Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758565Ab3GPAym (ORCPT ); Mon, 15 Jul 2013 20:54:42 -0400 Received: from mail-pd0-f181.google.com ([209.85.192.181]:42934 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758435Ab3GPAyi (ORCPT ); Mon, 15 Jul 2013 20:54:38 -0400 From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy , David Gibson , Benjamin Herrenschmidt , Paul Mackerras , Alexander Graf , Alex Williamson , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org Subject: [PATCH 03/10] vfio: add external user support Date: Tue, 16 Jul 2013 10:53:58 +1000 Message-Id: <1373936045-22653-4-git-send-email-aik@ozlabs.ru> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1373936045-22653-1-git-send-email-aik@ozlabs.ru> References: <1373936045-22653-1-git-send-email-aik@ozlabs.ru> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4714 Lines: 148 VFIO is designed to be used via ioctls on file descriptors returned by VFIO. However in some situations support for an external user is required. The first user is KVM on PPC64 (SPAPR TCE protocol) which is going to use the existing VFIO groups for exclusive access in real/virtual mode on a host to avoid passing map/unmap requests to the user space which would made things pretty slow. The protocol includes: 1. do normal VFIO init operation: - opening a new container; - attaching group(s) to it; - setting an IOMMU driver for a container. When IOMMU is set for a container, all groups in it are considered ready to use by an external user. 2. User space passes a group fd to an external user. The external user calls vfio_group_get_external_user() to verify that: - the group is initialized; - IOMMU is set for it. If both checks passed, vfio_group_get_external_user() increments the container user counter to prevent the VFIO group from disposal before KVM exits. 3. The external user calls vfio_external_user_iommu_id() to know an IOMMU ID. PPC64 KVM uses it to link logical bus number (LIOBN) with IOMMU ID. 4. When the external KVM finishes, it calls vfio_group_put_external_user() to release the VFIO group. This call decrements the container user counter. Everything gets released. The "vfio: Limit group opens" patch is also required for the consistency. Signed-off-by: Alexey Kardashevskiy --- Changes: 2013/07/11: * added vfio_group_get()/vfio_group_put() * protocol description changed Signed-off-by: Alexey Kardashevskiy --- drivers/vfio/vfio.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/vfio.h | 7 ++++++ 2 files changed, 69 insertions(+) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index c488da5..58b034b 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -1370,6 +1370,68 @@ static const struct file_operations vfio_device_fops = { }; /** + * External user API, exported by symbols to be linked dynamically. + * + * The protocol includes: + * 1. do normal VFIO init operation: + * - opening a new container; + * - attaching group(s) to it; + * - setting an IOMMU driver for a container. + * When IOMMU is set for a container, all groups in it are + * considered ready to use by an external user. + * + * 2. User space passes a group fd to an external user. + * The external user calls vfio_group_get_external_user() + * to verify that: + * - the group is initialized; + * - IOMMU is set for it. + * If both checks passed, vfio_group_get_external_user() + * increments the container user counter to prevent + * the VFIO group from disposal before KVM exits. + * + * 3. The external user calls vfio_external_user_iommu_id() + * to know an IOMMU ID. + * + * 4. When the external KVM finishes, it calls + * vfio_group_put_external_user() to release the VFIO group. + * This call decrements the container user counter. + */ +struct vfio_group *vfio_group_get_external_user(struct file *filep) +{ + struct vfio_group *group = filep->private_data; + + if (filep->f_op != &vfio_group_fops) + return ERR_PTR(-EINVAL); + + if (!atomic_inc_not_zero(&group->container_users)) + return ERR_PTR(-EINVAL); + + if (!group->container->iommu_driver || + !vfio_group_viable(group)) { + atomic_dec(&group->container_users); + return ERR_PTR(-EINVAL); + } + + vfio_group_get(group); + + return group; +} +EXPORT_SYMBOL_GPL(vfio_group_get_external_user); + +void vfio_group_put_external_user(struct vfio_group *group) +{ + vfio_group_put(group); + vfio_group_try_dissolve_container(group); +} +EXPORT_SYMBOL_GPL(vfio_group_put_external_user); + +int vfio_external_user_iommu_id(struct vfio_group *group) +{ + return iommu_group_id(group->iommu_group); +} +EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id); + +/** * Module/class support */ static char *vfio_devnode(struct device *dev, umode_t *mode) diff --git a/include/linux/vfio.h b/include/linux/vfio.h index ac8d488..24579a0 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -90,4 +90,11 @@ extern void vfio_unregister_iommu_driver( TYPE tmp; \ offsetof(TYPE, MEMBER) + sizeof(tmp.MEMBER); }) \ +/* + * External user API + */ +extern struct vfio_group *vfio_group_get_external_user(struct file *filep); +extern void vfio_group_put_external_user(struct vfio_group *group); +extern int vfio_external_user_iommu_id(struct vfio_group *group); + #endif /* VFIO_H */ -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/