linux-kernel - Re: [RFC PATCH 6/6] iommu/arm-smmu-v3: Avoid ILLEGAL setting of STE.S1STALLD and CD.S

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Date:   Wed, 6 Sep 2017 10:23:00 +0800
From:   Yisheng Xie <xieyisheng1@...wei.com>
To:     Jean-Philippe Brucker <jean-philippe.brucker@....com>
CC:     <joro@...tes.org>, <robh+dt@...nel.org>, <mark.rutland@....com>,
        <lorenzo.pieralisi@....com>, <hanjun.guo@...aro.org>,
        <sudeep.holla@....com>, <rjw@...ysocki.net>, <lenb@...nel.org>,
        <will.deacon@....com>, <robin.murphy@....com>,
        <robert.moore@...el.com>, <lv.zheng@...el.com>,
        <iommu@...ts.linux-foundation.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <devel@...ica.org>,
        <liubo95@...wei.com>, <chenjiankang1@...wei.com>,
        <xieyisheng@...wei.com>
Subject: Re: [RFC PATCH 6/6] iommu/arm-smmu-v3: Avoid ILLEGAL setting of
 STE.S1STALLD and CD.S

Hi Jean-Philippe,

On 2017/9/5 20:54, Jean-Philippe Brucker wrote:
> On 31/08/17 09:20, Yisheng Xie wrote:
>> It is ILLEGAL to set STE.S1STALLD if STALL_MODEL is not 0b00, which
>> means we should not disable stall mode if stall/terminate mode is not
>> configuable.
>>
>> Meanwhile, it is also ILLEGAL when STALL_MODEL==0b10 && CD.S==0 which
>> means if stall mode is force we should always set CD.S.
>>
>> This patch add ARM_SMMU_FEAT_TERMINATE feature bit for smmu, and use
>> TERMINATE feature checking to ensue above ILLEGAL cases from happening.
>>
>> Signed-off-by: Yisheng Xie <xieyisheng1@...wei.com>
>> ---
>>  drivers/iommu/arm-smmu-v3.c | 22 ++++++++++++++++------
>>  1 file changed, 16 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index dbda2eb..0745522 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -55,6 +55,7 @@
>>  #define IDR0_STALL_MODEL_SHIFT		24
>>  #define IDR0_STALL_MODEL_MASK		0x3
>>  #define IDR0_STALL_MODEL_STALL		(0 << IDR0_STALL_MODEL_SHIFT)
>> +#define IDR0_STALL_MODEL_NS		(1 << IDR0_STALL_MODEL_SHIFT)
>>  #define IDR0_STALL_MODEL_FORCE		(2 << IDR0_STALL_MODEL_SHIFT)
>>  #define IDR0_TTENDIAN_SHIFT		21
>>  #define IDR0_TTENDIAN_MASK		0x3
>> @@ -766,6 +767,7 @@ struct arm_smmu_device {
>>  #define ARM_SMMU_FEAT_SVM		(1 << 15)
>>  #define ARM_SMMU_FEAT_HA		(1 << 16)
>>  #define ARM_SMMU_FEAT_HD		(1 << 17)
>> +#define ARM_SMMU_FEAT_TERMINATE		(1 << 18)
> 
> I'd rather introduce something like "ARM_SMMU_FEAT_STALL_FORCE" instead.
> Terminate model has another meaning, and is defined by a different bit in
> IDR0.

Ok, sound more reasonable.

Thanks
Yisheng Xie

> 
> Thanks,
> Jean
> 
> .
>