[RFC PATCH v1 2/8] vhost/vsock: rework packet allocation logic
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STALE1590d
SUPERSEDED
From: Arseniy Krasnov <hidden>
Date: 2022-05-12 05:10:16
Also in:
kvm, lkml
Subsystem:
the rest, virtio and vhost vsock driver, virtio host (vhost) · Maintainers:
Linus Torvalds, Stefan Hajnoczi, Stefano Garzarella, "Michael S. Tsirkin", Jason Wang, Eugenio Pérez
Revision v1 of 3 in this series.
Revisions (3)
- v1 current
- v2 [diff vs current]
- v3 [diff vs current]
For packets received from virtio RX queue, use buddy allocator instead of 'kmalloc()' to be able to insert such pages to user provided vma. Single call to 'copy_from_iter()' replaced with per-page loop. Signed-off-by: Arseniy Krasnov <redacted> --- drivers/vhost/vsock.c | 49 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 41 insertions(+), 8 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 37f0b4274113..157798985389 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c@@ -360,6 +360,9 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq, struct iov_iter iov_iter; size_t nbytes; size_t len; + struct page *buf_page; + ssize_t pkt_len; + int page_idx; if (in != 0) { vq_err(vq, "Expected 0 input buffers, got %u\n", in);
@@ -393,20 +396,50 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq, return NULL; } - pkt->buf = kmalloc(pkt->len, GFP_KERNEL); - if (!pkt->buf) { + /* This creates memory overrun, as we allocate + * at least one page for each packet. + */ + buf_page = alloc_pages(GFP_KERNEL, get_order(pkt->len)); + + if (buf_page == NULL) { kfree(pkt); return NULL; } + pkt->buf = page_to_virt(buf_page); pkt->buf_len = pkt->len; - nbytes = copy_from_iter(pkt->buf, pkt->len, &iov_iter); - if (nbytes != pkt->len) { - vq_err(vq, "Expected %u byte payload, got %zu bytes\n", - pkt->len, nbytes); - virtio_transport_free_pkt(pkt); - return NULL; + page_idx = 0; + pkt_len = pkt->len; + + /* As allocated pages are not mapped, process + * pages one by one. + */ + while (pkt_len > 0) { + void *mapped; + size_t to_copy; + + mapped = kmap(buf_page + page_idx); + + if (mapped == NULL) { + virtio_transport_free_pkt(pkt); + return NULL; + } + + to_copy = min(pkt_len, ((ssize_t)PAGE_SIZE)); + + nbytes = copy_from_iter(mapped, to_copy, &iov_iter); + if (nbytes != to_copy) { + vq_err(vq, "Expected %zu byte payload, got %zu bytes\n", + to_copy, nbytes); + virtio_transport_free_pkt(pkt); + return NULL; + } + + kunmap(mapped); + + pkt_len -= to_copy; + page_idx++; } return pkt;
--
2.25.1