[RFC 17/20] iommu/iommufd: Report iova range to userspace

From: Liu Yi L
Date: Sun Sep 19 2021 - 02:44:55 EST

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[HACK. will fix in v2]

IOVA range is critical info for userspace to manage DMA for an I/O address
space. This patch reports the valid iova range info of a given device.

Due to aforementioned hack, this info comes from the hacked vfio type1
driver. To follow the same format in vfio, we also introduce a cap chain
format in IOMMU_DEVICE_GET_INFO to carry the iova range info.

Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
---
drivers/iommu/iommu.c | 2 ++
drivers/iommu/iommufd/iommufd.c | 41 +++++++++++++++++++++++++++-
drivers/vfio/vfio_iommu_type1.c | 47 ++++++++++++++++++++++++++++++---
include/linux/vfio.h | 2 ++
include/uapi/linux/iommu.h | 3 +++
5 files changed, 90 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b6178997aef1..44bba346ab52 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2755,6 +2755,7 @@ void iommu_get_resv_regions(struct device *dev, struct list_head *list)
if (ops && ops->get_resv_regions)
ops->get_resv_regions(dev, list);
}
+EXPORT_SYMBOL_GPL(iommu_get_resv_regions);

void iommu_put_resv_regions(struct device *dev, struct list_head *list)
{
@@ -2763,6 +2764,7 @@ void iommu_put_resv_regions(struct device *dev, struct list_head *list)
if (ops && ops->put_resv_regions)
ops->put_resv_regions(dev, list);
}
+EXPORT_SYMBOL_GPL(iommu_put_resv_regions);

/**
* generic_iommu_put_resv_regions - Reserved region driver helper
diff --git a/drivers/iommu/iommufd/iommufd.c b/drivers/iommu/iommufd/iommufd.c
index 25373a0e037a..cbf5e30062a6 100644
--- a/drivers/iommu/iommufd/iommufd.c
+++ b/drivers/iommu/iommufd/iommufd.c
@@ -19,6 +19,7 @@
#include <linux/iommufd.h>
#include <linux/xarray.h>
#include <asm-generic/bug.h>
+#include <linux/vfio.h>

/* Per iommufd */
struct iommufd_ctx {
@@ -298,6 +299,38 @@ iommu_find_device_from_cookie(struct iommufd_ctx *ictx, u64 dev_cookie)
return dev;
}

+static int iommu_device_add_cap_chain(struct device *dev, unsigned long arg,
+ struct iommu_device_info *info)
+{
+ struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
+ int ret;
+
+ ret = vfio_device_add_iova_cap(dev, &caps);
+ if (ret)
+ return ret;
+
+ if (caps.size) {
+ info->flags |= IOMMU_DEVICE_INFO_CAPS;
+
+ if (info->argsz < sizeof(*info) + caps.size) {
+ info->argsz = sizeof(*info) + caps.size;
+ } else {
+ vfio_info_cap_shift(&caps, sizeof(*info));
+ if (copy_to_user((void __user *)arg +
+ sizeof(*info), caps.buf,
+ caps.size)) {
+ kfree(caps.buf);
+ info->flags &= ~IOMMU_DEVICE_INFO_CAPS;
+ return -EFAULT;
+ }
+ info->cap_offset = sizeof(*info);
+ }
+
+ kfree(caps.buf);
+ }
+ return 0;
+}
+
static void iommu_device_build_info(struct device *dev,
struct iommu_device_info *info)
{
@@ -324,8 +357,9 @@ static int iommufd_get_device_info(struct iommufd_ctx *ictx,
struct iommu_device_info info;
unsigned long minsz;
struct device *dev;
+ int ret;

- minsz = offsetofend(struct iommu_device_info, addr_width);
+ minsz = offsetofend(struct iommu_device_info, cap_offset);

if (copy_from_user(&info, (void __user *)arg, minsz))
return -EFAULT;
@@ -341,6 +375,11 @@ static int iommufd_get_device_info(struct iommufd_ctx *ictx,

iommu_device_build_info(dev, &info);

+ info.cap_offset = 0;
+ ret = iommu_device_add_cap_chain(dev, arg, &info);
+ if (ret)
+ pr_info_ratelimited("No cap chain added, error %d\n", ret);
+
return copy_to_user((void __user *)arg, &info, minsz) ? -EFAULT : 0;
}

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index c1c6bc803d94..28c1699aed6b 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2963,15 +2963,15 @@ static int vfio_iommu_iova_add_cap(struct vfio_info_cap *caps,
return 0;
}

-static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
- struct vfio_info_cap *caps)
+static int vfio_iova_list_build_caps(struct list_head *iova_list,
+ struct vfio_info_cap *caps)
{
struct vfio_iommu_type1_info_cap_iova_range *cap_iovas;
struct vfio_iova *iova;
size_t size;
int iovas = 0, i = 0, ret;

- list_for_each_entry(iova, &iommu->iova_list, list)
+ list_for_each_entry(iova, iova_list, list)
iovas++;

if (!iovas) {
@@ -2990,7 +2990,7 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,

cap_iovas->nr_iovas = iovas;

- list_for_each_entry(iova, &iommu->iova_list, list) {
+ list_for_each_entry(iova, iova_list, list) {
cap_iovas->iova_ranges[i].start = iova->start;
cap_iovas->iova_ranges[i].end = iova->end;
i++;
@@ -3002,6 +3002,45 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
return ret;
}

+static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
+ struct vfio_info_cap *caps)
+{
+ return vfio_iova_list_build_caps(&iommu->iova_list, caps);
+}
+
+/* HACK: called by /dev/iommu core to build iova range cap for a device */
+int vfio_device_add_iova_cap(struct device *dev, struct vfio_info_cap *caps)
+{
+ u64 awidth;
+ dma_addr_t aperture_end;
+ LIST_HEAD(iova);
+ LIST_HEAD(dev_resv_regions);
+ int ret;
+
+ ret = iommu_device_get_info(dev, IOMMU_DEV_INFO_ADDR_WIDTH, &awidth);
+ if (ret)
+ return ret;
+
+ /* FIXME: needs to use geometry info reported by iommu core. */
+ aperture_end = ((dma_addr_t)1) << awidth;
+
+ ret = vfio_iommu_iova_insert(&iova, 0, aperture_end);
+ if (ret)
+ return ret;
+
+ iommu_get_resv_regions(dev, &dev_resv_regions);
+ ret = vfio_iommu_resv_exclude(&iova, &dev_resv_regions);
+ if (ret)
+ goto out;
+
+ ret = vfio_iova_list_build_caps(&iova, caps);
+out:
+ vfio_iommu_iova_free(&iova);
+ iommu_put_resv_regions(dev, &dev_resv_regions);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vfio_device_add_iova_cap);
+
static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu,
struct vfio_info_cap *caps)
{
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index d904ee5a68cc..605b8e828be4 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -212,6 +212,8 @@ extern int vfio_info_add_capability(struct vfio_info_cap *caps,
extern int vfio_set_irqs_validate_and_prepare(struct vfio_irq_set *hdr,
int num_irqs, int max_irq_type,
size_t *data_size);
+extern int vfio_device_add_iova_cap(struct device *dev,
+ struct vfio_info_cap *caps);

struct pci_dev;
#if IS_ENABLED(CONFIG_VFIO_SPAPR_EEH)
diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
index 49731be71213..f408ad3c8ade 100644
--- a/include/uapi/linux/iommu.h
+++ b/include/uapi/linux/iommu.h
@@ -68,6 +68,7 @@
* +---------------+------------+
* ...
* @addr_width: the address width of supported I/O address spaces.
+ * @cap_offset: Offset within info struct of first cap
*
* Availability: after device is bound to iommufd
*/
@@ -77,9 +78,11 @@ struct iommu_device_info {
#define IOMMU_DEVICE_INFO_ENFORCE_SNOOP (1 << 0) /* IOMMU enforced snoop */
#define IOMMU_DEVICE_INFO_PGSIZES (1 << 1) /* supported page sizes */
#define IOMMU_DEVICE_INFO_ADDR_WIDTH (1 << 2) /* addr_wdith field valid */
+#define IOMMU_DEVICE_INFO_CAPS (1 << 3) /* info supports cap chain */
__u64 dev_cookie;
__u64 pgsize_bitmap;
__u32 addr_width;
+ __u32 cap_offset;
};

#define IOMMU_DEVICE_GET_INFO _IO(IOMMU_TYPE, IOMMU_BASE + 1)
--
2.25.1

Next message: Liu Yi L: "[RFC 18/20] iommu/iommufd: Add IOMMU_[UN]MAP_DMA on IOASID"
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