Re: [Xen-devel] [PATCH v4 04/34] HYPERCALL_version_op. New hypercall mirroring XENVER_ but sane.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.03.16 at 03:37, <konrad.wilk@xxxxxxxxxx> wrote:
>> > --- a/xen/xsm/flask/hooks.c
>> > +++ b/xen/xsm/flask/hooks.c
>> > @@ -1658,6 +1658,40 @@ static int flask_xen_version (uint32_t op)
>> >      }
>> >  }
>> >  
>> > +static int flask_version_op (uint32_t op)
>> > +{
>> > +    u32 dsid = domain_sid(current->domain);
>> > +
>> > +    switch ( op )
>> > +    {
>> > +    case XEN_VERSION_version:
>> > +    case XEN_VERSION_platform_parameters:
>> > +    case XEN_VERSION_get_features:
>> > +        /* These MUST always be accessible to any guest by default. */
>> > +        return 0;
>> 
>> Perhaps these would better be taken care of in xsm_version_op()?
> 
> It would be the oddball one.
> All of the xsm_**() in the header file (include/xsm/xsm.h) call the function
> pointers.

True, but if there appeared any second implementation besides
FLASK, it would need to repeat code to meet this backend
independent policy. Anyway - I'll leave it to Daniel to judge.

> @@ -381,6 +389,123 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) 
> arg)
>      return -ENOSYS;
>  }
>  
> +/* Computed be kernel_cache_init. */

... by ...

And I also think kernel_cache_init is a bad name - you initialize the
capabilities cache, not some kernel cache.

> @@ -418,6 +543,20 @@ DO(ni_hypercall)(void)
>      return -ENOSYS;
>  }
>  
> +static int __init kernel_cache_init(void)
> +{
> +    /*
> +     * Pre-allocate the cache so we do not have to worry about
> +     * simultaneous invocations on safe_strcat by guests and the cache
> +     * data becoming garbage.
> +     */
> +    arch_get_xen_caps(&cached_cap);
> +    cached_cap_len = strlen(cached_cap) + 1;
> +
> +    return 0;
> +}

With this I'm now missing the conversion of arch_get_xen_caps()
to __init. Or was this meant to become a follow-up patch (since it
might get a little larger if at once also taking care of moving the
string literals into .init.*)?

Jan


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