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Date: Thu, 3 Dec 2020 21:23:01 +0800
From: Kunkun Jiang <jiangkunkun@...wei.com>
To: Auger Eric <eric.auger@...hat.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>,
<will@...nel.org>, <joro@...tes.org>, <maz@...nel.org>,
<robin.murphy@....com>, <alex.williamson@...hat.com>
CC: <jean-philippe@...aro.org>, <zhangfei.gao@...aro.org>,
<zhangfei.gao@...il.com>, <vivek.gautam@....com>,
<shameerali.kolothum.thodi@...wei.com>,
<jacob.jun.pan@...ux.intel.com>, <yi.l.liu@...el.com>,
<tn@...ihalf.com>, <nicoleotsuka@...il.com>,
<yuzenghui@...wei.com>, <wanghaibin.wang@...wei.com>,
Keqian Zhu <zhukeqian1@...wei.com>
Subject: Re: [PATCH v13 05/15] iommu/smmuv3: Get prepared for nested stage
support
On 2020/12/3 21:01, Auger Eric wrote:
> Hi Kunkun,
>
> On 12/3/20 1:32 PM, Kunkun Jiang wrote:
>> Hi Eric,
>>
>> On 2020/11/18 19:21, Eric Auger wrote:
>>> When nested stage translation is setup, both s1_cfg and
>>> s2_cfg are set.
>>>
>>> We introduce a new smmu domain abort field that will be set
>>> upon guest stage1 configuration passing.
>>>
>>> arm_smmu_write_strtab_ent() is modified to write both stage
>>> fields in the STE and deal with the abort field.
>>>
>>> In nested mode, only stage 2 is "finalized" as the host does
>>> not own/configure the stage 1 context descriptor; guest does.
>>>
>>> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>>>
>>> ---
>>> v10 -> v11:
>>> - Fix an issue reported by Shameer when switching from with vSMMU
>>> to without vSMMU. Despite the spec does not seem to mention it
>>> seems to be needed to reset the 2 high 64b when switching from
>>> S1+S2 cfg to S1 only. Especially dst[3] needs to be reset (S2TTB).
>>> On some implementations, if the S2TTB is not reset, this causes
>>> a C_BAD_STE error
>>> ---
>>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 64 +++++++++++++++++----
>>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 +
>>> 2 files changed, 56 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>> index 18ac5af1b284..412ea1bafa50 100644
>>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>> @@ -1181,8 +1181,10 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>>> * three cases at the moment:
>> Now, it should be *five cases*.
>>> *
>>> * 1. Invalid (all zero) -> bypass/fault (init)
>>> - * 2. Bypass/fault -> translation/bypass (attach)
>>> - * 3. Translation/bypass -> bypass/fault (detach)
>>> + * 2. Bypass/fault -> single stage translation/bypass (attach)
>>> + * 3. Single or nested stage Translation/bypass -> bypass/fault (detach)
>>> + * 4. S2 -> S1 + S2 (attach_pasid_table)
>> I was testing this series on one of our hardware board with SMMUv3. And
>> I found while trying to /"//attach_pasid_table//"/,
>>
>> the sequence of STE (host) config(bit[3:1]) is /"S2->abort->S1 + S2"/.
>> Because the maintenance is /"Write everything apart///
>>
>> /from dword 0, sync, write dword 0, sync"/ when we update the STE
>> (guest). Dose the sequence meet your expectation?
> yes it does. I will fix the comments accordingly.
>
> Is there anything to correct in the code or was it functional?
>
> Thanks
>
> Eric
No, thanks. I just want to clarify the sequence. :)
>>> + * 5. S1 + S2 -> S2 (detach_pasid_table)
>>> *
>>> * Given that we can't update the STE atomically and the SMMU
>>> * doesn't read the thing in a defined order, that leaves us
>>> @@ -1193,7 +1195,8 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>>> * 3. Update Config, sync
>>> */
>>> u64 val = le64_to_cpu(dst[0]);
>>> - bool ste_live = false;
>>> + bool s1_live = false, s2_live = false, ste_live;
>>> + bool abort, nested = false, translate = false;
>>> struct arm_smmu_device *smmu = NULL;
>>> struct arm_smmu_s1_cfg *s1_cfg;
>>> struct arm_smmu_s2_cfg *s2_cfg;
>>> @@ -1233,6 +1236,8 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>>> default:
>>> break;
>>> }
>>> + nested = s1_cfg->set && s2_cfg->set;
>>> + translate = s1_cfg->set || s2_cfg->set;
>>> }
>>>
>>> if (val & STRTAB_STE_0_V) {
>>> @@ -1240,23 +1245,36 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>>> case STRTAB_STE_0_CFG_BYPASS:
>>> break;
>>> case STRTAB_STE_0_CFG_S1_TRANS:
>>> + s1_live = true;
>>> + break;
>>> case STRTAB_STE_0_CFG_S2_TRANS:
>>> - ste_live = true;
>>> + s2_live = true;
>>> + break;
>>> + case STRTAB_STE_0_CFG_NESTED:
>>> + s1_live = true;
>>> + s2_live = true;
>>> break;
>>> case STRTAB_STE_0_CFG_ABORT:
>>> - BUG_ON(!disable_bypass);
>>> break;
>>> default:
>>> BUG(); /* STE corruption */
>>> }
>>> }
>>>
>>> + ste_live = s1_live || s2_live;
>>> +
>>> /* Nuke the existing STE_0 value, as we're going to rewrite it */
>>> val = STRTAB_STE_0_V;
>>>
>>> /* Bypass/fault */
>>> - if (!smmu_domain || !(s1_cfg->set || s2_cfg->set)) {
>>> - if (!smmu_domain && disable_bypass)
>>> +
>>> + if (!smmu_domain)
>>> + abort = disable_bypass;
>>> + else
>>> + abort = smmu_domain->abort;
>>> +
>>> + if (abort || !translate) {
>>> + if (abort)
>>> val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_ABORT);
>>> else
>>> val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_BYPASS);
>>> @@ -1274,8 +1292,16 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>>> return;
>>> }
>>>
>>> + BUG_ON(ste_live && !nested);
>>> +
>>> + if (ste_live) {
>>> + /* First invalidate the live STE */
>>> + dst[0] = cpu_to_le64(STRTAB_STE_0_CFG_ABORT);
>>> + arm_smmu_sync_ste_for_sid(smmu, sid);
>>> + }
>>> +
>>> if (s1_cfg->set) {
>>> - BUG_ON(ste_live);
>>> + BUG_ON(s1_live);
>>> dst[1] = cpu_to_le64(
>>> FIELD_PREP(STRTAB_STE_1_S1DSS, STRTAB_STE_1_S1DSS_SSID0) |
>>> FIELD_PREP(STRTAB_STE_1_S1CIR, STRTAB_STE_1_S1C_CACHE_WBRA) |
>>> @@ -1294,7 +1320,14 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>>> }
>>>
>>> if (s2_cfg->set) {
>>> - BUG_ON(ste_live);
>>> + u64 vttbr = s2_cfg->vttbr & STRTAB_STE_3_S2TTB_MASK;
>>> +
>>> + if (s2_live) {
>>> + u64 s2ttb = le64_to_cpu(dst[3] & STRTAB_STE_3_S2TTB_MASK);
>>> +
>>> + BUG_ON(s2ttb != vttbr);
>>> + }
>>> +
>>> dst[2] = cpu_to_le64(
>>> FIELD_PREP(STRTAB_STE_2_S2VMID, s2_cfg->vmid) |
>>> FIELD_PREP(STRTAB_STE_2_VTCR, s2_cfg->vtcr) |
>>> @@ -1304,9 +1337,12 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
>>> STRTAB_STE_2_S2PTW | STRTAB_STE_2_S2AA64 |
>>> STRTAB_STE_2_S2R);
>>>
>>> - dst[3] = cpu_to_le64(s2_cfg->vttbr & STRTAB_STE_3_S2TTB_MASK);
>>> + dst[3] = cpu_to_le64(vttbr);
>>>
>>> val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_S2_TRANS);
>>> + } else {
>>> + dst[2] = 0;
>>> + dst[3] = 0;
>>> }
>>>
>>> if (master->ats_enabled)
>>> @@ -1982,6 +2018,14 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain,
>>> return 0;
>>> }
>>>
>>> + if (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED &&
>>> + (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1) ||
>>> + !(smmu->features & ARM_SMMU_FEAT_TRANS_S2))) {
>>> + dev_info(smmu_domain->smmu->dev,
>>> + "does not implement two stages\n");
>>> + return -EINVAL;
>>> + }
>>> +
>>> /* Restrict the stage to what we can actually support */
>>> if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1))
>>> smmu_domain->stage = ARM_SMMU_DOMAIN_S2;
>>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
>>> index 07f59252dd21..269779dee8d1 100644
>>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
>>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
>>> @@ -206,6 +206,7 @@
>>> #define STRTAB_STE_0_CFG_BYPASS 4
>>> #define STRTAB_STE_0_CFG_S1_TRANS 5
>>> #define STRTAB_STE_0_CFG_S2_TRANS 6
>>> +#define STRTAB_STE_0_CFG_NESTED 7
>>>
>>> #define STRTAB_STE_0_S1FMT GENMASK_ULL(5, 4)
>>> #define STRTAB_STE_0_S1FMT_LINEAR 0
>>> @@ -682,6 +683,7 @@ struct arm_smmu_domain {
>>> enum arm_smmu_domain_stage stage;
>>> struct arm_smmu_s1_cfg s1_cfg;
>>> struct arm_smmu_s2_cfg s2_cfg;
>>> + bool abort;
>>>
>>> struct iommu_domain domain;
>> Thanks,
>>
>> Kunkun Jiang
>>
> .
Thanks
Kunkun Jiang
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