Re: [PATCH kernel 1/3] powerpc/pseries/iommu: Use dma_iommu_ops for Secure VM.

[Michael Ellerman <mpe@ellerman.id.au>]

Alexey Kardashevskiy <aik@ozlabs.ru> writes:

> From: Ram Pai <linuxram@us.ibm.com>
>
> Commit edea902c1c1e ("powerpc/pseries/iommu: Don't use dma_iommu_ops on
> 		secure guests")
> disabled dma_iommu_ops path, for secure VMs. Disabling dma_iommu_ops
> path for secure VMs, helped enable dma_direct path.  This enabled
> support for bounce-buffering through SWIOTLB.  However it fails to
> operate when IOMMU is enabled, since I/O pages are not TCE mapped.
>
> Reenable dma_iommu_ops path for pseries Secure VMs.  It handles all
> cases including, TCE mapping I/O pages, in the presence of a
> IOMMU.
>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

This seems like it should have a Fixes tag?

cheers

> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 6ba081dd61c9..df7db33ca93b 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -36,7 +36,6 @@
>  #include <asm/udbg.h>
>  #include <asm/mmzone.h>
>  #include <asm/plpar_wrappers.h>
> -#include <asm/svm.h>
>  
>  #include "pseries.h"
>  
> @@ -1320,15 +1319,7 @@ void iommu_init_early_pSeries(void)
>  	of_reconfig_notifier_register(&iommu_reconfig_nb);
>  	register_memory_notifier(&iommu_mem_nb);
>  
> -	/*
> -	 * Secure guest memory is inacessible to devices so regular DMA isn't
> -	 * possible.
> -	 *
> -	 * In that case keep devices' dma_map_ops as NULL so that the generic
> -	 * DMA code path will use SWIOTLB to bounce buffers for DMA.
> -	 */
> -	if (!is_secure_guest())
> -		set_pci_dma_ops(&dma_iommu_ops);
> +	set_pci_dma_ops(&dma_iommu_ops);
>  }
>  
>  static int __init disable_multitce(char *str)
> -- 
> 2.17.1