Re: [PATCH v7 18/23] iommu/smmuv3: Report non recoverable faults

Robin Murphy
2019-05-08T17:21:03Z

On 08/04/2019 13:19, 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>
>
> ---
> v4 -> v5:
> - s/IOMMU_FAULT_PERM_INST/IOMMU_FAULT_PERM_EXEC
> ---
> drivers/iommu/arm-smmu-v3.c | 169 +++++++++++++++++++++++++++++++++---
> 1 file changed, 158 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 8044445bc32a..1fd320788dcb 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -167,6 +167,26 @@
> #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)
> @@ -332,6 +352,15 @@
> #define EVTQ_MAX_SZ_SHIFT 7
>
> #define EVTQ_0_ID GENMASK_ULL(7, 0)
> +#define EVTQ_0_SSV GENMASK_ULL(11, 11)
> +#define EVTQ_0_SUBSTREAMID GENMASK_ULL(31, 12)
> +#define EVTQ_0_STREAMID GENMASK_ULL(63, 32)
> +#define EVTQ_1_PNU GENMASK_ULL(33, 33)
> +#define EVTQ_1_IND GENMASK_ULL(34, 34)
> +#define EVTQ_1_RNW GENMASK_ULL(35, 35)
> +#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
> @@ -639,6 +668,64 @@ struct arm_smmu_domain {
> spinlock_t devices_lock;
> };
>
> +/* fault propagation */
> +
> +#define IOMMU_FAULT_F_FIELDS (IOMMU_FAULT_UNRECOV_PASID_VALID | \
> + IOMMU_FAULT_UNRECOV_PERM_VALID | \
> + IOMMU_FAULT_UNRECOV_ADDR_VALID)
> +
> +struct arm_smmu_fault_propagation_data {
> + enum iommu_fault_reason reason;
> + bool s1_check;
> + u32 fields; /* IOMMU_FAULT_UNRECOV_*_VALID bits */
> +};
> +
> +/*
> + * Describes how SMMU faults translate into generic IOMMU faults
> + * and if they need to be reported externally
> + */
> +static const struct arm_smmu_fault_propagation_data fault_propagation[] = {
> +[ARM_SMMU_EVT_F_UUT] = { },
> +[ARM_SMMU_EVT_C_BAD_STREAMID] = { },
> +[ARM_SMMU_EVT_F_STE_FETCH] = { },
> +[ARM_SMMU_EVT_C_BAD_STE] = { },
> +[ARM_SMMU_EVT_F_BAD_ATS_TREQ] = { },
> +[ARM_SMMU_EVT_F_STREAM_DISABLED] = { },
> +[ARM_SMMU_EVT_F_TRANSL_FORBIDDEN] = { },
> +[ARM_SMMU_EVT_C_BAD_SUBSTREAMID] = {IOMMU_FAULT_REASON_PASID_INVALID,
> + false,
> + IOMMU_FAULT_UNRECOV_PASID_VALID
> + },
> +[ARM_SMMU_EVT_F_CD_FETCH] = {IOMMU_FAULT_REASON_PASID_FETCH,
> + false,
> + IOMMU_FAULT_UNRECOV_PASID_VALID |

It doesn't make sense to presume validity here, or in any of the faults
below...

> + IOMMU_FAULT_UNRECOV_FETCH_ADDR_VALID
> + },
> +[ARM_SMMU_EVT_C_BAD_CD] = {IOMMU_FAULT_REASON_BAD_PASID_ENTRY,
> + false,
> + IOMMU_FAULT_UNRECOV_PASID_VALID
> + },
> +[ARM_SMMU_EVT_F_WALK_EABT] = {IOMMU_FAULT_REASON_WALK_EABT, true,
> + IOMMU_FAULT_F_FIELDS |
> + IOMMU_FAULT_UNRECOV_FETCH_ADDR_VALID
> + },
> +[ARM_SMMU_EVT_F_TRANSLATION] = {IOMMU_FAULT_REASON_PTE_FETCH, true,
> + IOMMU_FAULT_F_FIELDS
> + },
> +[ARM_SMMU_EVT_F_ADDR_SIZE] = {IOMMU_FAULT_REASON_OOR_ADDRESS, true,
> + IOMMU_FAULT_F_FIELDS
> + },
> +[ARM_SMMU_EVT_F_ACCESS] = {IOMMU_FAULT_REASON_ACCESS, true,
> + IOMMU_FAULT_F_FIELDS
> + },
> +[ARM_SMMU_EVT_F_PERMISSION] = {IOMMU_FAULT_REASON_PERMISSION, true,
> + IOMMU_FAULT_F_FIELDS
> + },
> +[ARM_SMMU_EVT_F_TLB_CONFLICT] = { },
> +[ARM_SMMU_EVT_F_CFG_CONFLICT] = { },
> +[ARM_SMMU_EVT_E_PAGE_REQUEST] = { },
> +};
> +
> struct arm_smmu_option_prop {
> u32 opt;
> const char *prop;
> @@ -1258,7 +1345,6 @@ 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)
> {
> @@ -1284,24 +1370,85 @@ arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
> return master;
> }
>
> +/* Populates the record fields according to the input SMMU event */
> +static bool arm_smmu_transcode_fault(u64 *evt, u8 type,
> + struct iommu_fault_unrecoverable *record)
> +{
> + const struct arm_smmu_fault_propagation_data *data;
> + u32 fields;
> +
> + if (type >= ARRAY_SIZE(fault_propagation))
> + return false;
> +
> + data = &fault_propagation[type];
> + if (!data->reason)
> + return false;
> +
> + fields = data->fields;
> +
> + if (data->s1_check & FIELD_GET(EVTQ_1_S2, evt[1]))
> + return false; /* S2 related fault, don't propagate */
> +
> + if (fields & IOMMU_FAULT_UNRECOV_PASID_VALID) {
> + if (FIELD_GET(EVTQ_0_SSV, evt[0]))
> + record->pasid = FIELD_GET(EVTQ_0_SUBSTREAMID, evt[0]);
> + else
> + fields &= ~IOMMU_FAULT_UNRECOV_PASID_VALID;

...because this logic then breaks for C_BAD_SUBSTREAMID, which ends up
coming out of here *without* reporting the offending PASID.

> + }
> + if (fields & IOMMU_FAULT_UNRECOV_PERM_VALID) {
> + if (!FIELD_GET(EVTQ_1_RNW, evt[1]))
> + record->perm |= IOMMU_FAULT_PERM_WRITE;
> + if (FIELD_GET(EVTQ_1_PNU, evt[1]))
> + record->perm |= IOMMU_FAULT_PERM_PRIV;
> + if (FIELD_GET(EVTQ_1_IND, evt[1]))
> + record->perm |= IOMMU_FAULT_PERM_EXEC;
> + }
> + if (fields & IOMMU_FAULT_UNRECOV_ADDR_VALID)
> + record->addr = evt[2];
> +
> + if (fields & IOMMU_FAULT_UNRECOV_FETCH_ADDR_VALID)
> + record->fetch_addr = FIELD_GET(EVTQ_3_FETCH_ADDR, evt[3]);
> +
> + record->flags = fields;
> + return true;
> +}
> +
> +static void arm_smmu_report_event(struct arm_smmu_device *smmu, u64 *evt)
> +{
> + u32 sid = FIELD_GET(EVTQ_0_STREAMID, evt[0]);
> + u8 type = FIELD_GET(EVTQ_0_ID, evt[0]);
> + struct arm_smmu_master_data *master;
> + struct iommu_fault_event event = {};
> + int i;
> +
> + master = arm_smmu_find_master(smmu, sid);
> + if (WARN_ON(!master))
> + return;

NAK. If I'm getting global faults like C_BAD_STE where a device almost
certainly *isn't* configured (because hey, we would have initialised its
STEs if we knew), then I sure as hell want to see the actual faults.
Spamming a constant stream of stack traces *instead* of showing them is
worse than useless.

> +
> + event.fault.type = IOMMU_FAULT_DMA_UNRECOV;
> +
> + if (arm_smmu_transcode_fault(evt, type, &event.fault.event)) {
> + iommu_report_device_fault(master->dev, &event);
> + return;

And again, the vast majority of the time, there won't be a fault handler
registered, so unconditionally suppressing the most common and useful
stuff like translation and permission faults is very much not OK.

Robin.

> + }
> +
> + 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
>