From: Auger Eric <eric.auger@redhat.com>
To: "Tian, Kevin" <kevin.tian@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
Alex Williamson <alex.williamson@redhat.com>
Cc: "jacob.jun.pan@linux.intel.com" <jacob.jun.pan@linux.intel.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"Raj, Ashok" <ashok.raj@intel.com>,
"Tian, Jun J" <jun.j.tian@intel.com>,
"Sun, Yi Y" <yi.y.sun@intel.com>,
"jean-philippe@linaro.org" <jean-philippe@linaro.org>,
"peterx@redhat.com" <peterx@redhat.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Wu, Hao" <hao.wu@intel.com>
Subject: Re: [PATCH v1 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE
Date: Thu, 16 Apr 2020 17:12:20 +0200 [thread overview]
Message-ID: <4f7de577-dee7-91db-bc8c-637558016673@redhat.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19D823543@SHSMSX104.ccr.corp.intel.com>
Hi Kevin,
On 4/16/20 3:28 PM, Tian, Kevin wrote:
>> From: Auger Eric <eric.auger@redhat.com>
>> Sent: Thursday, April 16, 2020 8:43 PM
>>
>> Hi Kevin,
>> On 4/16/20 2:09 PM, Tian, Kevin wrote:
>>>> From: Liu, Yi L <yi.l.liu@intel.com>
>>>> Sent: Thursday, April 16, 2020 6:40 PM
>>>>
>>>> Hi Alex,
>>>> Still have a direction question with you. Better get agreement with you
>>>> before heading forward.
>>>>
>>>>> From: Alex Williamson <alex.williamson@redhat.com>
>>>>> Sent: Friday, April 3, 2020 11:35 PM
>>>> [...]
>>>>>>>> + *
>>>>>>>> + * returns: 0 on success, -errno on failure.
>>>>>>>> + */
>>>>>>>> +struct vfio_iommu_type1_cache_invalidate {
>>>>>>>> + __u32 argsz;
>>>>>>>> + __u32 flags;
>>>>>>>> + struct iommu_cache_invalidate_info cache_info;
>>>>>>>> +};
>>>>>>>> +#define VFIO_IOMMU_CACHE_INVALIDATE _IO(VFIO_TYPE,
>>>>> VFIO_BASE
>>>>>>> + 24)
>>>>>>>
>>>>>>> The future extension capabilities of this ioctl worry me, I wonder if
>>>>>>> we should do another data[] with flag defining that data as
>>>> CACHE_INFO.
>>>>>>
>>>>>> Can you elaborate? Does it mean with this way we don't rely on iommu
>>>>>> driver to provide version_to_size conversion and instead we just pass
>>>>>> data[] to iommu driver for further audit?
>>>>>
>>>>> No, my concern is that this ioctl has a single function, strictly tied
>>>>> to the iommu uapi. If we replace cache_info with data[] then we can
>>>>> define a flag to specify that data[] is struct
>>>>> iommu_cache_invalidate_info, and if we need to, a different flag to
>>>>> identify data[] as something else. For example if we get stuck
>>>>> expanding cache_info to meet new demands and develop a new uapi to
>>>>> solve that, how would we expand this ioctl to support it rather than
>>>>> also create a new ioctl? There's also a trade-off in making the ioctl
>>>>> usage more difficult for the user. I'd still expect the vfio layer to
>>>>> check the flag and interpret data[] as indicated by the flag rather
>>>>> than just passing a blob of opaque data to the iommu layer though.
>>>>> Thanks,
>>>>
>>>> Based on your comments about defining a single ioctl and a unified
>>>> vfio structure (with a @data[] field) for pasid_alloc/free, bind/
>>>> unbind_gpasid, cache_inv. After some offline trying, I think it would
>>>> be good for bind/unbind_gpasid and cache_inv as both of them use the
>>>> iommu uapi definition. While the pasid alloc/free operation doesn't.
>>>> It would be weird to put all of them together. So pasid alloc/free
>>>> may have a separate ioctl. It would look as below. Does this direction
>>>> look good per your opinion?
>>>>
>>>> ioctl #22: VFIO_IOMMU_PASID_REQUEST
>>>> /**
>>>> * @pasid: used to return the pasid alloc result when flags ==
>> ALLOC_PASID
>>>> * specify a pasid to be freed when flags == FREE_PASID
>>>> * @range: specify the allocation range when flags == ALLOC_PASID
>>>> */
>>>> struct vfio_iommu_pasid_request {
>>>> __u32 argsz;
>>>> #define VFIO_IOMMU_ALLOC_PASID (1 << 0)
>>>> #define VFIO_IOMMU_FREE_PASID (1 << 1)
>>>> __u32 flags;
>>>> __u32 pasid;
>>>> struct {
>>>> __u32 min;
>>>> __u32 max;
>>>> } range;
>>>> };
>>>>
>>>> ioctl #23: VFIO_IOMMU_NESTING_OP
>>>> struct vfio_iommu_type1_nesting_op {
>>>> __u32 argsz;
>>>> __u32 flags;
>>>> __u32 op;
>>>> __u8 data[];
>>>> };
>>>>
>>>> /* Nesting Ops */
>>>> #define VFIO_IOMMU_NESTING_OP_BIND_PGTBL 0
>>>> #define VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL 1
>>>> #define VFIO_IOMMU_NESTING_OP_CACHE_INVLD 2
>>>>
>>>
>>> Then why cannot we just put PASID into the header since the
>>> majority of nested usage is associated with a pasid?
>>>
>>> ioctl #23: VFIO_IOMMU_NESTING_OP
>>> struct vfio_iommu_type1_nesting_op {
>>> __u32 argsz;
>>> __u32 flags;
>>> __u32 op;
>>> __u32 pasid;
>>> __u8 data[];
>>> };
>>>
>>> In case of SMMUv2 which supports nested w/o PASID, this field can
>>> be ignored for that specific case.
>> On my side I would prefer keeping the pasid in the data[]. This is not
>> always used.
>>
>> For instance, in iommu_cache_invalidate_info/iommu_inv_pasid_info we
>> devised flags to tell whether the PASID is used.
>>
>
> But don't we include a PASID in both invalidate structures already?
The pasid presence is indicated by the IOMMU_INV_ADDR_FLAGS_PASID flag.
For instance for nested stage SMMUv3 I current performs an ARCHID (asid)
based invalidation only.
Eric
>
> struct iommu_inv_addr_info {
> #define IOMMU_INV_ADDR_FLAGS_PASID (1 << 0)
> #define IOMMU_INV_ADDR_FLAGS_ARCHID (1 << 1)
> #define IOMMU_INV_ADDR_FLAGS_LEAF (1 << 2)
> __u32 flags;
> __u32 archid;
> __u64 pasid;
> __u64 addr;
> __u64 granule_size;
> __u64 nb_granules;
> };
>
> struct iommu_inv_pasid_info {
> #define IOMMU_INV_PASID_FLAGS_PASID (1 << 0)
> #define IOMMU_INV_PASID_FLAGS_ARCHID (1 << 1)
> __u32 flags;
> __u32 archid;
> __u64 pasid;
> };
>
> then consolidating the pasid field into generic header doesn't
> hurt. the specific handler still rely on flags to tell whether it
> is used?
>
> Thanks
> Kevin
>
next prev parent reply other threads:[~2020-04-16 15:13 UTC|newest]
Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-22 12:31 [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs Liu, Yi L
2020-03-22 12:31 ` [PATCH v1 1/8] vfio: Add VFIO_IOMMU_PASID_REQUEST(alloc/free) Liu, Yi L
2020-03-22 16:21 ` kbuild test robot
2020-03-30 8:32 ` Tian, Kevin
2020-03-30 14:36 ` Liu, Yi L
2020-03-31 5:40 ` Tian, Kevin
2020-03-31 13:22 ` Liu, Yi L
2020-04-01 5:43 ` Tian, Kevin
2020-04-01 5:48 ` Liu, Yi L
2020-03-31 7:53 ` Christoph Hellwig
2020-03-31 8:17 ` Liu, Yi L
2020-03-31 8:32 ` Liu, Yi L
2020-03-31 8:36 ` Liu, Yi L
2020-03-31 9:15 ` Christoph Hellwig
2020-04-02 13:52 ` Jean-Philippe Brucker
2020-04-03 11:56 ` Liu, Yi L
2020-04-03 12:39 ` Jean-Philippe Brucker
2020-04-03 12:44 ` Liu, Yi L
2020-04-02 17:50 ` Alex Williamson
2020-04-03 5:58 ` Tian, Kevin
2020-04-03 15:14 ` Alex Williamson
2020-04-07 4:42 ` Tian, Kevin
2020-04-07 15:14 ` Alex Williamson
2020-04-03 13:12 ` Liu, Yi L
2020-04-03 17:50 ` Alex Williamson
2020-04-07 4:52 ` Tian, Kevin
2020-04-08 0:52 ` Liu, Yi L
2020-03-22 12:31 ` [PATCH v1 2/8] vfio/type1: Add vfio_iommu_type1 parameter for quota tuning Liu, Yi L
2020-03-22 17:20 ` kbuild test robot
2020-03-30 8:40 ` Tian, Kevin
2020-03-30 8:52 ` Liu, Yi L
2020-03-30 9:19 ` Tian, Kevin
2020-03-30 9:26 ` Liu, Yi L
2020-03-30 11:44 ` Tian, Kevin
2020-04-02 17:58 ` Alex Williamson
2020-04-03 8:15 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 3/8] vfio/type1: Report PASID alloc/free support to userspace Liu, Yi L
2020-03-30 9:43 ` Tian, Kevin
2020-04-01 7:46 ` Liu, Yi L
2020-04-01 9:41 ` Auger Eric
2020-04-01 13:13 ` Liu, Yi L
2020-04-02 18:01 ` Alex Williamson
2020-04-03 8:17 ` Liu, Yi L
2020-04-03 17:28 ` Alex Williamson
2020-04-04 11:36 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 4/8] vfio: Check nesting iommu uAPI version Liu, Yi L
2020-03-22 18:30 ` kbuild test robot
2020-03-22 12:32 ` [PATCH v1 5/8] vfio/type1: Report 1st-level/stage-1 format to userspace Liu, Yi L
2020-03-22 16:44 ` kbuild test robot
2020-03-30 11:48 ` Tian, Kevin
2020-04-01 7:38 ` Liu, Yi L
2020-04-01 7:56 ` Tian, Kevin
2020-04-01 8:06 ` Liu, Yi L
2020-04-01 8:08 ` Tian, Kevin
2020-04-01 8:09 ` Liu, Yi L
2020-04-01 8:51 ` Auger Eric
2020-04-01 12:51 ` Liu, Yi L
2020-04-01 13:01 ` Auger Eric
2020-04-03 8:23 ` Jean-Philippe Brucker
2020-04-07 9:43 ` Liu, Yi L
2020-04-08 1:02 ` Liu, Yi L
2020-04-08 10:27 ` Auger Eric
2020-04-09 8:14 ` Jean-Philippe Brucker
2020-04-09 9:01 ` Auger Eric
2020-04-09 12:47 ` Liu, Yi L
2020-04-10 3:28 ` Auger Eric
2020-04-10 3:48 ` Liu, Yi L
2020-04-10 12:30 ` Liu, Yi L
2020-04-02 19:20 ` Alex Williamson
2020-04-03 11:59 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 6/8] vfio/type1: Bind guest page tables to host Liu, Yi L
2020-03-22 18:10 ` kbuild test robot
2020-03-30 12:46 ` Tian, Kevin
2020-04-01 9:13 ` Liu, Yi L
2020-04-02 2:12 ` Tian, Kevin
2020-04-02 8:05 ` Liu, Yi L
2020-04-03 8:34 ` Jean-Philippe Brucker
2020-04-07 10:33 ` Liu, Yi L
2020-04-09 8:28 ` Jean-Philippe Brucker
2020-04-09 9:15 ` Liu, Yi L
2020-04-09 9:38 ` Jean-Philippe Brucker
2020-04-02 19:57 ` Alex Williamson
2020-04-03 13:30 ` Liu, Yi L
2020-04-03 18:11 ` Alex Williamson
2020-04-04 10:28 ` Liu, Yi L
2020-04-11 5:52 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE Liu, Yi L
2020-03-30 12:58 ` Tian, Kevin
2020-04-01 7:49 ` Liu, Yi L
2020-03-31 7:56 ` Christoph Hellwig
2020-03-31 10:48 ` Liu, Yi L
2020-04-02 20:24 ` Alex Williamson
2020-04-03 6:39 ` Tian, Kevin
2020-04-03 15:31 ` Jacob Pan
2020-04-03 15:34 ` Alex Williamson
2020-04-08 2:28 ` Liu, Yi L
2020-04-16 10:40 ` Liu, Yi L
2020-04-16 12:09 ` Tian, Kevin
2020-04-16 12:42 ` Auger Eric
2020-04-16 13:28 ` Tian, Kevin
2020-04-16 15:12 ` Auger Eric [this message]
2020-04-16 14:40 ` Alex Williamson
2020-04-16 14:48 ` Alex Williamson
2020-04-17 6:03 ` Liu, Yi L
2020-03-22 12:32 ` [PATCH v1 8/8] vfio/type1: Add vSVA support for IOMMU-backed mdevs Liu, Yi L
2020-03-30 13:18 ` Tian, Kevin
2020-04-01 7:51 ` Liu, Yi L
2020-04-02 20:33 ` Alex Williamson
2020-04-03 13:39 ` Liu, Yi L
2020-03-26 12:56 ` [PATCH v1 0/8] vfio: expose virtual Shared Virtual Addressing to VMs Liu, Yi L
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