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From: Julien Grall <julien@xen.org>
To: Simon Leiner <simon@leiner.me>,
	xen-devel@lists.xenproject.org, sstabellini@kernel.org,
	jgross@suse.com
Subject: Re: [PATCH 2/2] arm/xen: Add misuse warning to virt_to_gfn
Date: Wed, 26 Aug 2020 19:37:01 +0100
Message-ID: <eb1c9e1a-d8b5-cfd5-4575-3ae47f99ad44@xen.org> (raw)
In-Reply-To: <20200825093153.35500-2-simon@leiner.me>

Hi Simon,

On 25/08/2020 10:31, Simon Leiner wrote:
> As virt_to_gfn uses virt_to_phys, it will return invalid addresses when
> used with vmalloc'd addresses. This patch introduces a warning, when
> virt_to_gfn is used in this way.
> 
> Signed-off-by: Simon Leiner <simon@leiner.me>
> ---
>   include/xen/arm/page.h | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/include/xen/arm/page.h b/include/xen/arm/page.h
> index d7f6af50e200..b0d303b633d0 100644
> --- a/include/xen/arm/page.h
> +++ b/include/xen/arm/page.h
> @@ -76,7 +76,11 @@ static inline unsigned long bfn_to_pfn(unsigned long bfn)
>   #define bfn_to_local_pfn(bfn)	bfn_to_pfn(bfn)
>   
>   /* VIRT <-> GUEST conversion */
> -#define virt_to_gfn(v)		(pfn_to_gfn(virt_to_phys(v) >> XEN_PAGE_SHIFT))
> +#define virt_to_gfn(v)                                                         \
> +	({                                                                     \
> +		WARN_ON_ONCE(is_vmalloc_addr(v));                              \

virt_to_gfn() will usually be called from generic code. WARN_ON_ONCE() 
will only catch one instance and it means we would have to fix the first 
instance and then re-run to catch the others.

So I think we want to switch to WARN_ON() here.

Cheers,

-- 
Julien Grall


  parent reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Aw: [Linux] [ARM] Granting memory obtained from the DMA API>
2020-08-25  9:31 ` [PATCH 1/2] xen/xenbus: Fix granting of vmalloc'd memory Simon Leiner
2020-08-25  9:31   ` [PATCH 2/2] arm/xen: Add misuse warning to virt_to_gfn Simon Leiner
2020-08-25 12:16     ` Jan Beulich
2020-08-25 23:48       ` Stefano Stabellini
2020-08-26  6:20         ` Jan Beulich
2020-08-26  7:50           ` Simon Leiner
2020-08-26  7:59             ` Jürgen Groß
2020-08-26  8:14               ` Simon Leiner
2020-08-26  8:27                 ` Jürgen Groß
2020-08-26  8:30                   ` Simon Leiner
2020-08-25 23:58     ` Stefano Stabellini
2020-08-26 18:37     ` Julien Grall [this message]
2020-08-27  5:21       ` Jürgen Groß
2020-08-27  8:24         ` Julien Grall
2020-08-27  8:35           ` Jürgen Groß
2020-08-27 16:04             ` Stefano Stabellini
2020-08-25 23:55   ` [PATCH 1/2] xen/xenbus: Fix granting of vmalloc'd memory Stefano Stabellini

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