Re: [PATCH v6 02/11] xen/arm: add iounmap after initrd has been loaded in domain_build

[Julien Grall <julien@xxxxxxx>]

(+ Henry)

Hi,

On 04/11/2022 10:07, Wei Chen wrote:
> domain_build use ioremap_wc to map a new non-cacheable virtual
s/use/uses/

> address for initrd. After Xen copy initrd from this address to
> guest, this new allocated virtual address has not been unmapped.
>
> So in this patch, we add an iounmap to the end of domain_build,
> after Xen loaded initrd to guest memory.
Please a fixes tag. The issue was introduced by commit bb7e6d565d92.

> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>   xen/arch/arm/domain_build.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 4fb5c20b13..bd30d3798c 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -3418,6 +3418,8 @@ static void __init initrd_load(struct kernel_info *kinfo)
>                                             initrd, len);
>       if ( res != 0 )
>           panic("Unable to copy the initrd in the hwdom memory\n");
> +
> +    iounmap(initrd);
This looks good to me. But I am wondering whether using ioremap_wc() is 
actually correct because we are reading the region. So it seems strang 
to map it with write-combine.
So I would consider to use ioremap_cache(). That said, this would be a 
separate patch.
I think this wants to be in 4.17. This will avoid Xen to have two 
mappings with different caching attribute (initrd is part of the RAM and 
therefore directmap).
Cheers,

--
Julien Grall