linux-kernel - Re: [RESEND PATCH v17 2/5] iommu/arm-smmu: Invoke pm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 26 Nov 2018 16:56:42 +0530
From:   Vivek Gautam <vivek.gautam@...eaurora.org>
To:     Will Deacon <will.deacon@....com>
Cc:     Mark Rutland <mark.rutland@....com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, alex.williamson@...hat.com,
        Linux PM <linux-pm@...r.kernel.org>, sboyd@...nel.org,
        freedreno <freedreno@...ts.freedesktop.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        open list <linux-kernel@...r.kernel.org>,
        "list@....net:IOMMU DRIVERS" <iommu@...ts.linux-foundation.org>,
        Joerg Roedel <joro@...tes.org>, robh+dt <robh+dt@...nel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Robin Murphy <robin.murphy@....com>
Subject: Re: [RESEND PATCH v17 2/5] iommu/arm-smmu: Invoke pm_runtime during
 probe, add/remove device



On 11/26/2018 11:33 AM, Vivek Gautam wrote:
>
>
> On 11/24/2018 12:06 AM, Will Deacon wrote:
>> On Thu, Nov 22, 2018 at 05:32:24PM +0530, Vivek Gautam wrote:
>>> Hi Will,
>>>
>>> On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@....com> 
>>> wrote:
>>>> On Fri, Nov 16, 2018 at 04:54:27PM +0530, Vivek Gautam wrote:
>>>>> From: Sricharan R <sricharan@...eaurora.org>
>>>>>
>>>>> The smmu device probe/remove and add/remove master device callbacks
>>>>> gets called when the smmu is not linked to its master, that is 
>>>>> without
>>>>> the context of the master device. So calling runtime apis in those 
>>>>> places
>>>>> separately.
>>>>> Global locks are also initialized before enabling runtime pm as the
>>>>> runtime_resume() calls device_reset() which does tlb_sync_global()
>>>>> that ultimately requires locks to be initialized.
>>>>>
>>>>> Signed-off-by: Sricharan R <sricharan@...eaurora.org>
>>>>> [vivek: Cleanup pm runtime calls]
>>>>> Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
>>>>> Reviewed-by: Tomasz Figa <tfiga@...omium.org>
>>>>> Tested-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>>>>> Reviewed-by: Robin Murphy <robin.murphy@....com>
>>>>> ---
>>>>>   drivers/iommu/arm-smmu.c | 101 
>>>>> ++++++++++++++++++++++++++++++++++++++++++-----
>>>>>   1 file changed, 91 insertions(+), 10 deletions(-)
>>>> Given that you're doing the get/put in the TLBI ops unconditionally:
>>>>
>>>>>   static void arm_smmu_flush_iotlb_all(struct iommu_domain *domain)
>>>>>   {
>>>>>        struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>>>>> +     struct arm_smmu_device *smmu = smmu_domain->smmu;
>>>>>
>>>>> -     if (smmu_domain->tlb_ops)
>>>>> +     if (smmu_domain->tlb_ops) {
>>>>> +             arm_smmu_rpm_get(smmu);
>>>>> smmu_domain->tlb_ops->tlb_flush_all(smmu_domain);
>>>>> +             arm_smmu_rpm_put(smmu);
>>>>> +     }
>>>>>   }
>>>>>
>>>>>   static void arm_smmu_iotlb_sync(struct iommu_domain *domain)
>>>>>   {
>>>>>        struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>>>>> +     struct arm_smmu_device *smmu = smmu_domain->smmu;
>>>>>
>>>>> -     if (smmu_domain->tlb_ops)
>>>>> +     if (smmu_domain->tlb_ops) {
>>>>> +             arm_smmu_rpm_get(smmu);
>>>>> smmu_domain->tlb_ops->tlb_sync(smmu_domain);
>>>>> +             arm_smmu_rpm_put(smmu);
>>>>> +     }
>>>> Why do you need them around the map/unmap calls as well?
>>> We still have .tlb_add_flush path?
>> Ok, so we could add the ops around that as well. Right now, we've got
>> the runtime pm hooks crossing two parts of the API.
>
> Sure, will do that then, and remove the runtime pm hooks from map/unmap.

I missed this earlier -
We are adding runtime pm hooks in the 'iommu_ops' callbacks and not 
really to
'tlb_ops'. So how the runtime pm hooks crossing the paths?
'.map/.unmap' iommu_ops don't call '.flush_iotlb_all' or '.iotlb_sync' 
iommu_ops
anywhere.

E.g., only callers to domain->ops->flush_iotlb_all() are:
iommu_dma_flush_iotlb_all(), or iommu_flush_tlb_all() which are not in 
map/unmap paths.

Regards
Vivek

>
> Thanks
> Vivek
>>
>> Will
>