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References: <20220420112450.155624-1-apatel@ventanamicro.com> <20220420112450.155624-4-apatel@ventanamicro.com>
In-Reply-To: <20220420112450.155624-4-apatel@ventanamicro.com>
From:   Atish Patra <atishp@atishpatra.org>
Date:   Tue, 3 May 2022 19:14:38 -0700
Message-ID: <CAOnJCU+sDbJERnrcTUiLowvpfRDJ=-YPkc2dxzbfsD+qFBMUKw@mail.gmail.com>
Subject: Re: [PATCH v2 3/7] RISC-V: KVM: Treat SBI HFENCE calls as NOPs
To:     Anup Patel <apatel@ventanamicro.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Anup Patel <anup@brainfault.org>,
        KVM General <kvm@vger.kernel.org>,
        kvm-riscv@lists.infradead.org,
        linux-riscv <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>
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On Wed, Apr 20, 2022 at 4:25 AM Anup Patel <apatel@ventanamicro.com> wrote:
>
> We should treat SBI HFENCE calls as NOPs until nested virtualization
> is supported by KVM RISC-V. This will help us test booting a hypervisor
> under KVM RISC-V.
>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  arch/riscv/kvm/vcpu_sbi_replace.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kvm/vcpu_sbi_replace.c b/arch/riscv/kvm/vcpu_sbi_replace.c
> index 0f217365c287..3c1dcd38358e 100644
> --- a/arch/riscv/kvm/vcpu_sbi_replace.c
> +++ b/arch/riscv/kvm/vcpu_sbi_replace.c
> @@ -117,7 +117,11 @@ static int kvm_sbi_ext_rfence_handler(struct kvm_vcpu *vcpu, struct kvm_run *run
>         case SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID:
>         case SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA:
>         case SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID:
> -       /* TODO: implement for nested hypervisor case */
> +               /*
> +                * Until nested virtualization is implemented, the
> +                * SBI HFENCE calls should be treated as NOPs
> +                */
> +               break;
>         default:
>                 ret = -EOPNOTSUPP;
>         }
> --
> 2.25.1
>


Reviewed-by: Atish Patra <atishp@rivosinc.com>
-- 
Regards,
Atish