linux-kernel - Re: [PATCH v6 11/14] RISC-V: KVM: add SBI extension init()/deinit() functions

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Message-ID: <mhng-0c7b576b-882d-4020-996d-adb1b2bbcc4b@palmer-ri-x1c9a>
Date: Thu, 08 May 2025 10:27:42 -0700 (PDT)
From: Palmer Dabbelt <palmer@...belt.com>
To: anup@...infault.org, Atish Patra <atishp@...osinc.com>
CC: cleger@...osinc.com, Paul Walmsley <paul.walmsley@...ive.com>,
  anup@...infault.org, atishp@...shpatra.org, shuah@...nel.org, corbet@....net,
  linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, kvm@...r.kernel.org,
  kvm-riscv@...ts.infradead.org, linux-kselftest@...r.kernel.org, cleger@...osinc.com,
  samuel.holland@...ive.com, ajones@...tanamicro.com, debug@...osinc.com
Subject:     Re: [PATCH v6 11/14] RISC-V: KVM: add SBI extension init()/deinit() functions

On Thu, 24 Apr 2025 10:31:58 PDT (-0700), cleger@...osinc.com wrote:
> The FWFT SBI extension will need to dynamically allocate memory and do
> init time specific initialization. Add an init/deinit callbacks that
> allows to do so.
>
> Signed-off-by: Clément Léger <cleger@...osinc.com>
> Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
> ---
>  arch/riscv/include/asm/kvm_vcpu_sbi.h |  9 +++++++++
>  arch/riscv/kvm/vcpu.c                 |  2 ++
>  arch/riscv/kvm/vcpu_sbi.c             | 26 ++++++++++++++++++++++++++
>  3 files changed, 37 insertions(+)

There's 4 KVM patches in here without an Ack from Atish or Anup.  
They're all tied up in the SBIv3 stuff, so just LMK if you want me to 
take them into that staging branch or if you want me to wait.

For now I'm going to go look at other stuff, no rush on my end.

>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> index 4ed6203cdd30..bcb90757b149 100644
> --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> @@ -49,6 +49,14 @@ struct kvm_vcpu_sbi_extension {
>
>  	/* Extension specific probe function */
>  	unsigned long (*probe)(struct kvm_vcpu *vcpu);
> +
> +	/*
> +	 * Init/deinit function called once during VCPU init/destroy. These
> +	 * might be use if the SBI extensions need to allocate or do specific
> +	 * init time only configuration.
> +	 */
> +	int (*init)(struct kvm_vcpu *vcpu);
> +	void (*deinit)(struct kvm_vcpu *vcpu);
>  };
>
>  void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run);
> @@ -69,6 +77,7 @@ const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
>  bool riscv_vcpu_supports_sbi_ext(struct kvm_vcpu *vcpu, int idx);
>  int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);
>  void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu);
> +void kvm_riscv_vcpu_sbi_deinit(struct kvm_vcpu *vcpu);
>
>  int kvm_riscv_vcpu_get_reg_sbi_sta(struct kvm_vcpu *vcpu, unsigned long reg_num,
>  				   unsigned long *reg_val);
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 60d684c76c58..877bcc85c067 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -185,6 +185,8 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
>
>  void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
>  {
> +	kvm_riscv_vcpu_sbi_deinit(vcpu);
> +
>  	/* Cleanup VCPU AIA context */
>  	kvm_riscv_vcpu_aia_deinit(vcpu);
>
> diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
> index d1c83a77735e..3139f171c20f 100644
> --- a/arch/riscv/kvm/vcpu_sbi.c
> +++ b/arch/riscv/kvm/vcpu_sbi.c
> @@ -508,5 +508,31 @@ void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu)
>  		scontext->ext_status[idx] = ext->default_disabled ?
>  					KVM_RISCV_SBI_EXT_STATUS_DISABLED :
>  					KVM_RISCV_SBI_EXT_STATUS_ENABLED;
> +
> +		if (ext->init && ext->init(vcpu) != 0)
> +			scontext->ext_status[idx] = KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE;
> +	}
> +}
> +
> +void kvm_riscv_vcpu_sbi_deinit(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 idx, i;
> +
> +	for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
> +		entry = &sbi_ext[i];
> +		ext = entry->ext_ptr;
> +		idx = entry->ext_idx;
> +
> +		if (idx < 0 || idx >= ARRAY_SIZE(scontext->ext_status))
> +			continue;
> +
> +		if (scontext->ext_status[idx] == KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE ||
> +		    !ext->deinit)
> +			continue;
> +
> +		ext->deinit(vcpu);
>  	}
>  }