On Wed, May 01, 2019 at 02:58:19PM +0100, Julien Grall wrote: > On RT, iommu_dma_map_msi_msg() may be called from non-preemptible > context. This will lead to a splat with CONFIG_DEBUG_ATOMIC_SLEEP as > the function is using spin_lock (they can sleep on RT). > > iommu_dma_map_msi_msg() is used to map the MSI page in the IOMMU PT > and update the MSI message with the IOVA. > > Only the part to lookup for the MSI page requires to be called in > preemptible context. As the MSI page cannot change over the lifecycle > of the MSI interrupt, the lookup can be cached and re-used later on. > > iomma_dma_map_msi_msg() is now split in two functions: > - iommu_dma_prepare_msi(): This function will prepare the mapping > in the IOMMU and store the cookie in the structure msi_desc. This > function should be called in preemptible context. > - iommu_dma_compose_msi_msg(): This function will update the MSI > message with the IOVA when the device is behind an IOMMU. > > Signed-off-by: Julien Grall <julien.grall@xxxxxxx> > Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx> > Reviewed-by: Eric Auguer <eric.auger@xxxxxxxxxx> Acked-by: Joerg Roedel <jroedel@xxxxxxx>
