Re: [RFC v3 17/21] iommu/smmuv3: Report non recoverable faults

Jean-Philippe Brucker
2019-01-11T17:46:39Z

On 08/01/2019 10:26, Eric Auger wrote:
> When a stage 1 related fault event is read from the event queue,
> let's propagate it to potential external fault listeners, ie. users
> who registered a fault handler.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> drivers/iommu/arm-smmu-v3.c | 124 ++++++++++++++++++++++++++++++++----
> 1 file changed, 113 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 999ee470a2ae..6a711cbbb228 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -168,6 +168,26 @@
> #define ARM_SMMU_PRIQ_IRQ_CFG1 0xd8
> #define ARM_SMMU_PRIQ_IRQ_CFG2 0xdc
>
> +/* Events */
> +#define ARM_SMMU_EVT_F_UUT 0x01
> +#define ARM_SMMU_EVT_C_BAD_STREAMID 0x02
> +#define ARM_SMMU_EVT_F_STE_FETCH 0x03
> +#define ARM_SMMU_EVT_C_BAD_STE 0x04
> +#define ARM_SMMU_EVT_F_BAD_ATS_TREQ 0x05
> +#define ARM_SMMU_EVT_F_STREAM_DISABLED 0x06
> +#define ARM_SMMU_EVT_F_TRANSL_FORBIDDEN 0x07
> +#define ARM_SMMU_EVT_C_BAD_SUBSTREAMID 0x08
> +#define ARM_SMMU_EVT_F_CD_FETCH 0x09
> +#define ARM_SMMU_EVT_C_BAD_CD 0x0a
> +#define ARM_SMMU_EVT_F_WALK_EABT 0x0b
> +#define ARM_SMMU_EVT_F_TRANSLATION 0x10
> +#define ARM_SMMU_EVT_F_ADDR_SIZE 0x11
> +#define ARM_SMMU_EVT_F_ACCESS 0x12
> +#define ARM_SMMU_EVT_F_PERMISSION 0x13
> +#define ARM_SMMU_EVT_F_TLB_CONFLICT 0x20
> +#define ARM_SMMU_EVT_F_CFG_CONFLICT 0x21
> +#define ARM_SMMU_EVT_E_PAGE_REQUEST 0x24
> +
> /* Common MSI config fields */
> #define MSI_CFG0_ADDR_MASK GENMASK_ULL(51, 2)
> #define MSI_CFG2_SH GENMASK(5, 4)
> @@ -333,6 +353,11 @@
> #define EVTQ_MAX_SZ_SHIFT 7
>
> #define EVTQ_0_ID GENMASK_ULL(7, 0)
> +#define EVTQ_0_SUBSTREAMID GENMASK_ULL(31, 12)
> +#define EVTQ_0_STREAMID GENMASK_ULL(63, 32)
> +#define EVTQ_1_S2 GENMASK_ULL(39, 39)
> +#define EVTQ_1_CLASS GENMASK_ULL(40, 41)
> +#define EVTQ_3_FETCH_ADDR GENMASK_ULL(51, 3)
>
> /* PRI queue */
> #define PRIQ_ENT_DWORDS 2
> @@ -1270,7 +1295,6 @@ static int arm_smmu_init_l2_strtab(struct arm_smmu_device *smmu, u32 sid)
> return 0;
> }
>
> -__maybe_unused
> static struct arm_smmu_master_data *
> arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
> {
> @@ -1296,24 +1320,102 @@ arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
> return master;
> }
>
> +static void arm_smmu_report_event(struct arm_smmu_device *smmu, u64 *evt)
> +{
> + u64 fetch_addr = FIELD_GET(EVTQ_3_FETCH_ADDR, evt[3]);
> + u32 sid = FIELD_GET(EVTQ_0_STREAMID, evt[0]);
> + bool s1 = !FIELD_GET(EVTQ_1_S2, evt[1]);
> + u8 type = FIELD_GET(EVTQ_0_ID, evt[0]);
> + struct arm_smmu_master_data *master;
> + struct iommu_fault_event event;
> + bool propagate = true;
> + u64 addr = evt[2];
> + int i;
> +
> + master = arm_smmu_find_master(smmu, sid);
> + if (WARN_ON(!master))
> + return;
> +
> + event.fault.type = IOMMU_FAULT_DMA_UNRECOV;
> +
> + switch (type) {
> + case ARM_SMMU_EVT_C_BAD_STREAMID:
> + event.fault.reason = IOMMU_FAULT_REASON_SOURCEID_INVALID;
> + break;
> + case ARM_SMMU_EVT_F_STREAM_DISABLED:
> + case ARM_SMMU_EVT_C_BAD_SUBSTREAMID:
> + event.fault.reason = IOMMU_FAULT_REASON_PASID_INVALID;
> + break;
> + case ARM_SMMU_EVT_F_CD_FETCH:
> + event.fault.reason = IOMMU_FAULT_REASON_PASID_FETCH;
> + break;
> + case ARM_SMMU_EVT_F_WALK_EABT:
> + event.fault.reason = IOMMU_FAULT_REASON_WALK_EABT;
> + event.fault.addr = addr;
> + event.fault.fetch_addr = fetch_addr;
> + propagate = s1;
> + break;
> + case ARM_SMMU_EVT_F_TRANSLATION:
> + event.fault.reason = IOMMU_FAULT_REASON_PTE_FETCH;
> + event.fault.addr = addr;
> + event.fault.fetch_addr = fetch_addr;
> + propagate = s1;
> + break;
> + case ARM_SMMU_EVT_F_PERMISSION:
> + event.fault.reason = IOMMU_FAULT_REASON_PERMISSION;
> + event.fault.addr = addr;
> + propagate = s1;
> + break;
> + case ARM_SMMU_EVT_F_ACCESS:
> + event.fault.reason = IOMMU_FAULT_REASON_ACCESS;
> + event.fault.addr = addr;
> + propagate = s1;
> + break;
> + case ARM_SMMU_EVT_C_BAD_STE:
> + event.fault.reason = IOMMU_FAULT_REASON_BAD_DEVICE_CONTEXT_ENTRY;
> + break;
> + case ARM_SMMU_EVT_C_BAD_CD:
> + event.fault.reason = IOMMU_FAULT_REASON_BAD_PASID_ENTRY;
> + break;
> + case ARM_SMMU_EVT_F_ADDR_SIZE:
> + event.fault.reason = IOMMU_FAULT_REASON_OOR_ADDRESS;
> + propagate = s1;
> + break;
> + case ARM_SMMU_EVT_F_STE_FETCH:
> + event.fault.reason = IOMMU_FAULT_REASON_DEVICE_CONTEXT_FETCH;
> + event.fault.fetch_addr = fetch_addr;
> + break;
> + /* End of addition */
> + case ARM_SMMU_EVT_E_PAGE_REQUEST:
> + case ARM_SMMU_EVT_F_TLB_CONFLICT:
> + case ARM_SMMU_EVT_F_CFG_CONFLICT:
> + case ARM_SMMU_EVT_F_BAD_ATS_TREQ:
> + case ARM_SMMU_EVT_F_TRANSL_FORBIDDEN:
> + case ARM_SMMU_EVT_F_UUT:
> + default:
> + event.fault.reason = IOMMU_FAULT_REASON_UNKNOWN;
> + }
> + /* only propagate the error if it relates to stage 1 */
> + if (s1)

if (propagate)

But I don't quite understand how we're deciding what to propagate: a
C_BAD_STE is most likely a bug in the SMMU driver, but is reported to
userspace. On the other hand a stage-2 F_TRANSLATION is likely an error
from the VMM (didn't setup stage-2 mappings properly), but we're not
reporting it. Maybe we should add a bit to event.fault that tells
whether the fault was stage 1 or 2, and let the VMM deal with it?

> + iommu_report_device_fault(master->dev, &event);

We should return here if the fault is successfully injected

Thanks,
Jean

> +
> + dev_info(smmu->dev, "event 0x%02x received:\n", type);
> + for (i = 0; i < EVTQ_ENT_DWORDS; ++i) {
> + dev_info(smmu->dev, "\t0x%016llx\n",
> + (unsigned long long)evt[i]);
> + }
> +}
> +
> /* IRQ and event handlers */
> static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
> {
> - int i;
> struct arm_smmu_device *smmu = dev;
> struct arm_smmu_queue *q = &smmu->evtq.q;
> u64 evt[EVTQ_ENT_DWORDS];
>
> do {
> - while (!queue_remove_raw(q, evt)) {
> - u8 id = FIELD_GET(EVTQ_0_ID, evt[0]);
> -
> - dev_info(smmu->dev, "event 0x%02x received:\n", id);
> - for (i = 0; i < ARRAY_SIZE(evt); ++i)
> - dev_info(smmu->dev, "\t0x%016llx\n",
> - (unsigned long long)evt[i]);
> -
> - }
> + while (!queue_remove_raw(q, evt))
> + arm_smmu_report_event(smmu, evt);
>
> /*
> * Not much we can do on overflow, so scream and pretend we're
>