> -----Original Message----- > From: zhenwei pi [mailto:pizhenwei@xxxxxxxxxxxxx] > Sent: Thursday, May 5, 2022 5:24 PM > To: Gonglei (Arei) <arei.gonglei@xxxxxxxxxx>; mst@xxxxxxxxxx > Cc: jasowang@xxxxxxxxxx; herbert@xxxxxxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; > linux-crypto@xxxxxxxxxxxxxxx; helei.sig11@xxxxxxxxxxxxx; > pizhenwei@xxxxxxxxxxxxx; davem@xxxxxxxxxxxxx > Subject: [PATCH v5 3/5] virtio-crypto: wait ctrl queue instead of busy polling > > Originally, after submitting request into virtio crypto control queue, the guest > side polls the result from the virt queue. This works like following: > CPU0 CPU1 ... CPUx CPUy > | | | | > \ \ / / > \--------spin_lock(&vcrypto->ctrl_lock)-------/ > | > virtqueue add & kick > | > busy poll virtqueue > | > spin_unlock(&vcrypto->ctrl_lock) > ... > > There are two problems: > 1, The queue depth is always 1, the performance of a virtio crypto > device gets limited. Multi user processes share a single control > queue, and hit spin lock race from control queue. Test on Intel > Platinum 8260, a single worker gets ~35K/s create/close session > operations, and 8 workers get ~40K/s operations with 800% CPU > utilization. > 2, The control request is supposed to get handled immediately, but > in the current implementation of QEMU(v6.2), the vCPU thread kicks > another thread to do this work, the latency also gets unstable. > Tracking latency of virtio_crypto_alg_akcipher_close_session in 5s: > usecs : count distribution > 0 -> 1 : 0 | | > 2 -> 3 : 7 | | > 4 -> 7 : 72 | | > 8 -> 15 : 186485 |************************| > 16 -> 31 : 687 | | > 32 -> 63 : 5 | | > 64 -> 127 : 3 | | > 128 -> 255 : 1 | | > 256 -> 511 : 0 | | > 512 -> 1023 : 0 | | > 1024 -> 2047 : 0 | | > 2048 -> 4095 : 0 | | > 4096 -> 8191 : 0 | | > 8192 -> 16383 : 2 | | > This means that a CPU may hold vcrypto->ctrl_lock as long as 8192~16383us. > > To improve the performance of control queue, a request on control queue waits > completion instead of busy polling to reduce lock racing, and gets completed by > control queue callback. > CPU0 CPU1 ... CPUx CPUy > | | | | > \ \ / / > \--------spin_lock(&vcrypto->ctrl_lock)-------/ > | > virtqueue add & kick > | > ---------spin_unlock(&vcrypto->ctrl_lock)------ > / / \ \ > | | | | > wait wait wait wait > > Test this patch, the guest side get ~200K/s operations with 300% CPU > utilization. > > Cc: Michael S. Tsirkin <mst@xxxxxxxxxx> > Cc: Jason Wang <jasowang@xxxxxxxxxx> > Cc: Gonglei <arei.gonglei@xxxxxxxxxx> > Signed-off-by: zhenwei pi <pizhenwei@xxxxxxxxxxxxx> > --- > .../virtio/virtio_crypto_akcipher_algs.c | 29 ++--------- > drivers/crypto/virtio/virtio_crypto_common.h | 4 ++ > drivers/crypto/virtio/virtio_crypto_core.c | 52 ++++++++++++++++++- > .../virtio/virtio_crypto_skcipher_algs.c | 34 ++---------- > 4 files changed, 64 insertions(+), 55 deletions(-) > Reviewed-by: Gonglei <arei.gonglei@xxxxxxxxxx> Regards, -Gonglei > diff --git a/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c > b/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c > index 698ea57e2649..382ccec9ab12 100644 > --- a/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c > +++ b/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c > @@ -103,7 +103,6 @@ static int > virtio_crypto_alg_akcipher_init_session(struct virtio_crypto_akcipher > struct scatterlist outhdr_sg, key_sg, inhdr_sg, *sgs[3]; > struct virtio_crypto *vcrypto = ctx->vcrypto; > uint8_t *pkey; > - unsigned int inlen; > int err; > unsigned int num_out = 0, num_in = 0; > struct virtio_crypto_op_ctrl_req *ctrl; @@ -135,18 +134,9 @@ static int > virtio_crypto_alg_akcipher_init_session(struct virtio_crypto_akcipher > sg_init_one(&inhdr_sg, input, sizeof(*input)); > sgs[num_out + num_in++] = &inhdr_sg; > > - spin_lock(&vcrypto->ctrl_lock); > - err = virtqueue_add_sgs(vcrypto->ctrl_vq, sgs, num_out, num_in, vcrypto, > GFP_ATOMIC); > - if (err < 0) { > - spin_unlock(&vcrypto->ctrl_lock); > + err = virtio_crypto_ctrl_vq_request(vcrypto, sgs, num_out, num_in, > vc_ctrl_req); > + if (err < 0) > goto out; > - } > - > - virtqueue_kick(vcrypto->ctrl_vq); > - while (!virtqueue_get_buf(vcrypto->ctrl_vq, &inlen) && > - !virtqueue_is_broken(vcrypto->ctrl_vq)) > - cpu_relax(); > - spin_unlock(&vcrypto->ctrl_lock); > > if (le32_to_cpu(input->status) != VIRTIO_CRYPTO_OK) { > pr_err("virtio_crypto: Create session failed status: %u\n", @@ > -171,7 +161,7 @@ static int virtio_crypto_alg_akcipher_close_session(struct > virtio_crypto_akciphe > struct scatterlist outhdr_sg, inhdr_sg, *sgs[2]; > struct virtio_crypto_destroy_session_req *destroy_session; > struct virtio_crypto *vcrypto = ctx->vcrypto; > - unsigned int num_out = 0, num_in = 0, inlen; > + unsigned int num_out = 0, num_in = 0; > int err; > struct virtio_crypto_op_ctrl_req *ctrl; > struct virtio_crypto_inhdr *ctrl_status; @@ -199,18 +189,9 @@ static int > virtio_crypto_alg_akcipher_close_session(struct virtio_crypto_akciphe > sg_init_one(&inhdr_sg, &ctrl_status->status, sizeof(ctrl_status->status)); > sgs[num_out + num_in++] = &inhdr_sg; > > - spin_lock(&vcrypto->ctrl_lock); > - err = virtqueue_add_sgs(vcrypto->ctrl_vq, sgs, num_out, num_in, vcrypto, > GFP_ATOMIC); > - if (err < 0) { > - spin_unlock(&vcrypto->ctrl_lock); > + err = virtio_crypto_ctrl_vq_request(vcrypto, sgs, num_out, num_in, > vc_ctrl_req); > + if (err < 0) > goto out; > - } > - > - virtqueue_kick(vcrypto->ctrl_vq); > - while (!virtqueue_get_buf(vcrypto->ctrl_vq, &inlen) && > - !virtqueue_is_broken(vcrypto->ctrl_vq)) > - cpu_relax(); > - spin_unlock(&vcrypto->ctrl_lock); > > if (ctrl_status->status != VIRTIO_CRYPTO_OK) { > pr_err("virtio_crypto: Close session failed status: %u, session_id: > 0x%llx\n", diff --git a/drivers/crypto/virtio/virtio_crypto_common.h > b/drivers/crypto/virtio/virtio_crypto_common.h > index 2422237ec4e6..59a4c0259456 100644 > --- a/drivers/crypto/virtio/virtio_crypto_common.h > +++ b/drivers/crypto/virtio/virtio_crypto_common.h > @@ -90,6 +90,7 @@ struct virtio_crypto_ctrl_request { > struct virtio_crypto_op_ctrl_req ctrl; > struct virtio_crypto_session_input input; > struct virtio_crypto_inhdr ctrl_status; > + struct completion compl; > }; > > struct virtio_crypto_request; > @@ -141,5 +142,8 @@ int virtio_crypto_skcipher_algs_register(struct > virtio_crypto *vcrypto); void virtio_crypto_skcipher_algs_unregister(struct > virtio_crypto *vcrypto); int virtio_crypto_akcipher_algs_register(struct > virtio_crypto *vcrypto); void virtio_crypto_akcipher_algs_unregister(struct > virtio_crypto *vcrypto); > +int virtio_crypto_ctrl_vq_request(struct virtio_crypto *vcrypto, struct > scatterlist *sgs[], > + unsigned int out_sgs, unsigned int in_sgs, > + struct virtio_crypto_ctrl_request *vc_ctrl_req); > > #endif /* _VIRTIO_CRYPTO_COMMON_H */ > diff --git a/drivers/crypto/virtio/virtio_crypto_core.c > b/drivers/crypto/virtio/virtio_crypto_core.c > index c6f482db0bc0..60490ffa3df1 100644 > --- a/drivers/crypto/virtio/virtio_crypto_core.c > +++ b/drivers/crypto/virtio/virtio_crypto_core.c > @@ -22,6 +22,56 @@ virtcrypto_clear_request(struct virtio_crypto_request > *vc_req) > } > } > > +static void virtio_crypto_ctrlq_callback(struct > +virtio_crypto_ctrl_request *vc_ctrl_req) { > + complete(&vc_ctrl_req->compl); > +} > + > +static void virtcrypto_ctrlq_callback(struct virtqueue *vq) { > + struct virtio_crypto *vcrypto = vq->vdev->priv; > + struct virtio_crypto_ctrl_request *vc_ctrl_req; > + unsigned long flags; > + unsigned int len; > + > + spin_lock_irqsave(&vcrypto->ctrl_lock, flags); > + do { > + virtqueue_disable_cb(vq); > + while ((vc_ctrl_req = virtqueue_get_buf(vq, &len)) != NULL) { > + spin_unlock_irqrestore(&vcrypto->ctrl_lock, flags); > + virtio_crypto_ctrlq_callback(vc_ctrl_req); > + spin_lock_irqsave(&vcrypto->ctrl_lock, flags); > + } > + if (unlikely(virtqueue_is_broken(vq))) > + break; > + } while (!virtqueue_enable_cb(vq)); > + spin_unlock_irqrestore(&vcrypto->ctrl_lock, flags); } > + > +int virtio_crypto_ctrl_vq_request(struct virtio_crypto *vcrypto, struct > scatterlist *sgs[], > + unsigned int out_sgs, unsigned int in_sgs, > + struct virtio_crypto_ctrl_request *vc_ctrl_req) { > + int err; > + unsigned long flags; > + > + init_completion(&vc_ctrl_req->compl); > + > + spin_lock_irqsave(&vcrypto->ctrl_lock, flags); > + err = virtqueue_add_sgs(vcrypto->ctrl_vq, sgs, out_sgs, in_sgs, > vc_ctrl_req, GFP_ATOMIC); > + if (err < 0) { > + spin_unlock_irqrestore(&vcrypto->ctrl_lock, flags); > + return err; > + } > + > + virtqueue_kick(vcrypto->ctrl_vq); > + spin_unlock_irqrestore(&vcrypto->ctrl_lock, flags); > + > + wait_for_completion(&vc_ctrl_req->compl); > + > + return 0; > +} > + > static void virtcrypto_dataq_callback(struct virtqueue *vq) { > struct virtio_crypto *vcrypto = vq->vdev->priv; @@ -73,7 +123,7 @@ > static int virtcrypto_find_vqs(struct virtio_crypto *vi) > goto err_names; > > /* Parameters for control virtqueue */ > - callbacks[total_vqs - 1] = NULL; > + callbacks[total_vqs - 1] = virtcrypto_ctrlq_callback; > names[total_vqs - 1] = "controlq"; > > /* Allocate/initialize parameters for data virtqueues */ diff --git > a/drivers/crypto/virtio/virtio_crypto_skcipher_algs.c > b/drivers/crypto/virtio/virtio_crypto_skcipher_algs.c > index 6aaf0869b211..e553ccadbcbc 100644 > --- a/drivers/crypto/virtio/virtio_crypto_skcipher_algs.c > +++ b/drivers/crypto/virtio/virtio_crypto_skcipher_algs.c > @@ -118,7 +118,6 @@ static int virtio_crypto_alg_skcipher_init_session( > int encrypt) > { > struct scatterlist outhdr, key_sg, inhdr, *sgs[3]; > - unsigned int tmp; > struct virtio_crypto *vcrypto = ctx->vcrypto; > int op = encrypt ? VIRTIO_CRYPTO_OP_ENCRYPT : > VIRTIO_CRYPTO_OP_DECRYPT; > int err; > @@ -170,23 +169,9 @@ static int virtio_crypto_alg_skcipher_init_session( > sg_init_one(&inhdr, input, sizeof(*input)); > sgs[num_out + num_in++] = &inhdr; > > - spin_lock(&vcrypto->ctrl_lock); > - err = virtqueue_add_sgs(vcrypto->ctrl_vq, sgs, num_out, > - num_in, vcrypto, GFP_ATOMIC); > - if (err < 0) { > - spin_unlock(&vcrypto->ctrl_lock); > + err = virtio_crypto_ctrl_vq_request(vcrypto, sgs, num_out, num_in, > vc_ctrl_req); > + if (err < 0) > goto out; > - } > - virtqueue_kick(vcrypto->ctrl_vq); > - > - /* > - * Trapping into the hypervisor, so the request should be > - * handled immediately. > - */ > - while (!virtqueue_get_buf(vcrypto->ctrl_vq, &tmp) && > - !virtqueue_is_broken(vcrypto->ctrl_vq)) > - cpu_relax(); > - spin_unlock(&vcrypto->ctrl_lock); > > if (le32_to_cpu(input->status) != VIRTIO_CRYPTO_OK) { > pr_err("virtio_crypto: Create session failed status: %u\n", @@ > -212,7 +197,6 @@ static int virtio_crypto_alg_skcipher_close_session( > int encrypt) > { > struct scatterlist outhdr, status_sg, *sgs[2]; > - unsigned int tmp; > struct virtio_crypto_destroy_session_req *destroy_session; > struct virtio_crypto *vcrypto = ctx->vcrypto; > int err; > @@ -247,19 +231,9 @@ static int virtio_crypto_alg_skcipher_close_session( > sg_init_one(&status_sg, &ctrl_status->status, > sizeof(ctrl_status->status)); > sgs[num_out + num_in++] = &status_sg; > > - spin_lock(&vcrypto->ctrl_lock); > - err = virtqueue_add_sgs(vcrypto->ctrl_vq, sgs, num_out, > - num_in, vcrypto, GFP_ATOMIC); > - if (err < 0) { > - spin_unlock(&vcrypto->ctrl_lock); > + err = virtio_crypto_ctrl_vq_request(vcrypto, sgs, num_out, num_in, > vc_ctrl_req); > + if (err < 0) > goto out; > - } > - virtqueue_kick(vcrypto->ctrl_vq); > - > - while (!virtqueue_get_buf(vcrypto->ctrl_vq, &tmp) && > - !virtqueue_is_broken(vcrypto->ctrl_vq)) > - cpu_relax(); > - spin_unlock(&vcrypto->ctrl_lock); > > if (ctrl_status->status != VIRTIO_CRYPTO_OK) { > pr_err("virtio_crypto: Close session failed status: %u, session_id: > 0x%llx\n", > -- > 2.20.1
