linux-kernel - Re: [PATCH v6 2/6] iommufd: Add IOMMU_HWPT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <eb4394b1-66d1-40ae-9d40-fb517ce18b6e@intel.com>
Date:   Mon, 11 Dec 2023 15:49:06 +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>
Subject: Re: [PATCH v6 2/6] iommufd: Add IOMMU_HWPT_INVALIDATE

On 2023/12/7 17:04, Tian, Kevin wrote:
>> From: Liu, Yi L <yi.l.liu@...el.com>
>> Sent: Thursday, December 7, 2023 2:59 PM
>>
>> On 2023/11/17 21:07, Yi Liu wrote:
>>> @@ -613,4 +614,38 @@ struct iommu_hwpt_get_dirty_bitmap {
>>>    #define IOMMU_HWPT_GET_DIRTY_BITMAP _IO(IOMMUFD_TYPE, \
>>>
>> 	IOMMUFD_CMD_HWPT_GET_DIRTY_BITMAP)
>>>
>>> +/**
>>> + * struct iommu_hwpt_invalidate - ioctl(IOMMU_HWPT_INVALIDATE)
>>> + * @size: sizeof(struct iommu_hwpt_invalidate)
>>> + * @hwpt_id: HWPT ID of a nested HWPT for cache invalidation
>>> + * @reqs_uptr: User pointer to an array having @req_num of cache
>> invalidation
>>> + *             requests. The request entries in the array are of fixed width
>>> + *             @req_len, and contain a user data structure for invalidation
>>> + *             request specific to the given hardware page table.
>>> + * @req_type: One of enum iommu_hwpt_data_type, defining the data
>> type of all
>>> + *            the entries in the invalidation request array. It should suit
>>> + *            with the data_type passed per the allocation of the hwpt pointed
>>> + *            by @hwpt_id.
>>
>> @Jason and Kevin,
>>
>> Here a check with you two. I had a conversation with Nic on the definition
>> of req_type here. It was added to support potential multiple kinds of cache
>> invalidation data types for a invalidating cache for a single hwpt type[1].
>> But we defined it as reusing the hwpt_data_type. In this way, it is not
>> able to support the potential case in[1]. is it? Shall we define a separate
>> enum for invalidation data types? And how can we let user know the
>> available invalidation data types for a hwpt type? Any idea?
>>
>> [1] https://lore.kernel.org/linux-
>> iommu/20231018163720.GA3952@...dia.com/
>>
> 
>  From that thread Jason mentioned to make the invalidation format
> part of domain allocation. If that is the direction to go then there
> won't be multiple invalidation formats per hwpt. The user should
> create multiple hwpt's per invalidation format (though mixing
> formats in one virtual platform is very unlikely)?

yes, following that, the hwpt data type would be a kind of a combination
of page table type and cache invalidation type. In this way, the req_type
may also be dropped as the hwpt allocation path can record the type and
reuse it in the cache invalidation path.

-- 
Regards,
Yi Liu