linux-kernel - Re: [PATCH v2 2/7] RISC-V: KVM: Add Sv57x4 mode support for G-stage

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Date:   Tue, 3 May 2022 19:14:07 -0700
From:   Atish Patra <atishp@...shpatra.org>
To:     Anup Patel <apatel@...tanamicro.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Alistair Francis <Alistair.Francis@....com>,
        Anup Patel <anup@...infault.org>,
        KVM General <kvm@...r.kernel.org>,
        kvm-riscv@...ts.infradead.org,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/7] RISC-V: KVM: Add Sv57x4 mode support for G-stage

On Wed, Apr 20, 2022 at 4:25 AM Anup Patel <apatel@...tanamicro.com> wrote:
>
> Latest QEMU supports G-stage Sv57x4 mode so this patch extends KVM
> RISC-V G-stage handling to detect and use Sv57x4 mode when available.
>
> Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> ---
>  arch/riscv/include/asm/csr.h |  1 +
>  arch/riscv/kvm/main.c        |  3 +++
>  arch/riscv/kvm/mmu.c         | 11 ++++++++++-
>  3 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
> index e935f27b10fd..cc40521e438b 100644
> --- a/arch/riscv/include/asm/csr.h
> +++ b/arch/riscv/include/asm/csr.h
> @@ -117,6 +117,7 @@
>  #define HGATP_MODE_SV32X4      _AC(1, UL)
>  #define HGATP_MODE_SV39X4      _AC(8, UL)
>  #define HGATP_MODE_SV48X4      _AC(9, UL)
> +#define HGATP_MODE_SV57X4      _AC(10, UL)
>
>  #define HGATP32_MODE_SHIFT     31
>  #define HGATP32_VMID_SHIFT     22
> diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> index c374dad82eee..1549205fe5fe 100644
> --- a/arch/riscv/kvm/main.c
> +++ b/arch/riscv/kvm/main.c
> @@ -105,6 +105,9 @@ int kvm_arch_init(void *opaque)
>         case HGATP_MODE_SV48X4:
>                 str = "Sv48x4";
>                 break;
> +       case HGATP_MODE_SV57X4:
> +               str = "Sv57x4";
> +               break;
>         default:
>                 return -ENODEV;
>         }
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index dc0520792e31..8823eb32dcde 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -751,14 +751,23 @@ void kvm_riscv_gstage_update_hgatp(struct kvm_vcpu *vcpu)
>  void kvm_riscv_gstage_mode_detect(void)
>  {
>  #ifdef CONFIG_64BIT
> +       /* Try Sv57x4 G-stage mode */
> +       csr_write(CSR_HGATP, HGATP_MODE_SV57X4 << HGATP_MODE_SHIFT);
> +       if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV57X4) {
> +               gstage_mode = (HGATP_MODE_SV57X4 << HGATP_MODE_SHIFT);
> +               gstage_pgd_levels = 5;
> +               goto skip_sv48x4_test;
> +       }
> +
>         /* Try Sv48x4 G-stage mode */
>         csr_write(CSR_HGATP, HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT);
>         if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV48X4) {
>                 gstage_mode = (HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT);
>                 gstage_pgd_levels = 4;
>         }
> -       csr_write(CSR_HGATP, 0);
> +skip_sv48x4_test:
>
> +       csr_write(CSR_HGATP, 0);
>         __kvm_riscv_hfence_gvma_all();
>  #endif
>  }
> --
> 2.25.1
>

Reviewed-by: Atish Patra <atishp@...osinc.com>

-- 
Regards,
Atish