Re: [PATCH 01/11] iommu/vt-d: Add pasid private data helpers
From: Jacob Pan
Date: Fri May 21 2021 - 17:23:04 EST
Hi BaoLu,
On Thu, 20 May 2021 11:15:21 +0800, Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
wrote:
> We are about to use iommu_sva_alloc/free_pasid() helpers in iommu core.
> That means the pasid life cycle will be managed by iommu core. Use a
> local array to save the per pasid private data instead of attaching it
> the real pasid.
>
I feel a little awkward to have a separate xarray for storing per IOASID
data. Seems duplicated.
Jason suggested in another thread that we can make ioasid_data public
and embeded in struct intel_svm, then we can get rid of the private data
pointer. ioasid_find will return the ioasid_data, then we can retrieve the
private data with container_of.
roughly,
struct intel_svm {
...
struct ioasid_data;
};
struct ioasid_data {
ioasid_t id;
refcount_t refs;
struct mm_struct *mm;
};
This can be a separate patch/effort if it make sense to you.
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> ---
> drivers/iommu/intel/svm.c | 62 ++++++++++++++++++++++++++-------------
> 1 file changed, 41 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index 5165cea90421..82b0627ad7e7 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -17,6 +17,7 @@
> #include <linux/dmar.h>
> #include <linux/interrupt.h>
> #include <linux/mm_types.h>
> +#include <linux/xarray.h>
> #include <linux/ioasid.h>
> #include <asm/page.h>
> #include <asm/fpu/api.h>
> @@ -28,6 +29,23 @@ static void intel_svm_drain_prq(struct device *dev,
> u32 pasid);
> #define PRQ_ORDER 0
>
> +static DEFINE_XARRAY_ALLOC(pasid_private_array);
> +static int pasid_private_add(ioasid_t pasid, void *priv)
> +{
> + return xa_alloc(&pasid_private_array, &pasid, priv,
> + XA_LIMIT(pasid, pasid), GFP_ATOMIC);
> +}
> +
> +static void pasid_private_remove(ioasid_t pasid)
> +{
> + xa_erase(&pasid_private_array, pasid);
> +}
> +
> +static void *pasid_private_find(ioasid_t pasid)
> +{
> + return xa_load(&pasid_private_array, pasid);
> +}
> +
> int intel_svm_enable_prq(struct intel_iommu *iommu)
> {
> struct page *pages;
> @@ -224,7 +242,7 @@ static int pasid_to_svm_sdev(struct device *dev,
> unsigned int pasid, if (pasid == INVALID_IOASID || pasid >= PASID_MAX)
> return -EINVAL;
>
> - svm = ioasid_find(NULL, pasid, NULL);
> + svm = pasid_private_find(pasid);
> if (IS_ERR(svm))
> return PTR_ERR(svm);
>
> @@ -334,7 +352,7 @@ int intel_svm_bind_gpasid(struct iommu_domain
> *domain, struct device *dev, svm->gpasid = data->gpasid;
> svm->flags |= SVM_FLAG_GUEST_PASID;
> }
> - ioasid_set_data(data->hpasid, svm);
> + pasid_private_add(data->hpasid, svm);
> INIT_LIST_HEAD_RCU(&svm->devs);
> mmput(svm->mm);
> }
> @@ -388,7 +406,7 @@ int intel_svm_bind_gpasid(struct iommu_domain
> *domain, struct device *dev, list_add_rcu(&sdev->list, &svm->devs);
> out:
> if (!IS_ERR_OR_NULL(svm) && list_empty(&svm->devs)) {
> - ioasid_set_data(data->hpasid, NULL);
> + pasid_private_remove(data->hpasid);
> kfree(svm);
> }
>
> @@ -431,7 +449,7 @@ int intel_svm_unbind_gpasid(struct device *dev, u32
> pasid)
> * the unbind, IOMMU driver will get
> notified
> * and perform cleanup.
> */
> - ioasid_set_data(pasid, NULL);
> + pasid_private_remove(pasid);
> kfree(svm);
> }
> }
> @@ -547,8 +565,7 @@ intel_svm_bind_mm(struct device *dev, unsigned int
> flags, svm = kzalloc(sizeof(*svm), GFP_KERNEL);
> if (!svm) {
> ret = -ENOMEM;
> - kfree(sdev);
> - goto out;
> + goto sdev_err;
> }
>
> if (pasid_max > intel_pasid_max_id)
> @@ -556,13 +573,16 @@ intel_svm_bind_mm(struct device *dev, unsigned int
> flags,
> /* Do not use PASID 0, reserved for RID to PASID */
> svm->pasid = ioasid_alloc(NULL, PASID_MIN,
> - pasid_max - 1, svm);
> + pasid_max - 1, NULL);
> if (svm->pasid == INVALID_IOASID) {
> - kfree(svm);
> - kfree(sdev);
> ret = -ENOSPC;
> - goto out;
> + goto svm_err;
> }
> +
> + ret = pasid_private_add(svm->pasid, svm);
> + if (ret)
> + goto pasid_err;
> +
> svm->notifier.ops = &intel_mmuops;
> svm->mm = mm;
> svm->flags = flags;
> @@ -571,12 +591,8 @@ intel_svm_bind_mm(struct device *dev, unsigned int
> flags, ret = -ENOMEM;
> if (mm) {
> ret = mmu_notifier_register(&svm->notifier, mm);
> - if (ret) {
> - ioasid_put(svm->pasid);
> - kfree(svm);
> - kfree(sdev);
> - goto out;
> - }
> + if (ret)
> + goto priv_err;
> }
>
> spin_lock_irqsave(&iommu->lock, iflags);
> @@ -590,8 +606,13 @@ intel_svm_bind_mm(struct device *dev, unsigned int
> flags, if (ret) {
> if (mm)
> mmu_notifier_unregister(&svm->notifier,
> mm); +priv_err:
> + pasid_private_remove(svm->pasid);
> +pasid_err:
> ioasid_put(svm->pasid);
> +svm_err:
> kfree(svm);
> +sdev_err:
> kfree(sdev);
> goto out;
> }
> @@ -614,10 +635,8 @@ intel_svm_bind_mm(struct device *dev, unsigned int
> flags, (cpu_feature_enabled(X86_FEATURE_LA57) ?
> PASID_FLAG_FL5LP : 0));
> spin_unlock_irqrestore(&iommu->lock, iflags);
> - if (ret) {
> - kfree(sdev);
> - goto out;
> - }
> + if (ret)
> + goto sdev_err;
> }
> list_add_rcu(&sdev->list, &svm->devs);
> success:
> @@ -670,6 +689,7 @@ static int intel_svm_unbind_mm(struct device *dev,
> u32 pasid) load_pasid(svm->mm, PASID_DISABLED);
> }
> list_del(&svm->list);
> + pasid_private_remove(svm->pasid);
> /* We mandate that no page faults may be
> outstanding
> * for the PASID when
> intel_svm_unbind_mm() is called.
> * If that is not obeyed, subtle errors
> will happen. @@ -924,7 +944,7 @@ static irqreturn_t prq_event_thread(int
> irq, void *d) }
> if (!svm || svm->pasid != req->pasid) {
> rcu_read_lock();
> - svm = ioasid_find(NULL, req->pasid, NULL);
> + svm = pasid_private_find(req->pasid);
> /* It *can't* go away, because the driver is not
> permitted
> * to unbind the mm while any page faults are
> outstanding.
> * So we only need RCU to protect the internal
> idr code. */
Thanks,
Jacob