Re: [PATCH v2 09/13] libx86: Introduce a helper to deserialise cpuid_policy objects

[Wei Liu <wei.liu2@citrix.com>]

On Fri, Jul 13, 2018 at 09:03:10PM +0100, Andrew Cooper wrote:
> As with the serialise side, Xen's copy_from_guest API is used, with a
> compatibility wrapper for the userspace build.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Wei Liu <wei.liu2@citrix.com>
> CC: Roger Pau Monné <roger.pau@citrix.com>
> CC: Sergey Dyasli <sergey.dyasli@citrix.com>
> CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
> 
> v2:
>  * Rewrite copy_from_buffer_offset() to avoid multiple evaluation of its
>    arguments.
>  * Expand boundary justifications.
> ---
>  xen/common/libx86/cpuid.c      | 94 ++++++++++++++++++++++++++++++++++++++++++
>  xen/common/libx86/private.h    | 14 +++++++
>  xen/include/xen/libx86/cpuid.h | 11 +++++
>  3 files changed, 119 insertions(+)
> 
> diff --git a/xen/common/libx86/cpuid.c b/xen/common/libx86/cpuid.c
> index cf7dbd3..73cd574 100644
> --- a/xen/common/libx86/cpuid.c
> +++ b/xen/common/libx86/cpuid.c
> @@ -123,6 +123,100 @@ int x86_cpuid_copy_to_buffer(const struct cpuid_policy *p,
>      return 0;
>  }
>  
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/common/libx86/private.h b/xen/common/libx86/private.h
> index e874fb6..dc451d0 100644
> --- a/xen/common/libx86/private.h
> +++ b/xen/common/libx86/private.h
> @@ -12,6 +12,7 @@
>  #include <asm/msr-index.h>
>  
>  #define copy_to_buffer_offset copy_to_guest_offset
> +#define copy_from_buffer_offset copy_from_guest_offset
>  
>  #else
>  
> @@ -44,6 +45,19 @@ static inline bool test_bit(unsigned int bit, const void *vaddr)
>      0;                                                  \
>  })
>  
> +/* memcpy(), but with copy_from_guest_offset()'s API. */
> +#define copy_from_buffer_offset(dst, src, index, nr)    \
> +({                                                      \
> +    const typeof(*(dst)) *src_ = (src);                 \

Same issue as previous patch here. Also enforcing dst_ and src_ are of
the same type would be good.

Otherwise:

Reviewed-by: Wei Liu <wei.liu2@citrix.com>

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