Re: [Xen-devel] [PATCH v2 01/20] x86: make hvm_{get/set}_param accessible

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 18/12/2019 19:40, Tamas K Lengyel wrote:
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 614ed60fe4..5a3a962fbb 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -4072,16 +4072,17 @@ static int hvmop_set_evtchn_upcall_vector(
>  }
>  
>  static int hvm_allow_set_param(struct domain *d,
> -                               const struct xen_hvm_param *a)
> +                               uint32_t index,
> +                               uint64_t new_value)

These two lines can be folded together.

> @@ -4134,13 +4135,11 @@ static int hvm_allow_set_param(struct domain *d,
>      return rc;
>  }
>  
> -static int hvmop_set_param(
> +int hvmop_set_param(
>      XEN_GUEST_HANDLE_PARAM(xen_hvm_param_t) arg)

and here.

> @@ -4160,23 +4159,42 @@ static int hvmop_set_param(
>      if ( !is_hvm_domain(d) )
>          goto out;
>  
> -    rc = hvm_allow_set_param(d, &a);
> +    rc = hvm_set_param(d, a.index, a.value);
> +
> + out:
> +    rcu_unlock_domain(d);
> +    return rc;
> +}
> +
> +int hvm_set_param(
> +    struct domain *d,
> +    uint32_t index,
> +    uint64_t value)

and again.

> @@ -4340,34 +4358,33 @@ static int hvmop_set_param(
>           * 256 bits interrupt redirection bitmap + 64k bits I/O bitmap
>           * plus one padding byte).
>           */
> -        if ( (a.value >> 32) > sizeof(struct tss32) +
> +        if ( (value >> 32) > sizeof(struct tss32) +
>                                 (0x100 / 8) + (0x10000 / 8) + 1 )
> -            a.value = (uint32_t)a.value |
> +            value = (uint32_t)value |
>                        ((sizeof(struct tss32) + (0x100 / 8) +
>                                                 (0x10000 / 8) + 1) << 32);

Can you reindent the surrounding lines so they line up again?

> @@ -4429,42 +4446,60 @@ static int hvmop_get_param(
>      if ( !is_hvm_domain(d) )
>          goto out;
>  
> -    rc = hvm_allow_get_param(d, &a);
> +    rc = hvm_get_param(d, a.index, &a.value);
>      if ( rc )
>          goto out;
>  
> -    switch ( a.index )
> +    rc = __copy_to_guest(arg, &a, 1) ? -EFAULT : 0;
> +
> +    HVM_DBG_LOG(DBG_LEVEL_HCALL, "get param %u = %"PRIx64,
> +                a.index, a.value);
> +
> + out:
> +    rcu_unlock_domain(d);
> +    return rc;
> +}
> +
> +int hvm_get_param(
> +    struct domain *d,
> +    uint32_t index,
> +    uint64_t *value)

Fold.

> +{
> +    int rc;
> +
> +    if ( index >= HVM_NR_PARAMS || !value )

No need for !value.  It had better only ever point onto the hypervisor
stack now that this is an internal function.

> diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
> index 1d7b66f927..a6f4ae76a1 100644
> --- a/xen/include/asm-x86/hvm/hvm.h
> +++ b/xen/include/asm-x86/hvm/hvm.h
> @@ -335,6 +335,10 @@ unsigned long hvm_cr4_guest_valid_bits(const struct 
> domain *d, bool restore);
>  bool hvm_flush_vcpu_tlb(bool (*flush_vcpu)(void *ctxt, struct vcpu *v),
>                          void *ctxt);
>  
> +/* Caller must hold domain locks */

How about asserting so?

No major problems so Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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