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

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Message-ID: <CAAhSdy1JspaC6aYjkMQn_fvjc1eFakdu2JMTQFuCzrh4h4o_3w@mail.gmail.com>
Date: Fri, 9 May 2025 08:50:24 +0530
From: Anup Patel <anup@...infault.org>
To: Palmer Dabbelt <palmer@...belt.com>
Cc: Atish Patra <atishp@...osinc.com>, cleger@...osinc.com, 
	Paul Walmsley <paul.walmsley@...ive.com>, 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, 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

Hi Palmer,

On Thu, May 8, 2025 at 10:57 PM Palmer Dabbelt <palmer@...belt.com> wrote:
>
> 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.

The 4 KVM patches of this series should go through the KVM RISC-V
tree to avoid conflicts when it reaches Linus. I am okay doing a shared
tag for the first 10 patches.

Regards,
Anup

>
> >
> > 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);
> >       }
> >  }