From addb665924f39f01dc1d6b2de3d21ebbc1232de6 Mon Sep 17 00:00:00 2001 From: Nicolin Chen Date: Mon, 17 Jul 2023 15:12:09 -0300 Subject: [PATCH] iommu: Introduce a new iommu_group_replace_domain() API qemu has a need to replace the translations associated with a domain when the guest does large-scale operations like switching between an IDENTITY domain and, say, dma-iommu.c. Currently, it does this by replacing all the mappings in a single domain, but this is very inefficient and means that domains have to be per-device rather than per-translation. Provide a high-level API to allow replacements of one domain with another. This is similar to a detach/attach cycle except it doesn't force the group to go to the blocking domain in-between. By removing this forced blocking domain the iommu driver has the opportunity to implement a non-disruptive replacement of the domain to the greatest extent its hardware allows. This allows the qemu emulation of the vIOMMU to be more complete, as real hardware often has a non-distruptive replacement capability. It could be possible to address this by simply removing the protection from the iommu_attach_group(), but it is not so clear if that is safe for the few users. Thus, add a new API to serve this new purpose. All drivers are already required to support changing between active UNMANAGED domains when using their attach_dev ops. This API is expected to be used only by IOMMUFD, so add to the iommu-priv header and mark it as IOMMUFD_INTERNAL. Link: https://lore.kernel.org/r/13-v8-6659224517ea+532-iommufd_alloc_jgg@nvidia.com Suggested-by: Jason Gunthorpe Reviewed-by: Kevin Tian Reviewed-by: Lu Baolu Tested-by: Nicolin Chen Signed-off-by: Nicolin Chen Signed-off-by: Jason Gunthorpe --- drivers/iommu/iommu-priv.h | 10 ++++++++++ drivers/iommu/iommu.c | 27 +++++++++++++++++++++++++++ 2 files changed, 37 insertions(+) create mode 100644 drivers/iommu/iommu-priv.h diff --git a/drivers/iommu/iommu-priv.h b/drivers/iommu/iommu-priv.h new file mode 100644 index 0000000..7c8011b --- /dev/null +++ b/drivers/iommu/iommu-priv.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __LINUX_IOMMU_PRIV_H +#define __LINUX_IOMMU_PRIV_H + +#include + +int iommu_group_replace_domain(struct iommu_group *group, + struct iommu_domain *new_domain); + +#endif /* __LINUX_IOMMU_PRIV_H */ diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index b0804fb..5876196 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -34,6 +34,7 @@ #include #include "dma-iommu.h" +#include "iommu-priv.h" #include "iommu-sva.h" @@ -2114,6 +2115,32 @@ int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group) } EXPORT_SYMBOL_GPL(iommu_attach_group); +/** + * iommu_group_replace_domain - replace the domain that a group is attached to + * @new_domain: new IOMMU domain to replace with + * @group: IOMMU group that will be attached to the new domain + * + * This API allows the group to switch domains without being forced to go to + * the blocking domain in-between. + * + * If the currently attached domain is a core domain (e.g. a default_domain), + * it will act just like the iommu_attach_group(). + */ +int iommu_group_replace_domain(struct iommu_group *group, + struct iommu_domain *new_domain) +{ + int ret; + + if (!new_domain) + return -EINVAL; + + mutex_lock(&group->mutex); + ret = __iommu_group_set_domain(group, new_domain); + mutex_unlock(&group->mutex); + return ret; +} +EXPORT_SYMBOL_NS_GPL(iommu_group_replace_domain, IOMMUFD_INTERNAL); + static int __iommu_device_set_domain(struct iommu_group *group, struct device *dev, struct iommu_domain *new_domain, -- 2.7.4