From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: Ram Pai <linuxram@us.ibm.com>, mpe@ellerman.id.au
Cc: linuxppc-dev@lists.ozlabs.org, benh@kernel.crashing.org,
david@gibson.dropbear.id.au, paulus@ozlabs.org,
mdroth@linux.vnet.ibm.com, hch@lst.de, andmike@us.ibm.com,
sukadev@linux.vnet.ibm.com, mst@redhat.com, ram.n.pai@gmail.com,
cai@lca.pw, tglx@linutronix.de, bauerman@linux.ibm.com,
linux-kernel@vger.kernel.org, leonardo@linux.ibm.com
Subject: Re: [PATCH v5 2/2] powerpc/pseries/iommu: Use dma_iommu_ops for Secure VM.
Date: Tue, 10 Dec 2019 14:08:52 +1100 [thread overview]
Message-ID: <5ee813ba-8f83-efd1-074c-1d9b2cb24334@ozlabs.ru> (raw)
In-Reply-To: <1575681159-30356-3-git-send-email-linuxram@us.ibm.com>
On 07/12/2019 12:12, Ram Pai wrote:
> 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@us.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Although I still do not totally understand the mechanics of this
(swiotlb on top of huge DDW at 0x800.0000.0000.0000), this change looks
reasonable anyway.
> ---
> 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"
> @@ -1346,15 +1345,7 @@ 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)
>
--
Alexey
next prev parent reply other threads:[~2019-12-10 3:09 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-07 1:12 [PATCH v5 0/2] Enable IOMMU support for pseries Secure VMs Ram Pai
2019-12-07 1:12 ` [PATCH v5 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor Ram Pai
2019-12-07 1:12 ` [PATCH v5 2/2] powerpc/pseries/iommu: Use dma_iommu_ops for Secure VM Ram Pai
2019-12-10 3:08 ` Alexey Kardashevskiy [this message]
2019-12-10 22:09 ` Thiago Jung Bauermann
2019-12-11 1:43 ` Michael Roth
2019-12-11 8:36 ` Alexey Kardashevskiy
2019-12-11 18:07 ` Michael Roth
2019-12-11 18:20 ` Christoph Hellwig
2019-12-12 6:45 ` Ram Pai
2019-12-13 0:19 ` Michael Roth
2019-12-10 3:07 ` [PATCH v5 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor Alexey Kardashevskiy
2019-12-10 5:12 ` Ram Pai
2019-12-10 5:32 ` Alexey Kardashevskiy
2019-12-10 15:35 ` Ram Pai
2019-12-11 8:15 ` Alexey Kardashevskiy
2019-12-11 20:31 ` Michael Roth
2019-12-11 22:47 ` Alexey Kardashevskiy
2019-12-12 2:39 ` Alexey Kardashevskiy
2019-12-13 0:22 ` Michael Roth
2019-12-12 4:11 ` Ram Pai
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