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charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Lennert, On 7/19/2021 4:54 AM, Lennert Buytenhek wrote: > This patch makes iommu/amd call report_iommu_fault() when an I/O page > fault occurs, which has two effects: > > 1) It allows device drivers to register a callback to be notified of > I/O page faults, via the iommu_set_fault_handler() API. > > 2) It triggers the io_page_fault tracepoint in report_iommu_fault() > when an I/O page fault occurs. > > I'm mainly interested in (2). We have a daemon with some rasdaemon-like > functionality for handling platform errors, and being able to be notified > of I/O page faults for initiating corrective action is very useful -- and > receiving such events via event tracing is a lot nicer than having to > scrape them from kmsg. Interesting. Just curious what types of error handling are done here? > A number of other IOMMU drivers already use report_iommu_fault(), and > I/O page faults on those IOMMUs therefore already seem to trigger this > tracepoint -- but this isn't (yet) the case for AMD-Vi and Intel DMAR. > > I copied the logic from the other callers of report_iommu_fault(), where > if that function returns zero, the driver will have handled the fault, > in which case we avoid logging information about the fault to the printk > buffer from the IOMMU driver. > > With this patch I see io_page_fault event tracing entries as expected: > > irq/24-AMD-Vi-48 [002] .... 978.554289: io_page_fault: IOMMU:[drvname] 0000:05:00.0 iova=0x0000000091482640 flags=0x0000 > irq/24-AMD-Vi-48 [002] .... 978.554294: io_page_fault: IOMMU:[drvname] 0000:05:00.0 iova=0x0000000091482650 flags=0x0000 > irq/24-AMD-Vi-48 [002] .... 978.554299: io_page_fault: IOMMU:[drvname] 0000:05:00.0 iova=0x0000000091482660 flags=0x0000 > irq/24-AMD-Vi-48 [002] .... 978.554305: io_page_fault: IOMMU:[drvname] 0000:05:00.0 iova=0x0000000091482670 flags=0x0000 > irq/24-AMD-Vi-48 [002] .... 978.554310: io_page_fault: IOMMU:[drvname] 0000:05:00.0 iova=0x0000000091482680 flags=0x0000 > irq/24-AMD-Vi-48 [002] .... 978.554315: io_page_fault: IOMMU:[drvname] 0000:05:00.0 iova=0x00000000914826a0 flags=0x0000 > > For determining IOMMU_FAULT_{READ,WRITE}, I followed the AMD IOMMU > spec, but I haven't tested that bit of the code, as the page faults I > encounter are all to non-present (!EVENT_FLAG_PR) mappings, in which > case EVENT_FLAG_RW doesn't make sense. Since, IO_PAGE_FAULT event is used to communicate various types of fault events, why don't we just pass the flags as-is? This way, it can be used to report/trace various types of IO_PAGE_FAULT events (e.g. for I/O page table, interrupt remapping, and etc). Interested parties can register domain fault handler, and it can takes care of parsing information of the flag as needed. > Signed-off-by: Lennert Buytenhek > --- > drivers/iommu/amd/amd_iommu_types.h | 4 ++++ > drivers/iommu/amd/iommu.c | 25 +++++++++++++++++++++++++ > 2 files changed, 29 insertions(+) > > diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h > index 94c1a7a9876d..2f2c6630c24c 100644 > --- a/drivers/iommu/amd/amd_iommu_types.h > +++ b/drivers/iommu/amd/amd_iommu_types.h > @@ -138,6 +138,10 @@ > #define EVENT_DOMID_MASK_HI 0xf0000 > #define EVENT_FLAGS_MASK 0xfff > #define EVENT_FLAGS_SHIFT 0x10 > +#define EVENT_FLAG_TR 0x100 > +#define EVENT_FLAG_RW 0x020 > +#define EVENT_FLAG_PR 0x010 > +#define EVENT_FLAG_I 0x008 > > /* feature control bits */ > #define CONTROL_IOMMU_EN 0x00ULL > diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c > index 811a49a95d04..a02ace7ee794 100644 > --- a/drivers/iommu/amd/iommu.c > +++ b/drivers/iommu/amd/iommu.c > @@ -480,6 +480,30 @@ static void amd_iommu_report_page_fault(u16 devid, u16 domain_id, > if (pdev) > dev_data = dev_iommu_priv_get(&pdev->dev); > > + if (dev_data) { > + int report_flags; > + > + /* > + * AMD I/O Virtualization Technology (IOMMU) Specification, > + * revision 3.00, section 2.5.3 ("IO_PAGE_FAULT Event") says > + * that the RW ("read-write") bit is only valid if the I/O > + * page fault was caused by a memory transaction request > + * referencing a page that was marked present. > + */ > + report_flags = 0; > + if ((flags & (EVENT_FLAG_TR | EVENT_FLAG_PR | EVENT_FLAG_I)) == > + EVENT_FLAG_PR) { Let's not do this check .... > + if (flags & EVENT_FLAG_RW) > + report_flags |= IOMMU_FAULT_WRITE; > + else > + report_flags |= IOMMU_FAULT_READ; ... and then we don't need to translate the EVENT_FLAG_XX to IOMMU_FAULT_XXX flags. > + } > + > + if (!report_iommu_fault(&dev_data->domain->domain, > + &pdev->dev, address, report_flags)) Let's just pass the "flags" here. Thanks, Suravee > + goto out; > + } > + > if (dev_data && __ratelimit(&dev_data->rs)) { > pci_err(pdev, "Event logged [IO_PAGE_FAULT domain=0x%04x address=0x%llx flags=0x%04x]\n", > domain_id, address, flags); > @@ -489,6 +513,7 @@ static void amd_iommu_report_page_fault(u16 devid, u16 domain_id, > domain_id, address, flags); > } > > +out: > if (pdev) > pci_dev_put(pdev); > } > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu