[Qemu-devel] [PATCH v6 07/10] target-arm: A64: Emulate the HVC insn

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

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

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
---
 target-arm/cpu.h           |  1 +
 target-arm/helper-a64.c    |  1 +
 target-arm/helper.c        | 28 +++++++++++++++++++++++++++-
 target-arm/helper.h        |  1 +
 target-arm/internals.h     |  6 ++++++
 target-arm/op_helper.c     | 32 ++++++++++++++++++++++++++++++++
 target-arm/translate-a64.c | 30 +++++++++++++++++++++---------
 7 files changed, 89 insertions(+), 10 deletions(-)

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 7f8a410..b553f3d 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -51,6 +51,7 @@
 #define EXCP_EXCEPTION_EXIT  8   /* Return from v7M exception.  */
 #define EXCP_KERNEL_TRAP     9   /* Jumped to kernel code page.  */
 #define EXCP_STREX          10
+#define EXCP_HVC            11   /* HyperVisor Call */
 
 #define ARMV7M_EXCP_RESET   1
 #define ARMV7M_EXCP_NMI     2
diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
index c6ef8e9..4e6ca26 100644
--- a/target-arm/helper-a64.c
+++ b/target-arm/helper-a64.c
@@ -476,6 +476,7 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
     case EXCP_BKPT:
     case EXCP_UDEF:
     case EXCP_SWI:
+    case EXCP_HVC:
         env->cp15.esr_el[new_el] = env->exception.syndrome;
         break;
     case EXCP_IRQ:
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 4431fbb..504ff42 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -3652,7 +3652,33 @@ void switch_mode(CPUARMState *env, int mode)
  */
 unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx)
 {
-    return 1;
+    CPUARMState *env = cs->env_ptr;
+    unsigned int cur_el = arm_current_pl(env);
+    unsigned int target_el = 1;
+    bool route_to_el2 = false;
+    /* FIXME: Use actual secure state.  */
+    bool secure = false;
+
+    if (!env->aarch64) {
+        /* TODO: Add EL2 and 3 exception handling for AArch32.  */
+        return 1;
+    }
+
+    if (!secure
+        && arm_feature(env, ARM_FEATURE_EL2)
+        && cur_el < 2
+        && (env->cp15.hcr_el2 & HCR_TGE)) {
+        route_to_el2 = true;
+    }
+
+    target_el = MAX(cur_el, route_to_el2 ? 2 : 1);
+
+    switch (excp_idx) {
+    case EXCP_HVC:
+        target_el = MAX(target_el, 2);
+        break;
+    }
+    return target_el;
 }
 
 static void v7m_push(CPUARMState *env, uint32_t val)
diff --git a/target-arm/helper.h b/target-arm/helper.h
index 1d7003b..75fc1b3 100644
--- a/target-arm/helper.h
+++ b/target-arm/helper.h
@@ -50,6 +50,7 @@ DEF_HELPER_2(exception_internal, void, env, i32)
 DEF_HELPER_3(exception_with_syndrome, void, env, i32, i32)
 DEF_HELPER_1(wfi, void, env)
 DEF_HELPER_1(wfe, void, env)
+DEF_HELPER_1(pre_hvc, void, env)
 
 DEF_HELPER_3(cpsr_write, void, env, i32, i32)
 DEF_HELPER_1(cpsr_read, i32, env)
diff --git a/target-arm/internals.h b/target-arm/internals.h
index 64751a0..afcc4e0 100644
--- a/target-arm/internals.h
+++ b/target-arm/internals.h
@@ -53,6 +53,7 @@ static const char * const excnames[] = {
     [EXCP_EXCEPTION_EXIT] = "QEMU v7M exception exit",
     [EXCP_KERNEL_TRAP] = "QEMU intercept of kernel commpage",
     [EXCP_STREX] = "QEMU intercept of STREX",
+    [EXCP_HVC] = "Hypervisor Call",
 };
 
 static inline void arm_log_exception(int idx)
@@ -215,6 +216,11 @@ static inline uint32_t syn_aa64_svc(uint32_t imm16)
     return (EC_AA64_SVC << ARM_EL_EC_SHIFT) | ARM_EL_IL | (imm16 & 0xffff);
 }
 
+static inline uint32_t syn_aa64_hvc(uint32_t imm16)
+{
+    return (EC_AA64_HVC << ARM_EL_EC_SHIFT) | ARM_EL_IL | (imm16 & 0xffff);
+}
+
 static inline uint32_t syn_aa32_svc(uint32_t imm16, bool is_thumb)
 {
     return (EC_AA32_SVC << ARM_EL_EC_SHIFT) | (imm16 & 0xffff)
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index b956216..8441c27 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -374,6 +374,38 @@ void HELPER(clear_pstate_ss)(CPUARMState *env)
     env->pstate &= ~PSTATE_SS;
 }
 
+void HELPER(pre_hvc)(CPUARMState *env)
+{
+    int cur_el = arm_current_pl(env);
+    /* FIXME: Use actual secure state.  */
+    bool secure = false;
+    bool udef;
+
+    /* We've already checked that EL2 exists at translation time.
+     * EL3.HCE has priority over EL2.HCD.
+     */
+    if (arm_feature(env, ARM_FEATURE_EL3)) {
+        udef = !(env->cp15.scr_el3 & SCR_HCE);
+    } else {
+        udef = env->cp15.hcr_el2 & HCR_HCD;
+    }
+
+    /* In ARMv7 and ARMv8/AArch32, HVC is udef in secure state.
+     * For ARMv8/AArch64, HVC is allowed in EL3.
+     * Note that we've already trapped HVC from EL0 at translation
+     * time.
+     */
+    if (secure && (!is_a64(env) || cur_el == 1)) {
+        udef = true;
+    }
+
+    if (udef) {
+        /* UDEFs trap on the HVC, roll back to the PC to the HVC insn.  */
+        env->exception.syndrome = syn_uncategorized();
+        raise_exception(env, EXCP_UDEF);
+    }
+}
+
 void HELPER(exception_return)(CPUARMState *env)
 {
     int cur_el = arm_current_pl(env);
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 8e66b6c..8eaa85f 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -1473,20 +1473,32 @@ static void disas_exc(DisasContext *s, uint32_t insn)
 
     switch (opc) {
     case 0:
-        /* SVC, HVC, SMC; since we don't support the Virtualization
-         * or TrustZone extensions these all UNDEF except SVC.
-         */
-        if (op2_ll != 1) {
-            unallocated_encoding(s);
-            break;
-        }
         /* For SVC, HVC and SMC we advance the single-step state
          * machine before taking the exception. This is architecturally
          * mandated, to ensure that single-stepping a system call
          * instruction works properly.
          */
-        gen_ss_advance(s);
-        gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16));
+        switch (op2_ll) {
+        case 1:
+            gen_ss_advance(s);
+            gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16));
+            break;
+        case 2:
+            if (!arm_dc_feature(s, ARM_FEATURE_EL2) || s->current_pl == 0) {
+                unallocated_encoding(s);
+                break;
+            }
+            /* The pre HVC helper handles cases when HVC gets trapped
+             * as an undefined insn by runtime configuration.  */
+            gen_a64_set_pc_im(s->pc - 4);
+            gen_helper_pre_hvc(cpu_env);
+            gen_ss_advance(s);
+            gen_exception_insn(s, 0, EXCP_HVC, syn_aa64_hvc(imm16));
+            break;
+        default:
+            unallocated_encoding(s);
+            break;
+        }
         break;
     case 1:
         if (op2_ll != 0) {
-- 
1.9.1