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Date: Fri, 22 Sep 2023 06:46:39 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: virtualization@...ts.linux-foundation.org,
Richard Weinberger <richard@....at>,
Anton Ivanov <anton.ivanov@...bridgegreys.com>,
Johannes Berg <johannes@...solutions.net>,
Jason Wang <jasowang@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Hans de Goede <hdegoede@...hat.com>,
Mark Gross <markgross@...nel.org>,
Vadim Pasternak <vadimp@...dia.com>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Cornelia Huck <cohuck@...hat.com>,
Halil Pasic <pasic@...ux.ibm.com>,
Eric Farman <farman@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
Vincent Whitchurch <vincent.whitchurch@...s.com>,
linux-um@...ts.infradead.org, netdev@...r.kernel.org,
platform-driver-x86@...r.kernel.org,
linux-remoteproc@...r.kernel.org, linux-s390@...r.kernel.org,
kvm@...r.kernel.org, bpf@...r.kernel.org,
kangjie.xu@...ux.alibaba.com
Subject: Re: [PATCH v14 30/42] virtio_pci: introduce helper to get/set queue
reset
On Fri, Sep 22, 2023 at 09:49:18AM +0800, Xuan Zhuo wrote:
> On Thu, 21 Sep 2023 10:02:53 -0400, "Michael S. Tsirkin" <mst@...hat.com> wrote:
> > On Mon, Aug 01, 2022 at 02:38:50PM +0800, Xuan Zhuo wrote:
> > > Introduce new helpers to implement queue reset and get queue reset
> > > status.
> > >
> > > https://github.com/oasis-tcs/virtio-spec/issues/124
> > > https://github.com/oasis-tcs/virtio-spec/issues/139
> > >
> > > Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> > > Acked-by: Jason Wang <jasowang@...hat.com>
> > > ---
> > > drivers/virtio/virtio_pci_modern_dev.c | 39 ++++++++++++++++++++++++++
> > > include/linux/virtio_pci_modern.h | 2 ++
> > > 2 files changed, 41 insertions(+)
> > >
> > > diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> > > index fa2a9445bb18..869cb46bef96 100644
> > > --- a/drivers/virtio/virtio_pci_modern_dev.c
> > > +++ b/drivers/virtio/virtio_pci_modern_dev.c
> > > @@ -3,6 +3,7 @@
> > > #include <linux/virtio_pci_modern.h>
> > > #include <linux/module.h>
> > > #include <linux/pci.h>
> > > +#include <linux/delay.h>
> > >
> > > /*
> > > * vp_modern_map_capability - map a part of virtio pci capability
> > > @@ -474,6 +475,44 @@ void vp_modern_set_status(struct virtio_pci_modern_device *mdev,
> > > }
> > > EXPORT_SYMBOL_GPL(vp_modern_set_status);
> > >
> > > +/*
> > > + * vp_modern_get_queue_reset - get the queue reset status
> > > + * @mdev: the modern virtio-pci device
> > > + * @index: queue index
> > > + */
> > > +int vp_modern_get_queue_reset(struct virtio_pci_modern_device *mdev, u16 index)
> > > +{
> > > + struct virtio_pci_modern_common_cfg __iomem *cfg;
> > > +
> > > + cfg = (struct virtio_pci_modern_common_cfg __iomem *)mdev->common;
> > > +
> > > + vp_iowrite16(index, &cfg->cfg.queue_select);
> > > + return vp_ioread16(&cfg->queue_reset);
> > > +}
> > > +EXPORT_SYMBOL_GPL(vp_modern_get_queue_reset);
> > > +
> >
> > Actually, this does not validate that the config structure is big
> > enough. So it can access some unrelated memory. Don't know whether
> > that's exploitable e.g. for CoCo but not nice, anyway.
> > Need to validate the size and disable reset if it's too small.
>
>
> static int vp_modern_disable_vq_and_reset(struct virtqueue *vq)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> struct virtio_pci_vq_info *info;
> unsigned long flags;
>
> -> if (!virtio_has_feature(vq->vdev, VIRTIO_F_RING_RESET))
> return -ENOENT;
>
> vp_modern_set_queue_reset(mdev, vq->index);
>
>
> I checked VIRTIO_F_RING_RESET before call this.
Yes but the point is that virtio is used with untrusted devices
(e.g. for SEV/TDX), so you can't really assume config structures
are in sync with feature bits.
> Do you mean, we should put the check to this function.
>
>
> Thanks.
>
>
>
> >
> >
> > > +/*
> > > + * vp_modern_set_queue_reset - reset the queue
> > > + * @mdev: the modern virtio-pci device
> > > + * @index: queue index
> > > + */
> > > +void vp_modern_set_queue_reset(struct virtio_pci_modern_device *mdev, u16 index)
> > > +{
> > > + struct virtio_pci_modern_common_cfg __iomem *cfg;
> > > +
> > > + cfg = (struct virtio_pci_modern_common_cfg __iomem *)mdev->common;
> > > +
> > > + vp_iowrite16(index, &cfg->cfg.queue_select);
> > > + vp_iowrite16(1, &cfg->queue_reset);
> > > +
> > > + while (vp_ioread16(&cfg->queue_reset))
> > > + msleep(1);
> > > +
> > > + while (vp_ioread16(&cfg->cfg.queue_enable))
> > > + msleep(1);
> > > +}
> > > +EXPORT_SYMBOL_GPL(vp_modern_set_queue_reset);
> > > +
> > > /*
> > > * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
> > > * @mdev: the modern virtio-pci device
> > > diff --git a/include/linux/virtio_pci_modern.h b/include/linux/virtio_pci_modern.h
> > > index 05123b9a606f..c4eeb79b0139 100644
> > > --- a/include/linux/virtio_pci_modern.h
> > > +++ b/include/linux/virtio_pci_modern.h
> > > @@ -113,4 +113,6 @@ void __iomem * vp_modern_map_vq_notify(struct virtio_pci_modern_device *mdev,
> > > u16 index, resource_size_t *pa);
> > > int vp_modern_probe(struct virtio_pci_modern_device *mdev);
> > > void vp_modern_remove(struct virtio_pci_modern_device *mdev);
> > > +int vp_modern_get_queue_reset(struct virtio_pci_modern_device *mdev, u16 index);
> > > +void vp_modern_set_queue_reset(struct virtio_pci_modern_device *mdev, u16 index);
> > > #endif
> > > --
> > > 2.31.0
> >
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