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RISC-V: KVM: Mark the existing SBI implementation as v0.1
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The existing SBI specification impelementation follows v0.1
specification. The latest specification allows more scalability
and performance improvements.

Rename the existing implementation as v0.1 and provide a way
to allow future extensions.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
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Atish Patra authored and Anup Patel committed Jan 6, 2022
1 parent cc4f602 commit cf70be9
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Showing 2 changed files with 144 additions and 32 deletions.
29 changes: 29 additions & 0 deletions arch/riscv/include/asm/kvm_vcpu_sbi.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,29 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/**
* Copyright (c) 2021 Western Digital Corporation or its affiliates.
*
* Authors:
* Atish Patra <atish.patra@wdc.com>
*/

#ifndef __RISCV_KVM_VCPU_SBI_H__
#define __RISCV_KVM_VCPU_SBI_H__

#define KVM_SBI_VERSION_MAJOR 0
#define KVM_SBI_VERSION_MINOR 2

struct kvm_vcpu_sbi_extension {
unsigned long extid_start;
unsigned long extid_end;
/**
* SBI extension handler. It can be defined for a given extension or group of
* extension. But it should always return linux error codes rather than SBI
* specific error codes.
*/
int (*handler)(struct kvm_vcpu *vcpu, struct kvm_run *run,
unsigned long *out_val, struct kvm_cpu_trap *utrap,
bool *exit);
};

const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(unsigned long extid);
#endif /* __RISCV_KVM_VCPU_SBI_H__ */
147 changes: 115 additions & 32 deletions arch/riscv/kvm/vcpu_sbi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -12,9 +12,25 @@
#include <asm/csr.h>
#include <asm/sbi.h>
#include <asm/kvm_vcpu_timer.h>
#include <asm/kvm_vcpu_sbi.h>

#define SBI_VERSION_MAJOR 0
#define SBI_VERSION_MINOR 1
static int kvm_linux_err_map_sbi(int err)
{
switch (err) {
case 0:
return SBI_SUCCESS;
case -EPERM:
return SBI_ERR_DENIED;
case -EINVAL:
return SBI_ERR_INVALID_PARAM;
case -EFAULT:
return SBI_ERR_INVALID_ADDRESS;
case -EOPNOTSUPP:
return SBI_ERR_NOT_SUPPORTED;
default:
return SBI_ERR_FAILURE;
};
}

static void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu,
struct kvm_run *run)
Expand Down Expand Up @@ -72,21 +88,19 @@ static void kvm_sbi_system_shutdown(struct kvm_vcpu *vcpu,
run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
}

int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
static int kvm_sbi_ext_v01_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
unsigned long *out_val,
struct kvm_cpu_trap *utrap,
bool *exit)
{
ulong hmask;
int i, ret = 1;
int i, ret = 0;
u64 next_cycle;
struct kvm_vcpu *rvcpu;
bool next_sepc = true;
struct cpumask cm, hm;
struct kvm *kvm = vcpu->kvm;
struct kvm_cpu_trap utrap = { 0 };
struct kvm_cpu_context *cp = &vcpu->arch.guest_context;

if (!cp)
return -EINVAL;

switch (cp->a7) {
case SBI_EXT_0_1_CONSOLE_GETCHAR:
case SBI_EXT_0_1_CONSOLE_PUTCHAR:
Expand All @@ -95,56 +109,50 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
* handled in kernel so we forward these to user-space
*/
kvm_riscv_vcpu_sbi_forward(vcpu, run);
next_sepc = false;
ret = 0;
*exit = true;
break;
case SBI_EXT_0_1_SET_TIMER:
#if __riscv_xlen == 32
next_cycle = ((u64)cp->a1 << 32) | (u64)cp->a0;
#else
next_cycle = (u64)cp->a0;
#endif
kvm_riscv_vcpu_timer_next_event(vcpu, next_cycle);
ret = kvm_riscv_vcpu_timer_next_event(vcpu, next_cycle);
break;
case SBI_EXT_0_1_CLEAR_IPI:
kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_VS_SOFT);
ret = kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_VS_SOFT);
break;
case SBI_EXT_0_1_SEND_IPI:
if (cp->a0)
hmask = kvm_riscv_vcpu_unpriv_read(vcpu, false, cp->a0,
&utrap);
utrap);
else
hmask = (1UL << atomic_read(&kvm->online_vcpus)) - 1;
if (utrap.scause) {
utrap.sepc = cp->sepc;
kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
next_sepc = false;
if (utrap->scause)
break;
}

for_each_set_bit(i, &hmask, BITS_PER_LONG) {
rvcpu = kvm_get_vcpu_by_id(vcpu->kvm, i);
kvm_riscv_vcpu_set_interrupt(rvcpu, IRQ_VS_SOFT);
ret = kvm_riscv_vcpu_set_interrupt(rvcpu, IRQ_VS_SOFT);
if (ret < 0)
break;
}
break;
case SBI_EXT_0_1_SHUTDOWN:
kvm_sbi_system_shutdown(vcpu, run, KVM_SYSTEM_EVENT_SHUTDOWN);
next_sepc = false;
ret = 0;
*exit = true;
break;
case SBI_EXT_0_1_REMOTE_FENCE_I:
case SBI_EXT_0_1_REMOTE_SFENCE_VMA:
case SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID:
if (cp->a0)
hmask = kvm_riscv_vcpu_unpriv_read(vcpu, false, cp->a0,
&utrap);
utrap);
else
hmask = (1UL << atomic_read(&kvm->online_vcpus)) - 1;
if (utrap.scause) {
utrap.sepc = cp->sepc;
kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
next_sepc = false;
if (utrap->scause)
break;
}

cpumask_clear(&cm);
for_each_set_bit(i, &hmask, BITS_PER_LONG) {
rvcpu = kvm_get_vcpu_by_id(vcpu->kvm, i);
Expand All @@ -154,22 +162,97 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
}
riscv_cpuid_to_hartid_mask(&cm, &hm);
if (cp->a7 == SBI_EXT_0_1_REMOTE_FENCE_I)
sbi_remote_fence_i(cpumask_bits(&hm));
ret = sbi_remote_fence_i(cpumask_bits(&hm));
else if (cp->a7 == SBI_EXT_0_1_REMOTE_SFENCE_VMA)
sbi_remote_hfence_vvma(cpumask_bits(&hm),
ret = sbi_remote_hfence_vvma(cpumask_bits(&hm),
cp->a1, cp->a2);
else
sbi_remote_hfence_vvma_asid(cpumask_bits(&hm),
ret = sbi_remote_hfence_vvma_asid(cpumask_bits(&hm),
cp->a1, cp->a2, cp->a3);
break;
default:
ret = -EINVAL;
break;
}

return ret;
}

const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01 = {
.extid_start = SBI_EXT_0_1_SET_TIMER,
.extid_end = SBI_EXT_0_1_SHUTDOWN,
.handler = kvm_sbi_ext_v01_handler,
};

static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
&vcpu_sbi_ext_v01,
};

const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(unsigned long extid)
{
int i = 0;

for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
if (sbi_ext[i]->extid_start <= extid &&
sbi_ext[i]->extid_end >= extid)
return sbi_ext[i];
}

return NULL;
}

int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
int ret = 1;
bool next_sepc = true;
bool userspace_exit = false;
struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
const struct kvm_vcpu_sbi_extension *sbi_ext;
struct kvm_cpu_trap utrap = { 0 };
unsigned long out_val = 0;
bool ext_is_v01 = false;

sbi_ext = kvm_vcpu_sbi_find_ext(cp->a7);
if (sbi_ext && sbi_ext->handler) {
if (cp->a7 >= SBI_EXT_0_1_SET_TIMER &&
cp->a7 <= SBI_EXT_0_1_SHUTDOWN)
ext_is_v01 = true;
ret = sbi_ext->handler(vcpu, run, &out_val, &utrap, &userspace_exit);
} else {
/* Return error for unsupported SBI calls */
cp->a0 = SBI_ERR_NOT_SUPPORTED;
break;
goto ecall_done;
}

/* Handle special error cases i.e trap, exit or userspace forward */
if (utrap.scause) {
/* No need to increment sepc or exit ioctl loop */
ret = 1;
utrap.sepc = cp->sepc;
kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
next_sepc = false;
goto ecall_done;
}

/* Exit ioctl loop or Propagate the error code the guest */
if (userspace_exit) {
next_sepc = false;
ret = 0;
} else {
/**
* SBI extension handler always returns an Linux error code. Convert
* it to the SBI specific error code that can be propagated the SBI
* caller.
*/
ret = kvm_linux_err_map_sbi(ret);
cp->a0 = ret;
ret = 1;
}
ecall_done:
if (next_sepc)
cp->sepc += 4;
if (!ext_is_v01)
cp->a1 = out_val;

return ret;
}
Expand Down

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