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linux/arch/riscv/kvm/vcpu_sbi.c
Yong-Xuan Wang 2121cadec4 RISCV: KVM: Introduce mp_state_lock to avoid lock inversion 
Documentation/virt/kvm/locking.rst advises that kvm->lock should be
acquired outside vcpu->mutex and kvm->srcu. However, when KVM/RISC-V
handling SBI_EXT_HSM_HART_START, the lock ordering is vcpu->mutex,
kvm->srcu then kvm->lock.

Although the lockdep checking no longer complains about this after commit
f0f44752f5 ("rcu: Annotate SRCU's update-side lockdep dependencies"),
it's necessary to replace kvm->lock with a new dedicated lock to ensure
only one hart can execute the SBI_EXT_HSM_HART_START call for the target
hart simultaneously.

Additionally, this patch also rename "power_off" to "mp_state" with two
possible values. The vcpu->mp_state_lock also protects the access of
vcpu->mp_state.

Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240417074528.16506-2-yongxuan.wang@sifive.com
Signed-off-by: Anup Patel <anup@brainfault.org>
2024-04-22 10:37:11 +05:30

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2019 Western Digital Corporation or its affiliates.
*
* Authors:
* Atish Patra <atish.patra@wdc.com>
*/
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kvm_host.h>
#include <asm/sbi.h>
#include <asm/kvm_vcpu_sbi.h>
#ifndef CONFIG_RISCV_SBI_V01
static const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01 = {
.extid_start = -1UL,
.extid_end = -1UL,
.handler = NULL,
};
#endif
#ifndef CONFIG_RISCV_PMU_SBI
static const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pmu = {
.extid_start = -1UL,
.extid_end = -1UL,
.handler = NULL,
};
#endif
struct kvm_riscv_sbi_extension_entry {
enum KVM_RISCV_SBI_EXT_ID ext_idx;
const struct kvm_vcpu_sbi_extension *ext_ptr;
};
static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
{
.ext_idx = KVM_RISCV_SBI_EXT_V01,
.ext_ptr = &vcpu_sbi_ext_v01,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_MAX, /* Can't be disabled */
.ext_ptr = &vcpu_sbi_ext_base,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_TIME,
.ext_ptr = &vcpu_sbi_ext_time,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_IPI,
.ext_ptr = &vcpu_sbi_ext_ipi,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_RFENCE,
.ext_ptr = &vcpu_sbi_ext_rfence,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_SRST,
.ext_ptr = &vcpu_sbi_ext_srst,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_HSM,
.ext_ptr = &vcpu_sbi_ext_hsm,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_PMU,
.ext_ptr = &vcpu_sbi_ext_pmu,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_DBCN,
.ext_ptr = &vcpu_sbi_ext_dbcn,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_STA,
.ext_ptr = &vcpu_sbi_ext_sta,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_EXPERIMENTAL,
.ext_ptr = &vcpu_sbi_ext_experimental,
},
{
.ext_idx = KVM_RISCV_SBI_EXT_VENDOR,
.ext_ptr = &vcpu_sbi_ext_vendor,
},
};
static const struct kvm_riscv_sbi_extension_entry *
riscv_vcpu_get_sbi_ext(struct kvm_vcpu *vcpu, unsigned long idx)
{
const struct kvm_riscv_sbi_extension_entry *sext = NULL;
if (idx >= KVM_RISCV_SBI_EXT_MAX)
return NULL;
for (int i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
if (sbi_ext[i].ext_idx == idx) {
sext = &sbi_ext[i];
break;
}
}
return sext;
}
bool riscv_vcpu_supports_sbi_ext(struct kvm_vcpu *vcpu, int idx)
{
struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
const struct kvm_riscv_sbi_extension_entry *sext;
sext = riscv_vcpu_get_sbi_ext(vcpu, idx);
return sext && scontext->ext_status[sext->ext_idx] != KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE;
}
void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
vcpu->arch.sbi_context.return_handled = 0;
vcpu->stat.ecall_exit_stat++;
run->exit_reason = KVM_EXIT_RISCV_SBI;
run->riscv_sbi.extension_id = cp->a7;
run->riscv_sbi.function_id = cp->a6;
run->riscv_sbi.args[0] = cp->a0;
run->riscv_sbi.args[1] = cp->a1;
run->riscv_sbi.args[2] = cp->a2;
run->riscv_sbi.args[3] = cp->a3;
run->riscv_sbi.args[4] = cp->a4;
run->riscv_sbi.args[5] = cp->a5;
run->riscv_sbi.ret[0] = cp->a0;
run->riscv_sbi.ret[1] = cp->a1;
}
void kvm_riscv_vcpu_sbi_system_reset(struct kvm_vcpu *vcpu,
struct kvm_run *run,
u32 type, u64 reason)
{
unsigned long i;
struct kvm_vcpu *tmp;
kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
spin_lock(&vcpu->arch.mp_state_lock);
WRITE_ONCE(tmp->arch.mp_state.mp_state, KVM_MP_STATE_STOPPED);
spin_unlock(&vcpu->arch.mp_state_lock);
}
kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
memset(&run->system_event, 0, sizeof(run->system_event));
run->system_event.type = type;
run->system_event.ndata = 1;
run->system_event.data[0] = reason;
run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
}
int kvm_riscv_vcpu_sbi_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
/* Handle SBI return only once */
if (vcpu->arch.sbi_context.return_handled)
return 0;
vcpu->arch.sbi_context.return_handled = 1;
/* Update return values */
cp->a0 = run->riscv_sbi.ret[0];
cp->a1 = run->riscv_sbi.ret[1];
/* Move to next instruction */
vcpu->arch.guest_context.sepc += 4;
return 0;
}
static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu,
unsigned long reg_num,
unsigned long reg_val)
{
struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
const struct kvm_riscv_sbi_extension_entry *sext;
if (reg_val != 1 && reg_val != 0)
return -EINVAL;
sext = riscv_vcpu_get_sbi_ext(vcpu, reg_num);
if (!sext || scontext->ext_status[sext->ext_idx] == KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE)
return -ENOENT;
scontext->ext_status[sext->ext_idx] = (reg_val) ?
KVM_RISCV_SBI_EXT_STATUS_ENABLED :
KVM_RISCV_SBI_EXT_STATUS_DISABLED;
return 0;
}
static int riscv_vcpu_get_sbi_ext_single(struct kvm_vcpu *vcpu,
unsigned long reg_num,
unsigned long *reg_val)
{
struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
const struct kvm_riscv_sbi_extension_entry *sext;
sext = riscv_vcpu_get_sbi_ext(vcpu, reg_num);
if (!sext || scontext->ext_status[sext->ext_idx] == KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE)
return -ENOENT;
*reg_val = scontext->ext_status[sext->ext_idx] ==
KVM_RISCV_SBI_EXT_STATUS_ENABLED;
return 0;
}
static int riscv_vcpu_set_sbi_ext_multi(struct kvm_vcpu *vcpu,
unsigned long reg_num,
unsigned long reg_val, bool enable)
{
unsigned long i, ext_id;
if (reg_num > KVM_REG_RISCV_SBI_MULTI_REG_LAST)
return -ENOENT;
for_each_set_bit(i, &reg_val, BITS_PER_LONG) {
ext_id = i + reg_num * BITS_PER_LONG;
if (ext_id >= KVM_RISCV_SBI_EXT_MAX)
break;
riscv_vcpu_set_sbi_ext_single(vcpu, ext_id, enable);
}
return 0;
}
static int riscv_vcpu_get_sbi_ext_multi(struct kvm_vcpu *vcpu,
unsigned long reg_num,
unsigned long *reg_val)
{
unsigned long i, ext_id, ext_val;
if (reg_num > KVM_REG_RISCV_SBI_MULTI_REG_LAST)
return -ENOENT;
for (i = 0; i < BITS_PER_LONG; i++) {
ext_id = i + reg_num * BITS_PER_LONG;
if (ext_id >= KVM_RISCV_SBI_EXT_MAX)
break;
ext_val = 0;
riscv_vcpu_get_sbi_ext_single(vcpu, ext_id, &ext_val);
if (ext_val)
*reg_val |= KVM_REG_RISCV_SBI_MULTI_MASK(ext_id);
}
return 0;
}
int kvm_riscv_vcpu_set_reg_sbi_ext(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg)
{
unsigned long __user *uaddr =
(unsigned long __user *)(unsigned long)reg->addr;
unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
KVM_REG_SIZE_MASK |
KVM_REG_RISCV_SBI_EXT);
unsigned long reg_val, reg_subtype;
if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
return -EINVAL;
if (vcpu->arch.ran_atleast_once)
return -EBUSY;
reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
return -EFAULT;
switch (reg_subtype) {
case KVM_REG_RISCV_SBI_SINGLE:
return riscv_vcpu_set_sbi_ext_single(vcpu, reg_num, reg_val);
case KVM_REG_RISCV_SBI_MULTI_EN:
return riscv_vcpu_set_sbi_ext_multi(vcpu, reg_num, reg_val, true);
case KVM_REG_RISCV_SBI_MULTI_DIS:
return riscv_vcpu_set_sbi_ext_multi(vcpu, reg_num, reg_val, false);
default:
return -ENOENT;
}
return 0;
}
int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg)
{
int rc;
unsigned long __user *uaddr =
(unsigned long __user *)(unsigned long)reg->addr;
unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
KVM_REG_SIZE_MASK |
KVM_REG_RISCV_SBI_EXT);
unsigned long reg_val, reg_subtype;
if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
return -EINVAL;
reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
reg_val = 0;
switch (reg_subtype) {
case KVM_REG_RISCV_SBI_SINGLE:
rc = riscv_vcpu_get_sbi_ext_single(vcpu, reg_num, &reg_val);
break;
case KVM_REG_RISCV_SBI_MULTI_EN:
case KVM_REG_RISCV_SBI_MULTI_DIS:
rc = riscv_vcpu_get_sbi_ext_multi(vcpu, reg_num, &reg_val);
if (!rc && reg_subtype == KVM_REG_RISCV_SBI_MULTI_DIS)
reg_val = ~reg_val;
break;
default:
rc = -ENOENT;
}
if (rc)
return rc;
if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
return -EFAULT;
return 0;
}
int kvm_riscv_vcpu_set_reg_sbi(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg)
{
unsigned long __user *uaddr =
(unsigned long __user *)(unsigned long)reg->addr;
unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
KVM_REG_SIZE_MASK |
KVM_REG_RISCV_SBI_STATE);
unsigned long reg_subtype, reg_val;
if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
return -EINVAL;
if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
return -EFAULT;
reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
switch (reg_subtype) {
case KVM_REG_RISCV_SBI_STA:
return kvm_riscv_vcpu_set_reg_sbi_sta(vcpu, reg_num, reg_val);
default:
return -EINVAL;
}
return 0;
}
int kvm_riscv_vcpu_get_reg_sbi(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg)
{
unsigned long __user *uaddr =
(unsigned long __user *)(unsigned long)reg->addr;
unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
KVM_REG_SIZE_MASK |
KVM_REG_RISCV_SBI_STATE);
unsigned long reg_subtype, reg_val;
int ret;
if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
return -EINVAL;
reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
switch (reg_subtype) {
case KVM_REG_RISCV_SBI_STA:
ret = kvm_riscv_vcpu_get_reg_sbi_sta(vcpu, reg_num, &reg_val);
break;
default:
return -EINVAL;
}
if (ret)
return ret;
if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
return -EFAULT;
return 0;
}
const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
struct kvm_vcpu *vcpu, unsigned long extid)
{
struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
const struct kvm_riscv_sbi_extension_entry *entry;
const struct kvm_vcpu_sbi_extension *ext;
int i;
for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
entry = &sbi_ext[i];
ext = entry->ext_ptr;
if (ext->extid_start <= extid && ext->extid_end >= extid) {
if (entry->ext_idx >= KVM_RISCV_SBI_EXT_MAX ||
scontext->ext_status[entry->ext_idx] ==
KVM_RISCV_SBI_EXT_STATUS_ENABLED)
return ext;
return NULL;
}
}
return NULL;
}
int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
int ret = 1;
bool next_sepc = true;
struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
const struct kvm_vcpu_sbi_extension *sbi_ext;
struct kvm_cpu_trap utrap = {0};
struct kvm_vcpu_sbi_return sbi_ret = {
.out_val = 0,
.err_val = 0,
.utrap = &utrap,
};
bool ext_is_v01 = false;
sbi_ext = kvm_vcpu_sbi_find_ext(vcpu, cp->a7);
if (sbi_ext && sbi_ext->handler) {
#ifdef CONFIG_RISCV_SBI_V01
if (cp->a7 >= SBI_EXT_0_1_SET_TIMER &&
cp->a7 <= SBI_EXT_0_1_SHUTDOWN)
ext_is_v01 = true;
#endif
ret = sbi_ext->handler(vcpu, run, &sbi_ret);
} else {
/* Return error for unsupported SBI calls */
cp->a0 = SBI_ERR_NOT_SUPPORTED;
goto ecall_done;
}
/*
* When the SBI extension returns a Linux error code, it exits the ioctl
* loop and forwards the error to userspace.
*/
if (ret < 0) {
next_sepc = false;
goto ecall_done;
}
/* Handle special error cases i.e trap, exit or userspace forward */
if (sbi_ret.utrap->scause) {
/* No need to increment sepc or exit ioctl loop */
ret = 1;
sbi_ret.utrap->sepc = cp->sepc;
kvm_riscv_vcpu_trap_redirect(vcpu, sbi_ret.utrap);
next_sepc = false;
goto ecall_done;
}
/* Exit ioctl loop or Propagate the error code the guest */
if (sbi_ret.uexit) {
next_sepc = false;
ret = 0;
} else {
cp->a0 = sbi_ret.err_val;
ret = 1;
}
ecall_done:
if (next_sepc)
cp->sepc += 4;
/* a1 should only be updated when we continue the ioctl loop */
if (!ext_is_v01 && ret == 1)
cp->a1 = sbi_ret.out_val;
return ret;
}
void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
const struct kvm_riscv_sbi_extension_entry *entry;
const struct kvm_vcpu_sbi_extension *ext;
int i;
for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
entry = &sbi_ext[i];
ext = entry->ext_ptr;
if (ext->probe && !ext->probe(vcpu)) {
scontext->ext_status[entry->ext_idx] =
KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE;
continue;
}
scontext->ext_status[entry->ext_idx] = ext->default_disabled ?
KVM_RISCV_SBI_EXT_STATUS_DISABLED :
KVM_RISCV_SBI_EXT_STATUS_ENABLED;
}
}
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