linux-kernel - [RFC PATCH v3 01/11] virtio/vsock: rework packet allocation logic

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Message-ID: <f896b8fd-50d2-2512-3966-3775245e9b96@sberdevices.ru>
Date:   Sun, 6 Nov 2022 19:36:02 +0000
From:   Arseniy Krasnov <AVKrasnov@...rdevices.ru>
To:     Stefano Garzarella <sgarzare@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Krasnov Arseniy <oxffffaa@...il.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        kernel <kernel@...rdevices.ru>
Subject: [RFC PATCH v3 01/11] virtio/vsock: rework packet allocation logic

To support zerocopy receive, packet's buffer allocation is changed: for
buffers which could be mapped to user's vma we can't use 'kmalloc()'(as
kernel restricts to map slab pages to user's vma) and raw buddy
allocator now called. But, for tx packets(such packets won't be mapped
to user), previous 'kmalloc()' way is used, but with special flag in
packet's structure which allows to distinguish between 'kmalloc()' and
raw pages buffers.

Signed-off-by: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
---
 drivers/vhost/vsock.c                   |  1 +
 include/linux/virtio_vsock.h            |  1 +
 net/vmw_vsock/virtio_transport.c        |  8 ++++++--
 net/vmw_vsock/virtio_transport_common.c | 10 +++++++++-
 4 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 5703775af129..65475d128a1d 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -399,6 +399,7 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
 		return NULL;
 	}
 
+	pkt->slab_buf = true;
 	pkt->buf_len = pkt->len;
 
 	nbytes = copy_from_iter(pkt->buf, pkt->len, &iov_iter);
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 35d7eedb5e8e..d02cb7aa922f 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -50,6 +50,7 @@ struct virtio_vsock_pkt {
 	u32 off;
 	bool reply;
 	bool tap_delivered;
+	bool slab_buf;
 };
 
 struct virtio_vsock_pkt_info {
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index ad64f403536a..19909c1e9ba3 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -255,16 +255,20 @@ static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
 	vq = vsock->vqs[VSOCK_VQ_RX];
 
 	do {
+		struct page *buf_page;
+
 		pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
 		if (!pkt)
 			break;
 
-		pkt->buf = kmalloc(buf_len, GFP_KERNEL);
-		if (!pkt->buf) {
+		buf_page = alloc_page(GFP_KERNEL);
+
+		if (!buf_page) {
 			virtio_transport_free_pkt(pkt);
 			break;
 		}
 
+		pkt->buf = page_to_virt(buf_page);
 		pkt->buf_len = buf_len;
 		pkt->len = buf_len;
 
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index a9980e9b9304..37e8dbfe2f5d 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -69,6 +69,7 @@ virtio_transport_alloc_pkt(struct virtio_vsock_pkt_info *info,
 		if (!pkt->buf)
 			goto out_pkt;
 
+		pkt->slab_buf = true;
 		pkt->buf_len = len;
 
 		err = memcpy_from_msg(pkt->buf, info->msg, len);
@@ -1339,7 +1340,14 @@ EXPORT_SYMBOL_GPL(virtio_transport_recv_pkt);
 
 void virtio_transport_free_pkt(struct virtio_vsock_pkt *pkt)
 {
-	kvfree(pkt->buf);
+	if (pkt->buf_len) {
+		if (pkt->slab_buf)
+			kvfree(pkt->buf);
+		else
+			free_pages((unsigned long)pkt->buf,
+				   get_order(pkt->buf_len));
+	}
+
 	kfree(pkt);
 }
 EXPORT_SYMBOL_GPL(virtio_transport_free_pkt);
-- 
2.35.0