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

[Lu Baolu <baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

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.

> 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-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> Signed-off-by: Liu, Yi L <yi.l.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> Signed-off-by: Ashok Raj <ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
>  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?

> +		goto free_work;
> +	}
> +
> +	bus = PCI_BUS_NUM(dfw->sid);
> +	devfn = PCI_DEVFN(PCI_SLOT(dfw->sid), PCI_FUNC(dfw->sid));
> +	/*
> +	 * we need to check if the fault reporting is requested for the
> +	 * offending device.
> +	 */
> +	pdev = pci_get_domain_bus_and_slot(dfw->iommu->segment, bus, devfn);
> +	if (!pdev) {
> +		pr_warn("No PCI device found for source ID %x\n", dfw->sid);
> +		goto free_work;
> +	}
> +	/*
> +	 * unrecoverable fault is reported per IOMMU, notifier handler can
> +	 * resolve PCI device based on source ID.
> +	 */
> +	event.reason = to_iommu_fault_reason(dfw->reason);
> +	event.addr = dfw->addr;
> +	event.type = IOMMU_FAULT_DMA_UNRECOV;
> +	event.prot = dfw->type ? IOMMU_READ : IOMMU_WRITE;
> +	dev_warn(&pdev->dev, "report device unrecoverable fault: %d, %x, %d\n",
> +		event.reason, dfw->sid, event.type);

No need to print this warn message.

> +	iommu_report_device_fault(&pdev->dev, &event);
> +	pci_dev_put(pdev);
> +
> +free_work:
> +	kfree(dfw);
> +}
> +
>  static int dmar_fault_do_one(struct intel_iommu *iommu, int type,
>  		u8 fault_reason, u16 source_id, unsigned long long addr)
>  {
>  	const char *reason;
>  	int fault_type;
> +	struct dmar_fault_work *dfw;
>  
>  	reason = dmar_get_fault_reason(fault_reason, &fault_type);
>  
> @@ -1647,11 +1759,29 @@ static int dmar_fault_do_one(struct intel_iommu *iommu, int type,
>  			source_id >> 8, PCI_SLOT(source_id & 0xFF),
>  			PCI_FUNC(source_id & 0xFF), addr >> 48,
>  			fault_reason, reason);
> -	else
> +	else {
>  		pr_err("[%s] Request device [%02x:%02x.%d] fault addr %llx [fault reason %02d] %s\n",
>  		       type ? "DMA Read" : "DMA Write",
>  		       source_id >> 8, PCI_SLOT(source_id & 0xFF),
>  		       PCI_FUNC(source_id & 0xFF), addr, fault_reason, reason);
> +	}

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.

> +		kfree(dfw);
> +		return -EBUSY;
> +	}
> +
>  	return 0;
>  }
>  
> @@ -1731,10 +1861,28 @@ irqreturn_t dmar_fault(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> -int dmar_set_interrupt(struct intel_iommu *iommu)
> +static int dmar_set_fault_wq(struct intel_iommu *iommu)
> +{
> +	if (iommu->fault_wq)
> +		return 0;
> +
> +	iommu->fault_wq = alloc_ordered_workqueue(iommu->name, 0);
> +	if (!iommu->fault_wq)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +int dmar_set_interrupt(struct intel_iommu *iommu, bool queue_fault)
>  {
>  	int irq, ret;
>  
> +	/* fault can be reported back to device drivers via a wq */
> +	if (queue_fault) {
> +		ret = dmar_set_fault_wq(iommu);
> +		if (ret)
> +			pr_err("Failed to create fault handling workqueue\n");
> +	}
>  	/*
>  	 * Check if the fault interrupt is already initialized.
>  	 */
> @@ -1748,10 +1896,11 @@ int dmar_set_interrupt(struct intel_iommu *iommu)
>  		pr_err("No free IRQ vectors\n");
>  		return -EINVAL;
>  	}
> -
>  	ret = request_irq(irq, dmar_fault, IRQF_NO_THREAD, iommu->name, iommu);
> -	if (ret)
> +	if (ret) {
>  		pr_err("Can't request irq\n");
> +		dmar_free_fault_wq(iommu);
> +	}
>  	return ret;
>  }
>  
> @@ -1765,7 +1914,7 @@ int __init enable_drhd_fault_handling(void)
>  	 */
>  	for_each_iommu(iommu, drhd) {
>  		u32 fault_status;
> -		int ret = dmar_set_interrupt(iommu);
> +		int ret = dmar_set_interrupt(iommu, false);
>  
>  		if (ret) {
>  			pr_err("DRHD %Lx: failed to enable fault, interrupt, ret %d\n",
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 684bd98..3949b3cf 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -3401,10 +3401,10 @@ static int __init init_dmars(void)
>  				goto free_iommu;
>  		}
>  #endif
> -		ret = dmar_set_interrupt(iommu);
> +		ret = dmar_set_interrupt(iommu, true);
> +
>  		if (ret)
>  			goto free_iommu;
> -
>  		if (!translation_pre_enabled(iommu))
>  			iommu_enable_translation(iommu);
>  
> @@ -4291,7 +4291,7 @@ static int intel_iommu_add(struct dmar_drhd_unit *dmaru)
>  			goto disable_iommu;
>  	}
>  #endif
> -	ret = dmar_set_interrupt(iommu);
> +	ret = dmar_set_interrupt(iommu, true);
>  	if (ret)
>  		goto disable_iommu;
>  
> diff --git a/include/linux/dmar.h b/include/linux/dmar.h
> index e2433bc..21f2162 100644
> --- a/include/linux/dmar.h
> +++ b/include/linux/dmar.h
> @@ -278,7 +278,7 @@ extern void dmar_msi_unmask(struct irq_data *data);
>  extern void dmar_msi_mask(struct irq_data *data);
>  extern void dmar_msi_read(int irq, struct msi_msg *msg);
>  extern void dmar_msi_write(int irq, struct msi_msg *msg);
> -extern int dmar_set_interrupt(struct intel_iommu *iommu);
> +extern int dmar_set_interrupt(struct intel_iommu *iommu, bool queue_fault);
>  extern irqreturn_t dmar_fault(int irq, void *dev_id);
>  extern int dmar_alloc_hwirq(int id, int node, void *arg);
>  extern void dmar_free_hwirq(int irq);
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index 5ac0c28..b3a26c7 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -472,6 +472,7 @@ struct intel_iommu {
>  	struct iommu_device iommu;  /* IOMMU core code handle */
>  	int		node;
>  	u32		flags;      /* Software defined flags */
> +	struct workqueue_struct *fault_wq; /* Reporting IOMMU fault to device */
>  };
>  
>  /* PCI domain-device relationship */

Best regards,
Lu Baolu