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Date: Fri, 4 Apr 2014 12:58:51 -0400 From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> To: Roger Pau Monne <roger.pau@...rix.com> Cc: xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org, David Vrabel <david.vrabel@...rix.com>, Boris Ostrovsky <boris.ostrovsky@...cle.com> Subject: Re: [PATCH] xen-blkback: only attach blkback if the required features are met On Fri, Apr 04, 2014 at 04:41:11PM +0200, Roger Pau Monne wrote: > Blkback cannot work properly on auto-translated guests if Xen doesn't > update the IOMMU when performing grant maps/unmaps, so only attach if > the newly introduced XENFEAT_hvm_gntmap_supports_iommu is found. Could you point to the git commit that introduces it in the patch please? > > Signed-off-by: Roger Pau Monné <roger.pau@...rix.com> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> > Cc: David Vrabel <david.vrabel@...rix.com> > Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com> > --- > drivers/block/xen-blkback/blkback.c | 12 ++++++++++++ > include/xen/interface/features.h | 6 ++++++ > 2 files changed, 18 insertions(+), 0 deletions(-) > > diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c > index 64c60ed..4c23ddd 100644 > --- a/drivers/block/xen-blkback/blkback.c > +++ b/drivers/block/xen-blkback/blkback.c > @@ -1381,6 +1381,18 @@ static int __init xen_blkif_init(void) > if (!xen_domain()) > return -ENODEV; > > +#ifdef CONFIG_X86 > + if (xen_feature(XENFEAT_auto_translated_physmap) && > + !xen_feature(XENFEAT_hvm_gntmap_supports_iommu)) { > + /* > + * blkback cannot work properly on auto-translated guests > + * if grant table mappings don't update the IOMMU entries. > + */ > + pr_debug(DRV_PFX "Disabling blkback because Xen is missing feature XENFEAT_hvm_gntmap_supports_iommu\n"); > + return -ENODEV; > + } > +#endif /* CONFIG_X86 */ > + > rc = xen_blkif_interface_init(); > if (rc) > goto failed_init; > diff --git a/include/xen/interface/features.h b/include/xen/interface/features.h > index 131a6cc..d1e0f23 100644 > --- a/include/xen/interface/features.h > +++ b/include/xen/interface/features.h > @@ -53,6 +53,12 @@ > /* operation as Dom0 is supported */ > #define XENFEAT_dom0 11 > > +/* > + * If set, GNTTABOP_map_grant_ref sets the proper IOMMU mappings so the > + * resulting mapped page can be used for IO with hardware devices. > + */ > +#define XENFEAT_hvm_gntmap_supports_iommu 12 > + > #define XENFEAT_NR_SUBMAPS 1 > > #endif /* __XEN_PUBLIC_FEATURES_H__ */ > -- > 1.7.7.5 (Apple Git-26) > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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