linux-kernel - Re: [PATCH v7 1/9] iommu: Add cache_invalidate

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Date: Tue, 26 Dec 2023 10:24:25 +0800
From: Yi Liu <yi.l.liu@...el.com>
To: "Tian, Kevin" <kevin.tian@...el.com>, "joro@...tes.org" <joro@...tes.org>,
	"alex.williamson@...hat.com" <alex.williamson@...hat.com>, "jgg@...dia.com"
	<jgg@...dia.com>, "robin.murphy@....com" <robin.murphy@....com>,
	"baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>
CC: "cohuck@...hat.com" <cohuck@...hat.com>, "eric.auger@...hat.com"
	<eric.auger@...hat.com>, "nicolinc@...dia.com" <nicolinc@...dia.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>, "mjrosato@...ux.ibm.com"
	<mjrosato@...ux.ibm.com>, "chao.p.peng@...ux.intel.com"
	<chao.p.peng@...ux.intel.com>, "yi.y.sun@...ux.intel.com"
	<yi.y.sun@...ux.intel.com>, "peterx@...hat.com" <peterx@...hat.com>,
	"jasowang@...hat.com" <jasowang@...hat.com>,
	"shameerali.kolothum.thodi@...wei.com"
	<shameerali.kolothum.thodi@...wei.com>, "lulu@...hat.com" <lulu@...hat.com>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	"iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>, "Duan,
 Zhenzhong" <zhenzhong.duan@...el.com>, "joao.m.martins@...cle.com"
	<joao.m.martins@...cle.com>, "Zeng, Xin" <xin.zeng@...el.com>, "Zhao, Yan Y"
	<yan.y.zhao@...el.com>, "j.granados@...sung.com" <j.granados@...sung.com>
Subject: Re: [PATCH v7 1/9] iommu: Add cache_invalidate_user op

On 2023/12/22 10:30, Tian, Kevin wrote:
>> From: Liu, Yi L <yi.l.liu@...el.com>
>> Sent: Thursday, December 21, 2023 11:40 PM
>>
>> From: Lu Baolu <baolu.lu@...ux.intel.com>
>>
>> The updates of the PTEs in the nested page table will be propagated to the
>> hardware caches on both IOMMU (IOTLB) and devices (DevTLB/ATC).
> 
> this is incorrect. the scope of this cmd is driver specific.

yes. May just say the hardware caches.

> 
>>
>> Add a new domain op cache_invalidate_user for the userspace to flush the
>> hardware caches for a nested domain through iommufd. No wrapper for it,
>> as it's only supposed to be used by iommufd. Then, pass in invalidation
>> requests in form of a user data array conatining a number of invalidation
>> data entries.
>>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
>> Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
>> Signed-off-by: Yi Liu <yi.l.liu@...el.com>
>> ---
>>   include/linux/iommu.h | 27 +++++++++++++++++++++++++++
>>   1 file changed, 27 insertions(+)
>>
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 6291aa7b079b..5c4a17f13761 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -284,6 +284,24 @@ struct iommu_user_data {
>>   	size_t len;
>>   };
>>
>> +/**
>> + * struct iommu_user_data_array - iommu driver specific user space data
>> array
>> + * @type: The data type of all the entries in the user buffer array
>> + * @uptr: Pointer to the user buffer array for copy_from_user()
> 
> remove 'for copy_from_user();
> 
>> + * @entry_len: The fixed-width length of a entry in the array, in bytes
> 
> s/a/an/
> 
>> + * @entry_num: The number of total entries in the array
>> + *
>> + * A array having a @entry_num number of @entry_len sized entries, each
> 
> the first sentence is redundant.
> 
>> entry is
>> + * user space data, an uAPI defined in include/uapi/linux/iommufd.h where
>> @type
>> + * is also defined as enum iommu_xyz_data_type.
> 
> I'd just say:
> 
> "The user buffer includes an array of requests with format defined
> in include/uapi/linux/iommufd.h"

sure.

-- 
Regards,
Yi Liu