Re: [PATCH v7 09/11] iommu/vt-d: Add bind guest PASID support
From: Lu Baolu
Date: Fri Oct 25 2019 - 22:04:12 EST
Hi,
On 10/25/19 3:55 AM, Jacob Pan wrote:
When supporting guest SVA with emulated IOMMU, the guest PASID
table is shadowed in VMM. Updates to guest vIOMMU PASID table
will result in PASID cache flush which will be passed down to
the host as bind guest PASID calls.
For the SL page tables, it will be harvested from device's
default domain (request w/o PASID), or aux domain in case of
mediated device.
.-------------. .---------------------------.
| vIOMMU | | Guest process CR3, FL only|
| | '---------------------------'
.----------------/
| PASID Entry |--- PASID cache flush -
'-------------' |
| | V
| | CR3 in GPA
'-------------'
Guest
------| Shadow |--------------------------|--------
v v v
Host
.-------------. .----------------------.
| pIOMMU | | Bind FL for GVA-GPA |
| | '----------------------'
.----------------/ |
| PASID Entry | V (Nested xlate)
'----------------\.------------------------------.
| | |SL for GPA-HPA, default domain|
| | '------------------------------'
'-------------'
Where:
- FL = First level/stage one page tables
- SL = Second level/stage two page tables
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxxxxxxxx>
---
drivers/iommu/intel-iommu.c | 4 +
drivers/iommu/intel-svm.c | 184 ++++++++++++++++++++++++++++++++++++++++++++
include/linux/intel-iommu.h | 8 +-
include/linux/intel-svm.h | 17 ++++
4 files changed, 212 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index acd1ac787d8b..5fab32fbc4b4 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -6026,6 +6026,10 @@ const struct iommu_ops intel_iommu_ops = {
.dev_disable_feat = intel_iommu_dev_disable_feat,
.is_attach_deferred = intel_iommu_is_attach_deferred,
.pgsize_bitmap = INTEL_IOMMU_PGSIZES,
+#ifdef CONFIG_INTEL_IOMMU_SVM
+ .sva_bind_gpasid = intel_svm_bind_gpasid,
+ .sva_unbind_gpasid = intel_svm_unbind_gpasid,
+#endif
};
static void quirk_iommu_igfx(struct pci_dev *dev)
diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index a18b02a9709d..ae13a310cf96 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -216,6 +216,190 @@ static LIST_HEAD(global_svm_list);
list_for_each_entry(sdev, &svm->devs, list) \
if (dev == sdev->dev) \
Add an indent tab please.
+int intel_svm_bind_gpasid(struct iommu_domain *domain,
+ struct device *dev,
+ struct iommu_gpasid_bind_data *data)
+{
+ struct intel_iommu *iommu = intel_svm_device_to_iommu(dev);
+ struct dmar_domain *ddomain;
+ struct intel_svm_dev *sdev;
+ struct intel_svm *svm;
+ int ret = 0;
+
+ if (WARN_ON(!iommu) || !data)
+ return -EINVAL;
+
+ if (data->version != IOMMU_GPASID_BIND_VERSION_1 ||
+ data->format != IOMMU_PASID_FORMAT_INTEL_VTD)
Alignment should match open parenthesis.
Run "scripts/checkpatch.pl --strict" for all in this patch. I will
ignore others.
+ return -EINVAL;
+
+ if (dev_is_pci(dev)) {
+ /* VT-d supports devices with full 20 bit PASIDs only */
+ if (pci_max_pasids(to_pci_dev(dev)) != PASID_MAX)
+ return -EINVAL;
+ }
+
+ /*
+ * We only check host PASID range, we have no knowledge to check
+ * guest PASID range nor do we use the guest PASID.
+ */
+ if (data->hpasid <= 0 || data->hpasid >= PASID_MAX)
+ return -EINVAL;
+
+ ddomain = to_dmar_domain(domain);
+ /* REVISIT:
+ * Sanity check adddress width and paging mode support
s/adddress/address/g
+ * width matching in two dimensions:
+ * 1. paging mode CPU <= IOMMU
+ * 2. address width Guest <= Host.
+ */ > + mutex_lock(&pasid_mutex);
+ svm = ioasid_find(NULL, data->hpasid, NULL);
+ if (IS_ERR(svm)) {
+ ret = PTR_ERR(svm);
+ goto out;
+ }
A blank line looks better.
+ if (svm) {
+ /*
+ * If we found svm for the PASID, there must be at
+ * least one device bond, otherwise svm should be freed.
+ */
+ BUG_ON(list_empty(&svm->devs));
Avoid crashing kernel, use WARN_ON() instead.
if (WARN_ON(list_empty(&svm->devs))) {
ret = -EINVAL;
goto out;
}
+
+ for_each_svm_dev(svm, dev) {
+ /* In case of multiple sub-devices of the same pdev assigned, we should
Make line shorter. Not over 80 characters.
The same for other lines.
+ * allow multiple bind calls with the same PASID and pdev.
+ */
+ sdev->users++;
+ goto out;
+ }
I remember I ever pointed this out before. But I forgot how we addressed
it. So forgive me if this has been addressed.
What if we have a valid bound svm but @dev doesn't belong to it
(a.k.a. @dev not in svm->devs list)?
+ } else {
+ /* We come here when PASID has never been bond to a device. */
+ svm = kzalloc(sizeof(*svm), GFP_KERNEL);
+ if (!svm) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ /* REVISIT: upper layer/VFIO can track host process that bind the PASID.
+ * ioasid_set = mm might be sufficient for vfio to check pasid VMM
+ * ownership.
+ */
+ svm->mm = get_task_mm(current);
+ svm->pasid = data->hpasid;
+ if (data->flags & IOMMU_SVA_GPASID_VAL) {
+ svm->gpasid = data->gpasid;
+ svm->flags |= SVM_FLAG_GUEST_PASID;
+ }
+ ioasid_set_data(data->hpasid, svm);
+ INIT_LIST_HEAD_RCU(&svm->devs);
+ INIT_LIST_HEAD(&svm->list);
+
+ mmput(svm->mm);
+ }
A blank line, please.
+ sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
+ if (!sdev) {
+ if (list_empty(&svm->devs))
+ kfree(svm);
This is dangerous. This might leave a wild pointer bound with gpasid.
+ ret = -ENOMEM;
+ goto out;
+ }
+ sdev->dev = dev;
+ sdev->users = 1;
+
+ /* Set up device context entry for PASID if not enabled already */
+ ret = intel_iommu_enable_pasid(iommu, sdev->dev);
+ if (ret) {
+ dev_err(dev, "Failed to enable PASID capability\n");
+ kfree(sdev);
+ goto out;
+ }
+
+ /*
+ * For guest bind, we need to set up PASID table entry as follows:
+ * - FLPM matches guest paging mode
+ * - turn on nested mode
+ * - SL guest address width matching
+ */
+ ret = intel_pasid_setup_nested(iommu,
+ dev,
+ (pgd_t *)data->gpgd,
+ data->hpasid,
+ &data->vtd,
+ ddomain,
+ data->addr_width);
+ if (ret) {
+ dev_err(dev, "Failed to set up PASID %llu in nested mode, Err %d\n",
+ data->hpasid, ret);
This error handling is insufficient. You should at least:
1. free sdev
2. if list_empty(&svm->devs)
unbound the svm from gpasid
free svm
The same for above error handling. Add a branch for error recovery at
the end of function might help here.
+ kfree(sdev);
+ goto out;
+ }
+ svm->flags |= SVM_FLAG_GUEST_MODE;
+
+ init_rcu_head(&sdev->rcu);
+ list_add_rcu(&sdev->list, &svm->devs);
+ out:
+ mutex_unlock(&pasid_mutex);
+ return ret;
+}
+
+int intel_svm_unbind_gpasid(struct device *dev, int pasid)
+{
+ struct intel_svm_dev *sdev;
+ struct intel_iommu *iommu;
+ struct intel_svm *svm;
+ int ret = -EINVAL;
+
+ mutex_lock(&pasid_mutex);
+ iommu = intel_svm_device_to_iommu(dev);
+ if (!iommu)
+ goto out;
Make it symmetrical with bind function.
if (WARN_ON(!iommu))
goto out;
+
+ svm = ioasid_find(NULL, pasid, NULL);
+ if (IS_ERR_OR_NULL(svm)) {
+ ret = PTR_ERR(svm);
If svm == NULL, this function will return success. This is not expected,
right?
+ goto out;
+ }
+
+ for_each_svm_dev(svm, dev) {
+ ret = 0;
+ sdev->users--;
+ if (!sdev->users) {
+ list_del_rcu(&sdev->list);
+ intel_pasid_tear_down_entry(iommu, dev, svm->pasid);
+ /* TODO: Drain in flight PRQ for the PASID since it
+ * may get reused soon, we don't want to
+ * confuse with its previous life.
+ * intel_svm_drain_prq(dev, pasid);
+ */
+ kfree_rcu(sdev, rcu);
+
+ if (list_empty(&svm->devs)) {
+ list_del(&svm->list);
+ kfree(svm);
+ /*
+ * We do not free PASID here until explicit call
+ * from VFIO to free. The PASID life cycle
+ * management is largely tied to VFIO management
+ * of assigned device life cycles. In case of
+ * guest exit without a explicit free PASID call,
+ * the responsibility lies in VFIO layer to free
+ * the PASIDs allocated for the guest.
+ * For security reasons, VFIO has to track the
+ * PASID ownership per guest anyway to ensure
+ * that PASID allocated by one guest cannot be
+ * used by another.
+ */
+ ioasid_set_data(pasid, NULL);
Exchange order. First unbind svm from gpasid and then free svm.
+ }
+ }
+ break;
+ }
+ out:
+ mutex_unlock(&pasid_mutex);
+
+ return ret;
+}
+
int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_ops *ops)
{
struct intel_iommu *iommu = intel_svm_device_to_iommu(dev);
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 3dba6ad3e9ad..6c74c71b1ebf 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -673,7 +673,9 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct device *dev);
int intel_svm_init(struct intel_iommu *iommu);
extern int intel_svm_enable_prq(struct intel_iommu *iommu);
extern int intel_svm_finish_prq(struct intel_iommu *iommu);
-
+extern int intel_svm_bind_gpasid(struct iommu_domain *domain,
+ struct device *dev, struct iommu_gpasid_bind_data *data);
+extern int intel_svm_unbind_gpasid(struct device *dev, int pasid);
struct svm_dev_ops;
struct intel_svm_dev {
@@ -690,9 +692,13 @@ struct intel_svm_dev {
struct intel_svm {
struct mmu_notifier notifier;
struct mm_struct *mm;
+
struct intel_iommu *iommu;
int flags;
int pasid;
+ int gpasid; /* Guest PASID in case of vSVA bind with non-identity host
+ * to guest PASID mapping.
+ */
struct list_head devs;
struct list_head list;
};
diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h
index 94f047a8a845..a2c189ad0b01 100644
--- a/include/linux/intel-svm.h
+++ b/include/linux/intel-svm.h
@@ -44,6 +44,23 @@ struct svm_dev_ops {
* do such IOTLB flushes automatically.
*/
#define SVM_FLAG_SUPERVISOR_MODE (1<<1)
+/*
+ * The SVM_FLAG_GUEST_MODE flag is used when a guest process bind to a device.
+ * In this case the mm_struct is in the guest kernel or userspace, its life
+ * cycle is managed by VMM and VFIO layer. For IOMMU driver, this API provides
+ * means to bind/unbind guest CR3 with PASIDs allocated for a device.
+ */
+#define SVM_FLAG_GUEST_MODE (1<<2)
How about keeping this aligned with top by adding a tab?
BIT macro is preferred. Hence, make it BIT(1), BIT(2), BIT(3) is
preferred.
+/*
+ * The SVM_FLAG_GUEST_PASID flag is used when a guest has its own PASID space,
+ * which requires guest and host PASID translation at both directions. We keep
+ * track of guest PASID in order to provide lookup service to device drivers.
+ * One such example is a physical function (PF) driver that supports mediated
+ * device (mdev) assignment. Guest programming of mdev configuration space can
+ * only be done with guest PASID, therefore PF driver needs to find the matching
+ * host PASID to program the real hardware.
+ */
+#define SVM_FLAG_GUEST_PASID (1<<3)
Ditto.
Best regards,
baolu