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RISC-V: KVM: Initial skeletal support for AIA
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@ventanamicro.com> Reviewed-by: Atish Patra <atishp@rivosinc.com> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Signed-off-by: Anup Patel <anup@brainfault.org>
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Diff for: ‎arch/riscv/include/asm/hwcap.h

+6
Original file line numberDiff line numberDiff line change
@@ -48,6 +48,12 @@
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#define RISCV_ISA_EXT_MAX 64
4949
#define RISCV_ISA_EXT_NAME_LEN_MAX 32
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#ifdef CONFIG_RISCV_M_MODE
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#define RISCV_ISA_EXT_SxAIA RISCV_ISA_EXT_SMAIA
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#else
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#define RISCV_ISA_EXT_SxAIA RISCV_ISA_EXT_SSAIA
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#endif
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5157
#ifndef __ASSEMBLY__
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#include <linux/jump_label.h>

Diff for: ‎arch/riscv/include/asm/kvm_aia.h

+109
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,109 @@
1+
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2021 Western Digital Corporation or its affiliates.
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* Copyright (C) 2022 Ventana Micro Systems Inc.
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*
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* Authors:
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* Anup Patel <apatel@ventanamicro.com>
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*/
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#ifndef __KVM_RISCV_AIA_H
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#define __KVM_RISCV_AIA_H
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#include <linux/jump_label.h>
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#include <linux/kvm_types.h>
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struct kvm_aia {
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/* In-kernel irqchip created */
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bool in_kernel;
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/* In-kernel irqchip initialized */
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bool initialized;
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};
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struct kvm_vcpu_aia {
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};
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#define kvm_riscv_aia_initialized(k) ((k)->arch.aia.initialized)
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#define irqchip_in_kernel(k) ((k)->arch.aia.in_kernel)
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DECLARE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
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#define kvm_riscv_aia_available() \
33+
static_branch_unlikely(&kvm_riscv_aia_available)
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static inline void kvm_riscv_vcpu_aia_flush_interrupts(struct kvm_vcpu *vcpu)
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{
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}
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static inline void kvm_riscv_vcpu_aia_sync_interrupts(struct kvm_vcpu *vcpu)
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{
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}
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static inline bool kvm_riscv_vcpu_aia_has_interrupts(struct kvm_vcpu *vcpu,
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u64 mask)
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{
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return false;
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}
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static inline void kvm_riscv_vcpu_aia_update_hvip(struct kvm_vcpu *vcpu)
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{
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}
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static inline void kvm_riscv_vcpu_aia_load(struct kvm_vcpu *vcpu, int cpu)
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{
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}
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static inline void kvm_riscv_vcpu_aia_put(struct kvm_vcpu *vcpu)
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{
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}
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static inline int kvm_riscv_vcpu_aia_get_csr(struct kvm_vcpu *vcpu,
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unsigned long reg_num,
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unsigned long *out_val)
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{
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*out_val = 0;
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return 0;
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}
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static inline int kvm_riscv_vcpu_aia_set_csr(struct kvm_vcpu *vcpu,
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unsigned long reg_num,
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unsigned long val)
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{
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return 0;
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}
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#define KVM_RISCV_VCPU_AIA_CSR_FUNCS
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static inline int kvm_riscv_vcpu_aia_update(struct kvm_vcpu *vcpu)
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{
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return 1;
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}
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static inline void kvm_riscv_vcpu_aia_reset(struct kvm_vcpu *vcpu)
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{
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}
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static inline int kvm_riscv_vcpu_aia_init(struct kvm_vcpu *vcpu)
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{
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return 0;
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}
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static inline void kvm_riscv_vcpu_aia_deinit(struct kvm_vcpu *vcpu)
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{
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}
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static inline void kvm_riscv_aia_init_vm(struct kvm *kvm)
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{
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}
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static inline void kvm_riscv_aia_destroy_vm(struct kvm *kvm)
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{
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}
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void kvm_riscv_aia_enable(void);
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void kvm_riscv_aia_disable(void);
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int kvm_riscv_aia_init(void);
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void kvm_riscv_aia_exit(void);
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#endif

Diff for: ‎arch/riscv/include/asm/kvm_host.h

+7
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@
1414
#include <linux/kvm_types.h>
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#include <linux/spinlock.h>
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#include <asm/hwcap.h>
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#include <asm/kvm_aia.h>
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#include <asm/kvm_vcpu_fp.h>
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#include <asm/kvm_vcpu_insn.h>
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#include <asm/kvm_vcpu_sbi.h>
@@ -94,6 +95,9 @@ struct kvm_arch {
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/* Guest Timer */
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struct kvm_guest_timer timer;
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/* AIA Guest/VM context */
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struct kvm_aia aia;
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};
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struct kvm_cpu_trap {
@@ -221,6 +225,9 @@ struct kvm_vcpu_arch {
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/* SBI context */
222226
struct kvm_vcpu_sbi_context sbi_context;
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/* AIA VCPU context */
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struct kvm_vcpu_aia aia_context;
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/* Cache pages needed to program page tables with spinlock held */
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struct kvm_mmu_memory_cache mmu_page_cache;
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Diff for: ‎arch/riscv/kvm/Makefile

+1
Original file line numberDiff line numberDiff line change
@@ -26,3 +26,4 @@ kvm-y += vcpu_sbi_replace.o
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kvm-y += vcpu_sbi_hsm.o
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kvm-y += vcpu_timer.o
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kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o vcpu_sbi_pmu.o
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kvm-y += aia.o

Diff for: ‎arch/riscv/kvm/aia.c

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,66 @@
1+
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2021 Western Digital Corporation or its affiliates.
4+
* Copyright (C) 2022 Ventana Micro Systems Inc.
5+
*
6+
* Authors:
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* Anup Patel <apatel@ventanamicro.com>
8+
*/
9+
10+
#include <linux/kvm_host.h>
11+
#include <asm/hwcap.h>
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13+
DEFINE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
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static void aia_set_hvictl(bool ext_irq_pending)
16+
{
17+
unsigned long hvictl;
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19+
/*
20+
* HVICTL.IID == 9 and HVICTL.IPRIO == 0 represents
21+
* no interrupt in HVICTL.
22+
*/
23+
24+
hvictl = (IRQ_S_EXT << HVICTL_IID_SHIFT) & HVICTL_IID;
25+
hvictl |= ext_irq_pending;
26+
csr_write(CSR_HVICTL, hvictl);
27+
}
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29+
void kvm_riscv_aia_enable(void)
30+
{
31+
if (!kvm_riscv_aia_available())
32+
return;
33+
34+
aia_set_hvictl(false);
35+
csr_write(CSR_HVIPRIO1, 0x0);
36+
csr_write(CSR_HVIPRIO2, 0x0);
37+
#ifdef CONFIG_32BIT
38+
csr_write(CSR_HVIPH, 0x0);
39+
csr_write(CSR_HIDELEGH, 0x0);
40+
csr_write(CSR_HVIPRIO1H, 0x0);
41+
csr_write(CSR_HVIPRIO2H, 0x0);
42+
#endif
43+
}
44+
45+
void kvm_riscv_aia_disable(void)
46+
{
47+
if (!kvm_riscv_aia_available())
48+
return;
49+
50+
aia_set_hvictl(false);
51+
}
52+
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int kvm_riscv_aia_init(void)
54+
{
55+
if (!riscv_isa_extension_available(NULL, SxAIA))
56+
return -ENODEV;
57+
58+
/* Enable KVM AIA support */
59+
static_branch_enable(&kvm_riscv_aia_available);
60+
61+
return 0;
62+
}
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void kvm_riscv_aia_exit(void)
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{
66+
}

Diff for: ‎arch/riscv/kvm/main.c

+21-1
Original file line numberDiff line numberDiff line change
@@ -44,11 +44,15 @@ int kvm_arch_hardware_enable(void)
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4545
csr_write(CSR_HVIP, 0);
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47+
kvm_riscv_aia_enable();
48+
4749
return 0;
4850
}
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5052
void kvm_arch_hardware_disable(void)
5153
{
54+
kvm_riscv_aia_disable();
55+
5256
/*
5357
* After clearing the hideleg CSR, the host kernel will receive
5458
* spurious interrupts if hvip CSR has pending interrupts and the
@@ -63,6 +67,7 @@ void kvm_arch_hardware_disable(void)
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6468
static int __init riscv_kvm_init(void)
6569
{
70+
int rc;
6671
const char *str;
6772

6873
if (!riscv_isa_extension_available(NULL, h)) {
@@ -84,6 +89,10 @@ static int __init riscv_kvm_init(void)
8489

8590
kvm_riscv_gstage_vmid_detect();
8691

92+
rc = kvm_riscv_aia_init();
93+
if (rc && rc != -ENODEV)
94+
return rc;
95+
8796
kvm_info("hypervisor extension available\n");
8897

8998
switch (kvm_riscv_gstage_mode()) {
@@ -106,12 +115,23 @@ static int __init riscv_kvm_init(void)
106115

107116
kvm_info("VMID %ld bits available\n", kvm_riscv_gstage_vmid_bits());
108117

109-
return kvm_init(sizeof(struct kvm_vcpu), 0, THIS_MODULE);
118+
if (kvm_riscv_aia_available())
119+
kvm_info("AIA available\n");
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121+
rc = kvm_init(sizeof(struct kvm_vcpu), 0, THIS_MODULE);
122+
if (rc) {
123+
kvm_riscv_aia_exit();
124+
return rc;
125+
}
126+
127+
return 0;
110128
}
111129
module_init(riscv_kvm_init);
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113131
static void __exit riscv_kvm_exit(void)
114132
{
133+
kvm_riscv_aia_exit();
134+
115135
kvm_exit();
116136
}
117137
module_exit(riscv_kvm_exit);

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