Re: [PATCH v2 11/19] iommu/vt-d: Replace Intel specific PASID allocator with IOASID

Auger Eric
2019-04-25T10:04:01Z

Hi Jacob,

On 4/24/19 1:31 AM, Jacob Pan wrote:
> Make use of generic IOASID code to manage PASID allocation,
> free, and lookup.
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> drivers/iommu/Kconfig | 1 +
> drivers/iommu/intel-iommu.c | 9 ++++-----
> drivers/iommu/intel-pasid.c | 36 ------------------------------------
> drivers/iommu/intel-svm.c | 41 ++++++++++++++++++++++++-----------------
> 4 files changed, 29 insertions(+), 58 deletions(-)
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 6f07f3b..7f92009 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -204,6 +204,7 @@ config INTEL_IOMMU_SVM
> bool "Support for Shared Virtual Memory with Intel IOMMU"
> depends on INTEL_IOMMU && X86
> select PCI_PASID
> + select IOASID
> select MMU_NOTIFIER
> help
> Shared Virtual Memory (SVM) provides a facility for devices
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index ec6f22d..785330a 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -5153,7 +5153,7 @@ static void auxiliary_unlink_device(struct dmar_domain *domain,
> domain->auxd_refcnt--;
>
> if (!domain->auxd_refcnt && domain->default_pasid > 0)
> - intel_pasid_free_id(domain->default_pasid);
> + ioasid_free(domain->default_pasid);
> }
>
> static int aux_domain_add_dev(struct dmar_domain *domain,
> @@ -5171,9 +5171,8 @@ static int aux_domain_add_dev(struct dmar_domain *domain,
> if (domain->default_pasid <= 0) {
> int pasid;
>
> - pasid = intel_pasid_alloc_id(domain, PASID_MIN,
> - pci_max_pasids(to_pci_dev(dev)),
> - GFP_KERNEL);
> + pasid = ioasid_alloc(NULL, PASID_MIN, pci_max_pasids(to_pci_dev(dev)) - 1,
> + domain);
> if (pasid <= 0) {
ioasid_t is a uint and returns INVALID_IOASID on error. Wouldn't it be
simpler to make ioasid_alloc return an int?
> pr_err("Can't allocate default pasid\n");
> return -ENODEV;
> @@ -5210,7 +5209,7 @@ static int aux_domain_add_dev(struct dmar_domain *domain,
> spin_unlock(&iommu->lock);
> spin_unlock_irqrestore(&device_domain_lock, flags);
> if (!domain->auxd_refcnt && domain->default_pasid > 0)
> - intel_pasid_free_id(domain->default_pasid);
> + ioasid_free(domain->default_pasid);
>
> return ret;
> }
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index 5b1d3be..d339e8f 100644
> --- a/drivers/iommu/intel-pasid.c
> +++ b/drivers/iommu/intel-pasid.c
> @@ -26,42 +26,6 @@
> */
> static DEFINE_SPINLOCK(pasid_lock);
> u32 intel_pasid_max_id = PASID_MAX;
> -static DEFINE_IDR(pasid_idr);
> -
> -int intel_pasid_alloc_id(void *ptr, int start, int end, gfp_t gfp)
> -{
> - int ret, min, max;
> -
> - min = max_t(int, start, PASID_MIN);
> - max = min_t(int, end, intel_pasid_max_id);
> -
> - WARN_ON(in_interrupt());
> - idr_preload(gfp);
> - spin_lock(&pasid_lock);
> - ret = idr_alloc(&pasid_idr, ptr, min, max, GFP_ATOMIC);
> - spin_unlock(&pasid_lock);
> - idr_preload_end();
> -
> - return ret;
> -}
> -
> -void intel_pasid_free_id(int pasid)
> -{
> - spin_lock(&pasid_lock);
> - idr_remove(&pasid_idr, pasid);
> - spin_unlock(&pasid_lock);
> -}
> -
> -void *intel_pasid_lookup_id(int pasid)
> -{
> - void *p;
> -
> - spin_lock(&pasid_lock);
> - p = idr_find(&pasid_idr, pasid);
> - spin_unlock(&pasid_lock);
> -
> - return p;
> -}
>
> int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int *pasid)
> {
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> index 8f87304..8fff212 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -25,6 +25,7 @@
> #include <linux/dmar.h>
> #include <linux/interrupt.h>
> #include <linux/mm_types.h>
> +#include <linux/ioasid.h>
> #include <asm/page.h>
>
> #include "intel-pasid.h"
> @@ -211,7 +212,9 @@ static void intel_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
> rcu_read_lock();
> list_for_each_entry_rcu(sdev, &svm->devs, list) {
> intel_pasid_tear_down_entry(svm->iommu, sdev->dev, svm->pasid);
> - intel_flush_svm_range_dev(svm, sdev, 0, -1, 0, !svm->mm)> + /* for emulated iommu, PASID cache invalidation implies IOTLB/DTLB */
> + if (!cap_caching_mode(svm->iommu->cap))
> + intel_flush_svm_range_dev(svm, sdev, 0, -1, 0, !svm->mm);
This change is not documented in the commit message. Isn't it a separate
fix?
> }
> rcu_read_unlock();
>
> @@ -332,16 +335,15 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
> if (pasid_max > intel_pasid_max_id)
> pasid_max = intel_pasid_max_id;
>
> - /* Do not use PASID 0 in caching mode (virtualised IOMMU) */
> - ret = intel_pasid_alloc_id(svm,
> - !!cap_caching_mode(iommu->cap),
> - pasid_max - 1, GFP_KERNEL);
> - if (ret < 0) {
> + /* Do not use PASID 0, reserved for RID to PASID */
> + svm->pasid = ioasid_alloc(NULL, PASID_MIN,
> + pasid_max - 1, svm);
the fact the max is not decremented compared to intel_pasid_alloc_id
looks suspicious to me (exclusive to inclusive move). I guess it is a
fix in which case this may be documented in the commit msg?
> + if (svm->pasid == INVALID_IOASID) {
> kfree(svm);
> kfree(sdev);
> + ret = ENOSPC;
-ENOSPC
> goto out;
> }
> - svm->pasid = ret;
> svm->notifier.ops = &intel_mmuops;
> svm->mm = mm;
> svm->flags = flags;
> @@ -351,7 +353,7 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
> if (mm) {
> ret = mmu_notifier_register(&svm->notifier, mm);
> if (ret) {
> - intel_pasid_free_id(svm->pasid);
> + ioasid_free(svm->pasid);
> kfree(svm);
> kfree(sdev);
> goto out;
> @@ -367,7 +369,7 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
> if (ret) {
> if (mm)
> mmu_notifier_unregister(&svm->notifier, mm);
> - intel_pasid_free_id(svm->pasid);
> + ioasid_free(svm->pasid);
the ioasid_free returned value never is tested. Is it useful?
> kfree(svm);
> kfree(sdev);
> goto out;
> @@ -400,7 +402,12 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
> if (!iommu)
> goto out;
>
> - svm = intel_pasid_lookup_id(pasid);
> + svm = ioasid_find(NULL, pasid, NULL);
> + if (IS_ERR(svm)) {
> + ret = PTR_ERR(svm);
> + goto out;
> + }
> +
> if (!svm)
> goto out;
>
> @@ -422,7 +429,7 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
> kfree_rcu(sdev, rcu);
>
> if (list_empty(&svm->devs)) {
> - intel_pasid_free_id(svm->pasid);
> + ioasid_free(svm->pasid);
> if (svm->mm)
> mmu_notifier_unregister(&svm->notifier, svm->mm);
>
> @@ -457,10 +464,11 @@ int intel_svm_is_pasid_valid(struct device *dev, int pasid)
> if (!iommu)
> goto out;
>
> - svm = intel_pasid_lookup_id(pasid);
> - if (!svm)
> + svm = ioasid_find(NULL, pasid, NULL);
> + if (IS_ERR(svm)) {
> + ret = PTR_ERR(svm);
> goto out;
> -
> + }
> /* init_mm is used in this case */
> if (!svm->mm)
> ret = 1;
> @@ -567,13 +575,12 @@ static irqreturn_t prq_event_thread(int irq, void *d)
>
> if (!svm || svm->pasid != req->pasid) {
> rcu_read_lock();
> - svm = intel_pasid_lookup_id(req->pasid);
> + svm = ioasid_find(NULL, req->pasid, NULL);
> /* 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. */
> rcu_read_unlock();
> -
> - if (!svm) {
> + if (IS_ERR(svm) || !svm) {
> pr_err("%s: Page request for invalid PASID %d: %08llx %08llx\n",
> iommu->name, req->pasid, ((unsigned long long *)req)[0],
> ((unsigned long long *)req)[1]);
>

Thanks

Eric