Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751018Ab2K0FCc (ORCPT ); Tue, 27 Nov 2012 00:02:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:62595 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750771Ab2K0FCb (ORCPT ); Tue, 27 Nov 2012 00:02:31 -0500 Message-ID: <1353990588.1809.148.camel@bling.home> Subject: Re: [PATCH 1/2] vfio powerpc: implemented IOMMU driver for VFIO From: Alex Williamson To: Alexey Kardashevskiy Cc: Benjamin Herrenschmidt , Paul Mackerras , David Gibson , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Date: Mon, 26 Nov 2012 21:29:48 -0700 In-Reply-To: <50B43C36.60707@ozlabs.ru> References: <1353435584.2234.87.camel@bling.home> <1353661396-14374-1-git-send-email-aik@ozlabs.ru> <1353661396-14374-2-git-send-email-aik@ozlabs.ru> <1353954038.1809.114.camel@bling.home> <50B43C36.60707@ozlabs.ru> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10459 Lines: 301 On Tue, 2012-11-27 at 15:06 +1100, Alexey Kardashevskiy wrote: > On 27/11/12 05:20, Alex Williamson wrote: > > On Fri, 2012-11-23 at 20:03 +1100, Alexey Kardashevskiy wrote: > >> VFIO implements platform independent stuff such as > >> a PCI driver, BAR access (via read/write on a file descriptor > >> or direct mapping when possible) and IRQ signaling. > >> > >> The platform dependent part includes IOMMU initialization > >> and handling. This patch implements an IOMMU driver for VFIO > >> which does mapping/unmapping pages for the guest IO and > >> provides information about DMA window (required by a POWERPC > >> guest). > >> > >> The counterpart in QEMU is required to support this functionality. > >> > >> Cc: David Gibson > >> Signed-off-by: Alexey Kardashevskiy > >> --- > >> drivers/vfio/Kconfig | 6 + > >> drivers/vfio/Makefile | 1 + > >> drivers/vfio/vfio_iommu_spapr_tce.c | 247 +++++++++++++++++++++++++++++++++++ > >> include/linux/vfio.h | 20 +++ > >> 4 files changed, 274 insertions(+) > >> create mode 100644 drivers/vfio/vfio_iommu_spapr_tce.c > >> > >> diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig > >> index 7cd5dec..b464687 100644 > >> --- a/drivers/vfio/Kconfig > >> +++ b/drivers/vfio/Kconfig > >> @@ -3,10 +3,16 @@ config VFIO_IOMMU_TYPE1 > >> depends on VFIO > >> default n > >> > >> +config VFIO_IOMMU_SPAPR_TCE > >> + tristate > >> + depends on VFIO && SPAPR_TCE_IOMMU > >> + default n > >> + > >> menuconfig VFIO > >> tristate "VFIO Non-Privileged userspace driver framework" > >> depends on IOMMU_API > >> select VFIO_IOMMU_TYPE1 if X86 > >> + select VFIO_IOMMU_SPAPR_TCE if PPC_POWERNV > >> help > >> VFIO provides a framework for secure userspace device drivers. > >> See Documentation/vfio.txt for more details. > >> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile > >> index 2398d4a..72bfabc 100644 > >> --- a/drivers/vfio/Makefile > >> +++ b/drivers/vfio/Makefile > >> @@ -1,3 +1,4 @@ > >> obj-$(CONFIG_VFIO) += vfio.o > >> obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o > >> +obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o > >> obj-$(CONFIG_VFIO_PCI) += pci/ > >> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c > >> new file mode 100644 > >> index 0000000..46a6298 > >> --- /dev/null > >> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c > >> @@ -0,0 +1,247 @@ > >> +/* > >> + * VFIO: IOMMU DMA mapping support for TCE on POWER > >> + * > >> + * Copyright (C) 2012 IBM Corp. All rights reserved. > >> + * Author: Alexey Kardashevskiy > >> + * > >> + * This program is free software; you can redistribute it and/or modify > >> + * it under the terms of the GNU General Public License version 2 as > >> + * published by the Free Software Foundation. > >> + * > >> + * Derived from original vfio_iommu_type1.c: > >> + * Copyright (C) 2012 Red Hat, Inc. All rights reserved. > >> + * Author: Alex Williamson > >> + */ > >> + > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> +#include > >> + > >> +#define DRIVER_VERSION "0.1" > >> +#define DRIVER_AUTHOR "aik@ozlabs.ru" > >> +#define DRIVER_DESC "VFIO IOMMU SPAPR TCE" > >> + > >> +static void tce_iommu_detach_group(void *iommu_data, > >> + struct iommu_group *iommu_group); > >> + > >> +/* > >> + * VFIO IOMMU fd for SPAPR_TCE IOMMU implementation > >> + */ > >> + > >> +/* > >> + * The container descriptor supports only a single group per container. > >> + * Required by the API as the container is not supplied with the IOMMU group > >> + * at the moment of initialization. > >> + */ > >> +struct tce_container { > >> + struct mutex lock; > >> + struct iommu_table *tbl; > >> +}; > >> + > >> +static void *tce_iommu_open(unsigned long arg) > >> +{ > >> + struct tce_container *container; > >> + > >> + if (arg != VFIO_SPAPR_TCE_IOMMU) { > >> + printk(KERN_ERR "tce_vfio: Wrong IOMMU type\n"); > >> + return ERR_PTR(-EINVAL); > >> + } > >> + > >> + container = kzalloc(sizeof(*container), GFP_KERNEL); > >> + if (!container) > >> + return ERR_PTR(-ENOMEM); > >> + > >> + mutex_init(&container->lock); > >> + > >> + return container; > >> +} > >> + > >> +static void tce_iommu_release(void *iommu_data) > >> +{ > >> + struct tce_container *container = iommu_data; > >> + > >> + WARN_ON(container->tbl && !container->tbl->it_group); > > > > I think your patch ordering is backwards here. it_group isn't added > > until 2/2. I'd really like to see the arch/powerpc code approved and > > merged by the powerpc maintainer before we add the code that makes use > > of it into vfio. Otherwise we just get lots of churn if interfaces > > change or they disapprove of it altogether. > > > Makes sense, thanks. > > > >> + if (container->tbl && container->tbl->it_group) > >> + tce_iommu_detach_group(iommu_data, container->tbl->it_group); > >> + > >> + mutex_destroy(&container->lock); > >> + > >> + kfree(container); > >> +} > >> + > >> +static long tce_iommu_ioctl(void *iommu_data, > >> + unsigned int cmd, unsigned long arg) > >> +{ > >> + struct tce_container *container = iommu_data; > >> + unsigned long minsz; > >> + > >> + switch (cmd) { > >> + case VFIO_CHECK_EXTENSION: { > >> + return (arg == VFIO_SPAPR_TCE_IOMMU) ? 1 : 0; > >> + } > >> + case VFIO_IOMMU_SPAPR_TCE_GET_INFO: { > >> + struct vfio_iommu_spapr_tce_info info; > >> + struct iommu_table *tbl = container->tbl; > >> + > >> + if (WARN_ON(!tbl)) > >> + return -ENXIO; > >> + > >> + minsz = offsetofend(struct vfio_iommu_spapr_tce_info, > >> + dma64_window_size); > >> + > >> + if (copy_from_user(&info, (void __user *)arg, minsz)) > >> + return -EFAULT; > >> + > >> + if (info.argsz < minsz) > >> + return -EINVAL; > >> + > >> + info.dma32_window_start = tbl->it_offset << IOMMU_PAGE_SHIFT; > >> + info.dma32_window_size = tbl->it_size << IOMMU_PAGE_SHIFT; > >> + info.dma64_window_start = 0; > >> + info.dma64_window_size = 0; > >> + info.flags = 0; > >> + > >> + if (copy_to_user((void __user *)arg, &info, minsz)) > >> + return -EFAULT; > >> + > >> + return 0; > >> + } > >> + case VFIO_IOMMU_MAP_DMA: { > >> + vfio_iommu_spapr_tce_dma_map param; > >> + struct iommu_table *tbl = container->tbl; > >> + enum dma_data_direction direction = DMA_NONE; > >> + > >> + if (WARN_ON(!tbl)) > >> + return -ENXIO; > >> + > >> + minsz = offsetofend(vfio_iommu_spapr_tce_dma_map, size); > >> + > >> + if (copy_from_user(¶m, (void __user *)arg, minsz)) > >> + return -EFAULT; > >> + > >> + if (param.argsz < minsz) > >> + return -EINVAL; > >> + > >> + if ((param.flags & VFIO_DMA_MAP_FLAG_READ) && > >> + (param.flags & VFIO_DMA_MAP_FLAG_WRITE)) { > >> + direction = DMA_BIDIRECTIONAL; > >> + } else if (param.flags & VFIO_DMA_MAP_FLAG_READ) { > >> + direction = DMA_TO_DEVICE; > >> + } else if (param.flags & VFIO_DMA_MAP_FLAG_WRITE) { > >> + direction = DMA_FROM_DEVICE; > >> + } > >> + > >> + param.size += param.iova & ~IOMMU_PAGE_MASK; > >> + param.size = _ALIGN_UP(param.size, IOMMU_PAGE_SIZE); > > > > On x86 we force iova, vaddr, and size to all be aligned to the smallest > > page granularity of the iommu and return -EINVAL if it doesn't fit. > > What does it imply to the user if they're always aligned to work here? > > Won't this interface happily map overlapping entries with no indication > > to the user that the previous mapping is no longer valid? > > Maybe another reason why a combined unmap/map makes me nervous, we have > > to assume the user knows what they're doing. > > > I got used to guests which do know what they are doing so I am pretty calm :) > but ok, I'll move alignment to the QEMU, it makes sense. > > > >> + > >> + return iommu_put_tces(tbl, param.iova >> IOMMU_PAGE_SHIFT, > >> + param.vaddr & IOMMU_PAGE_MASK, direction, > >> + param.size >> IOMMU_PAGE_SHIFT); > >> + } > >> + case VFIO_IOMMU_UNMAP_DMA: { > >> + vfio_iommu_spapr_tce_dma_unmap param; > >> + struct iommu_table *tbl = container->tbl; > >> + > >> + if (WARN_ON(!tbl)) > >> + return -ENXIO; > >> + > >> + minsz = offsetofend(vfio_iommu_spapr_tce_dma_unmap, size); > >> + > >> + if (copy_from_user(¶m, (void __user *)arg, minsz)) > >> + return -EFAULT; > >> + > >> + if (param.argsz < minsz) > >> + return -EINVAL; > >> + > >> + param.size += param.iova & ~IOMMU_PAGE_MASK; > >> + param.size = _ALIGN_UP(param.size, IOMMU_PAGE_SIZE); > >> + > >> + return iommu_put_tces(tbl, param.iova >> IOMMU_PAGE_SHIFT, > >> + 0, DMA_NONE, param.size >> IOMMU_PAGE_SHIFT); > >> + } > >> + default: > >> + printk(KERN_WARNING "tce_vfio: unexpected cmd %x\n", cmd); > > > > pr_warn > > > >> + } > >> + > >> + return -ENOTTY; > >> +} > >> + > >> +static int tce_iommu_attach_group(void *iommu_data, > >> + struct iommu_group *iommu_group) > >> +{ > >> + struct tce_container *container = iommu_data; > >> + struct iommu_table *tbl = iommu_group_get_iommudata(iommu_group); > >> + > >> + BUG_ON(!tbl); > >> + mutex_lock(&container->lock); > >> + pr_debug("tce_vfio: Attaching group #%u to iommu %p\n", > >> + iommu_group_id(iommu_group), iommu_group); > >> + if (container->tbl) { > >> + printk(KERN_WARNING "tce_vfio: Only one group per IOMMU container is allowed, existing id=%d, attaching id=%d\n", > > > > pr_warn > > > >> + iommu_group_id(container->tbl->it_group), > >> + iommu_group_id(iommu_group)); > >> + mutex_unlock(&container->lock); > >> + return -EBUSY; > >> + } > >> + > >> + container->tbl = tbl; > > > > Would it be too much paranoia to clear all the tce here as you do below > > on detach? > > Guess so. I do unmap on detach() and the guest calls put_tce(0) (i.e. > unmaps) the whole DMA window at the boot time. But that's just one user of this interface, we can't assume they'll all be so agreeable. If any tces were enabled here, a malicious user would have a window to host memory, right? Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/