Re: [PATCH 04/19] KVM: arm64: Push checks for 64bit registers into the low-level accessors

[Reiji Watanabe <reijiw@xxxxxxxxxx>]

Hi Marc,

On Wed, Jul 6, 2022 at 9:43 AM Marc Zyngier <maz@xxxxxxxxxx> wrote:
>
> Make sure the check occurs on every paths where we can pick
> a sysreg from userspace, including the GICv3 paths.
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
>  arch/arm64/kvm/sys_regs.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 0fbdb21a3600..89e7eddea937 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -2656,6 +2656,10 @@ const struct sys_reg_desc *get_reg_by_id(u64 id,
>  {
>         struct sys_reg_params params;
>
> +       /* 64 bit is the only way */
> +       if (KVM_REG_SIZE(id) != sizeof(__u64))
> +               return NULL;

This doesn't seem to be necessary since the equivalent check
is done by index_to_params().

Thank you,
Reiji

> +
>         if (!index_to_params(id, &params))
>                 return NULL;
>
> @@ -2871,9 +2875,6 @@ int kvm_arm_sys_reg_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
>         if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX)
>                 return demux_c15_get(reg->id, uaddr);
>
> -       if (KVM_REG_SIZE(reg->id) != sizeof(__u64))
> -               return -ENOENT;
> -
>         err = get_invariant_sys_reg(reg->id, uaddr);
>         if (err != -ENOENT)
>                 return err;
> @@ -2906,9 +2907,6 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
>         if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX)
>                 return demux_c15_set(reg->id, uaddr);
>
> -       if (KVM_REG_SIZE(reg->id) != sizeof(__u64))
> -               return -ENOENT;
> -
>         err = set_invariant_sys_reg(reg->id, uaddr);
>         if (err != -ENOENT)
>                 return err;
> --
> 2.34.1
>
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