linux-kernel - Re: [PATCH 4/7] iommu/amd: make sure TLB to be flushed before IOVA freed

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Date:   Mon, 4 Jun 2018 19:41:39 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Robin Murphy <robin.murphy@....com>,
        Will Deacon <will.deacon@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Rob Clark <robdclark@...il.com>,
        Joerg Roedel <joro@...tes.org>,
        linux-mediatek <linux-mediatek@...ts.infradead.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        iommu <iommu@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
CC:     Hanjun Guo <guohanjun@...wei.com>, Libin <huawei.libin@...wei.com>,
        "Guozhu Li" <liguozhu@...ilicon.com>,
        Xinwei Hu <huxinwei@...wei.com>
Subject: Re: [PATCH 4/7] iommu/amd: make sure TLB to be flushed before IOVA
 freed



On 2018/5/31 21:04, Robin Murphy wrote:
> On 31/05/18 08:42, Zhen Lei wrote:
>> Although the mapping has already been removed in the page table, it maybe
>> still exist in TLB. Suppose the freed IOVAs is reused by others before the
>> flush operation completed, the new user can not correctly access to its
>> meomory.
> 
> This change seems reasonable in isolation, but why is it right in the middle of a series which has nothing to do with x86?
Because I described more in the previous patch, which may help this patch to be understood well.

You're right, I will repost this patch separately.

> 
> Robin.
> 
>> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
>> ---
>>   drivers/iommu/amd_iommu.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
>> index 8fb8c73..93aa389 100644
>> --- a/drivers/iommu/amd_iommu.c
>> +++ b/drivers/iommu/amd_iommu.c
>> @@ -2402,9 +2402,9 @@ static void __unmap_single(struct dma_ops_domain *dma_dom,
>>       }
>>         if (amd_iommu_unmap_flush) {
>> -        dma_ops_free_iova(dma_dom, dma_addr, pages);
>>           domain_flush_tlb(&dma_dom->domain);
>>           domain_flush_complete(&dma_dom->domain);
>> +        dma_ops_free_iova(dma_dom, dma_addr, pages);
>>       } else {
>>           pages = __roundup_pow_of_two(pages);
>>           queue_iova(&dma_dom->iovad, dma_addr >> PAGE_SHIFT, pages, 0);
>>
> 
> .
> 

-- 
Thanks!
BestRegards