SVM fixes for Linux 4.5

Minor register size and interrupt acknowledgement fixes which only showed
 up in testing on newer hardware, but mostly a fix to the MM refcount
 handling to prevent a recursive refcount issue when mmap() is used on
 the file descriptor associated with a bound PASID.
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Merge tag 'for-linus-20160216' of git://git.infradead.org/intel-iommu

Pull IOMMU SVM fixes from David Woodhouse:
 "Minor register size and interrupt acknowledgement fixes which only
  showed up in testing on newer hardware, but mostly a fix to the MM
  refcount handling to prevent a recursive refcount issue when mmap() is
  used on the file descriptor associated with a bound PASID"

* tag 'for-linus-20160216' of git://git.infradead.org/intel-iommu:
  iommu/vt-d: Clear PPR bit to ensure we get more page request interrupts
  iommu/vt-d: Fix 64-bit accesses to 32-bit DMAR_GSTS_REG
  iommu/vt-d: Fix mm refcounting to hold mm_count not mm_users
This commit is contained in:
Linus Torvalds 2016-02-16 08:04:06 -08:00
commit 87bbcfdecc
4 changed files with 36 additions and 8 deletions

View File

@ -1353,7 +1353,7 @@ void dmar_disable_qi(struct intel_iommu *iommu)
raw_spin_lock_irqsave(&iommu->register_lock, flags);
sts = dmar_readq(iommu->reg + DMAR_GSTS_REG);
sts = readl(iommu->reg + DMAR_GSTS_REG);
if (!(sts & DMA_GSTS_QIES))
goto end;

View File

@ -249,12 +249,30 @@ static void intel_flush_pasid_dev(struct intel_svm *svm, struct intel_svm_dev *s
static void intel_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
struct intel_svm *svm = container_of(mn, struct intel_svm, notifier);
struct intel_svm_dev *sdev;
/* This might end up being called from exit_mmap(), *before* the page
* tables are cleared. And __mmu_notifier_release() will delete us from
* the list of notifiers so that our invalidate_range() callback doesn't
* get called when the page tables are cleared. So we need to protect
* against hardware accessing those page tables.
*
* We do it by clearing the entry in the PASID table and then flushing
* the IOTLB and the PASID table caches. This might upset hardware;
* perhaps we'll want to point the PASID to a dummy PGD (like the zero
* page) so that we end up taking a fault that the hardware really
* *has* to handle gracefully without affecting other processes.
*/
svm->iommu->pasid_table[svm->pasid].val = 0;
wmb();
rcu_read_lock();
list_for_each_entry_rcu(sdev, &svm->devs, list) {
intel_flush_pasid_dev(svm, sdev, svm->pasid);
intel_flush_svm_range_dev(svm, sdev, 0, -1, 0, !svm->mm);
}
rcu_read_unlock();
/* There's no need to do any flush because we can't get here if there
* are any devices left anyway. */
WARN_ON(!list_empty(&svm->devs));
}
static const struct mmu_notifier_ops intel_mmuops = {
@ -379,7 +397,6 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
goto out;
}
iommu->pasid_table[svm->pasid].val = (u64)__pa(mm->pgd) | 1;
mm = NULL;
} else
iommu->pasid_table[svm->pasid].val = (u64)__pa(init_mm.pgd) | 1 | (1ULL << 11);
wmb();
@ -442,11 +459,11 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
kfree_rcu(sdev, rcu);
if (list_empty(&svm->devs)) {
mmu_notifier_unregister(&svm->notifier, svm->mm);
idr_remove(&svm->iommu->pasid_idr, svm->pasid);
if (svm->mm)
mmput(svm->mm);
mmu_notifier_unregister(&svm->notifier, svm->mm);
/* 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.
@ -507,6 +524,10 @@ static irqreturn_t prq_event_thread(int irq, void *d)
struct intel_svm *svm = NULL;
int head, tail, handled = 0;
/* Clear PPR bit before reading head/tail registers, to
* ensure that we get a new interrupt if needed. */
writel(DMA_PRS_PPR, iommu->reg + DMAR_PRS_REG);
tail = dmar_readq(iommu->reg + DMAR_PQT_REG) & PRQ_RING_MASK;
head = dmar_readq(iommu->reg + DMAR_PQH_REG) & PRQ_RING_MASK;
while (head != tail) {
@ -551,6 +572,9 @@ static irqreturn_t prq_event_thread(int irq, void *d)
* any faults on kernel addresses. */
if (!svm->mm)
goto bad_req;
/* If the mm is already defunct, don't handle faults. */
if (!atomic_inc_not_zero(&svm->mm->mm_users))
goto bad_req;
down_read(&svm->mm->mmap_sem);
vma = find_extend_vma(svm->mm, address);
if (!vma || address < vma->vm_start)
@ -567,6 +591,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
result = QI_RESP_SUCCESS;
invalid:
up_read(&svm->mm->mmap_sem);
mmput(svm->mm);
bad_req:
/* Accounting for major/minor faults? */
rcu_read_lock();

View File

@ -629,7 +629,7 @@ static void iommu_disable_irq_remapping(struct intel_iommu *iommu)
raw_spin_lock_irqsave(&iommu->register_lock, flags);
sts = dmar_readq(iommu->reg + DMAR_GSTS_REG);
sts = readl(iommu->reg + DMAR_GSTS_REG);
if (!(sts & DMA_GSTS_IRES))
goto end;

View File

@ -235,6 +235,9 @@ static inline void dmar_writeq(void __iomem *addr, u64 val)
/* low 64 bit */
#define dma_frcd_page_addr(d) (d & (((u64)-1) << PAGE_SHIFT))
/* PRS_REG */
#define DMA_PRS_PPR ((u32)1)
#define IOMMU_WAIT_OP(iommu, offset, op, cond, sts) \
do { \
cycles_t start_time = get_cycles(); \