++++++++++++++---
 target-arm/helper-a64.c |  2 ++
 target-arm/helper.c     |  4 ++++
 target-arm/internals.h  |  2 ++
 6 files changed, 76 insertions(+), 14 deletions(-)

diff --git a/cpu-exec.c b/cpu-exec.c
index d017588..6203ba5 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -616,6 +616,18 @@ int cpu_exec(CPUArchState *env)
                         cc->do_interrupt(cpu);
                         next_tb = 0;
                     }
+                    if (interrupt_request & CPU_INTERRUPT_VIRQ
+                        && arm_excp_unmasked(cpu, EXCP_VIRQ)) {
+                        cpu->exception_index = EXCP_VIRQ;
+                        cc->do_interrupt(cpu);
+                        next_tb = 0;
+                    }
+                    if (interrupt_request & CPU_INTERRUPT_VFIQ
+                        && arm_excp_unmasked(cpu, EXCP_VFIQ)) {
+                        cpu->exception_index = EXCP_VFIQ;
+                        cc->do_interrupt(cpu);
+                        next_tb = 0;
+                    }
 #elif defined(TARGET_UNICORE32)
                     if (interrupt_request & CPU_INTERRUPT_HARD
                         && !(env->uncached_asr & ASR_I)) {
diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index 7ea12bd..209ad2b 100644
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -41,7 +41,9 @@ static void arm_cpu_set_pc(CPUState *cs, vaddr value)
 static bool arm_cpu_has_work(CPUState *cs)
 {
     return cs->interrupt_request &
-        (CPU_INTERRUPT_FIQ | CPU_INTERRUPT_HARD | CPU_INTERRUPT_EXITTB);
+        (CPU_INTERRUPT_FIQ | CPU_INTERRUPT_HARD
+         | CPU_INTERRUPT_VFIQ | CPU_INTERRUPT_VIRQ
+         | CPU_INTERRUPT_EXITTB);
 }
 
 static void cp_reg_reset(gpointer key, gpointer value, gpointer opaque)
@@ -192,21 +194,29 @@ static void arm_cpu_reset(CPUState *s)
 static void arm_cpu_set_irq(void *opaque, int irq, int level)
 {
     ARMCPU *cpu = opaque;
+    CPUARMState *env = &cpu->env;
     CPUState *cs = CPU(cpu);
+    static const int mask[] = {
+        [ARM_CPU_IRQ] = CPU_INTERRUPT_HARD,
+        [ARM_CPU_FIQ] = CPU_INTERRUPT_FIQ,
+        [ARM_CPU_VIRQ] = CPU_INTERRUPT_VIRQ,
+        [ARM_CPU_VFIQ] = CPU_INTERRUPT_VFIQ
+    };
 
     switch (irq) {
-    case ARM_CPU_IRQ:
-        if (level) {
-            cpu_interrupt(cs, CPU_INTERRUPT_HARD);
-        } else {
-            cpu_reset_interrupt(cs, CPU_INTERRUPT_HARD);
+    case ARM_CPU_VIRQ:
+    case ARM_CPU_VFIQ:
+        if (!arm_feature(env, ARM_FEATURE_EL2)) {
+            hw_error("%s: Virtual interrupt line %d with no EL2 support\n",
+                     __func__, irq);
         }
-        break;
+        /* fall through */
+    case ARM_CPU_IRQ:
     case ARM_CPU_FIQ:
         if (level) {
-            cpu_interrupt(cs, CPU_INTERRUPT_FIQ);
+            cpu_interrupt(cs, mask[irq]);
         } else {
-            cpu_reset_interrupt(cs, CPU_INTERRUPT_FIQ);
+            cpu_reset_interrupt(cs, mask[irq]);
         }
         break;
     default:
@@ -256,9 +266,12 @@ static void arm_cpu_initfn(Object *obj)
 #ifndef CONFIG_USER_ONLY
     /* Our inbound IRQ and FIQ lines */
     if (kvm_enabled()) {
-        qdev_init_gpio_in(DEVICE(cpu), arm_cpu_kvm_set_irq, 2);
+        /* VIRQ and VFIQ are unused with KVM but we add them to maintain
+         * the same interface as non-KVM CPUs.
+         */
+        qdev_init_gpio_in(DEVICE(cpu), arm_cpu_kvm_set_irq, 4);
     } else {
-        qdev_init_gpio_in(DEVICE(cpu), arm_cpu_set_irq, 2);
+        qdev_init_gpio_in(DEVICE(cpu), arm_cpu_set_irq, 4);
     }
 
     cpu->gt_timer[GTIMER_PHYS] = timer_new(QEMU_CLOCK_VIRTUAL, GTIMER_SCALE,
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 00b3ad4..aa6fb3c 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -54,6 +54,8 @@
 #define EXCP_HVC            11   /* HyperVisor Call */
 #define EXCP_HYP_TRAP       12
 #define EXCP_SMC            13   /* Secure Monitor Call */
+#define EXCP_VIRQ           14
+#define EXCP_VFIQ           15
 
 #define ARMV7M_EXCP_RESET   1
 #define ARMV7M_EXCP_NMI     2
@@ -68,6 +70,8 @@
 
 /* ARM-specific interrupt pending bits.  */
 #define CPU_INTERRUPT_FIQ   CPU_INTERRUPT_TGT_EXT_1
+#define CPU_INTERRUPT_VIRQ  CPU_INTERRUPT_TGT_EXT_2
+#define CPU_INTERRUPT_VFIQ  CPU_INTERRUPT_TGT_EXT_3
 
 /* The usual mapping for an AArch64 system register to its AArch32
  * counterpart is for the 32 bit world to have access to the lower
@@ -83,9 +87,11 @@
 #define offsetofhigh32(S, M) (offsetof(S, M) + sizeof(uint32_t))
 #endif
 
-/* Meanings of the ARMCPU object's two inbound GPIO lines */
+/* Meanings of the ARMCPU object's four inbound GPIO lines */
 #define ARM_CPU_IRQ 0
 #define ARM_CPU_FIQ 1
+#define ARM_CPU_VIRQ 2
+#define ARM_CPU_VFIQ 3
 
 typedef void ARMWriteCPFunc(void *opaque, int cp_info,
                             int srcreg, int operand, uint32_t value);
@@ -1183,6 +1189,18 @@ static inline bool arm_excp_unmasked(CPUState *cs, unsigned int excp_idx)
     bool secure = false;
     /* If in EL1/0, Physical IRQ routing to EL2 only happens from NS state.  */
     bool irq_can_hyp = !secure && cur_el < 2 && target_el == 2;
+    /* ARMv7-M interrupt return works by loading a magic value
+     * into the PC.  On real hardware the load causes the
+     * return to occur.  The qemu implementation performs the
+     * jump normally, then does the exception return when the
+     * CPU tries to execute code at the magic address.
+     * This will cause the magic PC value to be pushed to
+     * the stack if an interrupt occurred at the wrong time.
+     * We avoid this by disabling interrupts when
+     * pc contains a magic address.
+     */
+    bool irq_unmasked = !(env->daif & PSTATE_I)
+                        && (!IS_M(env) || env->regs[15] < 0xfffffff0);
 
     /* Don't take exceptions if they target a lower EL.  */
     if (cur_el > target_el) {
@@ -1199,8 +1217,19 @@ static inline bool arm_excp_unmasked(CPUState *cs, unsigned int excp_idx)
         if (irq_can_hyp && (env->cp15.hcr_el2 & HCR_IMO)) {
             return true;
         }
-        return !(env->daif & PSTATE_I)
-               && (!IS_M(env) || env->regs[15] < 0xfffffff0);
+        return irq_unmasked;
+    case EXCP_VFIQ:
+        if (!secure && !(env->cp15.hcr_el2 & HCR_FMO)) {
+            /* VFIQs are only taken when hypervized and non-secure.  */
+            return false;
+        }
+        return !(env->daif & PSTATE_F);
+    case EXCP_VIRQ:
+        if (!secure && !(env->cp15.hcr_el2 & HCR_IMO)) {
+            /* VIRQs are only taken when hypervized and non-secure.  */
+            return false;
+        }
+        return irq_unmasked;
     default:
         g_assert_not_reached();
     }
diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
index 0011488..8228e29 100644
--- a/target-arm/helper-a64.c
+++ b/target-arm/helper-a64.c
@@ -482,9 +482,11 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
         env->cp15.esr_el[new_el] = env->exception.syndrome;
         break;
     case EXCP_IRQ:
+    case EXCP_VIRQ:
         addr += 0x80;
         break;
     case EXCP_FIQ:
+    case EXCP_VFIQ:
         addr += 0x100;
         break;
     default:
diff --git a/target-arm/helper.c b/target-arm/helper.c
index c3a70d6..098a507 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -3687,6 +3687,10 @@ unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx)
         }
         break;
     }
+    case EXCP_VIRQ:
+    case EXCP_VFIQ:
+        target_el = 1;
+        break;
     default:
         target_el = MAX(cur_el, 1);
         break;
diff --git a/target-arm/internals.h b/target-arm/internals.h
index 198cc0e..9bb40ca 100644
--- a/target-arm/internals.h
+++ b/target-arm/internals.h
@@ -56,6 +56,8 @@ static const char * const excnames[] = {
     [EXCP_HVC] = "Hypervisor Call",
     [EXCP_HYP_TRAP] = "Hypervisor Trap",
     [EXCP_SMC] = "Secure Monitor Call",
+    [EXCP_VIRQ] = "Virtual IRQ",
+    [EXCP_VFIQ] = "Virtual FIQ",
 };
 
 static inline void arm_log_exception(int idx)
-- 
1.9.1