On a VT-d capable machine Linux will enable IOMMU by default. If it then kexec's a second kernel with intel_iommu=off, this second kernel will leave the DMA remapping engine on with no code handling it. The symptom is at least USB and SATA drives stop working. This patch fixes the problem by always disabling DMA remapping when intel_iommu=off.
Signed-off-by: Wei Hu <[email protected]> --- drivers/iommu/intel-iommu.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 0099667..0b8f8bb 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -3681,8 +3681,12 @@ int __init intel_iommu_init(void) return -ENODEV; } - if (no_iommu || dmar_disabled) + if (no_iommu || dmar_disabled) { + struct dmar_drhd_unit *drhd; + for_each_drhd_unit(drhd) + iommu_disable_translation(drhd->iommu); return -ENODEV; + } if (iommu_init_mempool()) { if (force_on) -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
