Messages in this thread | | | Subject | Re: [PATCH v2 2/7] iommu/vt-d: Multiple descriptors per qi_submit_sync() | From | Lu Baolu <> | Date | Wed, 15 Apr 2020 16:30:20 +0800 |
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On 2020/4/15 16:18, Tian, Kevin wrote: >> From: Lu Baolu<baolu.lu@linux.intel.com> >> Sent: Wednesday, April 15, 2020 1:26 PM >> >> Extend qi_submit_sync() function to support multiple descriptors. >> >> Signed-off-by: Jacob Pan<jacob.jun.pan@linux.intel.com> >> Signed-off-by: Lu Baolu<baolu.lu@linux.intel.com> >> --- >> drivers/iommu/dmar.c | 39 +++++++++++++++++++++++-------------- >> include/linux/intel-iommu.h | 1 + >> 2 files changed, 25 insertions(+), 15 deletions(-) >> >> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c >> index bb42177e2369..61d049e91f84 100644 >> --- a/drivers/iommu/dmar.c >> +++ b/drivers/iommu/dmar.c >> @@ -1157,12 +1157,11 @@ static inline void reclaim_free_desc(struct >> q_inval *qi) >> } >> } >> >> -static int qi_check_fault(struct intel_iommu *iommu, int index) >> +static int qi_check_fault(struct intel_iommu *iommu, int index, int >> wait_index) >> { >> u32 fault; >> int head, tail; >> struct q_inval *qi = iommu->qi; >> - int wait_index = (index + 1) % QI_LENGTH; >> int shift = qi_shift(iommu); >> >> if (qi->desc_status[wait_index] == QI_ABORT) >> @@ -1234,12 +1233,12 @@ static int qi_check_fault(struct intel_iommu >> *iommu, int index) >> int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc, >> unsigned int count, unsigned long options) >> { >> - int rc; >> struct q_inval *qi = iommu->qi; >> - int offset, shift, length; >> struct qi_desc wait_desc; >> int wait_index, index; >> unsigned long flags; >> + int offset, shift; >> + int rc, i; >> >> if (!qi) >> return 0; >> @@ -1248,32 +1247,41 @@ int qi_submit_sync(struct intel_iommu *iommu, >> struct qi_desc *desc, >> rc = 0; >> >> raw_spin_lock_irqsave(&qi->q_lock, flags); >> - while (qi->free_cnt < 3) { >> + /* >> + * Check if we have enough empty slots in the queue to submit, >> + * the calculation is based on: >> + * # of desc + 1 wait desc + 1 space between head and tail >> + */ >> + while (qi->free_cnt < count + 2) { >> raw_spin_unlock_irqrestore(&qi->q_lock, flags); >> cpu_relax(); >> raw_spin_lock_irqsave(&qi->q_lock, flags); >> } >> >> index = qi->free_head; >> - wait_index = (index + 1) % QI_LENGTH; >> + wait_index = (index + count) % QI_LENGTH; >> shift = qi_shift(iommu); >> - length = 1 << shift; >> >> - qi->desc_status[index] = qi->desc_status[wait_index] = QI_IN_USE; >> + for (i = 0; i < count; i++) { >> + offset = ((index + i) % QI_LENGTH) << shift; >> + memcpy(qi->desc + offset, &desc[i], 1 << shift); >> + qi->desc_status[(index + i) % QI_LENGTH] = QI_IN_USE; >> + } > what about doing one memcpy and leave the loop only for updating > qi status? >
One memcpy might cross the table boundary.
Best regards, baolu
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