Messages in this thread | | | Subject | Re: [PATCH v7 18/23] iommu/smmuv3: Report non recoverable faults | From | Robin Murphy <> | Date | Mon, 13 May 2019 14:47:07 +0100 |
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On 13/05/2019 13:32, Auger Eric wrote: > Hi Robin, > On 5/13/19 1:54 PM, Robin Murphy wrote: >> On 13/05/2019 08:46, Auger Eric wrote: >>> Hi Robin, >>> >>> On 5/8/19 7:20 PM, Robin Murphy wrote: >>>> 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. >>> Correct. >>>> >>>>> + } >>>>> + 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. >>> Sure, if !master I will output the original traces. >>>> >>>>> + >>>>> + 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. >>> Going to test whether we are in nested mode before entering that path. >> >> I don't think this has to be exclusive to nesting - the generic >> reporting mechanism feels like it might ultimately be extensible to >> other things like Rob's case for generalised stalling. It's just that >> for robustness, even when a fault handler is present, we still want the >> driver to be able to report if it didn't actually handle a fault. > > > Jean-Philippe pointed out in a previous review > (https://patchwork.kernel.org/patch/10751801/#22424047) that the guest > can flood the host log with S1 related faults. At the moment we do not > check that a fault handler is registered in nested mode. Maybe we > should? Even if the fault handler is registered, as it is based on a > circular buffer, this latter can be full and lead to a log flood.
Ah, right, I didn't quite have the full picture in mind, thanks for the jog. I guess in that case we want some degree of special-casing for nested configs - anything S1-related that we expect the fault handler to simply inject back into the guest, we can indeed suppress on the host, but I do think it's worth anticipating host-related faults (and entirely host-owned fault-handlers in future) as well.
Robin.
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