lkml.org 
[lkml]   [2018]   [Nov]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v4 04/12] iommu/vt-d: Add 256-bit invalidation descriptor support
From
Date
Hi,

On 11/8/18 11:49 AM, Liu, Yi L wrote:
> Hi,
>
>> From: Lu Baolu [mailto:baolu.lu@linux.intel.com]
>> Sent: Thursday, November 8, 2018 10:17 AM
>> Subject: Re: [PATCH v4 04/12] iommu/vt-d: Add 256-bit invalidation descriptor
>> support
>>
>> Hi Yi,
>>
>> On 11/7/18 2:07 PM, Liu, Yi L wrote:
>>> Hi Baolu,
>>>
>>>> From: Lu Baolu [mailto:baolu.lu@linux.intel.com]
>>>> Sent: Monday, November 5, 2018 1:32 PM
>>>
>>> [...]
>>>
>>>> ---
>>>> drivers/iommu/dmar.c | 83 +++++++++++++++++++----------
>>>> drivers/iommu/intel-svm.c | 76 ++++++++++++++++----------
>>>> drivers/iommu/intel_irq_remapping.c | 6 ++-
>>>> include/linux/intel-iommu.h | 9 +++-
>>>> 4 files changed, 115 insertions(+), 59 deletions(-)
>>>>
>>>> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c index
>>>> d9c748b6f9e4..ec10427b98ac 100644
>>>> --- a/drivers/iommu/dmar.c
>>>> +++ b/drivers/iommu/dmar.c
>>>> @@ -1160,6 +1160,7 @@ static int qi_check_fault(struct intel_iommu
>>>> *iommu, int
>>>> index)
>>>> int head, tail;
>>>> struct q_inval *qi = iommu->qi;
>>>> int wait_index = (index + 1) % QI_LENGTH;
>>>> + int shift = qi_shift(iommu);
>>>>
>>>> if (qi->desc_status[wait_index] == QI_ABORT)
>>>> return -EAGAIN;
>>>> @@ -1173,13 +1174,15 @@ static int qi_check_fault(struct intel_iommu
>>>> *iommu, int index)
>>>> */
>>>> if (fault & DMA_FSTS_IQE) {
>>>> head = readl(iommu->reg + DMAR_IQH_REG);
>>>> - if ((head >> DMAR_IQ_SHIFT) == index) {
>>>> + if ((head >> shift) == index) {
>>>> + struct qi_desc *desc = qi->desc + head;
>>>> +
>>>> pr_err("VT-d detected invalid descriptor: "
>>>> "low=%llx, high=%llx\n",
>>>> - (unsigned long long)qi->desc[index].low,
>>>> - (unsigned long long)qi->desc[index].high);
>>>> - memcpy(&qi->desc[index], &qi->desc[wait_index],
>>>> - sizeof(struct qi_desc));
>>>> + (unsigned long long)desc->qw0,
>>>> + (unsigned long long)desc->qw1);
>>>
>>> Still missing qw2 and qw3. May make the print differ based on if smts is configed.
>>
>> qw2 and qw3 are reserved from software point of view. We don't need to print it for
>> information.
>
> But for Scalable mode, it should be valid?

No. It's reserved for software.

>
>>
>>>
>>>> + memcpy(desc, qi->desc + (wait_index << shift),
>>>
>>> Would "memcpy(desc, (unsigned long long) (qi->desc + (wait_index <<
>>> shift)," be more safe?
>>
>> Can that be compiled? memcpy() requires a "const void *" for the second parameter.
>> By the way, why it's safer with this casting?
>
> This is just an example. My point is the possibility that "qi->desc + (wait_index << shift)"
> would be treated as "qi->desc plus (wait_index << shift)*sizeof(*qi->desc)". Is it possible
> for kernel build?

qi->desc is of type of "void *".

Best regards,
Lu Baolu

\
 
 \ /
  Last update: 2018-11-08 06:28    [W:0.090 / U:0.088 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site