linux-kernel - Re: [PATCH v5 2/2] powerpc/pseries/iommu: Use dma_iommu

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Date:   Tue, 10 Dec 2019 19:09:45 -0300
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     Ram Pai <linuxram@...ibm.com>
Cc:     mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org,
        benh@...nel.crashing.org, david@...son.dropbear.id.au,
        paulus@...abs.org, mdroth@...ux.vnet.ibm.com, hch@....de,
        andmike@...ibm.com, sukadev@...ux.vnet.ibm.com, mst@...hat.com,
        ram.n.pai@...il.com, aik@...abs.ru, cai@....pw, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, leonardo@...ux.ibm.com
Subject: Re: [PATCH v5 2/2] powerpc/pseries/iommu: Use dma_iommu_ops for Secure VM.


Hello Ram,

Ram Pai <linuxram@...ibm.com> writes:

> 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.
>
> Renable 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@...ibm.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 11 +----------
>  1 file changed, 1 insertion(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 67b5009..4e27d66 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 <asm/ultravisor.h>
>
>  #include "pseries.h"

You still need to keep <asm/svm.h>, otherwise there won't be a
definition of is_secure_guest() when CONFIG_PPC_SVM=n.

--
Thiago Jung Bauermann
IBM Linux Technology Center