Re: [PATCH v5 17/23] iommu/vt-d: report non-recoverable faults to device

Jacob Pan
2018-05-29T17:30:46Z

On Mon, 14 May 2018 16:17:28 +0800
Lu Baolu <baolu.lu@linux.intel.com> wrote:

> Hi,
>
> On 05/12/2018 04:54 AM, Jacob Pan wrote:
> > Currently, dmar fault IRQ handler does nothing more than rate
> > limited printk, no critical hardware handling need to be done
> > in IRQ context.
>
> Not exactly. dmar_fault() needs to clear all the faults so that
> the subsequent faults could be logged.
True, but this is standard IRQ handling. Moving to threaded IRQ should
not be causing any functional problems, this is what I am trying to say.
>
> > For some use case such as vIOMMU, it might be useful to report
> > non-recoverable faults outside host IOMMU subsystem. DMAR fault
> > can come from both DMA and interrupt remapping which has to be
> > set up early before threaded IRQ is available.
> > This patch adds an option and a workqueue such that when faults
> > are requested, DMAR fault IRQ handler can use the IOMMU fault
> > reporting API to report.
> >
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
> > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> > ---
> > drivers/iommu/dmar.c | 159
> > ++++++++++++++++++++++++++++++++++++++++++--
> > drivers/iommu/intel-iommu.c | 6 +- include/linux/dmar.h
> > | 2 +- include/linux/intel-iommu.h | 1 +
> > 4 files changed, 159 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> > index 0b5b052..ef846e3 100644
> > --- a/drivers/iommu/dmar.c
> > +++ b/drivers/iommu/dmar.c
> > @@ -1110,6 +1110,12 @@ static int alloc_iommu(struct dmar_drhd_unit
> > *drhd) return err;
> > }
> >
> > +static inline void dmar_free_fault_wq(struct intel_iommu *iommu)
> > +{
> > + if (iommu->fault_wq)
> > + destroy_workqueue(iommu->fault_wq);
> > +}
> > +
> > static void free_iommu(struct intel_iommu *iommu)
> > {
> > if (intel_iommu_enabled) {
> > @@ -1126,6 +1132,7 @@ static void free_iommu(struct intel_iommu
> > *iommu) free_irq(iommu->irq, iommu);
> > dmar_free_hwirq(iommu->irq);
> > iommu->irq = 0;
> > + dmar_free_fault_wq(iommu);
> > }
> >
> > if (iommu->qi) {
> > @@ -1554,6 +1561,31 @@ static const char *irq_remap_fault_reasons[]
> > = "Blocked an interrupt request due to source-id verification
> > failure", };
> >
> > +/* fault data and status */
> > +enum intel_iommu_fault_reason {
> > + INTEL_IOMMU_FAULT_REASON_SW,
> > + INTEL_IOMMU_FAULT_REASON_ROOT_NOT_PRESENT,
> > + INTEL_IOMMU_FAULT_REASON_CONTEXT_NOT_PRESENT,
> > + INTEL_IOMMU_FAULT_REASON_CONTEXT_INVALID,
> > + INTEL_IOMMU_FAULT_REASON_BEYOND_ADDR_WIDTH,
> > + INTEL_IOMMU_FAULT_REASON_PTE_WRITE_ACCESS,
> > + INTEL_IOMMU_FAULT_REASON_PTE_READ_ACCESS,
> > + INTEL_IOMMU_FAULT_REASON_NEXT_PT_INVALID,
> > + INTEL_IOMMU_FAULT_REASON_ROOT_ADDR_INVALID,
> > + INTEL_IOMMU_FAULT_REASON_CONTEXT_PTR_INVALID,
> > + INTEL_IOMMU_FAULT_REASON_NONE_ZERO_RTP,
> > + INTEL_IOMMU_FAULT_REASON_NONE_ZERO_CTP,
> > + INTEL_IOMMU_FAULT_REASON_NONE_ZERO_PTE,
> > + NR_INTEL_IOMMU_FAULT_REASON,
> > +};
> > +
> > +/* fault reasons that are allowed to be reported outside IOMMU
> > subsystem */ +#define
> > INTEL_IOMMU_FAULT_REASON_ALLOWED \
> > + ((1ULL << INTEL_IOMMU_FAULT_REASON_BEYOND_ADDR_WIDTH)
> > | \
> > + (1ULL <<
> > INTEL_IOMMU_FAULT_REASON_PTE_WRITE_ACCESS) | \
> > + (1ULL << INTEL_IOMMU_FAULT_REASON_PTE_READ_ACCESS))
> > +
> > +
> > static const char *dmar_get_fault_reason(u8 fault_reason, int
> > *fault_type) {
> > if (fault_reason >= 0x20 && (fault_reason - 0x20 <
> > @@ -1634,11 +1666,91 @@ void dmar_msi_read(int irq, struct msi_msg
> > *msg) raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
> > }
> >
> > +static enum iommu_fault_reason to_iommu_fault_reason(u8 reason)
> > +{
> > + if (reason >= NR_INTEL_IOMMU_FAULT_REASON) {
> > + pr_warn("unknown DMAR fault reason %d\n", reason);
> > + return IOMMU_FAULT_REASON_UNKNOWN;
> > + }
> > + switch (reason) {
> > + case INTEL_IOMMU_FAULT_REASON_SW:
> > + case INTEL_IOMMU_FAULT_REASON_ROOT_NOT_PRESENT:
> > + case INTEL_IOMMU_FAULT_REASON_CONTEXT_NOT_PRESENT:
> > + case INTEL_IOMMU_FAULT_REASON_CONTEXT_INVALID:
> > + case INTEL_IOMMU_FAULT_REASON_BEYOND_ADDR_WIDTH:
> > + case INTEL_IOMMU_FAULT_REASON_ROOT_ADDR_INVALID:
> > + case INTEL_IOMMU_FAULT_REASON_CONTEXT_PTR_INVALID:
> > + return IOMMU_FAULT_REASON_INTERNAL;
> > + case INTEL_IOMMU_FAULT_REASON_NEXT_PT_INVALID:
> > + case INTEL_IOMMU_FAULT_REASON_PTE_WRITE_ACCESS:
> > + case INTEL_IOMMU_FAULT_REASON_PTE_READ_ACCESS:
> > + return IOMMU_FAULT_REASON_PERMISSION;
> > + default:
> > + return IOMMU_FAULT_REASON_UNKNOWN;
> > + }
> > +}
> > +
> > +struct dmar_fault_work {
> > + struct work_struct fault_work;
> > + struct intel_iommu *iommu;
> > + u64 addr;
> > + int type;
> > + int fault_type;
> > + enum intel_iommu_fault_reason reason;
> > + u16 sid;
> > +};
> > +
> > +static void report_fault_to_device(struct work_struct *work)
> > +{
> > + struct dmar_fault_work *dfw = container_of(work, struct
> > dmar_fault_work,
> > + fault_work);
> > + struct iommu_fault_event event;
> > + struct pci_dev *pdev;
> > + u8 bus, devfn;
> > +
> > + memset(&event, 0, sizeof(struct iommu_fault_event));
> > +
> > + /* check if fault reason is permitted to report outside
> > IOMMU */
> > + if (!((1 << dfw->reason) &
> > INTEL_IOMMU_FAULT_REASON_ALLOWED)) {
> > + pr_debug("Fault reason %d not allowed to report to
> > device\n",
> > + dfw->reason);
>
> No need to print this message. And how about moving this check ahead
> before queue the work?
>
Good point. rest of the points taken. Thanks!
> [...]
>
> No need to print this warn message.
>
> [...]
>
> No need to add braces.
>
> > +
> > + dfw = kmalloc(sizeof(*dfw), GFP_ATOMIC);
> > + if (!dfw)
> > + return -ENOMEM;
> > +
> > + INIT_WORK(&dfw->fault_work, report_fault_to_device);
> > + dfw->addr = addr;
> > + dfw->type = type;
> > + dfw->fault_type = fault_type;
> > + dfw->reason = fault_reason;
> > + dfw->sid = source_id;
> > + dfw->iommu = iommu;
> > + if (!queue_work(iommu->fault_wq, &dfw->fault_work)) {
>
> Check whether this fault is allowed to report to device before
> queuing the work.
>
> [...]
>
> Best regards,
> Lu Baolu

[Jacob Pan]