From: Si-Wei Liu <si-wei.liu@oracle.com>
To: Jason Wang <jasowang@redhat.com>, mst@redhat.com, qemu-devel@nongnu.org
Cc: elic@nvidia.com
Subject: Re: [PATCH 2/2] vhost-vdpa: doorbell mapping support
Date: Thu, 6 May 2021 14:15:07 -0700 [thread overview]
Message-ID: <ac0f3498-f57a-7b4f-24f7-5d8e58912b40@oracle.com> (raw)
In-Reply-To: <cb97a251-ed9e-4417-4aab-527a428c86d0@redhat.com>
On 5/5/2021 7:17 PM, Jason Wang wrote:
>
> 在 2021/5/1 上午6:32, Si-Wei Liu 写道:
>>
>>
>> On 4/15/2021 1:04 AM, Jason Wang wrote:
>>> This patch implements the doorbell mapping support for
>>> vhost-vDPA. This is simply done by using mmap()/munmap() for the
>>> vhost-vDPA fd during device start/stop. For the device without
>>> doorbell support, we fall back to eventfd based notification
>>> gracefully.
>>>
>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>> ---
>>> hw/virtio/vhost-vdpa.c | 85
>>> ++++++++++++++++++++++++++++++++++
>>> include/hw/virtio/vhost-vdpa.h | 7 +++
>>> 2 files changed, 92 insertions(+)
>>>
>>> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
>>> index dd4321bac2..c3a3b7566f 100644
>>> --- a/hw/virtio/vhost-vdpa.c
>>> +++ b/hw/virtio/vhost-vdpa.c
>>> @@ -285,12 +285,95 @@ static int vhost_vdpa_init(struct vhost_dev
>>> *dev, void *opaque)
>>> return 0;
>>> }
>>> +static void vhost_vdpa_host_notifier_uninit(struct vhost_dev *dev,
>>> + int queue_index)
>>> +{
>>> + size_t page_size = qemu_real_host_page_size;
>>> + struct vhost_vdpa *v = dev->opaque;
>>> + VirtIODevice *vdev = dev->vdev;
>>> + VhostVDPAHostNotifier *n;
>>> +
>>> + n = &v->notifier[queue_index];
>>> +
>>> + if (n->addr) {
>>> + virtio_queue_set_host_notifier_mr(vdev, queue_index,
>>> &n->mr, false);
>>> + object_unparent(OBJECT(&n->mr));
>>> + munmap(n->addr, page_size);
>>> + n->addr = NULL;
>>> + }
>>> +}
>>> +
>>> +static void vhost_vdpa_host_notifiers_uninit(struct vhost_dev *dev,
>>> int n)
>>> +{
>>> + int i;
>>> +
>>> + for (i = 0; i < n; i++) {
>>> + vhost_vdpa_host_notifier_uninit(dev, i);
>>> + }
>>> +}
>>> +
>>> +static int vhost_vdpa_host_notifier_init(struct vhost_dev *dev, int
>>> queue_index)
>>> +{
>>> + size_t page_size = qemu_real_host_page_size;
>>> + struct vhost_vdpa *v = dev->opaque;
>>> + VirtIODevice *vdev = dev->vdev;
>>> + VhostVDPAHostNotifier *n;
>>> + int fd = v->device_fd;
>>> + void *addr;
>>> + char *name;
>>> +
>>> + vhost_vdpa_host_notifier_uninit(dev, queue_index);
>>> +
>>> + n = &v->notifier[queue_index];
>>> +
>>> + addr = mmap(NULL, page_size, PROT_WRITE, MAP_SHARED, fd,
>>> + queue_index * page_size);
>>> + if (addr == MAP_FAILED) {
>>> + goto err;
>>> + }
>>> +
>>> + name = g_strdup_printf("vhost-vdpa/host-notifier@%p mmaps[%d]",
>>> + v, queue_index);
>>> + memory_region_init_ram_device_ptr(&n->mr, OBJECT(vdev), name,
>>> + page_size, addr);
>>> + g_free(name);
>>> +
>>> + if (virtio_queue_set_host_notifier_mr(vdev, queue_index,
>>> &n->mr, true)) {
>>> + munmap(addr, page_size);
>>> + goto err;
>>> + }
>>> + n->addr = addr;
>>> +
>>> + return 0;
>>> +
>>> +err:
>>> + return -1;
>>> +}
>>> +
>>> +static void vhost_vdpa_host_notifiers_init(struct vhost_dev *dev)
>>> +{
>>> + int i;
>>> +
>>> + for (i = 0; i < dev->nvqs; i++) {
>>> + if (vhost_vdpa_host_notifier_init(dev, i)) {
>> Shouldn't (hdev->vq_index + i) be used instead of i? or it's assumed
>> to be single QP for vhost-vdpa for the moment?
>
>
> Only single queue pair is supported, I'm working on the multiqueue
> support.
OK, I see.
>
>
>> If the latter, would be good to add some comment.
>
>
> I agree, and I think it's better to use vq_index + i to avoid future
> changes.
That'll be fine. I think that depends on the way how mq will be modeled
for vhost-vdpa, i.e. it doesn't need to be 1:1 between struct vhost_dev
and a queue pair, like what vhost-kernel is modeled after for mq.
>
>
>>> + goto err;
>>> + }
>>> + }
>>> +
>>> + return;
>>> +
>>> +err:
>>> + vhost_vdpa_host_notifiers_uninit(dev, i);
>> I'm not sure if it is really the intent to leave other vqs behind - I
>> presume that either none of them is mapped, or all mappable should be
>> mapped. Why here just uninit the first unmappable vq?
>
>
> I'm not sure I get here, there's a loop in
> vhost_vdpa_host_notifiers_uninit(), so we either:
>
> 1) map all doorbells
>
> or
>
> 2) no doorell is mapped
Oops, I missed the 's' in vhost_vdpa_host_notifiers_uninit() and thought
it was vhost_vdpa_host_notifier_uninit(). Sorry for the false alarm. The
error handling looks fine then.
Thanks!
-Siwei
>
>
>>
>>> + return;
>>> +}
>>> +
>>> static int vhost_vdpa_cleanup(struct vhost_dev *dev)
>>> {
>>> struct vhost_vdpa *v;
>>> assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_VDPA);
>>> v = dev->opaque;
>>> trace_vhost_vdpa_cleanup(dev, v);
>>> + vhost_vdpa_host_notifiers_uninit(dev, dev->nvqs);
>>> memory_listener_unregister(&v->listener);
>>> dev->opaque = NULL;
>>> @@ -467,6 +550,7 @@ static int vhost_vdpa_dev_start(struct vhost_dev
>>> *dev, bool started)
>>> if (started) {
>>> uint8_t status = 0;
>>> memory_listener_register(&v->listener,
>>> &address_space_memory);
>>> + vhost_vdpa_host_notifiers_init(dev);
>>> vhost_vdpa_set_vring_ready(dev);
>>> vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
>>> vhost_vdpa_call(dev, VHOST_VDPA_GET_STATUS, &status);
>>> @@ -476,6 +560,7 @@ static int vhost_vdpa_dev_start(struct vhost_dev
>>> *dev, bool started)
>>> vhost_vdpa_reset_device(dev);
>>> vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
>>> VIRTIO_CONFIG_S_DRIVER);
>>> + vhost_vdpa_host_notifiers_uninit(dev, dev->nvqs);
>>> memory_listener_unregister(&v->listener);
>>> return 0;
>>> diff --git a/include/hw/virtio/vhost-vdpa.h
>>> b/include/hw/virtio/vhost-vdpa.h
>>> index 9b81a409da..0f11ecff34 100644
>>> --- a/include/hw/virtio/vhost-vdpa.h
>>> +++ b/include/hw/virtio/vhost-vdpa.h
>>> @@ -14,11 +14,18 @@
>>> #include "hw/virtio/virtio.h"
>>> +typedef struct VhostVDPAHostNotifier {
>>> + MemoryRegion mr;
>>> + void *addr;
>>> +} VhostVDPAHostNotifier;
>>> +
>>> typedef struct vhost_vdpa {
>>> int device_fd;
>>> uint32_t msg_type;
>>> MemoryListener listener;
>>> struct vhost_dev *dev;
>>> + VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX];
>>> + bool host_notifier_set;
>> What this host_notifier_set is used for? Doesn't seem it's ever set
>> or referenced?
>
>
> Right, will remove it.
>
> Thanks
>
>
>>
>>> } VhostVDPA;
>>> extern AddressSpace address_space_memory;
>> Thanks,
>> -Siwei
>>
>
next prev parent reply other threads:[~2021-05-06 21:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 8:04 [PATCH 0/2] vhost-vDPA: doorbell mapping support Jason Wang
2021-04-15 8:04 ` [PATCH 1/2] vhost-vdpa: skip ram device from the IOTLB mapping Jason Wang
2021-04-15 8:04 ` [PATCH 2/2] vhost-vdpa: doorbell mapping support Jason Wang
2021-04-30 22:32 ` Si-Wei Liu
2021-05-06 2:17 ` Jason Wang
2021-05-06 21:15 ` Si-Wei Liu [this message]
2021-05-04 8:38 ` [PATCH 0/2] vhost-vDPA: " Michael S. Tsirkin
2021-05-06 7:20 ` Jason Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ac0f3498-f57a-7b4f-24f7-5d8e58912b40@oracle.com \
--to=si-wei.liu@oracle.com \
--cc=elic@nvidia.com \
--cc=jasowang@redhat.com \
--cc=mst@redhat.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).