diff mbox series

[RFC,v1,04/12] vhost/vsock: non-linear skb handling support

Message ID c1570fa9-1673-73cf-5545-995e9aac1dbb@sberdevices.ru (mailing list archive)
State New, archived
Headers show
Series vsock: MSG_ZEROCOPY flag support | expand

Commit Message

Arseniy Krasnov Feb. 6, 2023, 6:57 a.m. UTC 
This adds copying to guest's virtio buffers from non-linear skbs. Such
skbs are created by protocol layer when MSG_ZEROCOPY flags is used.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
---
 drivers/vhost/vsock.c        | 56 ++++++++++++++++++++++++++++++++----
 include/linux/virtio_vsock.h | 12 ++++++++
 2 files changed, 63 insertions(+), 5 deletions(-)

Comments

Stefano Garzarella Feb. 16, 2023, 2:09 p.m. UTC | #1 
On Mon, Feb 06, 2023 at 06:57:16AM +0000, Arseniy Krasnov wrote:
>This adds copying to guest's virtio buffers from non-linear skbs. Such
>skbs are created by protocol layer when MSG_ZEROCOPY flags is used.
>
>Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>---
> drivers/vhost/vsock.c        | 56 ++++++++++++++++++++++++++++++++----
> include/linux/virtio_vsock.h | 12 ++++++++
> 2 files changed, 63 insertions(+), 5 deletions(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index 1f3b89c885cc..60b9cafa3e31 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -86,6 +86,44 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
> 	return NULL;
> }
>
>+static int vhost_transport_copy_nonlinear_skb(struct sk_buff *skb,
>+					      struct iov_iter *iov_iter,
>+					      size_t len)
>+{
>+	size_t rest_len = len;
>+
>+	while (rest_len && virtio_vsock_skb_has_frags(skb)) {
>+		struct bio_vec *curr_vec;
>+		size_t curr_vec_end;
>+		size_t to_copy;
>+		int curr_frag;
>+		int curr_offs;
>+
>+		curr_frag = VIRTIO_VSOCK_SKB_CB(skb)->curr_frag;
>+		curr_offs = VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
>+		curr_vec = &skb_shinfo(skb)->frags[curr_frag];
>+
>+		curr_vec_end = curr_vec->bv_offset + curr_vec->bv_len;
>+		to_copy = min(rest_len, (size_t)(curr_vec_end - curr_offs));
>+
>+		if (copy_page_to_iter(curr_vec->bv_page, curr_offs,
>+				      to_copy, iov_iter) != to_copy)
>+			return -1;
>+
>+		rest_len -= to_copy;
>+		VIRTIO_VSOCK_SKB_CB(skb)->frag_off += to_copy;
>+
>+		if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off == (curr_vec_end)) {
>+			VIRTIO_VSOCK_SKB_CB(skb)->curr_frag++;
>+			VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0;
>+		}
>+	}

Can it happen that we exit this loop and rest_len is not 0?

In this case, is it correct to decrement data_len by len?

Thanks,
Stefano

>+
>+	skb->data_len -= len;
>+
>+	return 0;
>+}
>+
> static void
> vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 			    struct vhost_virtqueue *vq)
>@@ -197,11 +235,19 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 			break;
> 		}
>
>-		nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
>-		if (nbytes != payload_len) {
>-			kfree_skb(skb);
>-			vq_err(vq, "Faulted on copying pkt buf\n");
>-			break;
>+		if (skb_is_nonlinear(skb)) {
>+			if (vhost_transport_copy_nonlinear_skb(skb, &iov_iter,
>+							       payload_len)) {
>+				vq_err(vq, "Faulted on copying pkt buf from page\n");
>+				break;
>+			}
>+		} else {
>+			nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
>+			if (nbytes != payload_len) {
>+				kfree_skb(skb);
>+				vq_err(vq, "Faulted on copying pkt buf\n");
>+				break;
>+			}
> 		}
>
> 		/* Deliver to monitoring devices all packets that we
>diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>index 3f9c16611306..e7efdb78ce6e 100644
>--- a/include/linux/virtio_vsock.h
>+++ b/include/linux/virtio_vsock.h
>@@ -12,6 +12,10 @@
> struct virtio_vsock_skb_cb {
> 	bool reply;
> 	bool tap_delivered;
>+	/* Current fragment in 'frags' of skb. */
>+	u32 curr_frag;
>+	/* Offset from 0 in current fragment. */
>+	u32 frag_off;
> };
>
> #define VIRTIO_VSOCK_SKB_CB(skb) ((struct virtio_vsock_skb_cb *)((skb)->cb))
>@@ -46,6 +50,14 @@ static inline void virtio_vsock_skb_clear_tap_delivered(struct sk_buff *skb)
> 	VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = false;
> }
>
>+static inline bool virtio_vsock_skb_has_frags(struct sk_buff *skb)
>+{
>+	if (!skb_is_nonlinear(skb))
>+		return false;
>+
>+	return VIRTIO_VSOCK_SKB_CB(skb)->curr_frag != skb_shinfo(skb)->nr_frags;
>+}
>+
> static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb)
> {
> 	u32 len;
>-- 
>2.25.1
Arseniy Krasnov Feb. 20, 2023, 9:01 a.m. UTC | #2 
On 16.02.2023 17:09, Stefano Garzarella wrote:
> On Mon, Feb 06, 2023 at 06:57:16AM +0000, Arseniy Krasnov wrote:
>> This adds copying to guest's virtio buffers from non-linear skbs. Such
>> skbs are created by protocol layer when MSG_ZEROCOPY flags is used.
>>
>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>> ---
>> drivers/vhost/vsock.c        | 56 ++++++++++++++++++++++++++++++++----
>> include/linux/virtio_vsock.h | 12 ++++++++
>> 2 files changed, 63 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>> index 1f3b89c885cc..60b9cafa3e31 100644
>> --- a/drivers/vhost/vsock.c
>> +++ b/drivers/vhost/vsock.c
>> @@ -86,6 +86,44 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
>>     return NULL;
>> }
>>
>> +static int vhost_transport_copy_nonlinear_skb(struct sk_buff *skb,
>> +                          struct iov_iter *iov_iter,
>> +                          size_t len)
>> +{
>> +    size_t rest_len = len;
>> +
>> +    while (rest_len && virtio_vsock_skb_has_frags(skb)) {
>> +        struct bio_vec *curr_vec;
>> +        size_t curr_vec_end;
>> +        size_t to_copy;
>> +        int curr_frag;
>> +        int curr_offs;
>> +
>> +        curr_frag = VIRTIO_VSOCK_SKB_CB(skb)->curr_frag;
>> +        curr_offs = VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
>> +        curr_vec = &skb_shinfo(skb)->frags[curr_frag];
>> +
>> +        curr_vec_end = curr_vec->bv_offset + curr_vec->bv_len;
>> +        to_copy = min(rest_len, (size_t)(curr_vec_end - curr_offs));
>> +
>> +        if (copy_page_to_iter(curr_vec->bv_page, curr_offs,
>> +                      to_copy, iov_iter) != to_copy)
>> +            return -1;
>> +
>> +        rest_len -= to_copy;
>> +        VIRTIO_VSOCK_SKB_CB(skb)->frag_off += to_copy;
>> +
>> +        if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off == (curr_vec_end)) {
>> +            VIRTIO_VSOCK_SKB_CB(skb)->curr_frag++;
>> +            VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0;
>> +        }
>> +    }
> 
> Can it happen that we exit this loop and rest_len is not 0?
> 
> In this case, is it correct to decrement data_len by len?

I see

> 
> Thanks,
> Stefano
> 
>> +
>> +    skb->data_len -= len;
>> +
>> +    return 0;
>> +}
>> +
>> static void
>> vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>>                 struct vhost_virtqueue *vq)
>> @@ -197,11 +235,19 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>>             break;
>>         }
>>
>> -        nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
>> -        if (nbytes != payload_len) {
>> -            kfree_skb(skb);
>> -            vq_err(vq, "Faulted on copying pkt buf\n");
>> -            break;
>> +        if (skb_is_nonlinear(skb)) {
>> +            if (vhost_transport_copy_nonlinear_skb(skb, &iov_iter,
>> +                                   payload_len)) {
>> +                vq_err(vq, "Faulted on copying pkt buf from page\n");
>> +                break;
>> +            }
>> +        } else {
>> +            nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
>> +            if (nbytes != payload_len) {
>> +                kfree_skb(skb);
>> +                vq_err(vq, "Faulted on copying pkt buf\n");
>> +                break;
>> +            }
>>         }
>>
>>         /* Deliver to monitoring devices all packets that we
>> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>> index 3f9c16611306..e7efdb78ce6e 100644
>> --- a/include/linux/virtio_vsock.h
>> +++ b/include/linux/virtio_vsock.h
>> @@ -12,6 +12,10 @@
>> struct virtio_vsock_skb_cb {
>>     bool reply;
>>     bool tap_delivered;
>> +    /* Current fragment in 'frags' of skb. */
>> +    u32 curr_frag;
>> +    /* Offset from 0 in current fragment. */
>> +    u32 frag_off;
>> };
>>
>> #define VIRTIO_VSOCK_SKB_CB(skb) ((struct virtio_vsock_skb_cb *)((skb)->cb))
>> @@ -46,6 +50,14 @@ static inline void virtio_vsock_skb_clear_tap_delivered(struct sk_buff *skb)
>>     VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = false;
>> }
>>
>> +static inline bool virtio_vsock_skb_has_frags(struct sk_buff *skb)
>> +{
>> +    if (!skb_is_nonlinear(skb))
>> +        return false;
>> +
>> +    return VIRTIO_VSOCK_SKB_CB(skb)->curr_frag != skb_shinfo(skb)->nr_frags;
>> +}
>> +
>> static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb)
>> {
>>     u32 len;
>> -- 
>> 2.25.1
>
diff mbox series

Patch

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 1f3b89c885cc..60b9cafa3e31 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -86,6 +86,44 @@  static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
 	return NULL;
 }
 
+static int vhost_transport_copy_nonlinear_skb(struct sk_buff *skb,
+					      struct iov_iter *iov_iter,
+					      size_t len)
+{
+	size_t rest_len = len;
+
+	while (rest_len && virtio_vsock_skb_has_frags(skb)) {
+		struct bio_vec *curr_vec;
+		size_t curr_vec_end;
+		size_t to_copy;
+		int curr_frag;
+		int curr_offs;
+
+		curr_frag = VIRTIO_VSOCK_SKB_CB(skb)->curr_frag;
+		curr_offs = VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
+		curr_vec = &skb_shinfo(skb)->frags[curr_frag];
+
+		curr_vec_end = curr_vec->bv_offset + curr_vec->bv_len;
+		to_copy = min(rest_len, (size_t)(curr_vec_end - curr_offs));
+
+		if (copy_page_to_iter(curr_vec->bv_page, curr_offs,
+				      to_copy, iov_iter) != to_copy)
+			return -1;
+
+		rest_len -= to_copy;
+		VIRTIO_VSOCK_SKB_CB(skb)->frag_off += to_copy;
+
+		if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off == (curr_vec_end)) {
+			VIRTIO_VSOCK_SKB_CB(skb)->curr_frag++;
+			VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0;
+		}
+	}
+
+	skb->data_len -= len;
+
+	return 0;
+}
+
 static void
 vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
 			    struct vhost_virtqueue *vq)
@@ -197,11 +235,19 @@  vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
 			break;
 		}
 
-		nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
-		if (nbytes != payload_len) {
-			kfree_skb(skb);
-			vq_err(vq, "Faulted on copying pkt buf\n");
-			break;
+		if (skb_is_nonlinear(skb)) {
+			if (vhost_transport_copy_nonlinear_skb(skb, &iov_iter,
+							       payload_len)) {
+				vq_err(vq, "Faulted on copying pkt buf from page\n");
+				break;
+			}
+		} else {
+			nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
+			if (nbytes != payload_len) {
+				kfree_skb(skb);
+				vq_err(vq, "Faulted on copying pkt buf\n");
+				break;
+			}
 		}
 
 		/* Deliver to monitoring devices all packets that we
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 3f9c16611306..e7efdb78ce6e 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -12,6 +12,10 @@ 
 struct virtio_vsock_skb_cb {
 	bool reply;
 	bool tap_delivered;
+	/* Current fragment in 'frags' of skb. */
+	u32 curr_frag;
+	/* Offset from 0 in current fragment. */
+	u32 frag_off;
 };
 
 #define VIRTIO_VSOCK_SKB_CB(skb) ((struct virtio_vsock_skb_cb *)((skb)->cb))
@@ -46,6 +50,14 @@  static inline void virtio_vsock_skb_clear_tap_delivered(struct sk_buff *skb)
 	VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = false;
 }
 
+static inline bool virtio_vsock_skb_has_frags(struct sk_buff *skb)
+{
+	if (!skb_is_nonlinear(skb))
+		return false;
+
+	return VIRTIO_VSOCK_SKB_CB(skb)->curr_frag != skb_shinfo(skb)->nr_frags;
+}
+
 static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb)
 {
 	u32 len;