[PATCH v2 4/7] RISC-V: KVM: Initial skeletal support for AIA

From: Anup Patel
Date: Sat Jan 28 2023 - 02:28:28 EST

To incrementally implement AIA support, we first add minimal skeletal
support which only compiles and detects AIA hardware support at the
boot-time but does not provide any functionality.

Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
---
arch/riscv/include/asm/hwcap.h | 6 ++
arch/riscv/include/asm/kvm_aia.h | 109 ++++++++++++++++++++++++++++++
arch/riscv/include/asm/kvm_host.h | 7 ++
arch/riscv/kvm/Makefile | 1 +
arch/riscv/kvm/aia.c | 66 ++++++++++++++++++
arch/riscv/kvm/main.c | 13 ++++
arch/riscv/kvm/vcpu.c | 40 ++++++++++-
arch/riscv/kvm/vcpu_insn.c | 4 +-
arch/riscv/kvm/vm.c | 4 ++
9 files changed, 246 insertions(+), 4 deletions(-)
create mode 100644 arch/riscv/include/asm/kvm_aia.h
create mode 100644 arch/riscv/kvm/aia.c

diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 341ef30a3718..a03d51df517b 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -65,6 +65,12 @@ enum riscv_isa_ext_id {
};
static_assert(RISCV_ISA_EXT_ID_MAX <= RISCV_ISA_EXT_MAX);

+#ifdef CONFIG_RISCV_M_MODE
+#define RISCV_ISA_EXT_SxAIA RISCV_ISA_EXT_SMAIA
+#else
+#define RISCV_ISA_EXT_SxAIA RISCV_ISA_EXT_SSAIA
+#endif
+
/*
* This enum represents the logical ID for each RISC-V ISA extension static
* keys. We can use static key to optimize code path if some ISA extensions
diff --git a/arch/riscv/include/asm/kvm_aia.h b/arch/riscv/include/asm/kvm_aia.h
new file mode 100644
index 000000000000..258a835d4c32
--- /dev/null
+++ b/arch/riscv/include/asm/kvm_aia.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (C) 2022 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ * Anup Patel <apatel@xxxxxxxxxxxxxxxx>
+ */
+
+#ifndef __KVM_RISCV_AIA_H
+#define __KVM_RISCV_AIA_H
+
+#include <linux/jump_label.h>
+#include <linux/kvm_types.h>
+
+struct kvm_aia {
+ /* In-kernel irqchip created */
+ bool in_kernel;
+
+ /* In-kernel irqchip initialized */
+ bool initialized;
+};
+
+struct kvm_vcpu_aia {
+};
+
+#define kvm_riscv_aia_initialized(k) ((k)->arch.aia.initialized)
+
+#define irqchip_in_kernel(k) ((k)->arch.aia.in_kernel)
+
+DECLARE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
+#define kvm_riscv_aia_available() \
+ static_branch_unlikely(&kvm_riscv_aia_available)
+
+static inline void kvm_riscv_vcpu_aia_flush_interrupts(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline void kvm_riscv_vcpu_aia_sync_interrupts(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline bool kvm_riscv_vcpu_aia_has_interrupts(struct kvm_vcpu *vcpu,
+ u64 mask)
+{
+ return false;
+}
+
+static inline void kvm_riscv_vcpu_aia_update_hvip(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline void kvm_riscv_vcpu_aia_load(struct kvm_vcpu *vcpu, int cpu)
+{
+}
+
+static inline void kvm_riscv_vcpu_aia_put(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline int kvm_riscv_vcpu_aia_get_csr(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long *out_val)
+{
+ *out_val = 0;
+ return 0;
+}
+
+static inline int kvm_riscv_vcpu_aia_set_csr(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long val)
+{
+ return 0;
+}
+
+#define KVM_RISCV_VCPU_AIA_CSR_FUNCS
+
+static inline int kvm_riscv_vcpu_aia_update(struct kvm_vcpu *vcpu)
+{
+ return 1;
+}
+
+static inline void kvm_riscv_vcpu_aia_reset(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline int kvm_riscv_vcpu_aia_init(struct kvm_vcpu *vcpu)
+{
+ return 0;
+}
+
+static inline void kvm_riscv_vcpu_aia_deinit(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline void kvm_riscv_aia_init_vm(struct kvm *kvm)
+{
+}
+
+static inline void kvm_riscv_aia_destroy_vm(struct kvm *kvm)
+{
+}
+
+void kvm_riscv_aia_enable(void);
+void kvm_riscv_aia_disable(void);
+int kvm_riscv_aia_init(void);
+void kvm_riscv_aia_exit(void);
+
+#endif
diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 93f43a3e7886..8776e7a465c7 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -14,6 +14,7 @@
#include <linux/kvm_types.h>
#include <linux/spinlock.h>
#include <asm/hwcap.h>
+#include <asm/kvm_aia.h>
#include <asm/kvm_vcpu_fp.h>
#include <asm/kvm_vcpu_insn.h>
#include <asm/kvm_vcpu_sbi.h>
@@ -93,6 +94,9 @@ struct kvm_arch {

/* Guest Timer */
struct kvm_guest_timer timer;
+
+ /* AIA Guest/VM context */
+ struct kvm_aia aia;
};

struct kvm_cpu_trap {
@@ -220,6 +224,9 @@ struct kvm_vcpu_arch {
/* SBI context */
struct kvm_vcpu_sbi_context sbi_context;

+ /* AIA VCPU context */
+ struct kvm_vcpu_aia aia_context;
+
/* Cache pages needed to program page tables with spinlock held */
struct kvm_mmu_memory_cache mmu_page_cache;

diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 019df9208bdd..adbc85a94364 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -25,3 +25,4 @@ kvm-y += vcpu_sbi_base.o
kvm-y += vcpu_sbi_replace.o
kvm-y += vcpu_sbi_hsm.o
kvm-y += vcpu_timer.o
+kvm-y += aia.o
diff --git a/arch/riscv/kvm/aia.c b/arch/riscv/kvm/aia.c
new file mode 100644
index 000000000000..7a633331cd3e
--- /dev/null
+++ b/arch/riscv/kvm/aia.c
@@ -0,0 +1,66 @@
+// 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@xxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/hwcap.h>
+
+DEFINE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
+
+static void aia_set_hvictl(bool ext_irq_pending)
+{
+ unsigned long hvictl;
+
+ /*
+ * HVICTL.IID == 9 and HVICTL.IPRIO == 0 represents
+ * no interrupt in HVICTL.
+ */
+
+ hvictl = (IRQ_S_EXT << HVICTL_IID_SHIFT) & HVICTL_IID;
+ hvictl |= ext_irq_pending;
+ csr_write(CSR_HVICTL, hvictl);
+}
+
+void kvm_riscv_aia_enable(void)
+{
+ if (!kvm_riscv_aia_available())
+ return;
+
+ aia_set_hvictl(false);
+ csr_write(CSR_HVIPRIO1, 0x0);
+ csr_write(CSR_HVIPRIO2, 0x0);
+#ifdef CONFIG_32BIT
+ csr_write(CSR_HVIPH, 0x0);
+ csr_write(CSR_HIDELEGH, 0x0);
+ csr_write(CSR_HVIPRIO1H, 0x0);
+ csr_write(CSR_HVIPRIO2H, 0x0);
+#endif
+}
+
+void kvm_riscv_aia_disable(void)
+{
+ if (!kvm_riscv_aia_available())
+ return;
+
+ aia_set_hvictl(false);
+}
+
+int kvm_riscv_aia_init(void)
+{
+ if (!riscv_isa_extension_available(NULL, SxAIA))
+ return -ENODEV;
+
+ /* Enable KVM AIA support */
+ static_branch_enable(&kvm_riscv_aia_available);
+
+ return 0;
+}
+
+void kvm_riscv_aia_exit(void)
+{
+}
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index 58c5489d3031..d8ff44eb04ca 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -53,11 +53,15 @@ int kvm_arch_hardware_enable(void)

csr_write(CSR_HVIP, 0);

+ kvm_riscv_aia_enable();
+
return 0;
}

void kvm_arch_hardware_disable(void)
{
+ kvm_riscv_aia_disable();
+
/*
* After clearing the hideleg CSR, the host kernel will receive
* spurious interrupts if hvip CSR has pending interrupts and the
@@ -72,6 +76,7 @@ void kvm_arch_hardware_disable(void)

int kvm_arch_init(void *opaque)
{
+ int rc;
const char *str;

if (!riscv_isa_extension_available(NULL, h)) {
@@ -93,6 +98,10 @@ int kvm_arch_init(void *opaque)

kvm_riscv_gstage_vmid_detect();

+ rc = kvm_riscv_aia_init();
+ if (rc && rc != -ENODEV)
+ return rc;
+
kvm_info("hypervisor extension available\n");

switch (kvm_riscv_gstage_mode()) {
@@ -115,11 +124,15 @@ int kvm_arch_init(void *opaque)

kvm_info("VMID %ld bits available\n", kvm_riscv_gstage_vmid_bits());

+ if (kvm_riscv_aia_available())
+ kvm_info("AIA available\n");
+
return 0;
}

void kvm_arch_exit(void)
{
+ kvm_riscv_aia_exit();
}

static int __init riscv_kvm_init(void)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 2260adaf2de8..3cf50eadc8ce 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -135,6 +135,8 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)

kvm_riscv_vcpu_timer_reset(vcpu);

+ kvm_riscv_vcpu_aia_reset(vcpu);
+
WRITE_ONCE(vcpu->arch.irqs_pending, 0);
WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);

@@ -155,6 +157,7 @@ int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)

int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
{
+ int rc;
struct kvm_cpu_context *cntx;
struct kvm_vcpu_csr *reset_csr = &vcpu->arch.guest_reset_csr;
unsigned long host_isa, i;
@@ -194,6 +197,11 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
/* Setup VCPU timer */
kvm_riscv_vcpu_timer_init(vcpu);

+ /* Setup VCPU AIA */
+ rc = kvm_riscv_vcpu_aia_init(vcpu);
+ if (rc)
+ return rc;
+
/* Reset VCPU */
kvm_riscv_reset_vcpu(vcpu);

@@ -213,6 +221,9 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)

void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
{
+ /* Cleanup VCPU AIA context */
+ kvm_riscv_vcpu_aia_deinit(vcpu);
+
/* Cleanup VCPU timer */
kvm_riscv_vcpu_timer_deinit(vcpu);

@@ -730,6 +741,9 @@ void kvm_riscv_vcpu_flush_interrupts(struct kvm_vcpu *vcpu)
csr->hvip &= ~mask;
csr->hvip |= val;
}
+
+ /* Flush AIA high interrupts */
+ kvm_riscv_vcpu_aia_flush_interrupts(vcpu);
}

void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu)
@@ -755,6 +769,9 @@ void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu)
}
}

+ /* Sync-up AIA high interrupts */
+ kvm_riscv_vcpu_aia_sync_interrupts(vcpu);
+
/* Sync-up timer CSRs */
kvm_riscv_vcpu_timer_sync(vcpu);
}
@@ -791,10 +808,15 @@ int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq)

bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, unsigned long mask)
{
- unsigned long ie = ((vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK)
- << VSIP_TO_HVIP_SHIFT) & mask;
+ unsigned long ie;
+
+ ie = ((vcpu->arch.guest_csr.vsie & VSIP_VALID_MASK)
+ << VSIP_TO_HVIP_SHIFT) & mask;
+ if (READ_ONCE(vcpu->arch.irqs_pending) & ie)
+ return true;

- return (READ_ONCE(vcpu->arch.irqs_pending) & ie) ? true : false;
+ /* Check AIA high interrupts */
+ return kvm_riscv_vcpu_aia_has_interrupts(vcpu, mask);
}

void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu)
@@ -890,6 +912,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
kvm_riscv_vcpu_guest_fp_restore(&vcpu->arch.guest_context,
vcpu->arch.isa);

+ kvm_riscv_vcpu_aia_load(vcpu, cpu);
+
vcpu->cpu = cpu;
}

@@ -899,6 +923,8 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)

vcpu->cpu = -1;

+ kvm_riscv_vcpu_aia_put(vcpu);
+
kvm_riscv_vcpu_guest_fp_save(&vcpu->arch.guest_context,
vcpu->arch.isa);
kvm_riscv_vcpu_host_fp_restore(&vcpu->arch.host_context);
@@ -966,6 +992,7 @@ static void kvm_riscv_update_hvip(struct kvm_vcpu *vcpu)
struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;

csr_write(CSR_HVIP, csr->hvip);
+ kvm_riscv_vcpu_aia_update_hvip(vcpu);
}

/*
@@ -1040,6 +1067,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)

local_irq_disable();

+ /* Update AIA HW state before entering guest */
+ ret = kvm_riscv_vcpu_aia_update(vcpu);
+ if (ret <= 0) {
+ local_irq_enable();
+ continue;
+ }
+
/*
* Ensure we set mode to IN_GUEST_MODE after we disable
* interrupts and before the final VCPU requests check.
diff --git a/arch/riscv/kvm/vcpu_insn.c b/arch/riscv/kvm/vcpu_insn.c
index 0bb52761a3f7..07e8c121922b 100644
--- a/arch/riscv/kvm/vcpu_insn.c
+++ b/arch/riscv/kvm/vcpu_insn.c
@@ -213,7 +213,9 @@ struct csr_func {
unsigned long wr_mask);
};

-static const struct csr_func csr_funcs[] = { };
+static const struct csr_func csr_funcs[] = {
+ KVM_RISCV_VCPU_AIA_CSR_FUNCS
+};

/**
* kvm_riscv_vcpu_csr_return -- Handle CSR read/write after user space
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index 65a964d7e70d..bc03d2ddcb51 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -41,6 +41,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
return r;
}

+ kvm_riscv_aia_init_vm(kvm);
+
kvm_riscv_guest_timer_init(kvm);

return 0;
@@ -49,6 +51,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
void kvm_arch_destroy_vm(struct kvm *kvm)
{
kvm_destroy_vcpus(kvm);
+
+ kvm_riscv_aia_destroy_vm(kvm);
}

int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
--
2.34.1