From: "Liu, Yi L" <yi.l.liu@intel.com>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Sun, Yi Y" <yi.y.sun@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"Tian, Jun J" <jun.j.tian@intel.com>,
"Wu, Hao" <hao.wu@intel.com>
Subject: RE: [PATCH v1 1/8] vfio: Add VFIO_IOMMU_PASID_REQUEST(alloc/free)
Date: Fri, 3 Apr 2020 11:56:09 +0000 [thread overview]
Message-ID: <A2975661238FB949B60364EF0F2C25743A2209E3@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <20200402135240.GE1176452@myrica>
Hi Jean,
> From: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Sent: Thursday, April 2, 2020 9:53 PM
> To: Liu, Yi L <yi.l.liu@intel.com>
> Subject: Re: [PATCH v1 1/8] vfio: Add VFIO_IOMMU_PASID_REQUEST(alloc/free)
>
> Hi Yi,
>
> On Sun, Mar 22, 2020 at 05:31:58AM -0700, Liu, Yi L wrote:
> > From: Liu Yi L <yi.l.liu@intel.com>
> >
> > For a long time, devices have only one DMA address space from platform
> > IOMMU's point of view. This is true for both bare metal and directed-
> > access in virtualization environment. Reason is the source ID of DMA in
> > PCIe are BDF (bus/dev/fnc ID), which results in only device granularity
> > DMA isolation. However, this is changing with the latest advancement in
> > I/O technology area. More and more platform vendors are utilizing the PCIe
> > PASID TLP prefix in DMA requests, thus to give devices with multiple DMA
> > address spaces as identified by their individual PASIDs. For example,
> > Shared Virtual Addressing (SVA, a.k.a Shared Virtual Memory) is able to
> > let device access multiple process virtual address space by binding the
> > virtual address space with a PASID. Wherein the PASID is allocated in
> > software and programmed to device per device specific manner. Devices
> > which support PASID capability are called PASID-capable devices. If such
> > devices are passed through to VMs, guest software are also able to bind
> > guest process virtual address space on such devices. Therefore, the guest
> > software could reuse the bare metal software programming model, which
> > means guest software will also allocate PASID and program it to device
> > directly. This is a dangerous situation since it has potential PASID
> > conflicts and unauthorized address space access.
>
> It's worth noting that this applies to Intel VT-d with scalable mode, not
> IOMMUs that use one PASID space per VM
Oh yes. will add it.
>
> > It would be safer to
> > let host intercept in the guest software's PASID allocation. Thus PASID
> > are managed system-wide.
> >
> > This patch adds VFIO_IOMMU_PASID_REQUEST ioctl which aims to passdown
> > PASID allocation/free request from the virtual IOMMU. Additionally, such
> > requests are intended to be invoked by QEMU or other applications which
> > are running in userspace, it is necessary to have a mechanism to prevent
> > single application from abusing available PASIDs in system. With such
> > consideration, this patch tracks the VFIO PASID allocation per-VM. There
> > was a discussion to make quota to be per assigned devices. e.g. if a VM
> > has many assigned devices, then it should have more quota. However, it
> > is not sure how many PASIDs an assigned devices will use. e.g. it is
> > possible that a VM with multiples assigned devices but requests less
> > PASIDs. Therefore per-VM quota would be better.
> >
> > This patch uses struct mm pointer as a per-VM token. We also considered
> > using task structure pointer and vfio_iommu structure pointer. However,
> > task structure is per-thread, which means it cannot achieve per-VM PASID
> > alloc tracking purpose. While for vfio_iommu structure, it is visible
> > only within vfio. Therefore, structure mm pointer is selected. This patch
> > adds a structure vfio_mm. A vfio_mm is created when the first vfio
> > container is opened by a VM. On the reverse order, vfio_mm is free when
> > the last vfio container is released. Each VM is assigned with a PASID
> > quota, so that it is not able to request PASID beyond its quota. This
> > patch adds a default quota of 1000. This quota could be tuned by
> > administrator. Making PASID quota tunable will be added in another patch
> > in this series.
> >
> > Previous discussions:
> > https://patchwork.kernel.org/patch/11209429/
> >
> > Cc: Kevin Tian <kevin.tian@intel.com>
> > CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Cc: Alex Williamson <alex.williamson@redhat.com>
> > Cc: Eric Auger <eric.auger@redhat.com>
> > Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > ---
> > drivers/vfio/vfio.c | 130 ++++++++++++++++++++++++++++++++++++++++
> > drivers/vfio/vfio_iommu_type1.c | 104 ++++++++++++++++++++++++++++++++
> > include/linux/vfio.h | 20 +++++++
> > include/uapi/linux/vfio.h | 41 +++++++++++++
> > 4 files changed, 295 insertions(+)
> >
> > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> > index c848262..d13b483 100644
> > --- a/drivers/vfio/vfio.c
> > +++ b/drivers/vfio/vfio.c
> > @@ -32,6 +32,7 @@
> > #include <linux/vfio.h>
> > #include <linux/wait.h>
> > #include <linux/sched/signal.h>
> > +#include <linux/sched/mm.h>
> >
> > #define DRIVER_VERSION "0.3"
> > #define DRIVER_AUTHOR "Alex Williamson <alex.williamson@redhat.com>"
> > @@ -46,6 +47,8 @@ static struct vfio {
> > struct mutex group_lock;
> > struct cdev group_cdev;
> > dev_t group_devt;
> > + struct list_head vfio_mm_list;
> > + struct mutex vfio_mm_lock;
> > wait_queue_head_t release_q;
> > } vfio;
> >
> > @@ -2129,6 +2132,131 @@ int vfio_unregister_notifier(struct device *dev, enum
> vfio_notify_type type,
> > EXPORT_SYMBOL(vfio_unregister_notifier);
> >
> > /**
> > + * VFIO_MM objects - create, release, get, put, search
> > + * Caller of the function should have held vfio.vfio_mm_lock.
> > + */
> > +static struct vfio_mm *vfio_create_mm(struct mm_struct *mm)
> > +{
> > + struct vfio_mm *vmm;
> > + struct vfio_mm_token *token;
> > + int ret = 0;
> > +
> > + vmm = kzalloc(sizeof(*vmm), GFP_KERNEL);
> > + if (!vmm)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + /* Per mm IOASID set used for quota control and group operations */
> > + ret = ioasid_alloc_set((struct ioasid_set *) mm,
>
> Hmm, either we need to change the token of ioasid_alloc_set() to "void *",
> or pass an actual ioasid_set struct, but this cast doesn't look good :)
>
> As I commented on the IOASID series, I think we could embed a struct
> ioasid_set into vfio_mm, pass that struct to all other ioasid_* functions,
> and get rid of ioasid_sid.
I think change to "void *" is better as we needs the token to ensure all
threads within a single VM share the same ioasid_set.
> > + VFIO_DEFAULT_PASID_QUOTA, &vmm->ioasid_sid);
> > + if (ret) {
> > + kfree(vmm);
> > + return ERR_PTR(ret);
> > + }
> > +
> > + kref_init(&vmm->kref);
> > + token = &vmm->token;
> > + token->val = mm;
>
> Why the intermediate token struct? Could we just store the mm_struct
> pointer within vfio_mm?
Hmm, here we only want to use the pointer as a token, instead of using
the structure behind the pointer. If store the mm_struct directly, may
leave a space to further use its content, this is not good.
Regards,
Yi Liu
_______________________________________________
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iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-04-03 11:56 UTC|newest]
Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-22 12:31 [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs Liu, Yi L
2020-03-22 12:31 ` [PATCH v1 1/8] vfio: Add VFIO_IOMMU_PASID_REQUEST(alloc/free) Liu, Yi L
2020-03-22 16:21 ` kbuild test robot
2020-03-30 8:32 ` Tian, Kevin
2020-03-30 14:36 ` Liu, Yi L
2020-03-31 5:40 ` Tian, Kevin
2020-03-31 13:22 ` Liu, Yi L
2020-04-01 5:43 ` Tian, Kevin
2020-04-01 5:48 ` Liu, Yi L
2020-03-31 7:53 ` Christoph Hellwig
2020-03-31 8:17 ` Liu, Yi L
2020-03-31 8:32 ` Liu, Yi L
2020-03-31 8:36 ` Liu, Yi L
2020-03-31 9:15 ` Christoph Hellwig
2020-04-02 13:52 ` Jean-Philippe Brucker
2020-04-03 11:56 ` Liu, Yi L [this message]
2020-04-03 12:39 ` Jean-Philippe Brucker
2020-04-03 12:44 ` Liu, Yi L
2020-04-02 17:50 ` Alex Williamson
2020-04-03 5:58 ` Tian, Kevin
2020-04-03 15:14 ` Alex Williamson
2020-04-07 4:42 ` Tian, Kevin
2020-04-07 15:14 ` Alex Williamson
2020-04-03 13:12 ` Liu, Yi L
2020-04-03 17:50 ` Alex Williamson
2020-04-07 4:52 ` Tian, Kevin
2020-04-08 0:52 ` Liu, Yi L
2020-03-22 12:31 ` [PATCH v1 2/8] vfio/type1: Add vfio_iommu_type1 parameter for quota tuning Liu, Yi L
2020-03-22 17:20 ` kbuild test robot
2020-03-30 8:40 ` Tian, Kevin
2020-03-30 8:52 ` Liu, Yi L
2020-03-30 9:19 ` Tian, Kevin
2020-03-30 9:26 ` Liu, Yi L
2020-03-30 11:44 ` Tian, Kevin
2020-04-02 17:58 ` Alex Williamson
2020-04-03 8:15 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 3/8] vfio/type1: Report PASID alloc/free support to userspace Liu, Yi L
2020-03-30 9:43 ` Tian, Kevin
2020-04-01 7:46 ` Liu, Yi L
2020-04-01 9:41 ` Auger Eric
2020-04-01 13:13 ` Liu, Yi L
2020-04-02 18:01 ` Alex Williamson
2020-04-03 8:17 ` Liu, Yi L
2020-04-03 17:28 ` Alex Williamson
2020-04-04 11:36 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 4/8] vfio: Check nesting iommu uAPI version Liu, Yi L
2020-03-22 18:30 ` kbuild test robot
2020-03-22 12:32 ` [PATCH v1 5/8] vfio/type1: Report 1st-level/stage-1 format to userspace Liu, Yi L
2020-03-22 16:44 ` kbuild test robot
2020-03-30 11:48 ` Tian, Kevin
2020-04-01 7:38 ` Liu, Yi L
2020-04-01 7:56 ` Tian, Kevin
2020-04-01 8:06 ` Liu, Yi L
2020-04-01 8:08 ` Tian, Kevin
2020-04-01 8:09 ` Liu, Yi L
2020-04-01 8:51 ` Auger Eric
2020-04-01 12:51 ` Liu, Yi L
2020-04-01 13:01 ` Auger Eric
2020-04-03 8:23 ` Jean-Philippe Brucker
2020-04-07 9:43 ` Liu, Yi L
2020-04-08 1:02 ` Liu, Yi L
2020-04-08 10:27 ` Auger Eric
2020-04-09 8:14 ` Jean-Philippe Brucker
2020-04-09 9:01 ` Auger Eric
2020-04-09 12:47 ` Liu, Yi L
2020-04-10 3:28 ` Auger Eric
2020-04-10 3:48 ` Liu, Yi L
2020-04-10 12:30 ` Liu, Yi L
2020-04-02 19:20 ` Alex Williamson
2020-04-03 11:59 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 6/8] vfio/type1: Bind guest page tables to host Liu, Yi L
2020-03-22 18:10 ` kbuild test robot
2020-03-30 12:46 ` Tian, Kevin
2020-04-01 9:13 ` Liu, Yi L
2020-04-02 2:12 ` Tian, Kevin
2020-04-02 8:05 ` Liu, Yi L
2020-04-03 8:34 ` Jean-Philippe Brucker
2020-04-07 10:33 ` Liu, Yi L
2020-04-09 8:28 ` Jean-Philippe Brucker
2020-04-09 9:15 ` Liu, Yi L
2020-04-09 9:38 ` Jean-Philippe Brucker
2020-04-02 19:57 ` Alex Williamson
2020-04-03 13:30 ` Liu, Yi L
2020-04-03 18:11 ` Alex Williamson
2020-04-04 10:28 ` Liu, Yi L
2020-04-11 5:52 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE Liu, Yi L
2020-03-30 12:58 ` Tian, Kevin
2020-04-01 7:49 ` Liu, Yi L
2020-03-31 7:56 ` Christoph Hellwig
2020-03-31 10:48 ` Liu, Yi L
2020-04-02 20:24 ` Alex Williamson
2020-04-03 6:39 ` Tian, Kevin
2020-04-03 15:31 ` Jacob Pan
2020-04-03 15:34 ` Alex Williamson
2020-04-08 2:28 ` Liu, Yi L
2020-04-16 10:40 ` Liu, Yi L
2020-04-16 12:09 ` Tian, Kevin
2020-04-16 12:42 ` Auger Eric
2020-04-16 13:28 ` Tian, Kevin
2020-04-16 15:12 ` Auger Eric
2020-04-16 14:40 ` Alex Williamson
2020-04-16 14:48 ` Alex Williamson
2020-04-17 6:03 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 8/8] vfio/type1: Add vSVA support for IOMMU-backed mdevs Liu, Yi L
2020-03-30 13:18 ` Tian, Kevin
2020-04-01 7:51 ` Liu, Yi L
2020-04-02 20:33 ` Alex Williamson
2020-04-03 13:39 ` Liu, Yi L
2020-03-26 12:56 ` [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs Liu, Yi L
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