From: Yang Zhang <yang.zhang.wz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Jason Wang <jasowang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH RFC] vhost: basic device IOTLB support
Date: Mon, 4 Jan 2016 09:39:37 +0800 [thread overview]
Message-ID: <5689CD59.6030900@gmail.com> (raw)
In-Reply-To: <1451546025-15955-1-git-send-email-jasowang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
On 2015/12/31 15:13, Jason Wang wrote:
> This patch tries to implement an device IOTLB for vhost. This could be
> used with for co-operation with userspace(qemu) implementation of
> iommu for a secure DMA environment in guest.
>
> The idea is simple. When vhost meets an IOTLB miss, it will request
> the assistance of userspace to do the translation, this is done
> through:
>
> - Fill the translation request in a preset userspace address (This
> address is set through ioctl VHOST_SET_IOTLB_REQUEST_ENTRY).
> - Notify userspace through eventfd (This eventfd was set through ioctl
> VHOST_SET_IOTLB_FD).
>
> When userspace finishes the translation, it will update the vhost
> IOTLB through VHOST_UPDATE_IOTLB ioctl. Userspace is also in charge of
> snooping the IOTLB invalidation of IOMMU IOTLB and use
> VHOST_UPDATE_IOTLB to invalidate the possible entry in vhost.
Is there any performance data shows the difference with IOTLB
supporting? I doubt we may see performance decrease since the flush code
path is longer than before.
--
best regards
yang
WARNING: multiple messages have this Message-ID (diff)
From: Yang Zhang <yang.zhang.wz@gmail.com>
To: Jason Wang <jasowang@redhat.com>,
mst@redhat.com, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-api@vger.kernel.org
Subject: Re: [PATCH RFC] vhost: basic device IOTLB support
Date: Mon, 4 Jan 2016 09:39:37 +0800 [thread overview]
Message-ID: <5689CD59.6030900@gmail.com> (raw)
In-Reply-To: <1451546025-15955-1-git-send-email-jasowang@redhat.com>
On 2015/12/31 15:13, Jason Wang wrote:
> This patch tries to implement an device IOTLB for vhost. This could be
> used with for co-operation with userspace(qemu) implementation of
> iommu for a secure DMA environment in guest.
>
> The idea is simple. When vhost meets an IOTLB miss, it will request
> the assistance of userspace to do the translation, this is done
> through:
>
> - Fill the translation request in a preset userspace address (This
> address is set through ioctl VHOST_SET_IOTLB_REQUEST_ENTRY).
> - Notify userspace through eventfd (This eventfd was set through ioctl
> VHOST_SET_IOTLB_FD).
>
> When userspace finishes the translation, it will update the vhost
> IOTLB through VHOST_UPDATE_IOTLB ioctl. Userspace is also in charge of
> snooping the IOTLB invalidation of IOMMU IOTLB and use
> VHOST_UPDATE_IOTLB to invalidate the possible entry in vhost.
Is there any performance data shows the difference with IOTLB
supporting? I doubt we may see performance decrease since the flush code
path is longer than before.
--
best regards
yang
next prev parent reply other threads:[~2016-01-04 1:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-31 7:13 [PATCH RFC] vhost: basic device IOTLB support Jason Wang
2015-12-31 7:13 ` Jason Wang
2015-12-31 11:17 ` Michael S. Tsirkin
2016-01-04 6:08 ` Jason Wang
2016-01-04 6:08 ` Jason Wang
2015-12-31 11:17 ` Michael S. Tsirkin
[not found] ` <1451546025-15955-1-git-send-email-jasowang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-01-04 1:39 ` Yang Zhang [this message]
2016-01-04 1:39 ` Yang Zhang
2016-01-04 6:22 ` Jason Wang
2016-01-05 3:18 ` Yang Zhang
[not found] ` <568B35F8.7080302-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-01-06 4:57 ` Jason Wang
2016-01-06 4:57 ` Jason Wang
2016-01-06 4:57 ` Jason Wang
2016-01-04 1:39 ` Yang Zhang
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