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

Jacob Pan
2019-04-26T21:00:31Z

On Thu, 25 Apr 2019 12:04:01 +0200
Auger Eric <eric.auger@redhat.com> wrote:

> 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?
Well, I think we still want the full uint range - 1(INVALID_IOASID).
Intel uses 20bit but I think SMMUs use 32 bits for streamID? I
should just check
if (pasid == INVALID_IOASID) {

> > 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?
right, should be separate.

> > }
> > 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?
Yes, it should be in separate patch.

VT-d will always support device with full 20bit PASID range only, we
should fail svm_bind if device pasid_max < 20. It has to be
included in this series otherwise we could have assigned a device with <
20 PASID and our virtual command can only handle full 20bit.

> > + 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

[Jacob Pan]