From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57510) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZJxR2-0007QO-0N for qemu-devel@nongnu.org; Tue, 28 Jul 2015 01:28:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZJxQx-0001Kr-HQ for qemu-devel@nongnu.org; Tue, 28 Jul 2015 01:28:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34342) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZJxQx-0001Kd-AR for qemu-devel@nongnu.org; Tue, 28 Jul 2015 01:28:11 -0400 Message-ID: <55B712E5.8080306@redhat.com> Date: Tue, 28 Jul 2015 13:28:05 +0800 From: Jason Wang MIME-Version: 1.0 References: <1437615403-13554-1-git-send-email-marcandre.lureau@redhat.com> <1437615403-13554-5-git-send-email-marcandre.lureau@redhat.com> In-Reply-To: <1437615403-13554-5-git-send-email-marcandre.lureau@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH RFC 4/6] vhost: alloc shareable log List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?B?TWFyYy1BbmRyw6kgTHVyZWF1?= , qemu-devel@nongnu.org Cc: thibaut.collet@6wind.com, mst@redhat.com, haifeng.lin@huawei.com, pbonzini@redhat.com On 07/23/2015 09:36 AM, Marc-Andr=C3=A9 Lureau wrote: > If the backend is of type VHOST_BACKEND_TYPE_USER, allocate > shareable memory. > > Note: vhost_log_get() can use a global "vhost_log" that can be shared b= y > several vhost devices. We may want instead a common shareable log and a > common non-shareable one. > > Signed-off-by: Marc-Andr=C3=A9 Lureau > --- > hw/virtio/vhost.c | 42 +++++++++++++++++++++++++++++++++------= --- > include/hw/virtio/vhost.h | 3 ++- > 2 files changed, 35 insertions(+), 10 deletions(-) > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > index 2712c6f..12dd644 100644 > --- a/hw/virtio/vhost.c > +++ b/hw/virtio/vhost.c > @@ -286,20 +286,34 @@ static uint64_t vhost_get_log_size(struct vhost_d= ev *dev) > } > return log_size; > } > -static struct vhost_log *vhost_log_alloc(uint64_t size) > + > +static struct vhost_log *vhost_log_alloc(uint64_t size, bool share) > { > - struct vhost_log *log =3D g_malloc0(sizeof *log + size * sizeof(*(= log->log))); > + struct vhost_log *log; > + uint64_t logsize =3D size * sizeof(*(log->log)); > + int fd =3D -1; > + > + log =3D g_new0(struct vhost_log, 1); > + if (share) { > + log->log =3D qemu_memfd_alloc("vhost-log", logsize, > + F_SEAL_GROW|F_SEAL_SHRINK|F_SEAL_S= EAL, &fd); > + memset(log->log, 0, logsize); > + } else { > + log->log =3D g_malloc0(logsize); > + } > =20 > log->size =3D size; > log->refcnt =3D 1; > + log->fd =3D fd; > =20 > return log; > } > =20 > -static struct vhost_log *vhost_log_get(uint64_t size) > +static struct vhost_log *vhost_log_get(uint64_t size, bool share) > { > - if (!vhost_log || vhost_log->size !=3D size) { > - vhost_log =3D vhost_log_alloc(size); > + if (!vhost_log || vhost_log->size !=3D size || > + (share && vhost_log->fd =3D=3D -1)) { > + vhost_log =3D vhost_log_alloc(size, share); > } else { > ++vhost_log->refcnt; > } > @@ -324,21 +338,30 @@ static void vhost_log_put(struct vhost_dev *dev, = bool sync) > if (vhost_log =3D=3D log) { > vhost_log =3D NULL; > } > + > + if (log->fd =3D=3D -1) { > + g_free(log->log); > + } else { > + qemu_memfd_free(log->log, log->size * sizeof(*(log->log)), > + log->fd); > + } > g_free(log); > } > } > =20 > static inline void vhost_dev_log_resize(struct vhost_dev* dev, uint64_= t size) > { > - struct vhost_log *log =3D vhost_log_get(size); > + bool share =3D dev->vhost_ops->backend_type =3D=3D VHOST_BACKEND_T= YPE_USER; > + struct vhost_log *log =3D vhost_log_get(size, share); > uint64_t log_base =3D (uintptr_t)log->log; > int r; > =20 > - r =3D dev->vhost_ops->vhost_call(dev, VHOST_SET_LOG_BASE, &log_bas= e); > - assert(r >=3D 0); > vhost_log_put(dev, true); > dev->log =3D log; > dev->log_size =3D size; > + > + r =3D dev->vhost_ops->vhost_call(dev, VHOST_SET_LOG_BASE, &log_bas= e); > + assert(r >=3D 0); > } Why this change is needed? > =20 > static int vhost_verify_ring_mappings(struct vhost_dev *dev, > @@ -1136,9 +1159,10 @@ int vhost_dev_start(struct vhost_dev *hdev, Virt= IODevice *vdev) > =20 > if (hdev->log_enabled) { > uint64_t log_base; > + bool share =3D hdev->vhost_ops->backend_type =3D=3D VHOST_BACK= END_TYPE_USER; > =20 > hdev->log_size =3D vhost_get_log_size(hdev); > - hdev->log =3D vhost_log_get(hdev->log_size); > + hdev->log =3D vhost_log_get(hdev->log_size, share); > log_base =3D (uintptr_t)hdev->log->log; > r =3D hdev->vhost_ops->vhost_call(hdev, VHOST_SET_LOG_BASE, > hdev->log_size ? &log_base : N= ULL); > diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h > index 6467c73..ab1dcac 100644 > --- a/include/hw/virtio/vhost.h > +++ b/include/hw/virtio/vhost.h > @@ -31,7 +31,8 @@ typedef unsigned long vhost_log_chunk_t; > struct vhost_log { > unsigned long long size; > int refcnt; > - vhost_log_chunk_t log[0]; > + int fd; > + vhost_log_chunk_t *log; > }; > =20 > struct vhost_memory;