From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anshuman Khandual Subject: [RFC 4/4] virtio: Add platform specific DMA API translation for virito devices Date: Fri, 20 Jul 2018 09:29:41 +0530 Message-ID: <20180720035941.6844-5-khandual__31227.4546981373$1532059344$gmane$org@linux.vnet.ibm.com> References: <20180720035941.6844-1-khandual@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180720035941.6844-1-khandual@linux.vnet.ibm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Cc: robh@kernel.org, srikar@linux.vnet.ibm.com, mst@redhat.com, benh@kernel.crashing.org, linuxram@us.ibm.com, hch@infradead.org, paulus@samba.org, mpe@ellerman.id.au, joe@perches.com, khandual@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, haren@linux.vnet.ibm.com, david@gibson.dropbear.id.au List-Id: virtualization@lists.linuxfoundation.org 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 --- 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 #include #include +#include #include #include #include @@ -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; -- 2.9.3