From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: kevin.tian@intel.com, ashok.raj@intel.com,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
jacob.jun.pan@intel.com
Subject: Re: [PATCH 1/1] iommu/vt-d: Remove unnecessary WARN_ON_ONCE()
Date: Sat, 18 Jan 2020 10:14:11 +0800 [thread overview]
Message-ID: <b56e8a8f-acd7-b318-5a1c-f32c5a07657f@linux.intel.com> (raw)
In-Reply-To: <20200117095953.GB15760@8bytes.org>
Hi Joerg,
On 1/17/20 5:59 PM, Joerg Roedel wrote:
> On Thu, Jan 16, 2020 at 09:52:36AM +0800, Lu Baolu wrote:
>> Address field in device TLB invalidation descriptor is qualified
>> by the S field. If S field is zero, a single page at page address
>> specified by address [63:12] is requested to be invalidated. If S
>> field is set, the least significant bit in the address field with
>> value 0b (say bit N) indicates the invalidation address range. The
>> spec doesn't require the address [N - 1, 0] to be cleared, hence
>> remove the unnecessary WARN_ON_ONCE().
>>
>> Otherwise, the caller might set "mask = MAX_AGAW_PFN_WIDTH" in order
>> to invalidating all the cached mappings on an endpoint, and below
>> overflow error will be triggered.
>>
>> [...]
>> UBSAN: Undefined behaviour in drivers/iommu/dmar.c:1354:3
>> shift exponent 64 is too large for 64-bit type 'long long unsigned int'
>> [...]
>>
>> Reported-and-tested-by: Frank <fgndev@posteo.de>
>> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
>
> Does this need a Fixes and/or stable tag?
>
This doesn't cause any errors, just an unnecessary checking of
"0 & ((1UL << 64) - 1)"
in some cases.
>
> Regards,
>
> Joerg
Best regards,
baolu
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next prev parent reply other threads:[~2020-01-18 2:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 1:52 [PATCH 1/1] iommu/vt-d: Remove unnecessary WARN_ON_ONCE() Lu Baolu
2020-01-17 9:59 ` Joerg Roedel
2020-01-18 2:14 ` Lu Baolu [this message]
2020-01-24 14:36 ` Joerg Roedel
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