Re: [RFC PATCH 1/7] riscv: kvm: add support for FWFT SBI extension

[Deepak Gupta <debug@xxxxxxxxxxxx>]

On Thu, Apr 18, 2024 at 04:26:40PM +0200, Clément Léger wrote:
> Add support for FWFT extension in KVM
>
> Signed-off-by: Clément Léger <cleger@xxxxxxxxxxxx>
> ---
> arch/riscv/include/asm/kvm_host.h          |   5 +
> arch/riscv/include/asm/kvm_vcpu_sbi.h      |   1 +
> arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h |  37 ++++++
> arch/riscv/include/uapi/asm/kvm.h          |   1 +
> arch/riscv/kvm/Makefile                    |   1 +
> arch/riscv/kvm/vcpu.c                      |   5 +
> arch/riscv/kvm/vcpu_sbi.c                  |   4 +
> arch/riscv/kvm/vcpu_sbi_fwft.c             | 136 +++++++++++++++++++++
> 8 files changed, 190 insertions(+)
> create mode 100644 arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
> create mode 100644 arch/riscv/kvm/vcpu_sbi_fwft.c
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 484d04a92fa6..be60aaa07f57 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -19,6 +19,7 @@
> #include <asm/kvm_vcpu_fp.h>
> #include <asm/kvm_vcpu_insn.h>
> #include <asm/kvm_vcpu_sbi.h>
> +#include <asm/kvm_vcpu_sbi_fwft.h>
> #include <asm/kvm_vcpu_timer.h>
> #include <asm/kvm_vcpu_pmu.h>
>
> @@ -169,6 +170,7 @@ struct kvm_vcpu_csr {
> struct kvm_vcpu_config {
> 	u64 henvcfg;
> 	u64 hstateen0;
> +	u64 hedeleg;
> };
>
> struct kvm_vcpu_smstateen_csr {
> @@ -261,6 +263,9 @@ struct kvm_vcpu_arch {
> 	/* Performance monitoring context */
> 	struct kvm_pmu pmu_context;
>
> +	/* Firmware feature SBI extension context */
> +	struct kvm_sbi_fwft fwft_context;
> +
> 	/* 'static' configurations which are set only once */
> 	struct kvm_vcpu_config cfg;
>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> index b96705258cf9..3a33bbacc233 100644
> --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> @@ -86,6 +86,7 @@ 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_sta;
> +extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft;
> 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/asm/kvm_vcpu_sbi_fwft.h b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
> new file mode 100644
> index 000000000000..7dc1b80c7e6c
> --- /dev/null
> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
> @@ -0,0 +1,37 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2023 Rivos Inc
> + *
> + * Authors:
> + *     Atish Patra <atishp@xxxxxxxxxxxx>

nit: probably need to fix Copyright year and Authors here :-)
Same in all new files being introduced.

> + */
> +
> +#ifndef __KVM_VCPU_RISCV_FWFT_H
> +#define __KVM_VCPU_RISCV_FWFT_H
> +
> +#include <asm/sbi.h>
> +
> +#define KVM_SBI_FWFT_FEATURE_COUNT	1
> +
> +static int kvm_sbi_fwft_set(struct kvm_vcpu *vcpu,
> +			    enum sbi_fwft_feature_t feature,
> +			    unsigned long value, unsigned long flags)
> +{
> +	struct kvm_sbi_fwft_config *conf = kvm_sbi_fwft_get_config(vcpu,
> +								   feature);
> +	if (!conf)
> +		return SBI_ERR_DENIED;

Curious,
Why denied and not something like NOT_SUPPORTED NOT_AVAILABLE here?

> +
> +	if ((flags & ~SBI_FWFT_SET_FLAG_LOCK) != 0)
> +		return SBI_ERR_INVALID_PARAM;
> +
> +	if (conf->flags & SBI_FWFT_SET_FLAG_LOCK)
> +		return SBI_ERR_DENIED;
> +
> +	conf->flags = flags;
> +
> +	return conf->feature->set(vcpu, conf, value);
> +}
> +