| Message ID | 1575269124-17885-3-git-send-email-linuxram@us.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Enable IOMMU support for pseries Secure VMs | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (2e6c4d7e1c5990fa2ccca6db0868a05640ac1df1) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 23 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
On 02/12/2019 17:45, 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. The rationale for disabling > the dma_iommu_ops path, was to use the dma_direct path, since it had > inbuilt support for bounce-buffering through SWIOTLB. > > However dma_iommu_ops is functionally much richer. Depending on the > capabilities of the platform, it can handle direct DMA; with or without > bounce buffering, and it can handle indirect DMA. Hence its better to > leverage the richer functionality supported by dma_iommu_ops. What exactly do we leverage after applying this patch? afaict things are going to work in exact same old way with this applied, no? Thanks, > > Renable dma_iommu_ops path for pseries Secure VMs. > > Signed-off-by: Ram Pai <linuxram@us.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 0720831..6adf4d3 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" > @@ -1337,15 +1336,7 @@ 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) >
On Tue, Dec 03, 2019 at 11:58:18AM +1100, Alexey Kardashevskiy wrote: > > > On 02/12/2019 17:45, 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. The rationale for disabling > > the dma_iommu_ops path, was to use the dma_direct path, since it had > > inbuilt support for bounce-buffering through SWIOTLB. > > > > However dma_iommu_ops is functionally much richer. Depending on the > > capabilities of the platform, it can handle direct DMA; with or without > > bounce buffering, and it can handle indirect DMA. Hence its better to > > leverage the richer functionality supported by dma_iommu_ops. > > What exactly do we leverage after applying this patch? afaict things are > going to work in exact same old way with this applied, no? Thanks, Yes. You got it right. Another way of saying this is, it reverts the changes. RP
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index 0720831..6adf4d3 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" @@ -1337,15 +1336,7 @@ 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)
Commit edea902c1c1e ("powerpc/pseries/iommu: Don't use dma_iommu_ops on secure guests") disabled dma_iommu_ops path, for secure VMs. The rationale for disabling the dma_iommu_ops path, was to use the dma_direct path, since it had inbuilt support for bounce-buffering through SWIOTLB. However dma_iommu_ops is functionally much richer. Depending on the capabilities of the platform, it can handle direct DMA; with or without bounce buffering, and it can handle indirect DMA. Hence its better to leverage the richer functionality supported by dma_iommu_ops. Renable dma_iommu_ops path for pseries Secure VMs. Signed-off-by: Ram Pai <linuxram@us.ibm.com> --- arch/powerpc/platforms/pseries/iommu.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-)