[RFC PATCH v2 4/6] vfio: VFIO_IOMMU_ENABLE_IOPF
Shenming Lu
lushenming at huawei.com
Tue Mar 9 06:22:05 GMT 2021
Since enabling IOPF for devices may lead to a slow ramp up of
performance, we add an VFIO_IOMMU_ENABLE_IOPF ioctl to make it
configurable. And the IOPF enabling of a VFIO device includes
setting IOMMU_DEV_FEAT_IOPF and registering the VFIO page fault
handler. Note that VFIO_IOMMU_DISABLE_IOPF is not supported
since there may be inflight page faults when disabling.
Signed-off-by: Shenming Lu <lushenming at huawei.com>
---
drivers/vfio/vfio_iommu_type1.c | 139 +++++++++++++++++++++++++++++++-
include/uapi/linux/vfio.h | 6 ++
2 files changed, 142 insertions(+), 3 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 167d52c1468b..3997473be4a7 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -71,6 +71,7 @@ struct vfio_iommu {
struct rb_root dma_list;
struct blocking_notifier_head notifier;
struct mmu_notifier mn;
+ struct mm_struct *mm;
unsigned int dma_avail;
unsigned int vaddr_invalid_count;
uint64_t pgsize_bitmap;
@@ -81,6 +82,7 @@ struct vfio_iommu {
bool dirty_page_tracking;
bool pinned_page_dirty_scope;
bool container_open;
+ bool iopf_enabled;
};
struct vfio_domain {
@@ -2278,6 +2280,62 @@ static void vfio_iommu_iova_insert_copy(struct vfio_iommu *iommu,
list_splice_tail(iova_copy, iova);
}
+static int dev_disable_iopf(struct device *dev, void *data)
+{
+ int *enabled_dev_cnt = data;
+
+ if (enabled_dev_cnt && *enabled_dev_cnt <= 0)
+ return -1;
+
+ iommu_unregister_device_fault_handler(dev);
+ iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_IOPF);
+
+ if (enabled_dev_cnt)
+ (*enabled_dev_cnt)--;
+
+ return 0;
+}
+
+static int dev_enable_iopf(struct device *dev, void *data)
+{
+ int *enabled_dev_cnt = data;
+ struct iommu_domain *domain;
+ int nested;
+ u32 flags;
+ int ret;
+
+ ret = iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_IOPF);
+ if (ret)
+ return ret;
+
+ domain = iommu_get_domain_for_dev(dev);
+ if (!domain) {
+ ret = -ENODEV;
+ goto out_disable;
+ }
+
+ ret = iommu_domain_get_attr(domain, DOMAIN_ATTR_NESTING, &nested);
+ if (ret)
+ goto out_disable;
+
+ if (nested)
+ flags = IOPF_REPORT_NESTED | IOPF_REPORT_NESTED_L2_CONCERNED;
+ else
+ flags = IOPF_REPORT_FLAT;
+
+ ret = iommu_register_device_fault_handler(dev,
+ vfio_iommu_dev_fault_handler, flags, dev);
+ if (ret)
+ goto out_disable;
+
+ (*enabled_dev_cnt)++;
+ return 0;
+
+out_disable:
+ iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_IOPF);
+ return ret;
+}
+
static int vfio_iommu_type1_attach_group(void *iommu_data,
struct iommu_group *iommu_group)
{
@@ -2291,6 +2349,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
struct iommu_domain_geometry geo;
LIST_HEAD(iova_copy);
LIST_HEAD(group_resv_regions);
+ int iopf_enabled_dev_cnt = 0;
mutex_lock(&iommu->lock);
@@ -2368,6 +2427,13 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
if (ret)
goto out_domain;
+ if (iommu->iopf_enabled) {
+ ret = iommu_group_for_each_dev(iommu_group, &iopf_enabled_dev_cnt,
+ dev_enable_iopf);
+ if (ret)
+ goto out_detach;
+ }
+
/* Get aperture info */
iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY, &geo);
@@ -2449,9 +2515,11 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
vfio_test_domain_fgsp(domain);
/* replay mappings on new domains */
- ret = vfio_iommu_replay(iommu, domain);
- if (ret)
- goto out_detach;
+ if (!iommu->iopf_enabled) {
+ ret = vfio_iommu_replay(iommu, domain);
+ if (ret)
+ goto out_detach;
+ }
if (resv_msi) {
ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
@@ -2482,6 +2550,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
iommu_domain_free(domain->domain);
vfio_iommu_iova_free(&iova_copy);
vfio_iommu_resv_free(&group_resv_regions);
+ iommu_group_for_each_dev(iommu_group, &iopf_enabled_dev_cnt,
+ dev_disable_iopf);
out_free:
kfree(domain);
kfree(group);
@@ -2643,6 +2713,10 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
if (!group)
continue;
+ if (iommu->iopf_enabled)
+ iommu_group_for_each_dev(iommu_group, NULL,
+ dev_disable_iopf);
+
vfio_iommu_detach_group(domain, group);
update_dirty_scope = !group->pinned_page_dirty_scope;
list_del(&group->next);
@@ -2761,6 +2835,11 @@ static void vfio_iommu_type1_release(void *iommu_data)
vfio_iommu_iova_free(&iommu->iova_list);
+ if (iommu->iopf_enabled) {
+ mmu_notifier_unregister(&iommu->mn, iommu->mm);
+ mmdrop(iommu->mm);
+ }
+
kfree(iommu);
}
@@ -3164,6 +3243,58 @@ static const struct mmu_notifier_ops vfio_iommu_type1_mn_ops = {
.invalidate_range = mn_invalidate_range,
};
+static int vfio_iommu_type1_enable_iopf(struct vfio_iommu *iommu)
+{
+ struct vfio_domain *d;
+ struct vfio_group *g;
+ int enabled_dev_cnt = 0;
+ int ret;
+
+ if (!current->mm)
+ return -ENODEV;
+
+ mutex_lock(&iommu->lock);
+
+ mmgrab(current->mm);
+ iommu->mm = current->mm;
+ iommu->mn.ops = &vfio_iommu_type1_mn_ops;
+ ret = mmu_notifier_register(&iommu->mn, current->mm);
+ if (ret)
+ goto out_drop;
+
+ list_for_each_entry(d, &iommu->domain_list, next) {
+ list_for_each_entry(g, &d->group_list, next) {
+ ret = iommu_group_for_each_dev(g->iommu_group,
+ &enabled_dev_cnt, dev_enable_iopf);
+ if (ret)
+ goto out_unwind;
+ }
+ }
+
+ iommu->iopf_enabled = true;
+ goto out_unlock;
+
+out_unwind:
+ list_for_each_entry(d, &iommu->domain_list, next) {
+ list_for_each_entry(g, &d->group_list, next) {
+ if (iommu_group_for_each_dev(g->iommu_group,
+ &enabled_dev_cnt, dev_disable_iopf))
+ goto out_unregister;
+ }
+ }
+
+out_unregister:
+ mmu_notifier_unregister(&iommu->mn, current->mm);
+
+out_drop:
+ iommu->mm = NULL;
+ mmdrop(current->mm);
+
+out_unlock:
+ mutex_unlock(&iommu->lock);
+ return ret;
+}
+
static long vfio_iommu_type1_ioctl(void *iommu_data,
unsigned int cmd, unsigned long arg)
{
@@ -3180,6 +3311,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
return vfio_iommu_type1_unmap_dma(iommu, arg);
case VFIO_IOMMU_DIRTY_PAGES:
return vfio_iommu_type1_dirty_pages(iommu, arg);
+ case VFIO_IOMMU_ENABLE_IOPF:
+ return vfio_iommu_type1_enable_iopf(iommu);
default:
return -ENOTTY;
}
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 8ce36c1d53ca..5497036bebdc 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1208,6 +1208,12 @@ struct vfio_iommu_type1_dirty_bitmap_get {
#define VFIO_IOMMU_DIRTY_PAGES _IO(VFIO_TYPE, VFIO_BASE + 17)
+/*
+ * IOCTL to enable IOPF for the container.
+ * Called right after VFIO_SET_IOMMU.
+ */
+#define VFIO_IOMMU_ENABLE_IOPF _IO(VFIO_TYPE, VFIO_BASE + 18)
+
/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
/*
--
2.19.1
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