On Thu, Jul 07, 2022 at 01:56:37PM +0800, Guo Zhi wrote:
> On 2022/7/7 12:59, Michael S. Tsirkin wrote:
> > On Thu, Jul 07, 2022 at 10:44:09AM +0800, Guo Zhi wrote:
> > > Prior implementation don't use indirection feature because there is only
> > > one descriptor for every io event, actually prior implementation don't
> > > support indirection because vhost can't translate and find the indirect
> > > descriptors. This commit enable virtio_test malloc indirect descriptors
> > > in a indirect buffer and map this buffer to vhost, thus resolve this
> > > problem.
> > >
> > > Signed-off-by: Guo Zhi <qtxuning1999@xxxxxxxxxxx>
> > > ---
> > > tools/virtio/virtio_test.c | 50 ++++++++++++++++++++++++++++++++------
> > > 1 file changed, 42 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/tools/virtio/virtio_test.c b/tools/virtio/virtio_test.c
> > > index 363695b33..dca408a5c 100644
> > > --- a/tools/virtio/virtio_test.c
> > > +++ b/tools/virtio/virtio_test.c
> > > @@ -25,7 +25,7 @@
> > > #define RINGSIZE 256
> > > #define TEST_BUF_NUM 0x100000
> > > #define BUF_SIZE 1024
> > > -/* Unused */
> > > +#define INDIRECTS_SIZE (RINGSIZE * sizeof(struct vring_desc) * 8)
> > > void *__kmalloc_fake, *__kfree_ignore_start, *__kfree_ignore_end;
> > > struct vq_info {
> > > @@ -47,6 +47,8 @@ struct vdev_info {
> > > int nvqs;
> > > void *buf;
> > > size_t buf_size;
> > > + void *indirects;
> > > + size_t indirects_size;
> > What are these exactly?
> The buffer is used to put indirect descriptors, and the buffer will be added
> in the vhost iotlb through VHOST_SET_MEM_TABLE, so that vhost can translate
> the descriptors in user mode correctly.
Pls come up with a better name. indirect_buf and indirect_buf_size?
And add a comment.
> >
> > > struct vhost_memory *mem;
> > > };
> > > @@ -131,6 +133,8 @@ static void vq_info_add(struct vdev_info *dev, int num)
> > > static void vdev_info_init(struct vdev_info* dev, unsigned long long features)
> > > {
> > > int r;
> > > + int nregions = 2;
> > > +
> > > memset(dev, 0, sizeof *dev);
> > > dev->vdev.features = features;
> > > INIT_LIST_HEAD(&dev->vdev.vqs);
> > > @@ -138,19 +142,25 @@ static void vdev_info_init(struct vdev_info* dev, unsigned long long features)
> > > dev->buf_size = BUF_SIZE;
> > > dev->buf = malloc(dev->buf_size);
> > > assert(dev->buf);
> > > - dev->control = open("/dev/vhost-test", O_RDWR);
> > > + dev->indirects_size = INDIRECTS_SIZE;
> > > + dev->indirects = malloc(dev->indirects_size);
> > > + assert(dev->indirects);
> > > + dev->control = open("/dev/vhost-test", O_RDWR);
> > > assert(dev->control >= 0);
> > > r = ioctl(dev->control, VHOST_SET_OWNER, NULL);
> > > assert(r >= 0);
> > > dev->mem = malloc(offsetof(struct vhost_memory, regions) +
> > > - sizeof dev->mem->regions[0]);
> > > + (sizeof(dev->mem->regions[0])) * nregions);
> > > assert(dev->mem);
> > > memset(dev->mem, 0, offsetof(struct vhost_memory, regions) +
> > > - sizeof dev->mem->regions[0]);
> > > - dev->mem->nregions = 1;
> > > + (sizeof(dev->mem->regions[0])) * nregions);
> > > + dev->mem->nregions = nregions;
> > > dev->mem->regions[0].guest_phys_addr = (long)dev->buf;
> > > dev->mem->regions[0].userspace_addr = (long)dev->buf;
> > > dev->mem->regions[0].memory_size = dev->buf_size;
> > > + dev->mem->regions[1].guest_phys_addr = (long)dev->indirects;
> > > + dev->mem->regions[1].userspace_addr = (long)dev->indirects;
> > > + dev->mem->regions[1].memory_size = dev->indirects_size;
> > > r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);
> > > assert(r >= 0);
> > > }
> > > @@ -170,6 +180,19 @@ static void wait_for_interrupt(struct vdev_info *dev)
> > > }
> > > }
> > > +static int test_virtqueue_add_outbuf(struct virtqueue *vq,
> > > + struct scatterlist *sg, unsigned int num,
> > > + void *data, void *indirects)
> > > +{
> > > + int r;
> > > +
> > > + __kmalloc_fake = indirects;
> > > + r = virtqueue_add_outbuf(vq, sg, num, data,
> > > + GFP_ATOMIC);
> > > + __kmalloc_fake = NULL;
> > > + return r;
> > > +}
> > > +
> > Quite a hack. Please add comments with documentation. Also - no way to
> > avoid hacks?
>
> The __kmalloc_fake is refered from vringh_test.
>
> If not using __kmalloc_fake here, the vhost doesn't know how to translate
> the indirects descriptors(user address).
>
> We may could register a single region as large as the whole virtual space in
> the vhost iotlb using 1:1 mapping.
>
> But since they are tests, IMHO, better here to use VHOST_SET_MEM_TABLE with
> more regions.
But why do we need to do this on each buffer add?
> >
> > > static void run_test(struct vdev_info *dev, struct vq_info *vq,
> > > bool delayed, int batch, int reset_n, int bufs)
> > > {
> > > @@ -181,6 +204,7 @@ static void run_test(struct vdev_info *dev, struct vq_info *vq,
> > > unsigned len;
> > > long long spurious = 0;
> > > const bool random_batch = batch == RANDOM_BATCH;
> > > + void *indirects;
> > > r = ioctl(dev->control, VHOST_TEST_RUN, &test);
> > > assert(r >= 0);
> > > @@ -188,10 +212,15 @@ static void run_test(struct vdev_info *dev, struct vq_info *vq,
> > > next_reset = INT_MAX;
> > > }
> > > + /* Don't kfree indirects. */
> > > + __kfree_ignore_start = dev->indirects;
> > > + __kfree_ignore_end = dev->indirects + dev->indirects_size;
> > > +
> > > for (;;) {
> > > virtqueue_disable_cb(vq->vq);
> > > completed_before = completed;
> > > started_before = started;
> > > + indirects = dev->indirects;
> > > do {
> > > const bool reset = completed > next_reset;
> > > if (random_batch)
> > > @@ -203,9 +232,13 @@ static void run_test(struct vdev_info *dev, struct vq_info *vq,
> > > sg_init_table(sg, sg_size);
> > > for (int i = 0; i < sg_size; ++i)
> > > sg_set_buf(&sg[i], dev->buf + i, 0x1);
> > > - r = virtqueue_add_outbuf(vq->vq, sg, sg_size,
> > > - dev->buf + started,
> > > - GFP_ATOMIC);
> > > +
> > > + // use indirects buffer repeatedly
> >
> > C style comments please.
> It will be modified.
> >
> > > + if (indirects + sg_size * sizeof(struct vring_desc) >
> > > + dev->indirects + dev->indirects_size)
> > > + indirects = dev->indirects;
> > > + r = test_virtqueue_add_outbuf(vq->vq, sg, sg_size,
> > > + dev->buf + started, indirects);
> > > if (unlikely(r != 0)) {
> > > if (r == -ENOSPC &&
> > > started > started_before)
> > > @@ -216,6 +249,7 @@ static void run_test(struct vdev_info *dev, struct vq_info *vq,
> > > }
> > > ++started;
> > > + indirects += sg_size * sizeof(struct vring_desc);
> > > }
> > > if (unlikely(!virtqueue_kick(vq->vq))) {
> > > r = -1;
> > > --
> > > 2.17.1
>
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
