[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] xen-blkback: only attach blkback if the required features are met
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. Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Cc: David Vrabel <david.vrabel@xxxxxxxxxx> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> --- 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) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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