Re: [PATCH] xen/xenbus: fix xenbus_setup_ring()

[Juergen Gross <jgross@xxxxxxxx>]

On 15.09.22 16:47, Oleksandr Tyshchenko wrote:
> On 15.09.22 17:31, Juergen Gross wrote:
>
> Hello Juergen
>
> > Commit 4573240f0764 ("xen/xenbus: eliminate xenbus_grant_ring()")
> > introduced an error for initialization of multi-page rings.
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: 4573240f0764 ("xen/xenbus: eliminate xenbus_grant_ring()")
> > Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > ---
> >    drivers/xen/xenbus/xenbus_client.c | 9 ++++++---
> >    1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/xen/xenbus/xenbus_client.c 
> > b/drivers/xen/xenbus/xenbus_client.c
> > index d5f3f763717e..caa5c5c32f8e 100644
> > --- a/drivers/xen/xenbus/xenbus_client.c
> > +++ b/drivers/xen/xenbus/xenbus_client.c
> > @@ -382,9 +382,10 @@ int xenbus_setup_ring(struct xenbus_device *dev, gfp_t 
> > gfp, void **vaddr,
> >         unsigned long ring_size = nr_pages * XEN_PAGE_SIZE;
> >         grant_ref_t gref_head;
> >         unsigned int i;
> > +       void *addr;
> >         int ret;
> >    
> > -	*vaddr = alloc_pages_exact(ring_size, gfp | __GFP_ZERO);
> > +       addr = *vaddr = alloc_pages_exact(ring_size, gfp | __GFP_ZERO);
> >         if (!*vaddr) {
> >                 ret = -ENOMEM;
> >                 goto err;
> > @@ -401,13 +402,15 @@ int xenbus_setup_ring(struct xenbus_device *dev, gfp_t 
> > gfp, void **vaddr,
> >                 unsigned long gfn;
> >    
> >    		if (is_vmalloc_addr(*vaddr))
> > -                       gfn = pfn_to_gfn(vmalloc_to_pfn(vaddr[i]));
> > +                       gfn = pfn_to_gfn(vmalloc_to_pfn(addr));
> >                 else
> > -                       gfn = virt_to_gfn(vaddr[i]);
> > +                       gfn = virt_to_gfn(addr);
> >    
> >    		grefs[i] = gnttab_claim_grant_reference(&gref_head);
> >                 gnttab_grant_foreign_access_ref(grefs[i], dev->otherend_id,
> >                                                 gfn, 0);
> > +
> > +               addr += PAGE_SIZE;
> XEN_PAGE_SIZE?
Oh, indeed! Will change on commit.

> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Thanks,


Juergen

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