Re: [Xen-devel] [PATCH] xen/arm: Correctly implement domain_page_map_to_mfn

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-02-05 at 14:51 +0000, George Dunlap wrote:
> On 02/05/2014 02:16 PM, Julien Grall wrote:
> > The function domain_page_map_to_mfn can be used to translate a virtual
> > address mapped by both map_domain_page and map_domain_page_global.
> > The former is using vmap to map the mfn, therefore domain_page_map_to_mfn
> > will always fail because the address is not in DOMHEAP range.
> >
> > Check if the address is in vmap range and use __pa to translate it.
> >
> > This patch fix guest shutdown when the event fifo is used.
> >
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> 
> I assume this brings the arm paths into line with the x86 functionality?

Yes, functionality which is now expected by common code as well (FIFO
evthcn stuff).

> 
>   -George
> 
> 
> >
> > ---
> >      This is a bug fix for Xen 4.4. Without this patch, it's impossible to
> > use Linux 3.14 (and higher) as guest with the event fifo driver.
> > ---
> >   xen/arch/arm/mm.c |   10 +++++++---
> >   1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> > index 127cce0..bdca68a 100644
> > --- a/xen/arch/arm/mm.c
> > +++ b/xen/arch/arm/mm.c
> > @@ -325,11 +325,15 @@ void unmap_domain_page(const void *va)
> >       local_irq_restore(flags);
> >   }
> >   
> > -unsigned long domain_page_map_to_mfn(const void *va)
> > +unsigned long domain_page_map_to_mfn(const void *ptr)
> >   {
> > +    unsigned long va = (unsigned long)ptr;
> >       lpae_t *map = this_cpu(xen_dommap);
> > -    int slot = ((unsigned long) va - DOMHEAP_VIRT_START) >> SECOND_SHIFT;
> > -    unsigned long offset = ((unsigned long)va>>THIRD_SHIFT) & 
> > LPAE_ENTRY_MASK;
> > +    int slot = (va - DOMHEAP_VIRT_START) >> SECOND_SHIFT;
> > +    unsigned long offset = (va>>THIRD_SHIFT) & LPAE_ENTRY_MASK;
> > +
> > +    if ( va >= VMAP_VIRT_START && va < VMAP_VIRT_END )
> > +        return virt_to_mfn(va);
> >   
> >       ASSERT(slot >= 0 && slot < DOMHEAP_ENTRIES);
> >       ASSERT(map[slot].pt.avail != 0);
> 



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