| Message ID | 1438711972-18752-4-git-send-email-julien.grall@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 4 Aug 2015, Julien Grall wrote: > After the commit introducing convertion between DMA and guest address, ^ addresses > all the callers of pfn_to_mfn are expecting to get a GFN (Guest Frame > Number). On ARM, all the guests are auto-translated so the GFN is equal > to the Linux PFN (Pseudo-physical Frame Number). > > The current implementation may return an MFN if the caller is passing a > PFN associated to a mapped foreign grant. In pratical, I haven't seen ^ practice > the problem on running guest but we should fix it for the sake of > correctness. > > Correct the implementation by always returning the pfn passed in parameter. > > A follow-up patch will take care to rename pfn_to_mfn to a suitable > name. > > Signed-off-by: Julien Grall <julien.grall@citrix.com> > Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > Cc: Russell King <linux@arm.linux.org.uk> > Cc: linux-arm-kernel@lists.infradead.org Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > arch/arm/include/asm/xen/page.h | 8 -------- > 1 file changed, 8 deletions(-) > > diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h > index bc5e77c..087d86e 100644 > --- a/arch/arm/include/asm/xen/page.h > +++ b/arch/arm/include/asm/xen/page.h > @@ -36,14 +36,6 @@ extern struct rb_root phys_to_mach; > > static inline unsigned long pfn_to_mfn(unsigned long pfn) > { > - unsigned long mfn; > - > - if (phys_to_mach.rb_node != NULL) { > - mfn = __pfn_to_mfn(pfn); > - if (mfn != INVALID_P2M_ENTRY) > - return mfn; > - } > - > return pfn; > } > > -- > 2.1.4 >
diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h index bc5e77c..087d86e 100644 --- a/arch/arm/include/asm/xen/page.h +++ b/arch/arm/include/asm/xen/page.h @@ -36,14 +36,6 @@ extern struct rb_root phys_to_mach; static inline unsigned long pfn_to_mfn(unsigned long pfn) { - unsigned long mfn; - - if (phys_to_mach.rb_node != NULL) { - mfn = __pfn_to_mfn(pfn); - if (mfn != INVALID_P2M_ENTRY) - return mfn; - } - return pfn; }
After the commit introducing convertion between DMA and guest address, all the callers of pfn_to_mfn are expecting to get a GFN (Guest Frame Number). On ARM, all the guests are auto-translated so the GFN is equal to the Linux PFN (Pseudo-physical Frame Number). The current implementation may return an MFN if the caller is passing a PFN associated to a mapped foreign grant. In pratical, I haven't seen the problem on running guest but we should fix it for the sake of correctness. Correct the implementation by always returning the pfn passed in parameter. A follow-up patch will take care to rename pfn_to_mfn to a suitable name. Signed-off-by: Julien Grall <julien.grall@citrix.com> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: linux-arm-kernel@lists.infradead.org --- arch/arm/include/asm/xen/page.h | 8 -------- 1 file changed, 8 deletions(-)