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From: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Date: Wed, 22 May 2024 16:24:46 +0800
Message-ID: <CAMWQL2jvNV70dX46J+EzUQXxw1yzVGzB2+knuPFiWK7mF2TfFA@mail.gmail.com>
Subject: Re: [PATCH 1/1] RISC-V: KVM: No need to use mask when hart-index-bit
 is 0
To: linux-riscv@lists.infradead.org, kvm-riscv@lists.infradead.org
Cc: greentime.hu@sifive.com, vincent.chen@sifive.com, 
	Anup Patel <anup@brainfault.org>, Atish Patra <atishp@atishpatra.org>, 
	Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, 
	Albert Ou <aou@eecs.berkeley.edu>, kvm@vger.kernel.org, linux-kernel@vger.kernel.org
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Ping

On Mon, Apr 15, 2024 at 2:49=E2=80=AFPM Yong-Xuan Wang <yongxuan.wang@sifiv=
e.com> wrote:
>
> When the maximum hart number within groups is 1, hart-index-bit is set to
> 0. Consequently, there is no need to restore the hart ID from IMSIC
> addresses and hart-index-bit settings. Currently, QEMU and kvmtool do not
> pass correct hart-index-bit values when the maximum hart number is a
> power of 2, thereby avoiding this issue. Corresponding patches for QEMU
> and kvmtool will also be dispatched.
>
> Fixes: 89d01306e34d ("RISC-V: KVM: Implement device interface for AIA irq=
chip")
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
> ---
>  arch/riscv/kvm/aia_device.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/kvm/aia_device.c b/arch/riscv/kvm/aia_device.c
> index 0eb689351b7d..5cd407c6a8e4 100644
> --- a/arch/riscv/kvm/aia_device.c
> +++ b/arch/riscv/kvm/aia_device.c
> @@ -237,10 +237,11 @@ static gpa_t aia_imsic_ppn(struct kvm_aia *aia, gpa=
_t addr)
>
>  static u32 aia_imsic_hart_index(struct kvm_aia *aia, gpa_t addr)
>  {
> -       u32 hart, group =3D 0;
> +       u32 hart =3D 0, group =3D 0;
>
> -       hart =3D (addr >> (aia->nr_guest_bits + IMSIC_MMIO_PAGE_SHIFT)) &
> -               GENMASK_ULL(aia->nr_hart_bits - 1, 0);
> +       if (aia->nr_hart_bits)
> +               hart =3D (addr >> (aia->nr_guest_bits + IMSIC_MMIO_PAGE_S=
HIFT)) &
> +                      GENMASK_ULL(aia->nr_hart_bits - 1, 0);
>         if (aia->nr_group_bits)
>                 group =3D (addr >> aia->nr_group_shift) &
>                         GENMASK_ULL(aia->nr_group_bits - 1, 0);
> --
> 2.17.1
>