Re: [PATCH 1/1] RISC-V: KVM: No need to use mask when hart-index-bit is 0

[Anup Patel]

On Mon, Apr 15, 2024 at 12:19 PM Yong-Xuan Wang
<yongxuan.wang@xxxxxxxxxx> 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 irqchip")
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang@xxxxxxxxxx>

Queued this patch for Linux-6.10-rcX fixes.

Thanks,
Anup

> ---
>  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 = 0;
> +       u32 hart = 0, group = 0;
>
> -       hart = (addr >> (aia->nr_guest_bits + IMSIC_MMIO_PAGE_SHIFT)) &
> -               GENMASK_ULL(aia->nr_hart_bits - 1, 0);
> +       if (aia->nr_hart_bits)
> +               hart = (addr >> (aia->nr_guest_bits + IMSIC_MMIO_PAGE_SHIFT)) &
> +                      GENMASK_ULL(aia->nr_hart_bits - 1, 0);
>         if (aia->nr_group_bits)
>                 group = (addr >> aia->nr_group_shift) &
>                         GENMASK_ULL(aia->nr_group_bits - 1, 0);
> --
> 2.17.1
>