Re: [Xen-devel] [PATCH v3] arm/p2m: Fix regression during domain shutdown with active mem_access

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 25 Jan 2017, Julien Grall wrote:
> Hi Tamas,
> 
> On 25/01/2017 16:12, Tamas K Lengyel wrote:
> > The change in commit 438c5fe4f0c introduced a regression for domains where
> > mem_acces is or was active. When relinquish_p2m_mapping attempts to clear
> > a page where the order is not 0 the following ASSERT is triggered:
> > 
> >     ASSERT(!p2m->mem_access_enabled || page_order == 0);
> > 
> > This regression was unfortunately not caught during testing in preparation
> > for the 4.8 release.
> > 
> > In this patch we adjust the ASSERT to not trip when the domain
> > is being shutdown.
> > 
> > Ideally this fix would be part of Xen 4.8.1.
> 
> +1 for the backport.
> 
> 
> > 
> > Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>
> 
> Acked-by: Julien Grall <julien.grall@xxxxxxx>
> 

Done

> 
> > ---
> > Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > Cc: Julien Grall <julien.grall@xxxxxxx>
> > 
> > v3: Minor adjustments
> > ---
> >  xen/arch/arm/p2m.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> > index 09ceb378a5..7762f453f5 100644
> > --- a/xen/arch/arm/p2m.c
> > +++ b/xen/arch/arm/p2m.c
> > @@ -991,9 +991,10 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
> > 
> >      /*
> >       * The radix-tree can only work on 4KB. This is only used when
> > -     * memaccess is enabled.
> > +     * memaccess is enabled and during shutdown.
> >       */
> > -    ASSERT(!p2m->mem_access_enabled || page_order == 0);
> > +    ASSERT(!p2m->mem_access_enabled || page_order == 0 ||
> > +           p2m->domain->is_dying);
> >      /*
> >       * The access type should always be p2m_access_rwx when the mapping
> >       * is removed.
> > 
> 
> -- 
> Julien Grall
> 

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