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

From: Robin Murphy
Date: Wed May 08 2019 - 13:22:07 EST

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@xxxxxxxxxx>

---
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