Re: [Xen-devel] [PATCH V2] libxc: fix xc_translate_foreign_address()

[Julien Grall <julien.grall@xxxxxxx>]

On 05/04/17 16:03, Wei Liu wrote:
> On Wed, Apr 05, 2017 at 03:58:05PM +0100, Julien Grall wrote:
> > Hi Razvan,
> >
> > On 05/04/17 15:53, Razvan Cojocaru wrote:
> > > Currently xc_translate_foreign_address() only checks for the PSE bit on
> > > level 2 entries (that's 2 MB pages on x64 and 32-bit with PAE, and 4 MB
> > > pages on 32-bit). But the Linux kernel sometimes uses 1 GB pages. This
> > > patch fixes that, by checking the PSE bit on level 3 entries if the guest
> > > has 4 translation levels (that means 64-bit guests only).
> > >
> > > Signed-off-by: Cristian-Bogdan Sirb <csirb@xxxxxxxxxxxxxxx>
> > He is the author of the patch, correct? If so, he should be the author as
> > well (e.g From: ...).
> >
> > Also, you may want to add your signed-off-by here.
> Julien, if you agree to let this patch go in 4.9. I can fix those up.
Release-acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

> Razvan, please tell me what you want me to do.
>
> Code-wise:
>
> Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
>
>
> > Cheers,
> >
> > > ---
> > > Changes since V1:
> > >  - Added header comment.
> > > ---
> > >  tools/libxc/include/xenctrl.h | 3 +++
> > >  tools/libxc/xc_pagetab.c      | 2 +-
> > >  2 files changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
> > > index 2d97d36..ca4bb6c 100644
> > > --- a/tools/libxc/include/xenctrl.h
> > > +++ b/tools/libxc/include/xenctrl.h
> > > @@ -1460,6 +1460,9 @@ int xc_lockprof_query(xc_interface *xch,
> > >  void *xc_memalign(xc_interface *xch, size_t alignment, size_t size);
> > >
> > >  /**
> > > + * Avoid using this function, as it does not work for all cases (such
> > > + * as 4M superpages, or guests using PSE36). Only used for debugging.
> > > + *
> > >   * Translates a virtual address in the context of a given domain and
> > >   * vcpu returning the GFN containing the address (that is, an MFN for
> > >   * PV guests, a PFN for HVM guests).  Returns 0 for failure.
> > > diff --git a/tools/libxc/xc_pagetab.c b/tools/libxc/xc_pagetab.c
> > > index 92eebd6..db25c20 100644
> > > --- a/tools/libxc/xc_pagetab.c
> > > +++ b/tools/libxc/xc_pagetab.c
> > > @@ -93,7 +93,7 @@ unsigned long xc_translate_foreign_address(xc_interface *xch, 
> > > uint32_t dom,
> > >              return 0;
> > >          }
> > >          paddr = pte & 0x000ffffffffff000ull;
> > > -        if (level == 2 && (pte & PTE_PSE)) {
> > > +        if ((level == 2 || (level == 3 && pt_levels == 4)) && (pte & PTE_PSE)) 
> > > {
> > >              mask = ((mask ^ ~-mask) >> 1); /* All bits below first set bit */
> > >              return ((paddr & ~mask) | (virt & mask)) >> PAGE_SHIFT;
> > >          }
> > --
> > Julien Grall
--
Julien Grall

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