From 28fcb58c696f7dc418189377eae6812ae2bcc396 Mon Sep 17 00:00:00 2001
From: Peter Maydell <peter.maydell@linaro.org>
Date: Sat, 10 Nov 2018 09:23:17 -0500
Subject: [PATCH] target/arm: Implement HCR.VI and VF

The HCR_EL2 VI and VF bits are supposed to track whether there is
a pending virtual IRQ or virtual FIQ. For QEMU we store the
pending VIRQ/VFIQ status in cs->interrupt_request, so this means:
* if the register is read we must get these bit values from
cs->interrupt_request
* if the register is written then we must write the bit
values back into cs->interrupt_request

Backports commit 8a0fc3a29fc2315325400c738f807d0d4ae0ab7f from qemu
---
 qemu/target/arm/helper.c | 49 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 5 deletions(-)

diff --git a/qemu/target/arm/helper.c b/qemu/target/arm/helper.c
index d3419072..85c88f16 100644
--- a/qemu/target/arm/helper.c
+++ b/qemu/target/arm/helper.c
@@ -3485,6 +3485,7 @@ static const ARMCPRegInfo el3_no_el2_v8_cp_reginfo[] = {
 static void hcr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value)
 {
     ARMCPU *cpu = arm_env_get_cpu(env);
+    CPUState *cs = ENV_GET_CPU(env);
     uint64_t valid_mask = HCR_MASK;
 
     if (arm_feature(env, ARM_FEATURE_EL3)) {
@@ -3503,6 +3504,29 @@ static void hcr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value)
     /* Clear RES0 bits.  */
     value &= valid_mask;
 
+    /*
+     * VI and VF are kept in cs->interrupt_request. Modifying that
+     * requires that we have the iothread lock, which is done by
+     * marking the reginfo structs as ARM_CP_IO.
+     * Note that if a write to HCR pends a VIRQ or VFIQ it is never
+     * possible for it to be taken immediately, because VIRQ and
+     * VFIQ are masked unless running at EL0 or EL1, and HCR
+     * can only be written at EL2.
+     */
+    // Unicorn: Commented out
+    //g_assert(qemu_mutex_iothread_locked());
+    if (value & HCR_VI) {
+        cs->interrupt_request |= CPU_INTERRUPT_VIRQ;
+    } else {
+        cs->interrupt_request &= ~CPU_INTERRUPT_VIRQ;
+    }
+    if (value & HCR_VF) {
+        cs->interrupt_request |= CPU_INTERRUPT_VFIQ;
+    } else {
+        cs->interrupt_request &= ~CPU_INTERRUPT_VFIQ;
+    }
+    value &= ~(HCR_VI | HCR_VF);
+
     /* These bits change the MMU setup:
      * HCR_VM enables stage 2 translation
      * HCR_PTW forbids certain page-table setups
@@ -3530,13 +3554,28 @@ static void hcr_writelow(CPUARMState *env, const ARMCPRegInfo *ri,
     hcr_write(env, NULL, value);
 }
 
+static uint64_t hcr_read(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+    /* The VI and VF bits live in cs->interrupt_request */
+    uint64_t ret = env->cp15.hcr_el2 & ~(HCR_VI | HCR_VF);
+    CPUState *cs = ENV_GET_CPU(env);
+
+    if (cs->interrupt_request & CPU_INTERRUPT_VIRQ) {
+        ret |= HCR_VI;
+    }
+    if (cs->interrupt_request & CPU_INTERRUPT_VFIQ) {
+        ret |= HCR_VF;
+    }
+    return ret;
+}
+
 static const ARMCPRegInfo el2_cp_reginfo[] = {
     { "HCR_EL2", 0,1,1, 3,4,0, ARM_CP_STATE_AA64,
-      0, PL2_RW, 0, NULL, 0, offsetof(CPUARMState, cp15.hcr_el2), {0, 0},
-      NULL, NULL, hcr_write },
+      ARM_CP_IO, PL2_RW, 0, NULL, 0, offsetof(CPUARMState, cp15.hcr_el2), {0, 0},
+      NULL, hcr_read, hcr_write },
     { "HCR", 15,1,1, 0,4,0, ARM_CP_STATE_AA32,
-      ARM_CP_ALIAS, PL2_RW, 0, NULL, 0, offsetof(CPUARMState, cp15.hcr_el2),
-      {0, 0}, NULL, NULL, hcr_writelow },
+      ARM_CP_ALIAS | ARM_CP_IO, PL2_RW, 0, NULL, 0, offsetof(CPUARMState, cp15.hcr_el2),
+      {0, 0}, NULL, hcr_read, hcr_writelow },
     { "ELR_EL2", 0,4,0, 3,4,1, ARM_CP_STATE_AA64,
       ARM_CP_ALIAS, PL2_RW, 0, NULL, 0, offsetof(CPUARMState, elr_el[2]) },
     { "ESR_EL2", 0,5,2, 3,4,0, ARM_CP_STATE_BOTH, 0,
@@ -3700,7 +3739,7 @@ static const ARMCPRegInfo el2_cp_reginfo[] = {
 
 static const ARMCPRegInfo el2_v8_cp_reginfo[] = {
     { "HCR2", 15,1,1, 0,4,4, ARM_CP_STATE_AA32,
-      ARM_CP_ALIAS, PL2_RW, 0, NULL, 0, offsetofhigh32(CPUARMState, cp15.hcr_el2),
+      ARM_CP_ALIAS | ARM_CP_IO, PL2_RW, 0, NULL, 0, offsetofhigh32(CPUARMState, cp15.hcr_el2),
       {0, 0}, NULL, NULL, hcr_writehigh },
     REGINFO_SENTINEL
 };