Re: [Xen-devel] [PATCH 1/5] x86/hvm: Switch hvm_allow_get_param() to use a whitelist

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Sep 05, 2018 at 07:12:00PM +0100, Andrew Cooper wrote:
> There are holes in the HVM_PARAM space, some of which are from deprecated
> parameters, but toolstack and device models currently have blanket read
> access.
> 
> Rearrange hvm_allow_get_param() to have a whitelist of toolstack-readable
> parameters, with the default case failing with -EINVAL (which subsumes the
> HVM_NR_PARAMS check).
> 
> No expected change for the defined, in-use params.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Just one nit.

> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Paul Durrant <paul.durrant@xxxxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> ---
>  xen/arch/x86/hvm/hvm.c | 38 ++++++++++++++++++++++++++++----------
>  1 file changed, 28 insertions(+), 10 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index c22bf0b..96a6323 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -4350,7 +4350,7 @@ static int hvm_allow_get_param(struct domain *d,
>  
>      switch ( a->index )
>      {
> -    /* The following parameters can be read by the guest. */
> +        /* The following parameters can be read by the guest and toolstack. 
> */
>      case HVM_PARAM_CALLBACK_IRQ:
>      case HVM_PARAM_VM86_TSS:
>      case HVM_PARAM_VM86_TSS_SIZED:
> @@ -4363,18 +4363,39 @@ static int hvm_allow_get_param(struct domain *d,
>      case HVM_PARAM_ALTP2M:
>      case HVM_PARAM_X87_FIP_WIDTH:
>          break;
> -    /*
> -     * The following parameters must not be read by the guest
> -     * since the domain may need to be paused.
> -     */
> +
> +        /*
> +         * The following parameters are intended for toolstack usage only.
> +         * Some require the domain to be paused, and therefore may not read 
> by
                                                                         ^ be

Roger.

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