[PATCH v14 16/16] vfio/type1: Introduce MSI_RESV capability
From: Eric Auger
Date: Wed Oct 12 2016 - 09:25:07 EST
This patch allows the user-space to retrieve the MSI reserved region
requirements, if any. The implementation is based on capability chains,
now also added to VFIO_IOMMU_GET_INFO.
The returned info comprises the size and the alignment requirements
In case the userspace must provide the IOVA aperture, we currently report
a size/alignment based on all the doorbells registered by the host kernel.
This may exceed the actual needs.
Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
---
v13 -> v14:
- new capability struct
- change the padding in vfio_iommu_type1_info
v11 -> v12:
- msi_doorbell_pages was renamed msi_doorbell_calc_pages
v9 -> v10:
- move cap_offset after iova_pgsizes
- replace __u64 alignment by __u32 order
- introduce __u32 flags in vfio_iommu_type1_info_cap_msi_geometry and
fix alignment
- call msi-doorbell API to compute the size/alignment
v8 -> v9:
- use iommu_msi_supported flag instead of programmable
- replace IOMMU_INFO_REQUIRE_MSI_MAP flag by a more sophisticated
capability chain, reporting the MSI geometry
v7 -> v8:
- use iommu_domain_msi_geometry
v6 -> v7:
- remove the computation of the number of IOVA pages to be provisionned.
This number depends on the domain/group/device topology which can
dynamically change. Let's rely instead rely on an arbitrary max depending
on the system
v4 -> v5:
- move msi_info and ret declaration within the conditional code
v3 -> v4:
- replace former vfio_domains_require_msi_mapping by
more complex computation of MSI mapping requirements, especially the
number of pages to be provided by the user-space.
- reword patch title
RFC v1 -> v1:
- derived from
[RFC PATCH 3/6] vfio: Extend iommu-info to return MSIs automap state
- renamed allow_msi_reconfig into require_msi_mapping
- fixed VFIO_IOMMU_GET_INFO
---
drivers/vfio/vfio_iommu_type1.c | 67 ++++++++++++++++++++++++++++++++++++++++-
include/uapi/linux/vfio.h | 20 +++++++++++-
2 files changed, 85 insertions(+), 2 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c18ba9d..6775da3 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -1147,6 +1147,46 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
return ret;
}
+static int msi_resv_caps(struct vfio_iommu *iommu, struct vfio_info_cap *caps)
+{
+ struct iommu_domain_msi_resv msi_resv = {.size = 0, .alignment = 0};
+ struct vfio_iommu_type1_info_cap_msi_resv *cap;
+ struct vfio_info_cap_header *header;
+ struct iommu_domain_msi_resv iter;
+ struct vfio_domain *d;
+
+ mutex_lock(&iommu->lock);
+
+ list_for_each_entry(d, &iommu->domain_list, next) {
+ if (iommu_domain_get_attr(d->domain,
+ DOMAIN_ATTR_MSI_RESV, &iter))
+ continue;
+ if (iter.size > msi_resv.size) {
+ msi_resv.size = iter.size;
+ msi_resv.alignment = iter.alignment;
+ }
+ }
+
+ if (!msi_resv.size)
+ return 0;
+
+ mutex_unlock(&iommu->lock);
+
+ header = vfio_info_cap_add(caps, sizeof(*cap),
+ VFIO_IOMMU_TYPE1_INFO_CAP_MSI_RESV, 1);
+
+ if (IS_ERR(header))
+ return PTR_ERR(header);
+
+ cap = container_of(header, struct vfio_iommu_type1_info_cap_msi_resv,
+ header);
+
+ cap->alignment = msi_resv.alignment;
+ cap->size = msi_resv.size;
+
+ return 0;
+}
+
static long vfio_iommu_type1_ioctl(void *iommu_data,
unsigned int cmd, unsigned long arg)
{
@@ -1168,8 +1208,10 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
}
} else if (cmd == VFIO_IOMMU_GET_INFO) {
struct vfio_iommu_type1_info info;
+ struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
+ int ret;
- minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);
+ minsz = offsetofend(struct vfio_iommu_type1_info, cap_offset);
if (copy_from_user(&info, (void __user *)arg, minsz))
return -EFAULT;
@@ -1181,6 +1223,29 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
+ ret = msi_resv_caps(iommu, &caps);
+ if (ret)
+ return ret;
+
+ if (caps.size) {
+ info.flags |= VFIO_IOMMU_INFO_CAPS;
+ if (info.argsz < sizeof(info) + caps.size) {
+ info.argsz = sizeof(info) + caps.size;
+ info.cap_offset = 0;
+ } else {
+ vfio_info_cap_shift(&caps, sizeof(info));
+ if (copy_to_user((void __user *)arg +
+ sizeof(info), caps.buf,
+ caps.size)) {
+ kfree(caps.buf);
+ return -EFAULT;
+ }
+ info.cap_offset = sizeof(info);
+ }
+
+ kfree(caps.buf);
+ }
+
return copy_to_user((void __user *)arg, &info, minsz) ?
-EFAULT : 0;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 4a9dbc2..e34a9a6 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -488,7 +488,23 @@ struct vfio_iommu_type1_info {
__u32 argsz;
__u32 flags;
#define VFIO_IOMMU_INFO_PGSIZES (1 << 0) /* supported page sizes info */
- __u64 iova_pgsizes; /* Bitmap of supported page sizes */
+#define VFIO_IOMMU_INFO_CAPS (1 << 1) /* Info supports caps */
+ __u64 iova_pgsizes; /* Bitmap of supported page sizes */
+ __u32 cap_offset; /* Offset within info struct of first cap */
+ __u32 __resv;
+};
+
+/*
+ * The MSI_RESV capability allows to report the MSI reserved IOVA requirements:
+ * In case this capability is supported, the userspace must provide an IOVA
+ * window characterized by @size and @alignment using VFIO_IOMMU_MAP_DMA with
+ * RESERVED_MSI_IOVA flag.
+ */
+#define VFIO_IOMMU_TYPE1_INFO_CAP_MSI_RESV 1
+struct vfio_iommu_type1_info_cap_msi_resv {
+ struct vfio_info_cap_header header;
+ __u64 size; /* requested IOVA aperture size in bytes */
+ __u64 alignment; /* requested byte alignment of the window */
};
#define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
@@ -503,6 +519,8 @@ struct vfio_iommu_type1_info {
* IOVA region that will be used on some platforms to map the host MSI frames.
* In that specific case, vaddr is ignored. Once registered, an MSI reserved
* IOVA region stays until the container is closed.
+ * The requirement for provisioning such reserved IOVA range can be checked by
+ * checking the VFIO_IOMMU_TYPE1_INFO_CAP_MSI_RESV capability.
*/
struct vfio_iommu_type1_dma_map {
__u32 argsz;
--
1.9.1