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Message-ID: <20241110142303.GA50588@unreal>
Date: Sun, 10 Nov 2024 16:23:03 +0200
From: Leon Romanovsky <leon@...nel.org>
To: Bharat Bhushan <bbhushan2@...vell.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
sgoutham@...vell.com, gakula@...vell.com, sbhatta@...vell.com,
hkelam@...vell.com, davem@...emloft.net, edumazet@...gle.com,
kuba@...nel.org, pabeni@...hat.com, jerinj@...vell.com,
lcherian@...vell.com, ndabilpuram@...vell.com, sd@...asysnail.net
Subject: Re: [net-next PATCH v9 1/8] octeontx2-pf: map skb data as device
writeable
On Fri, Nov 08, 2024 at 10:27:01AM +0530, Bharat Bhushan wrote:
> Crypto hardware need write permission for in-place encrypt
> or decrypt operation on skb-data to support IPsec crypto
> offload. That patch uses skb_unshare to make skb data writeable
> for ipsec crypto offload and map skb fragment memory as
> device read-write.
>
> Signed-off-by: Bharat Bhushan <bbhushan2@...vell.com>
> ---
> v7->v8:
> - spell correction (s/sdk/skb) in description
>
> v6->v7:
> - skb data was mapped as device writeable but it was not ensured
> that skb is writeable. This version calls skb_unshare() to make
> skb data writeable.
>
> .../ethernet/marvell/octeontx2/nic/otx2_txrx.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> index 7aaf32e9aa95..49b6b091ba41 100644
> --- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> +++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> @@ -11,6 +11,7 @@
> #include <linux/bpf.h>
> #include <linux/bpf_trace.h>
> #include <net/ip6_checksum.h>
> +#include <net/xfrm.h>
>
> #include "otx2_reg.h"
> #include "otx2_common.h"
> @@ -83,10 +84,17 @@ static unsigned int frag_num(unsigned int i)
> static dma_addr_t otx2_dma_map_skb_frag(struct otx2_nic *pfvf,
> struct sk_buff *skb, int seg, int *len)
> {
> + enum dma_data_direction dir = DMA_TO_DEVICE;
> const skb_frag_t *frag;
> struct page *page;
> int offset;
>
> + /* Crypto hardware need write permission for ipsec crypto offload */
> + if (unlikely(xfrm_offload(skb))) {
> + dir = DMA_BIDIRECTIONAL;
> + skb = skb_unshare(skb, GFP_ATOMIC);
> + }
> +
> /* First segment is always skb->data */
> if (!seg) {
> page = virt_to_page(skb->data);
> @@ -98,16 +106,22 @@ static dma_addr_t otx2_dma_map_skb_frag(struct otx2_nic *pfvf,
> offset = skb_frag_off(frag);
> *len = skb_frag_size(frag);
> }
> - return otx2_dma_map_page(pfvf, page, offset, *len, DMA_TO_DEVICE);
> + return otx2_dma_map_page(pfvf, page, offset, *len, dir);
Did I read correctly and you perform DMA mapping on every SKB in data path?
How bad does it perform if you enable IOMMU?
Thanks
> }
>
> static void otx2_dma_unmap_skb_frags(struct otx2_nic *pfvf, struct sg_list *sg)
> {
> + enum dma_data_direction dir = DMA_TO_DEVICE;
> + struct sk_buff *skb = NULL;
> int seg;
>
> + skb = (struct sk_buff *)sg->skb;
> + if (unlikely(xfrm_offload(skb)))
> + dir = DMA_BIDIRECTIONAL;
> +
> for (seg = 0; seg < sg->num_segs; seg++) {
> otx2_dma_unmap_page(pfvf, sg->dma_addr[seg],
> - sg->size[seg], DMA_TO_DEVICE);
> + sg->size[seg], dir);
> }
> sg->num_segs = 0;
> }
> --
> 2.34.1
>
>
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