Messages in this thread Patch in this message | | | From | Thiago Jung Bauermann <> | Subject | Re: [PATCH v3 13/16] powerpc/pseries/iommu: Don't use dma_iommu_ops on secure guests | Date | Tue, 06 Aug 2019 22:37:34 -0300 |
| |
Hello Christoph,
Thanks for your review.
Christoph Hellwig <hch@lst.de> writes:
> On Tue, Aug 06, 2019 at 02:22:34AM -0300, Thiago Jung Bauermann wrote: >> @@ -1318,7 +1319,10 @@ void iommu_init_early_pSeries(void) >> of_reconfig_notifier_register(&iommu_reconfig_nb); >> register_memory_notifier(&iommu_mem_nb); >> >> - set_pci_dma_ops(&dma_iommu_ops); >> + if (is_secure_guest()) >> + set_pci_dma_ops(NULL); >> + else >> + set_pci_dma_ops(&dma_iommu_ops); > > Shoudn't: > > if (!is_secure_guest()) > set_pci_dma_ops(&dma_iommu_ops); > > be enough here, given that NULL is the default?
Indeed, it is enough.
> Also either way I think this conditional needs a comment explaining > why it is there.
Good point. I added the commit message as a comment in the code. New version of this patch below.
From 5dc3914efa4765eef2869d554d4ea1c676bb1e75 Mon Sep 17 00:00:00 2001 From: Thiago Jung Bauermann <bauerman@linux.ibm.com> Date: Thu, 24 Jan 2019 22:40:16 -0200 Subject: [PATCH] powerpc/pseries/iommu: Don't use dma_iommu_ops on secure guests
Secure guest memory is inacessible to devices so regular DMA isn't possible.
In that case set devices' dma_map_ops to NULL so that the generic DMA code path will use SWIOTLB to bounce buffers for DMA.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> --- arch/powerpc/platforms/pseries/iommu.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index 889dc2e44b89..8d9c2b17ad54 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -36,6 +36,7 @@ #include <asm/udbg.h> #include <asm/mmzone.h> #include <asm/plpar_wrappers.h> +#include <asm/svm.h> #include "pseries.h" @@ -1318,7 +1319,15 @@ void iommu_init_early_pSeries(void) of_reconfig_notifier_register(&iommu_reconfig_nb); register_memory_notifier(&iommu_mem_nb); - set_pci_dma_ops(&dma_iommu_ops); + /* + * 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); } static int __init disable_multitce(char *str)
| |