Message ID | 20180720035941.6844-5-khandual@linux.vnet.ibm.com (mailing list archive) |
---|---|
State | RFC |
Headers | show |
Series | Virtio uses DMA API for all devices | expand |
Context | Check | Description |
---|---|---|
snowpatch_ozlabs/apply_patch | success | next/apply_patch Successfully applied |
snowpatch_ozlabs/checkpatch | success | Test checkpatch on branch next |
snowpatch_ozlabs/build-ppc64le | warning | Test build-ppc64le on branch next |
snowpatch_ozlabs/build-ppc64be | warning | Test build-ppc64be on branch next |
snowpatch_ozlabs/build-ppc64e | success | Test build-ppc64e on branch next |
snowpatch_ozlabs/build-ppc32 | success | Test build-ppc32 on branch next |
On Fri, Jul 20, 2018 at 09:29:41AM +0530, Anshuman Khandual wrote: >Subject: Re: [RFC 4/4] virtio: Add platform specific DMA API translation for > virito devices s/virito/virtio/ > This adds a hook which a platform can define in order to allow it to > override virtio device's DMA OPS irrespective of whether it has the > flag VIRTIO_F_IOMMU_PLATFORM set or not. We want to use this to do > bounce-buffering of data on the new secure pSeries platform, currently > under development, where a KVM host cannot access all of the memory > space of a secure KVM guest. The host can only access the pages which > the guest has explicitly requested to be shared with the host, thus > the virtio implementation in the guest has to copy data to and from > shared pages. > > With this hook, the platform code in the secure guest can force the > use of swiotlb for virtio buffers, with a back-end for swiotlb which > will use a pool of pre-allocated shared pages. Thus all data being > sent or received by virtio devices will be copied through pages which > the host has access to. > > Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/dma-mapping.h | 6 ++++++ > arch/powerpc/platforms/pseries/iommu.c | 6 ++++++ > drivers/virtio/virtio.c | 7 +++++++ > 3 files changed, 19 insertions(+) > > diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h > index 8fa3945..bc5a9d3 100644 > --- a/arch/powerpc/include/asm/dma-mapping.h > +++ b/arch/powerpc/include/asm/dma-mapping.h > @@ -116,3 +116,9 @@ extern u64 __dma_get_required_mask(struct device *dev); > > #endif /* __KERNEL__ */ > #endif /* _ASM_DMA_MAPPING_H */ > + > +#define platform_override_dma_ops platform_override_dma_ops > + > +struct virtio_device; > + > +extern void platform_override_dma_ops(struct virtio_device *vdev); > diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c > index 06f0296..5773bc7 100644 > --- a/arch/powerpc/platforms/pseries/iommu.c > +++ b/arch/powerpc/platforms/pseries/iommu.c > @@ -38,6 +38,7 @@ > #include <linux/of.h> > #include <linux/iommu.h> > #include <linux/rculist.h> > +#include <linux/virtio.h> > #include <asm/io.h> > #include <asm/prom.h> > #include <asm/rtas.h> > @@ -1396,3 +1397,8 @@ static int __init disable_multitce(char *str) > __setup("multitce=", disable_multitce); > > machine_subsys_initcall_sync(pseries, tce_iommu_bus_notifier_init); > + > +void platform_override_dma_ops(struct virtio_device *vdev) > +{ > + /* Override vdev->parent.dma_ops if required */ > +} > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index 6b13987..432c332 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -168,6 +168,12 @@ EXPORT_SYMBOL_GPL(virtio_add_status); > > const struct dma_map_ops virtio_direct_dma_ops; > > +#ifndef platform_override_dma_ops > +static inline void platform_override_dma_ops(struct virtio_device *vdev) > +{ > +} > +#endif > + > int virtio_finalize_features(struct virtio_device *dev) > { > int ret = dev->config->finalize_features(dev); > @@ -179,6 +185,7 @@ int virtio_finalize_features(struct virtio_device *dev) > if (virtio_has_iommu_quirk(dev)) > set_dma_ops(dev->dev.parent, &virtio_direct_dma_ops); > > + platform_override_dma_ops(dev); Is there a single place where virtio_has_iommu_quirk is called now? If so, we could put this into virtio_has_iommu_quirk then. > if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) > return 0; > > -- > 2.9.3
On 07/20/2018 06:45 PM, Michael S. Tsirkin wrote: > On Fri, Jul 20, 2018 at 09:29:41AM +0530, Anshuman Khandual wrote: >> Subject: Re: [RFC 4/4] virtio: Add platform specific DMA API translation for >> virito devices > > s/virito/virtio/ Oops, will fix it. Thanks for pointing out. > >> This adds a hook which a platform can define in order to allow it to >> override virtio device's DMA OPS irrespective of whether it has the >> flag VIRTIO_F_IOMMU_PLATFORM set or not. We want to use this to do >> bounce-buffering of data on the new secure pSeries platform, currently >> under development, where a KVM host cannot access all of the memory >> space of a secure KVM guest. The host can only access the pages which >> the guest has explicitly requested to be shared with the host, thus >> the virtio implementation in the guest has to copy data to and from >> shared pages. >> >> With this hook, the platform code in the secure guest can force the >> use of swiotlb for virtio buffers, with a back-end for swiotlb which >> will use a pool of pre-allocated shared pages. Thus all data being >> sent or received by virtio devices will be copied through pages which >> the host has access to. >> >> Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> >> --- >> arch/powerpc/include/asm/dma-mapping.h | 6 ++++++ >> arch/powerpc/platforms/pseries/iommu.c | 6 ++++++ >> drivers/virtio/virtio.c | 7 +++++++ >> 3 files changed, 19 insertions(+) >> >> diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h >> index 8fa3945..bc5a9d3 100644 >> --- a/arch/powerpc/include/asm/dma-mapping.h >> +++ b/arch/powerpc/include/asm/dma-mapping.h >> @@ -116,3 +116,9 @@ extern u64 __dma_get_required_mask(struct device *dev); >> >> #endif /* __KERNEL__ */ >> #endif /* _ASM_DMA_MAPPING_H */ >> + >> +#define platform_override_dma_ops platform_override_dma_ops >> + >> +struct virtio_device; >> + >> +extern void platform_override_dma_ops(struct virtio_device *vdev); >> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c >> index 06f0296..5773bc7 100644 >> --- a/arch/powerpc/platforms/pseries/iommu.c >> +++ b/arch/powerpc/platforms/pseries/iommu.c >> @@ -38,6 +38,7 @@ >> #include <linux/of.h> >> #include <linux/iommu.h> >> #include <linux/rculist.h> >> +#include <linux/virtio.h> >> #include <asm/io.h> >> #include <asm/prom.h> >> #include <asm/rtas.h> >> @@ -1396,3 +1397,8 @@ static int __init disable_multitce(char *str) >> __setup("multitce=", disable_multitce); >> >> machine_subsys_initcall_sync(pseries, tce_iommu_bus_notifier_init); >> + >> +void platform_override_dma_ops(struct virtio_device *vdev) >> +{ >> + /* Override vdev->parent.dma_ops if required */ >> +} >> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c >> index 6b13987..432c332 100644 >> --- a/drivers/virtio/virtio.c >> +++ b/drivers/virtio/virtio.c >> @@ -168,6 +168,12 @@ EXPORT_SYMBOL_GPL(virtio_add_status); >> >> const struct dma_map_ops virtio_direct_dma_ops; >> >> +#ifndef platform_override_dma_ops >> +static inline void platform_override_dma_ops(struct virtio_device *vdev) >> +{ >> +} >> +#endif >> + >> int virtio_finalize_features(struct virtio_device *dev) >> { >> int ret = dev->config->finalize_features(dev); >> @@ -179,6 +185,7 @@ int virtio_finalize_features(struct virtio_device *dev) >> if (virtio_has_iommu_quirk(dev)) >> set_dma_ops(dev->dev.parent, &virtio_direct_dma_ops); >> >> + platform_override_dma_ops(dev); > > Is there a single place where virtio_has_iommu_quirk is called now? Not other than this one. But in the proposed implementation of platform_override_dma_ops on powerpc, we will again check on virtio_has_iommu_quirk before overriding it with SWIOTLB. void platform_override_dma_ops(struct virtio_device *vdev) { if (is_ultravisor_platform() && virtio_has_iommu_quirk(vdev)) set_dma_ops(vdev->dev.parent, &swiotlb_dma_ops); } > If so, we could put this into virtio_has_iommu_quirk then. Did you mean platform_override_dma_ops instead ? If so, yes that is possible. Default implementation of platform_override_dma_ops should just check on VIRTIO_F_IOMMU_PLATFORM feature and override with virtio_direct_dma_ops but arch implementation can check on what ever else they would like and override appropriately. Default platform_override_dma_ops will be like this #ifndef platform_override_dma_ops static inline void platform_override_dma_ops(struct virtio_device *vdev) { if(!virtio_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) set_dma_ops(dev->dev.parent, &virtio_direct_dma_ops); } #endif Proposed powerpc implementation will be like this instead void platform_override_dma_ops(struct virtio_device *vdev) { if (virtio_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) return; if (is_ultravisor_platform()) set_dma_ops(vdev->dev.parent, &swiotlb_dma_ops); else set_dma_ops(dev->dev.parent, &virtio_direct_dma_ops); } There is a redundant definition of virtio_has_iommu_quirk in the tools directory (tools/virtio/linux/virtio_config.h) which does not seem to be used any where. I guess that can be removed without problem.
On 07/23/2018 07:46 AM, Anshuman Khandual wrote: > On 07/20/2018 06:45 PM, Michael S. Tsirkin wrote: >> On Fri, Jul 20, 2018 at 09:29:41AM +0530, Anshuman Khandual wrote: >>> Subject: Re: [RFC 4/4] virtio: Add platform specific DMA API translation for >>> virito devices >> >> s/virito/virtio/ > > Oops, will fix it. Thanks for pointing out. > >> >>> This adds a hook which a platform can define in order to allow it to >>> override virtio device's DMA OPS irrespective of whether it has the >>> flag VIRTIO_F_IOMMU_PLATFORM set or not. We want to use this to do >>> bounce-buffering of data on the new secure pSeries platform, currently >>> under development, where a KVM host cannot access all of the memory >>> space of a secure KVM guest. The host can only access the pages which >>> the guest has explicitly requested to be shared with the host, thus >>> the virtio implementation in the guest has to copy data to and from >>> shared pages. >>> >>> With this hook, the platform code in the secure guest can force the >>> use of swiotlb for virtio buffers, with a back-end for swiotlb which >>> will use a pool of pre-allocated shared pages. Thus all data being >>> sent or received by virtio devices will be copied through pages which >>> the host has access to. >>> >>> Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> >>> --- >>> arch/powerpc/include/asm/dma-mapping.h | 6 ++++++ >>> arch/powerpc/platforms/pseries/iommu.c | 6 ++++++ >>> drivers/virtio/virtio.c | 7 +++++++ >>> 3 files changed, 19 insertions(+) >>> >>> diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h >>> index 8fa3945..bc5a9d3 100644 >>> --- a/arch/powerpc/include/asm/dma-mapping.h >>> +++ b/arch/powerpc/include/asm/dma-mapping.h >>> @@ -116,3 +116,9 @@ extern u64 __dma_get_required_mask(struct device *dev); >>> >>> #endif /* __KERNEL__ */ >>> #endif /* _ASM_DMA_MAPPING_H */ >>> + >>> +#define platform_override_dma_ops platform_override_dma_ops >>> + >>> +struct virtio_device; >>> + >>> +extern void platform_override_dma_ops(struct virtio_device *vdev); >>> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c >>> index 06f0296..5773bc7 100644 >>> --- a/arch/powerpc/platforms/pseries/iommu.c >>> +++ b/arch/powerpc/platforms/pseries/iommu.c >>> @@ -38,6 +38,7 @@ >>> #include <linux/of.h> >>> #include <linux/iommu.h> >>> #include <linux/rculist.h> >>> +#include <linux/virtio.h> >>> #include <asm/io.h> >>> #include <asm/prom.h> >>> #include <asm/rtas.h> >>> @@ -1396,3 +1397,8 @@ static int __init disable_multitce(char *str) >>> __setup("multitce=", disable_multitce); >>> >>> machine_subsys_initcall_sync(pseries, tce_iommu_bus_notifier_init); >>> + >>> +void platform_override_dma_ops(struct virtio_device *vdev) >>> +{ >>> + /* Override vdev->parent.dma_ops if required */ >>> +} >>> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c >>> index 6b13987..432c332 100644 >>> --- a/drivers/virtio/virtio.c >>> +++ b/drivers/virtio/virtio.c >>> @@ -168,6 +168,12 @@ EXPORT_SYMBOL_GPL(virtio_add_status); >>> >>> const struct dma_map_ops virtio_direct_dma_ops; >>> >>> +#ifndef platform_override_dma_ops >>> +static inline void platform_override_dma_ops(struct virtio_device *vdev) >>> +{ >>> +} >>> +#endif >>> + >>> int virtio_finalize_features(struct virtio_device *dev) >>> { >>> int ret = dev->config->finalize_features(dev); >>> @@ -179,6 +185,7 @@ int virtio_finalize_features(struct virtio_device *dev) >>> if (virtio_has_iommu_quirk(dev)) >>> set_dma_ops(dev->dev.parent, &virtio_direct_dma_ops); >>> >>> + platform_override_dma_ops(dev); >> >> Is there a single place where virtio_has_iommu_quirk is called now? > > Not other than this one. But in the proposed implementation of > platform_override_dma_ops on powerpc, we will again check on > virtio_has_iommu_quirk before overriding it with SWIOTLB. > > void platform_override_dma_ops(struct virtio_device *vdev) > { > if (is_ultravisor_platform() && virtio_has_iommu_quirk(vdev)) > set_dma_ops(vdev->dev.parent, &swiotlb_dma_ops); > } > >> If so, we could put this into virtio_has_iommu_quirk then. > > Did you mean platform_override_dma_ops instead ? If so, yes that > is possible. Default implementation of platform_override_dma_ops > should just check on VIRTIO_F_IOMMU_PLATFORM feature and override > with virtio_direct_dma_ops but arch implementation can check on > what ever else they would like and override appropriately. > > Default platform_override_dma_ops will be like this > > #ifndef platform_override_dma_ops > static inline void platform_override_dma_ops(struct virtio_device *vdev) > { > if(!virtio_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) > set_dma_ops(dev->dev.parent, &virtio_direct_dma_ops); > } > #endif > > Proposed powerpc implementation will be like this instead > > void platform_override_dma_ops(struct virtio_device *vdev) > { > if (virtio_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) > return; > > if (is_ultravisor_platform()) > set_dma_ops(vdev->dev.parent, &swiotlb_dma_ops); > else > set_dma_ops(dev->dev.parent, &virtio_direct_dma_ops); > > } > > There is a redundant definition of virtio_has_iommu_quirk in the tools > directory (tools/virtio/linux/virtio_config.h) which does not seem to > be used any where. I guess that can be removed without problem. Does this sound okay ? It will merge patch 3 and 4 into a single one. On the other hand it also passes the responsibility of dealing with VIRTIO_F_IOMMU_PLATFORM flag to the architecture callback which might be bit problematic. Keeping VIRTIO_F_IOMMU_PLATFORM handling in virtio core at least makes sure that the device has a working DMA ops to fall back on if the arch hook fails to take care of it somehow.
On Mon, Jul 23, 2018 at 07:46:09AM +0530, Anshuman Khandual wrote: > There is a redundant definition of virtio_has_iommu_quirk in the tools > directory (tools/virtio/linux/virtio_config.h) which does not seem to > be used any where. I guess that can be removed without problem. It's there just to make tools/virtio build. Try make -C tools/virtio/ In fact I see there's a missing definition for dma_rmb/dma_wmb there, I'll post a patch.
diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h index 8fa3945..bc5a9d3 100644 --- a/arch/powerpc/include/asm/dma-mapping.h +++ b/arch/powerpc/include/asm/dma-mapping.h @@ -116,3 +116,9 @@ extern u64 __dma_get_required_mask(struct device *dev); #endif /* __KERNEL__ */ #endif /* _ASM_DMA_MAPPING_H */ + +#define platform_override_dma_ops platform_override_dma_ops + +struct virtio_device; + +extern void platform_override_dma_ops(struct virtio_device *vdev); diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index 06f0296..5773bc7 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -38,6 +38,7 @@ #include <linux/of.h> #include <linux/iommu.h> #include <linux/rculist.h> +#include <linux/virtio.h> #include <asm/io.h> #include <asm/prom.h> #include <asm/rtas.h> @@ -1396,3 +1397,8 @@ static int __init disable_multitce(char *str) __setup("multitce=", disable_multitce); machine_subsys_initcall_sync(pseries, tce_iommu_bus_notifier_init); + +void platform_override_dma_ops(struct virtio_device *vdev) +{ + /* Override vdev->parent.dma_ops if required */ +} diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index 6b13987..432c332 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -168,6 +168,12 @@ EXPORT_SYMBOL_GPL(virtio_add_status); const struct dma_map_ops virtio_direct_dma_ops; +#ifndef platform_override_dma_ops +static inline void platform_override_dma_ops(struct virtio_device *vdev) +{ +} +#endif + int virtio_finalize_features(struct virtio_device *dev) { int ret = dev->config->finalize_features(dev); @@ -179,6 +185,7 @@ int virtio_finalize_features(struct virtio_device *dev) if (virtio_has_iommu_quirk(dev)) set_dma_ops(dev->dev.parent, &virtio_direct_dma_ops); + platform_override_dma_ops(dev); if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) return 0;
This adds a hook which a platform can define in order to allow it to override virtio device's DMA OPS irrespective of whether it has the flag VIRTIO_F_IOMMU_PLATFORM set or not. We want to use this to do bounce-buffering of data on the new secure pSeries platform, currently under development, where a KVM host cannot access all of the memory space of a secure KVM guest. The host can only access the pages which the guest has explicitly requested to be shared with the host, thus the virtio implementation in the guest has to copy data to and from shared pages. With this hook, the platform code in the secure guest can force the use of swiotlb for virtio buffers, with a back-end for swiotlb which will use a pool of pre-allocated shared pages. Thus all data being sent or received by virtio devices will be copied through pages which the host has access to. Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com> --- arch/powerpc/include/asm/dma-mapping.h | 6 ++++++ arch/powerpc/platforms/pseries/iommu.c | 6 ++++++ drivers/virtio/virtio.c | 7 +++++++ 3 files changed, 19 insertions(+)