Re: [Xen-devel] [PATCH for-4.11 1/2] libxc/x86: fix mapping of the start_info area

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Mar 21, 2018 at 02:42:10PM +0000, Roger Pau Monne wrote:
> The start_info size calculated in bootlate_hvm is wrong. It should use
> HVMLOADER_MODULE_MAX_COUNT instead of dom->num_modules and it doesn't
> take into account the size of the modules command line.
> 
> This is not a problem so far because the actually used amount of
> memory doesn't cross a page boundary, and so no page-fault is
> triggered.

I get the cmdline bit.

What does it need to be HVMLOADER_MODULE_MAX_COUNT? Isn't better to just
map what we need here?

Wei.

> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
>  tools/libxc/xc_dom_x86.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
> index 0b65dab4bc..e29c666b89 100644
> --- a/tools/libxc/xc_dom_x86.c
> +++ b/tools/libxc/xc_dom_x86.c
> @@ -1671,7 +1671,11 @@ static int bootlate_hvm(struct xc_dom_image *dom)
>      unsigned int i;
>  
>      start_info_size = sizeof(*start_info) + dom->cmdline_size;
> -    start_info_size += sizeof(struct hvm_modlist_entry) * dom->num_modules;
> +    start_info_size += sizeof(struct hvm_modlist_entry) *
> +                       HVMLOADER_MODULE_MAX_COUNT;
> +    start_info_size += HVMLOADER_MODULE_CMDLINE_SIZE *
> +                       HVMLOADER_MODULE_MAX_COUNT;
> +
>  
>      if ( start_info_size >
>           dom->start_info_seg.pages << XC_DOM_PAGE_SHIFT(dom) )
> -- 
> 2.16.2
> 

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