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Date: Mon, 13 May 2019 14:32:15 +0200
From: Auger Eric <eric.auger@...hat.com>
To: Robin Murphy <robin.murphy@....com>, eric.auger.pro@...il.com,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu, joro@...tes.org,
alex.williamson@...hat.com, jacob.jun.pan@...ux.intel.com,
yi.l.liu@...el.com, jean-philippe.brucker@....com,
will.deacon@....com
Cc: kevin.tian@...el.com, ashok.raj@...el.com, marc.zyngier@....com,
christoffer.dall@....com, peter.maydell@...aro.org,
vincent.stehle@....com
Subject: Re: [PATCH v7 18/23] iommu/smmuv3: Report non recoverable faults
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@...hat.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.
Thanks
Eric
>
> Thanks,
> Robin.
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