lkml.org 
[lkml]   [2020]   [Apr]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v11 05/10] iommu/vt-d: Add bind guest PASID support
From
Date
Hi Jacob,

On 4/3/20 8:42 PM, 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
>
> ---
> v11: Fixed locking, avoid duplicated paging mode check, added helper to
> free svm if device list is empty. Use rate limited error message since
> the bind gpasid call comes from user space.
> ---
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> ---
> drivers/iommu/intel-iommu.c | 4 +
> drivers/iommu/intel-svm.c | 206 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/intel-iommu.h | 8 +-
> include/linux/intel-svm.h | 17 ++++
> 4 files changed, 234 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index c0dadec5a6b3..94c7993dac6a 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -6178,6 +6178,10 @@ 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 d7f2a5358900..7cf711318b87 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -226,6 +226,212 @@ static LIST_HEAD(global_svm_list);
> list_for_each_entry((sdev), &(svm)->devs, list) \
> if ((d) != (sdev)->dev) {} else
>
> +
> +static inline void intel_svm_free_if_empty(struct intel_svm *svm, u64 pasid)
> +{
> + if (list_empty(&svm->devs)) {
> + ioasid_set_data(pasid, NULL);
> + kfree(svm);
> + }
> +}
> +
> +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 *dmar_domain;
> + 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)
> + 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;
> + } else {
> + return -ENOTSUPP;
> + }
> +
> + /*
> + * We only check host PASID range, we have no knowledge to check
> + * guest PASID range.
> + */
> + if (data->hpasid <= 0 || data->hpasid >= PASID_MAX)
> + return -EINVAL;
> +
> + dmar_domain = to_dmar_domain(domain);
> +
> + mutex_lock(&pasid_mutex);
> + svm = ioasid_find(NULL, data->hpasid, NULL);
> + if (IS_ERR(svm)) {
> + ret = PTR_ERR(svm);
> + goto out;
> + }
> +
> + if (svm) {
> + /*
> + * If we found svm for the PASID, there must be at
> + * least one device bond, otherwise svm should be freed.
> + */
> + if (WARN_ON(list_empty(&svm->devs))) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + for_each_svm_dev(sdev, svm, dev) {
> + /* In case of multiple sub-devices of the same pdev
> + * assigned, we should allow multiple bind calls with
> + * the same PASID and pdev.
> + */
> + sdev->users++;
What if this is not an mdev device. Is it also allowed?
> + goto out;
> + }
> + } 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. We can drop the following line once VFIO and IOASID set
> + * check is in place.
> + */
> + 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);
> + mmput(svm->mm);
> + }
> + sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
> + if (!sdev) {
> + /*
> + * If this is a new PASID that never bond to a device, then
> + * the device list must be empty which indicates struct svm
> + * was allocated in this function.
> + */
> + intel_svm_free_if_empty(svm, data->hpasid);
> + 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_ratelimited(dev, "Failed to enable PASID capability\n");
> + kfree(sdev);
> + intel_svm_free_if_empty(svm, data->hpasid);
> + goto out;
> + }
> +
> + /*
> + * PASID table is per device for better security. Therefore, for
> + * each bind of a new device even with an existing PASID, we need to
> + * call the nested mode setup function here.
> + */
> + spin_lock(&iommu->lock);
> + ret = intel_pasid_setup_nested(iommu,
> + dev,
> + (pgd_t *)data->gpgd,
> + data->hpasid,
> + &data->vtd,
> + dmar_domain,
> + data->addr_width);
> + if (ret) {
> + dev_err_ratelimited(dev, "Failed to set up PASID %llu in nested mode, Err %d\n",
> + data->hpasid, ret);
> + /*
> + * PASID entry should be in cleared state if nested mode
> + * set up failed. So we only need to clear IOASID tracking
> + * data such that free call will succeed.
> + */
> + kfree(sdev);
> + intel_svm_free_if_empty(svm, data->hpasid);
> + spin_unlock(&iommu->lock);
> + goto out;
> + }
> + spin_unlock(&iommu->lock);
> + 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)
> +{
This function's code looks very very similar to intel_svm_unbind_mm()
besides to the mmu_notifier_unregister and the ioasid_free(). Don't we
have means to factorize the code by checking the SVM_FLAG_GUEST_MODE flag?

Please could you explain again what does happen if the guest process
dies/VM dies. How do we make sure the svm get freed. I fail to
understand the whole picture at the moment as you cannot fully rely on
the userspace to call unbind_gpasid.
> + struct intel_iommu *iommu = intel_svm_device_to_iommu(dev);
> + struct intel_svm_dev *sdev;
> + struct intel_svm *svm;
> + int ret = -EINVAL;
> +
> + if (WARN_ON(!iommu))
> + return -EINVAL;
> +
> + mutex_lock(&pasid_mutex);
> + svm = ioasid_find(NULL, pasid, NULL);
> + if (!svm) {
> + ret = -EINVAL;
As per the discussion on the VFIO series, shall we return an error in
that case? Same below?
> + goto out;
> + }
> +
> + if (IS_ERR(svm)) {
> + ret = PTR_ERR(svm);
> + goto out;
> + }
> +
> + for_each_svm_dev(sdev, svm, dev) {
> + ret = 0;
> + sdev->users--;
> + if (!sdev->users) {
> + list_del_rcu(&sdev->list);
> + intel_pasid_tear_down_entry(iommu, dev, svm->pasid);
intel_svm_unbind_mm() calls intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
Don't we need to flush the (DEV-)IOTLBs as well?
> + /* 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)) {
> + /*
> + * We do not free the IOASID here in that
> + * IOMMU driver did not allocate it.
s/in/as?
> + * Unlike native SVM, IOASID for guest use was
> + * allocated prior to the bind call.> + * In any case, if the free call comes before
> + * the unbind, IOMMU driver will get notified
> + * and perform cleanup.
> + */
> + ioasid_set_data(pasid, NULL);
> + kfree(svm);
> + }
nit: you may use intel_svm_free_if_empty()
> + }
> + break;
> + }
> +out:
> + mutex_unlock(&pasid_mutex);
> +
nit : spare new line
> + 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 6da03f627ba3..a5bd53cf190c 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -706,7 +706,9 @@ struct dmar_domain *find_domain(struct device *dev);
> extern void intel_svm_check(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 {
> @@ -723,9 +725,13 @@ 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 d7c403d0dd27..c19690937540 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)
> +/*
> + * 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)
>
> #ifdef CONFIG_INTEL_IOMMU_SVM
>
>
Thanks

Eric

\
 
 \ /
  Last update: 2020-04-09 09:42    [W:0.255 / U:0.248 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site