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Message-ID: <CAAhSdy2gdUfgMn0B-z8tpsNbqdZDnN_dEfa=TB6TsLbu7uskfg@mail.gmail.com>
Date: Mon, 25 Oct 2021 13:23:10 +0530
From: Anup Patel <anup@...infault.org>
To: Atish Patra <atish.patra@....com>
Cc: "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Anup Patel <anup.patel@....com>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
kvm-riscv@...ts.infradead.org, KVM General <kvm@...r.kernel.org>,
linux-riscv <linux-riscv@...ts.infradead.org>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Vincent Chen <vincent.chen@...ive.com>
Subject: Re: [PATCH v3 1/5] RISC-V: Mark the existing SBI v0.1 implementation
as legacy
On Fri, Oct 8, 2021 at 8:50 AM Atish Patra <atish.patra@....com> wrote:
>
> The existing SBI specification impelementation follows v0.1 or legacy
> specification. The latest specification known as v0.2 allows more
> scalability and performance improvements.
>
> Rename the existing implementation as legacy and provide a way to allow
> future extensions.
>
> Signed-off-by: Atish Patra <atish.patra@....com>
> ---
> arch/riscv/include/asm/kvm_vcpu_sbi.h | 29 +++++
> arch/riscv/kvm/vcpu_sbi.c | 149 ++++++++++++++++++++------
> 2 files changed, 148 insertions(+), 30 deletions(-)
> create mode 100644 arch/riscv/include/asm/kvm_vcpu_sbi.h
>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> new file mode 100644
> index 000000000000..1a4cb0db2d0b
> --- /dev/null
> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> @@ -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@....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__ */
> diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
> index ebdcdbade9c6..8c168d305763 100644
> --- a/arch/riscv/kvm/vcpu_sbi.c
> +++ b/arch/riscv/kvm/vcpu_sbi.c
> @@ -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)
> @@ -72,16 +88,17 @@ 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_legacy_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)
> @@ -95,8 +112,7 @@ 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
> @@ -104,47 +120,42 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
> #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);
> @@ -154,22 +165,100 @@ 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:
> - /* Return error for unsupported SBI calls */
> - cp->a0 = SBI_ERR_NOT_SUPPORTED;
> + ret = -EINVAL;
> break;
> };
>
> + return ret;
> +}
> +
> +const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_legacy = {
> + .extid_start = SBI_EXT_0_1_SET_TIMER,
> + .extid_end = SBI_EXT_0_1_SHUTDOWN,
> + .handler = kvm_sbi_ext_legacy_handler,
> +};
> +
> +static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
> + &vcpu_sbi_ext_legacy,
> +};
> +
> +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;
> +
> + if (!cp)
> + return -EINVAL;
This is a redundant check because cp is always non-NULL.
> +
> + 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;
> + 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;
> }
> --
> 2.31.1
>
>
> --
> kvm-riscv mailing list
> kvm-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/kvm-riscv
Regards,
Anup
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