[PATCH 1/2] RISC-V: KVM: Add SBI system suspend support

[Anup Patel]

On Thu, Oct 17, 2024 at 1:15 PM Andrew Jones <ajones at ventanamicro.com> wrote:
>
> Implement a KVM SBI SUSP extension handler. The handler only
> validates the system suspend entry criteria and prepares for resuming
> in the appropriate state at the resume_addr (as specified by the SBI
> spec), but then it forwards the call to the VMM where any system
> suspend behavior may be implemented. Since VMM support is needed, KVM
> disables the extension by default.
>
> Signed-off-by: Andrew Jones <ajones at ventanamicro.com>

LGTM.

Reviewed-by: Anup Patel <anup at brainfault.org>

Regards,
Anup


> ---
>  arch/riscv/include/asm/kvm_vcpu_sbi.h |  1 +
>  arch/riscv/include/uapi/asm/kvm.h     |  1 +
>  arch/riscv/kvm/Makefile               |  1 +
>  arch/riscv/kvm/vcpu_sbi.c             |  4 ++
>  arch/riscv/kvm/vcpu_sbi_system.c      | 73 +++++++++++++++++++++++++++
>  5 files changed, 80 insertions(+)
>  create mode 100644 arch/riscv/kvm/vcpu_sbi_system.c
>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> index b96705258cf9..4ed6203cdd30 100644
> --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> @@ -85,6 +85,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence;
>  extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst;
>  extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
>  extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
> +extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_susp;
>  extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta;
>  extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
>  extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index e97db3296456..08e04ad8b1ab 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -194,6 +194,7 @@ enum KVM_RISCV_SBI_EXT_ID {
>         KVM_RISCV_SBI_EXT_VENDOR,
>         KVM_RISCV_SBI_EXT_DBCN,
>         KVM_RISCV_SBI_EXT_STA,
> +       KVM_RISCV_SBI_EXT_SUSP,
>         KVM_RISCV_SBI_EXT_MAX,
>  };
>
> diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
> index c2cacfbc06a0..4bfc6ef0e9ad 100644
> --- a/arch/riscv/kvm/Makefile
> +++ b/arch/riscv/kvm/Makefile
> @@ -25,6 +25,7 @@ kvm-y += vcpu_sbi.o
>  kvm-$(CONFIG_RISCV_SBI_V01) += vcpu_sbi_v01.o
>  kvm-y += vcpu_sbi_base.o
>  kvm-y += vcpu_sbi_replace.o
> +kvm-y += vcpu_sbi_system.o
>  kvm-y += vcpu_sbi_hsm.o
>  kvm-y += vcpu_sbi_sta.o
>  kvm-y += vcpu_timer.o
> diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
> index 7de128be8db9..7d8819640aff 100644
> --- a/arch/riscv/kvm/vcpu_sbi.c
> +++ b/arch/riscv/kvm/vcpu_sbi.c
> @@ -70,6 +70,10 @@ static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
>                 .ext_idx = KVM_RISCV_SBI_EXT_DBCN,
>                 .ext_ptr = &vcpu_sbi_ext_dbcn,
>         },
> +       {
> +               .ext_idx = KVM_RISCV_SBI_EXT_SUSP,
> +               .ext_ptr = &vcpu_sbi_ext_susp,
> +       },
>         {
>                 .ext_idx = KVM_RISCV_SBI_EXT_STA,
>                 .ext_ptr = &vcpu_sbi_ext_sta,
> diff --git a/arch/riscv/kvm/vcpu_sbi_system.c b/arch/riscv/kvm/vcpu_sbi_system.c
> new file mode 100644
> index 000000000000..5d55e08791fa
> --- /dev/null
> +++ b/arch/riscv/kvm/vcpu_sbi_system.c
> @@ -0,0 +1,73 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2024 Ventana Micro Systems Inc.
> + */
> +
> +#include <linux/kvm_host.h>
> +
> +#include <asm/kvm_vcpu_sbi.h>
> +#include <asm/sbi.h>
> +
> +static int kvm_sbi_ext_susp_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
> +                                   struct kvm_vcpu_sbi_return *retdata)
> +{
> +       struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
> +       struct kvm_cpu_context *reset_cntx;
> +       unsigned long funcid = cp->a6;
> +       unsigned long hva, i;
> +       struct kvm_vcpu *tmp;
> +
> +       switch (funcid) {
> +       case SBI_EXT_SUSP_SYSTEM_SUSPEND:
> +               if (cp->a0 != SBI_SUSP_SLEEP_TYPE_SUSPEND_TO_RAM) {
> +                       retdata->err_val = SBI_ERR_INVALID_PARAM;
> +                       return 0;
> +               }
> +
> +               if (!(cp->sstatus & SR_SPP)) {
> +                       retdata->err_val = SBI_ERR_FAILURE;
> +                       return 0;
> +               }
> +
> +               hva = kvm_vcpu_gfn_to_hva_prot(vcpu, cp->a1 >> PAGE_SHIFT, NULL);
> +               if (kvm_is_error_hva(hva)) {
> +                       retdata->err_val = SBI_ERR_INVALID_ADDRESS;
> +                       return 0;
> +               }
> +
> +               kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
> +                       if (tmp == vcpu)
> +                               continue;
> +                       if (!kvm_riscv_vcpu_stopped(tmp)) {
> +                               retdata->err_val = SBI_ERR_DENIED;
> +                               return 0;
> +                       }
> +               }
> +
> +               spin_lock(&vcpu->arch.reset_cntx_lock);
> +               reset_cntx = &vcpu->arch.guest_reset_context;
> +               reset_cntx->sepc = cp->a1;
> +               reset_cntx->a0 = vcpu->vcpu_id;
> +               reset_cntx->a1 = cp->a2;
> +               spin_unlock(&vcpu->arch.reset_cntx_lock);
> +
> +               kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
> +
> +               /* userspace provides the suspend implementation */
> +               kvm_riscv_vcpu_sbi_forward(vcpu, run);
> +               retdata->uexit = true;
> +               break;
> +       default:
> +               retdata->err_val = SBI_ERR_NOT_SUPPORTED;
> +               break;
> +       }
> +
> +       return 0;
> +}
> +
> +const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_susp = {
> +       .extid_start = SBI_EXT_SUSP,
> +       .extid_end = SBI_EXT_SUSP,
> +       .default_disabled = true,
> +       .handler = kvm_sbi_ext_susp_handler,
> +};
> --
> 2.46.2
>