From patchwork Fri Feb 2 09:39:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xuan Zhuo X-Patchwork-Id: 13542570 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C081C7C0B3; Fri, 2 Feb 2024 09:40:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.133 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706866817; cv=none; b=eIx+6FV1uDEcWkJ3PU1bepNpUicNzA4zF/z+RBT5TZXxptel/NwlXWX3l2ZbZGLMTTEzrxLlleIp9m0LdiYknBVlZ9xR8FmsY1NY7p7OHF8iAUlymPyO/17isnW11SAT+43w9iTLXZ47VE58tI/9enbcori38WTcpatqaiid8As= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706866817; c=relaxed/simple; bh=OLUJgu2GtDakzRNx8JjX/f1thHwVn9dH+TV16TIJ45Y=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=CoQscrVN2j0QeSeLqhiJ6/Okngyjpw0TJTGzx3q/TtnuHA6fpBvkEQijdI/Lhsxg6+nJEudfhkiEXEocnmsAE42ekN27mNAPD1eouUiMqTJ5NOwLnzG5TXA29BkMoWAnZADVlGm8SJHFfVJLehPfoogdBnd9RKlDSnTi2SoxoTo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=t1tSjvK5; arc=none smtp.client-ip=115.124.30.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="t1tSjvK5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1706866797; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=M/gA0U5hbdGfXbE+ate8yVaxvtF+5l5LRTg2RSnUFsU=; b=t1tSjvK5Ievi00Xp6B8QYQye8ClBZvwWCmxs9HUjq3cp0IukVd5Ci5+mSQ0xGl9JgyCVAdV7y4ZfPBYvnLjy+Jvm05sktxknMbn1kqaJ2M38Yt5b6tjlLRakEed7gZCkPmvU9NM5Rc+zvGGFWX3dcTk7Vk7dWeqxRyLVgVMwves= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045170;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=36;SR=0;TI=SMTPD_---0W.wb-jK_1706866795; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0W.wb-jK_1706866795) by smtp.aliyun-inc.com; Fri, 02 Feb 2024 17:39:56 +0800 From: Xuan Zhuo To: virtualization@lists.linux.dev Cc: Richard Weinberger , Anton Ivanov , Johannes Berg , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Hans de Goede , =?utf-8?q?Ilpo_J=C3=A4rvinen?= , Vadim Pasternak , Bjorn Andersson , Mathieu Poirier , Cornelia Huck , Halil Pasic , Eric Farman , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Benjamin Berg , linux-um@lists.infradead.org, netdev@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH vhost v1 02/19] virtio_ring: packed: remove double check of the unmap ops Date: Fri, 2 Feb 2024 17:39:34 +0800 Message-Id: <20240202093951.120283-3-xuanzhuo@linux.alibaba.com> X-Mailer: git-send-email 2.32.0.3.g01195cf9f In-Reply-To: <20240202093951.120283-1-xuanzhuo@linux.alibaba.com> References: <20240202093951.120283-1-xuanzhuo@linux.alibaba.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Git-Hash: 4c7bacd05cb8 In the functions vring_unmap_extra_packed and vring_unmap_desc_packed, multiple checks are made whether unmap is performed and whether it is INDIRECT. These two functions are usually called in a loop, and we should put the check outside the loop. And we unmap the descs with VRING_DESC_F_INDIRECT on the same path with other descs, that make the thing more complex. If we distinguish the descs with VRING_DESC_F_INDIRECT before unmap, thing will be clearer. 1. only one desc of the desc table is used, we do not need the loop 2. the called unmap api is difference from the other desc 3. the vq->premapped is not needed to check 4. the vq->indirect is not needed to check 5. the state->indir_desc must not be null Signed-off-by: Xuan Zhuo --- drivers/virtio/virtio_ring.c | 76 ++++++++++++++++++------------------ 1 file changed, 39 insertions(+), 37 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 4677831e6c26..7280a1706cca 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -1220,6 +1220,7 @@ static u16 packed_last_used(u16 last_used_idx) return last_used_idx & ~(-(1 << VRING_PACKED_EVENT_F_WRAP_CTR)); } +/* caller must check vring_need_unmap_buffer() */ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq, const struct vring_desc_extra *extra) { @@ -1227,33 +1228,18 @@ static void vring_unmap_extra_packed(const struct vring_virtqueue *vq, flags = extra->flags; - if (flags & VRING_DESC_F_INDIRECT) { - if (!vq->use_dma_api) - return; - - dma_unmap_single(vring_dma_dev(vq), - extra->addr, extra->len, - (flags & VRING_DESC_F_WRITE) ? - DMA_FROM_DEVICE : DMA_TO_DEVICE); - } else { - if (!vring_need_unmap_buffer(vq)) - return; - - dma_unmap_page(vring_dma_dev(vq), - extra->addr, extra->len, - (flags & VRING_DESC_F_WRITE) ? - DMA_FROM_DEVICE : DMA_TO_DEVICE); - } + dma_unmap_page(vring_dma_dev(vq), + extra->addr, extra->len, + (flags & VRING_DESC_F_WRITE) ? + DMA_FROM_DEVICE : DMA_TO_DEVICE); } +/* caller must check vring_need_unmap_buffer() */ static void vring_unmap_desc_packed(const struct vring_virtqueue *vq, const struct vring_packed_desc *desc) { u16 flags; - if (!vring_need_unmap_buffer(vq)) - return; - flags = le16_to_cpu(desc->flags); dma_unmap_page(vring_dma_dev(vq), @@ -1329,7 +1315,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, total_sg * sizeof(struct vring_packed_desc), DMA_TO_DEVICE); if (vring_mapping_error(vq, addr)) { - if (vq->premapped) + if (!vring_need_unmap_buffer(vq)) goto free_desc; goto unmap_release; @@ -1344,10 +1330,11 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, vq->packed.desc_extra[id].addr = addr; vq->packed.desc_extra[id].len = total_sg * sizeof(struct vring_packed_desc); - vq->packed.desc_extra[id].flags = VRING_DESC_F_INDIRECT | - vq->packed.avail_used_flags; } + vq->packed.desc_extra[id].flags = VRING_DESC_F_INDIRECT | + vq->packed.avail_used_flags; + /* * A driver MUST NOT make the first descriptor in the list * available before all subsequent descriptors comprising @@ -1388,6 +1375,8 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, unmap_release: err_idx = i; + WARN_ON(!vring_need_unmap_buffer(vq)); + for (i = 0; i < err_idx; i++) vring_unmap_desc_packed(vq, &desc[i]); @@ -1484,9 +1473,10 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, if (unlikely(vring_need_unmap_buffer(vq))) { vq->packed.desc_extra[curr].addr = addr; vq->packed.desc_extra[curr].len = sg->length; - vq->packed.desc_extra[curr].flags = - le16_to_cpu(flags); } + + vq->packed.desc_extra[curr].flags = le16_to_cpu(flags); + prev = curr; curr = vq->packed.desc_extra[curr].next; @@ -1536,6 +1526,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, vq->packed.avail_used_flags = avail_used_flags; + WARN_ON(!vring_need_unmap_buffer(vq)); + for (n = 0; n < total_sg; n++) { if (i == err_idx) break; @@ -1605,7 +1597,9 @@ static void detach_buf_packed(struct vring_virtqueue *vq, struct vring_desc_state_packed *state = NULL; struct vring_packed_desc *desc; unsigned int i, curr; + u16 flags; + flags = vq->packed.desc_extra[id].flags; state = &vq->packed.desc_state[id]; /* Clear data ptr. */ @@ -1615,22 +1609,32 @@ static void detach_buf_packed(struct vring_virtqueue *vq, vq->free_head = id; vq->vq.num_free += state->num; - if (unlikely(vring_need_unmap_buffer(vq))) { - curr = id; - for (i = 0; i < state->num; i++) { - vring_unmap_extra_packed(vq, - &vq->packed.desc_extra[curr]); - curr = vq->packed.desc_extra[curr].next; + if (!(flags & VRING_DESC_F_INDIRECT)) { + if (vring_need_unmap_buffer(vq)) { + curr = id; + for (i = 0; i < state->num; i++) { + vring_unmap_extra_packed(vq, + &vq->packed.desc_extra[curr]); + curr = vq->packed.desc_extra[curr].next; + } } - } - if (vq->indirect) { + if (ctx) + *ctx = state->indir_desc; + } else { + const struct vring_desc_extra *extra; u32 len; + if (vq->use_dma_api) { + extra = &vq->packed.desc_extra[id]; + dma_unmap_single(vring_dma_dev(vq), + extra->addr, extra->len, + (flags & VRING_DESC_F_WRITE) ? + DMA_FROM_DEVICE : DMA_TO_DEVICE); + } + /* Free the indirect table, if any, now that it's unmapped. */ desc = state->indir_desc; - if (!desc) - return; if (vring_need_unmap_buffer(vq)) { len = vq->packed.desc_extra[id].len; @@ -1640,8 +1644,6 @@ static void detach_buf_packed(struct vring_virtqueue *vq, } kfree(desc); state->indir_desc = NULL; - } else if (ctx) { - *ctx = state->indir_desc; } }