RISC-V: KVM: Add in-kernel emulation of AIA APLIC

There is no virtualization support in AIA APLIC so we add in-kernel
emulation of AIA APLIC which only supports MSI-mode (i.e. wired
interrupts forwarded to AIA IMSIC as MSIs).

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

1 files changed, 576 insertions, 0 deletions

diff --git a/arch/riscv/kvm/aia_aplic.c b/arch/riscv/kvm/aia_aplic.c
new file mode 100644
index 000000000000..eecd8f4abe21
--- /dev/null
+++ b/arch/riscv/kvm/aia_aplic.c
@@ -0,0 +1,576 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (C) 2022 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *	Anup Patel <apatel@ventanamicro.com>
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/math.h>
+#include <linux/spinlock.h>
+#include <linux/swab.h>
+#include <kvm/iodev.h>
+#include <asm/kvm_aia_aplic.h>
+
+struct aplic_irq {
+	raw_spinlock_t lock;
+	u32 sourcecfg;
+	u32 state;
+#define APLIC_IRQ_STATE_PENDING		BIT(0)
+#define APLIC_IRQ_STATE_ENABLED		BIT(1)
+#define APLIC_IRQ_STATE_ENPEND		(APLIC_IRQ_STATE_PENDING | \
+					 APLIC_IRQ_STATE_ENABLED)
+#define APLIC_IRQ_STATE_INPUT		BIT(8)
+	u32 target;
+};
+
+struct aplic {
+	struct kvm_io_device iodev;
+
+	u32 domaincfg;
+	u32 genmsi;
+
+	u32 nr_irqs;
+	u32 nr_words;
+	struct aplic_irq *irqs;
+};
+
+static u32 aplic_read_sourcecfg(struct aplic *aplic, u32 irq)
+{
+	u32 ret;
+	unsigned long flags;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return 0;
+	irqd = &aplic->irqs[irq];
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+	ret = irqd->sourcecfg;
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+
+	return ret;
+}
+
+static void aplic_write_sourcecfg(struct aplic *aplic, u32 irq, u32 val)
+{
+	unsigned long flags;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return;
+	irqd = &aplic->irqs[irq];
+
+	if (val & APLIC_SOURCECFG_D)
+		val = 0;
+	else
+		val &= APLIC_SOURCECFG_SM_MASK;
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+	irqd->sourcecfg = val;
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+}
+
+static u32 aplic_read_target(struct aplic *aplic, u32 irq)
+{
+	u32 ret;
+	unsigned long flags;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return 0;
+	irqd = &aplic->irqs[irq];
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+	ret = irqd->target;
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+
+	return ret;
+}
+
+static void aplic_write_target(struct aplic *aplic, u32 irq, u32 val)
+{
+	unsigned long flags;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return;
+	irqd = &aplic->irqs[irq];
+
+	val &= APLIC_TARGET_EIID_MASK |
+	       (APLIC_TARGET_HART_IDX_MASK << APLIC_TARGET_HART_IDX_SHIFT) |
+	       (APLIC_TARGET_GUEST_IDX_MASK << APLIC_TARGET_GUEST_IDX_SHIFT);
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+	irqd->target = val;
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+}
+
+static bool aplic_read_pending(struct aplic *aplic, u32 irq)
+{
+	bool ret;
+	unsigned long flags;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return false;
+	irqd = &aplic->irqs[irq];
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+	ret = (irqd->state & APLIC_IRQ_STATE_PENDING) ? true : false;
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+
+	return ret;
+}
+
+static void aplic_write_pending(struct aplic *aplic, u32 irq, bool pending)
+{
+	unsigned long flags, sm;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return;
+	irqd = &aplic->irqs[irq];
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+
+	sm = irqd->sourcecfg & APLIC_SOURCECFG_SM_MASK;
+	if (!pending &&
+	    ((sm == APLIC_SOURCECFG_SM_LEVEL_HIGH) ||
+	     (sm == APLIC_SOURCECFG_SM_LEVEL_LOW)))
+		goto skip_write_pending;
+
+	if (pending)
+		irqd->state |= APLIC_IRQ_STATE_PENDING;
+	else
+		irqd->state &= ~APLIC_IRQ_STATE_PENDING;
+
+skip_write_pending:
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+}
+
+static bool aplic_read_enabled(struct aplic *aplic, u32 irq)
+{
+	bool ret;
+	unsigned long flags;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return false;
+	irqd = &aplic->irqs[irq];
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+	ret = (irqd->state & APLIC_IRQ_STATE_ENABLED) ? true : false;
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+
+	return ret;
+}
+
+static void aplic_write_enabled(struct aplic *aplic, u32 irq, bool enabled)
+{
+	unsigned long flags;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return;
+	irqd = &aplic->irqs[irq];
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+	if (enabled)
+		irqd->state |= APLIC_IRQ_STATE_ENABLED;
+	else
+		irqd->state &= ~APLIC_IRQ_STATE_ENABLED;
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+}
+
+static bool aplic_read_input(struct aplic *aplic, u32 irq)
+{
+	bool ret;
+	unsigned long flags;
+	struct aplic_irq *irqd;
+
+	if (!irq || aplic->nr_irqs <= irq)
+		return false;
+	irqd = &aplic->irqs[irq];
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+	ret = (irqd->state & APLIC_IRQ_STATE_INPUT) ? true : false;
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+
+	return ret;
+}
+
+static void aplic_inject_msi(struct kvm *kvm, u32 irq, u32 target)
+{
+	u32 hart_idx, guest_idx, eiid;
+
+	hart_idx = target >> APLIC_TARGET_HART_IDX_SHIFT;
+	hart_idx &= APLIC_TARGET_HART_IDX_MASK;
+	guest_idx = target >> APLIC_TARGET_GUEST_IDX_SHIFT;
+	guest_idx &= APLIC_TARGET_GUEST_IDX_MASK;
+	eiid = target & APLIC_TARGET_EIID_MASK;
+	kvm_riscv_aia_inject_msi_by_id(kvm, hart_idx, guest_idx, eiid);
+}
+
+static void aplic_update_irq_range(struct kvm *kvm, u32 first, u32 last)
+{
+	bool inject;
+	u32 irq, target;
+	unsigned long flags;
+	struct aplic_irq *irqd;
+	struct aplic *aplic = kvm->arch.aia.aplic_state;
+
+	if (!(aplic->domaincfg & APLIC_DOMAINCFG_IE))
+		return;
+
+	for (irq = first; irq <= last; irq++) {
+		if (!irq || aplic->nr_irqs <= irq)
+			continue;
+		irqd = &aplic->irqs[irq];
+
+		raw_spin_lock_irqsave(&irqd->lock, flags);
+
+		inject = false;
+		target = irqd->target;
+		if ((irqd->state & APLIC_IRQ_STATE_ENPEND) ==
+		    APLIC_IRQ_STATE_ENPEND) {
+			irqd->state &= ~APLIC_IRQ_STATE_PENDING;
+			inject = true;
+		}
+
+		raw_spin_unlock_irqrestore(&irqd->lock, flags);
+
+		if (inject)
+			aplic_inject_msi(kvm, irq, target);
+	}
+}
+
+int kvm_riscv_aia_aplic_inject(struct kvm *kvm, u32 source, bool level)
+{
+	u32 target;
+	bool inject = false, ie;
+	unsigned long flags;
+	struct aplic_irq *irqd;
+	struct aplic *aplic = kvm->arch.aia.aplic_state;
+
+	if (!aplic || !source || (aplic->nr_irqs <= source))
+		return -ENODEV;
+	irqd = &aplic->irqs[source];
+	ie = (aplic->domaincfg & APLIC_DOMAINCFG_IE) ? true : false;
+
+	raw_spin_lock_irqsave(&irqd->lock, flags);
+
+	if (irqd->sourcecfg & APLIC_SOURCECFG_D)
+		goto skip_unlock;
+
+	switch (irqd->sourcecfg & APLIC_SOURCECFG_SM_MASK) {
+	case APLIC_SOURCECFG_SM_EDGE_RISE:
+		if (level && !(irqd->state & APLIC_IRQ_STATE_INPUT) &&
+		    !(irqd->state & APLIC_IRQ_STATE_PENDING))
+			irqd->state |= APLIC_IRQ_STATE_PENDING;
+		break;
+	case APLIC_SOURCECFG_SM_EDGE_FALL:
+		if (!level && (irqd->state & APLIC_IRQ_STATE_INPUT) &&
+		    !(irqd->state & APLIC_IRQ_STATE_PENDING))
+			irqd->state |= APLIC_IRQ_STATE_PENDING;
+		break;
+	case APLIC_SOURCECFG_SM_LEVEL_HIGH:
+		if (level && !(irqd->state & APLIC_IRQ_STATE_PENDING))
+			irqd->state |= APLIC_IRQ_STATE_PENDING;
+		break;
+	case APLIC_SOURCECFG_SM_LEVEL_LOW:
+		if (!level && !(irqd->state & APLIC_IRQ_STATE_PENDING))
+			irqd->state |= APLIC_IRQ_STATE_PENDING;
+		break;
+	}
+
+	if (level)
+		irqd->state |= APLIC_IRQ_STATE_INPUT;
+	else
+		irqd->state &= ~APLIC_IRQ_STATE_INPUT;
+
+	target = irqd->target;
+	if (ie && ((irqd->state & APLIC_IRQ_STATE_ENPEND) ==
+		   APLIC_IRQ_STATE_ENPEND)) {
+		irqd->state &= ~APLIC_IRQ_STATE_PENDING;
+		inject = true;
+	}
+
+skip_unlock:
+	raw_spin_unlock_irqrestore(&irqd->lock, flags);
+
+	if (inject)
+		aplic_inject_msi(kvm, source, target);
+
+	return 0;
+}
+
+static u32 aplic_read_input_word(struct aplic *aplic, u32 word)
+{
+	u32 i, ret = 0;
+
+	for (i = 0; i < 32; i++)
+		ret |= aplic_read_input(aplic, word * 32 + i) ? BIT(i) : 0;
+
+	return ret;
+}
+
+static u32 aplic_read_pending_word(struct aplic *aplic, u32 word)
+{
+	u32 i, ret = 0;
+
+	for (i = 0; i < 32; i++)
+		ret |= aplic_read_pending(aplic, word * 32 + i) ? BIT(i) : 0;
+
+	return ret;
+}
+
+static void aplic_write_pending_word(struct aplic *aplic, u32 word,
+				     u32 val, bool pending)
+{
+	u32 i;
+
+	for (i = 0; i < 32; i++) {
+		if (val & BIT(i))
+			aplic_write_pending(aplic, word * 32 + i, pending);
+	}
+}
+
+static u32 aplic_read_enabled_word(struct aplic *aplic, u32 word)
+{
+	u32 i, ret = 0;
+
+	for (i = 0; i < 32; i++)
+		ret |= aplic_read_enabled(aplic, word * 32 + i) ? BIT(i) : 0;
+
+	return ret;
+}
+
+static void aplic_write_enabled_word(struct aplic *aplic, u32 word,
+				     u32 val, bool enabled)
+{
+	u32 i;
+
+	for (i = 0; i < 32; i++) {
+		if (val & BIT(i))
+			aplic_write_enabled(aplic, word * 32 + i, enabled);
+	}
+}
+
+static int aplic_mmio_read_offset(struct kvm *kvm, gpa_t off, u32 *val32)
+{
+	u32 i;
+	struct aplic *aplic = kvm->arch.aia.aplic_state;
+
+	if ((off & 0x3) != 0)
+		return -EOPNOTSUPP;
+
+	if (off == APLIC_DOMAINCFG) {
+		*val32 = APLIC_DOMAINCFG_RDONLY |
+			 aplic->domaincfg | APLIC_DOMAINCFG_DM;
+	} else if ((off >= APLIC_SOURCECFG_BASE) &&
+		 (off < (APLIC_SOURCECFG_BASE + (aplic->nr_irqs - 1) * 4))) {
+		i = ((off - APLIC_SOURCECFG_BASE) >> 2) + 1;
+		*val32 = aplic_read_sourcecfg(aplic, i);
+	} else if ((off >= APLIC_SETIP_BASE) &&
+		   (off < (APLIC_SETIP_BASE + aplic->nr_words * 4))) {
+		i = (off - APLIC_SETIP_BASE) >> 2;
+		*val32 = aplic_read_pending_word(aplic, i);
+	} else if (off == APLIC_SETIPNUM) {
+		*val32 = 0;
+	} else if ((off >= APLIC_CLRIP_BASE) &&
+		   (off < (APLIC_CLRIP_BASE + aplic->nr_words * 4))) {
+		i = (off - APLIC_CLRIP_BASE) >> 2;
+		*val32 = aplic_read_input_word(aplic, i);
+	} else if (off == APLIC_CLRIPNUM) {
+		*val32 = 0;
+	} else if ((off >= APLIC_SETIE_BASE) &&
+		   (off < (APLIC_SETIE_BASE + aplic->nr_words * 4))) {
+		i = (off - APLIC_SETIE_BASE) >> 2;
+		*val32 = aplic_read_enabled_word(aplic, i);
+	} else if (off == APLIC_SETIENUM) {
+		*val32 = 0;
+	} else if ((off >= APLIC_CLRIE_BASE) &&
+		   (off < (APLIC_CLRIE_BASE + aplic->nr_words * 4))) {
+		*val32 = 0;
+	} else if (off == APLIC_CLRIENUM) {
+		*val32 = 0;
+	} else if (off == APLIC_SETIPNUM_LE) {
+		*val32 = 0;
+	} else if (off == APLIC_SETIPNUM_BE) {
+		*val32 = 0;
+	} else if (off == APLIC_GENMSI) {
+		*val32 = aplic->genmsi;
+	} else if ((off >= APLIC_TARGET_BASE) &&
+		   (off < (APLIC_TARGET_BASE + (aplic->nr_irqs - 1) * 4))) {
+		i = ((off - APLIC_TARGET_BASE) >> 2) + 1;
+		*val32 = aplic_read_target(aplic, i);
+	} else
+		return -ENODEV;
+
+	return 0;
+}
+
+static int aplic_mmio_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
+			   gpa_t addr, int len, void *val)
+{
+	if (len != 4)
+		return -EOPNOTSUPP;
+
+	return aplic_mmio_read_offset(vcpu->kvm,
+				      addr - vcpu->kvm->arch.aia.aplic_addr,
+				      val);
+}
+
+static int aplic_mmio_write_offset(struct kvm *kvm, gpa_t off, u32 val32)
+{
+	u32 i;
+	struct aplic *aplic = kvm->arch.aia.aplic_state;
+
+	if ((off & 0x3) != 0)
+		return -EOPNOTSUPP;
+
+	if (off == APLIC_DOMAINCFG) {
+		/* Only IE bit writeable */
+		aplic->domaincfg = val32 & APLIC_DOMAINCFG_IE;
+	} else if ((off >= APLIC_SOURCECFG_BASE) &&
+		 (off < (APLIC_SOURCECFG_BASE + (aplic->nr_irqs - 1) * 4))) {
+		i = ((off - APLIC_SOURCECFG_BASE) >> 2) + 1;
+		aplic_write_sourcecfg(aplic, i, val32);
+	} else if ((off >= APLIC_SETIP_BASE) &&
+		   (off < (APLIC_SETIP_BASE + aplic->nr_words * 4))) {
+		i = (off - APLIC_SETIP_BASE) >> 2;
+		aplic_write_pending_word(aplic, i, val32, true);
+	} else if (off == APLIC_SETIPNUM) {
+		aplic_write_pending(aplic, val32, true);
+	} else if ((off >= APLIC_CLRIP_BASE) &&
+		   (off < (APLIC_CLRIP_BASE + aplic->nr_words * 4))) {
+		i = (off - APLIC_CLRIP_BASE) >> 2;
+		aplic_write_pending_word(aplic, i, val32, false);
+	} else if (off == APLIC_CLRIPNUM) {
+		aplic_write_pending(aplic, val32, false);
+	} else if ((off >= APLIC_SETIE_BASE) &&
+		   (off < (APLIC_SETIE_BASE + aplic->nr_words * 4))) {
+		i = (off - APLIC_SETIE_BASE) >> 2;
+		aplic_write_enabled_word(aplic, i, val32, true);
+	} else if (off == APLIC_SETIENUM) {
+		aplic_write_enabled(aplic, val32, true);
+	} else if ((off >= APLIC_CLRIE_BASE) &&
+		   (off < (APLIC_CLRIE_BASE + aplic->nr_words * 4))) {
+		i = (off - APLIC_CLRIE_BASE) >> 2;
+		aplic_write_enabled_word(aplic, i, val32, false);
+	} else if (off == APLIC_CLRIENUM) {
+		aplic_write_enabled(aplic, val32, false);
+	} else if (off == APLIC_SETIPNUM_LE) {
+		aplic_write_pending(aplic, val32, true);
+	} else if (off == APLIC_SETIPNUM_BE) {
+		aplic_write_pending(aplic, __swab32(val32), true);
+	} else if (off == APLIC_GENMSI) {
+		aplic->genmsi = val32 & ~(APLIC_TARGET_GUEST_IDX_MASK <<
+					  APLIC_TARGET_GUEST_IDX_SHIFT);
+		kvm_riscv_aia_inject_msi_by_id(kvm,
+				val32 >> APLIC_TARGET_HART_IDX_SHIFT, 0,
+				val32 & APLIC_TARGET_EIID_MASK);
+	} else if ((off >= APLIC_TARGET_BASE) &&
+		   (off < (APLIC_TARGET_BASE + (aplic->nr_irqs - 1) * 4))) {
+		i = ((off - APLIC_TARGET_BASE) >> 2) + 1;
+		aplic_write_target(aplic, i, val32);
+	} else
+		return -ENODEV;
+
+	aplic_update_irq_range(kvm, 1, aplic->nr_irqs - 1);
+
+	return 0;
+}
+
+static int aplic_mmio_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
+			    gpa_t addr, int len, const void *val)
+{
+	if (len != 4)
+		return -EOPNOTSUPP;
+
+	return aplic_mmio_write_offset(vcpu->kvm,
+				       addr - vcpu->kvm->arch.aia.aplic_addr,
+				       *((const u32 *)val));
+}
+
+static struct kvm_io_device_ops aplic_iodoev_ops = {
+	.read = aplic_mmio_read,
+	.write = aplic_mmio_write,
+};
+
+int kvm_riscv_aia_aplic_init(struct kvm *kvm)
+{
+	int i, ret = 0;
+	struct aplic *aplic;
+
+	/* Do nothing if we have zero sources */
+	if (!kvm->arch.aia.nr_sources)
+		return 0;
+
+	/* Allocate APLIC global state */
+	aplic = kzalloc(sizeof(*aplic), GFP_KERNEL);
+	if (!aplic)
+		return -ENOMEM;
+	kvm->arch.aia.aplic_state = aplic;
+
+	/* Setup APLIC IRQs */
+	aplic->nr_irqs = kvm->arch.aia.nr_sources + 1;
+	aplic->nr_words = DIV_ROUND_UP(aplic->nr_irqs, 32);
+	aplic->irqs = kcalloc(aplic->nr_irqs,
+			      sizeof(*aplic->irqs), GFP_KERNEL);
+	if (!aplic->irqs) {
+		ret = -ENOMEM;
+		goto fail_free_aplic;
+	}
+	for (i = 0; i < aplic->nr_irqs; i++)
+		raw_spin_lock_init(&aplic->irqs[i].lock);
+
+	/* Setup IO device */
+	kvm_iodevice_init(&aplic->iodev, &aplic_iodoev_ops);
+	mutex_lock(&kvm->slots_lock);
+	ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS,
+				      kvm->arch.aia.aplic_addr,
+				      KVM_DEV_RISCV_APLIC_SIZE,
+				      &aplic->iodev);
+	mutex_unlock(&kvm->slots_lock);
+	if (ret)
+		goto fail_free_aplic_irqs;
+
+	/* Setup default IRQ routing */
+	ret = kvm_riscv_setup_default_irq_routing(kvm, aplic->nr_irqs);
+	if (ret)
+		goto fail_unreg_iodev;
+
+	return 0;
+
+fail_unreg_iodev:
+	mutex_lock(&kvm->slots_lock);
+	kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &aplic->iodev);
+	mutex_unlock(&kvm->slots_lock);
+fail_free_aplic_irqs:
+	kfree(aplic->irqs);
+fail_free_aplic:
+	kvm->arch.aia.aplic_state = NULL;
+	kfree(aplic);
+	return ret;
+}
+
+void kvm_riscv_aia_aplic_cleanup(struct kvm *kvm)
+{
+	struct aplic *aplic = kvm->arch.aia.aplic_state;
+
+	if (!aplic)
+		return;
+
+	mutex_lock(&kvm->slots_lock);
+	kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS, &aplic->iodev);
+	mutex_unlock(&kvm->slots_lock);
+
+	kfree(aplic->irqs);
+
+	kvm->arch.aia.aplic_state = NULL;
+	kfree(aplic);
+}