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Sun, 16 Aug 2020 08:41:11 -0400 X-MC-Unique: Nnagph-PNv-RJbVc_e8CZw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C82F68712F5; Sun, 16 Aug 2020 12:41:09 +0000 (UTC) Received: from [10.36.113.93] (ovpn-113-93.ams2.redhat.com [10.36.113.93]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3505639A75; Sun, 16 Aug 2020 12:40:59 +0000 (UTC) Subject: Re: [PATCH v6 02/15] iommu: Report domain nesting info To: "Liu, Yi L" , "alex.williamson@redhat.com" , "baolu.lu@linux.intel.com" , "joro@8bytes.org" References: <1595917664-33276-1-git-send-email-yi.l.liu@intel.com> <1595917664-33276-3-git-send-email-yi.l.liu@intel.com> <5c911565-c76a-c361-845e-56a91744d504@redhat.com> From: Auger Eric Message-ID: <342e8d77-1c1d-e637-0227-720ba67df8ba@redhat.com> Date: Sun, 16 Aug 2020 14:40:57 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Cc: "jean-philippe@linaro.org" , "Tian, Kevin" , "Raj, Ashok" , "kvm@vger.kernel.org" , "stefanha@gmail.com" , "Tian, Jun J" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "Sun, Yi Y" , "Wu, Hao" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Yi, On 8/14/20 9:15 AM, Liu, Yi L wrote: > Hi Eric, > >> From: Auger Eric >> Sent: Thursday, August 13, 2020 8:53 PM >> >> Yi, >> On 7/28/20 8:27 AM, Liu Yi L wrote: >>> IOMMUs that support nesting translation needs report the capability info >> s/needs/need to >>> to userspace. It gives information about requirements the userspace needs >>> to implement plus other features characterizing the physical implementation. >>> >>> This patch reports nesting info by DOMAIN_ATTR_NESTING. Caller can get >>> nesting info after setting DOMAIN_ATTR_NESTING. For VFIO, it is after >>> selecting VFIO_TYPE1_NESTING_IOMMU. >> This is not what this patch does ;-) It introduces a new IOMMU UAPI >> struct that gives information about the nesting capabilities and >> features. This struct is supposed to be returned by >> iommu_domain_get_attr() with DOMAIN_ATTR_NESTING attribute parameter, >> one a domain whose type has been set to DOMAIN_ATTR_NESTING. > > got it. let me apply your suggestion. thanks. :-) > >>> >>> Cc: Kevin Tian >>> CC: Jacob Pan >>> Cc: Alex Williamson >>> Cc: Eric Auger >>> Cc: Jean-Philippe Brucker >>> Cc: Joerg Roedel >>> Cc: Lu Baolu >>> Signed-off-by: Liu Yi L >>> Signed-off-by: Jacob Pan >>> --- >>> v5 -> v6: >>> *) rephrase the feature notes per comments from Eric Auger. >>> *) rename @size of struct iommu_nesting_info to @argsz. >>> >>> v4 -> v5: >>> *) address comments from Eric Auger. >>> >>> v3 -> v4: >>> *) split the SMMU driver changes to be a separate patch >>> *) move the @addr_width and @pasid_bits from vendor specific >>> part to generic part. >>> *) tweak the description for the @features field of struct >>> iommu_nesting_info. >>> *) add description on the @data[] field of struct iommu_nesting_info >>> >>> v2 -> v3: >>> *) remvoe cap/ecap_mask in iommu_nesting_info. >>> *) reuse DOMAIN_ATTR_NESTING to get nesting info. >>> *) return an empty iommu_nesting_info for SMMU drivers per Jean' >>> suggestion. >>> --- >>> include/uapi/linux/iommu.h | 74 >> ++++++++++++++++++++++++++++++++++++++++++++++ >>> 1 file changed, 74 insertions(+) >>> >>> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h >>> index 7c8e075..5e4745a 100644 >>> --- a/include/uapi/linux/iommu.h >>> +++ b/include/uapi/linux/iommu.h >>> @@ -332,4 +332,78 @@ struct iommu_gpasid_bind_data { >>> } vendor; >>> }; >>> >>> +/* >>> + * struct iommu_nesting_info - Information for nesting-capable IOMMU. >>> + * userspace should check it before using >>> + * nesting capability. >>> + * >>> + * @argsz: size of the whole structure. >>> + * @flags: currently reserved for future extension. must set to 0. >>> + * @format: PASID table entry format, the same definition as struct >>> + * iommu_gpasid_bind_data @format. >>> + * @features: supported nesting features. >>> + * @addr_width: The output addr width of first level/stage translation >>> + * @pasid_bits: Maximum supported PASID bits, 0 represents no PASID >>> + * support. >>> + * @data: vendor specific cap info. data[] structure type can be deduced >>> + * from @format field. >>> + * >>> + * >> +===============+=================================================== >> ===+ >>> + * | feature | Notes | >>> + * >> +===============+=================================================== >> ===+ >>> + * | SYSWIDE_PASID | IOMMU vendor driver sets it to mandate userspace | >>> + * | | to allocate PASID from kernel. All PASID allocation | >>> + * | | free must be mediated through the TBD API. | >> s/TBD/IOMMU > > got it. > >>> + * +---------------+------------------------------------------------------+ >>> + * | BIND_PGTBL | IOMMU vendor driver sets it to mandate userspace | >>> + * | | bind the first level/stage page table to associated | >> s/bind/to bind > > got it. > >>> + * | | PASID (either the one specified in bind request or | >>> + * | | the default PASID of iommu domain), through IOMMU | >>> + * | | UAPI. | >>> + * +---------------+------------------------------------------------------+ >>> + * | CACHE_INVLD | IOMMU vendor driver sets it to mandate userspace | >> >>> + * | | explicitly invalidate the IOMMU cache through IOMMU | >> to explicitly > > I see. > >>> + * | | U >>> API according to vendor-specific requirement when | >>> + * | | changing the 1st level/stage page table. | >>> + * +---------------+------------------------------------------------------+ >>> + * >>> + * @data[] types defined for @format: >>> + * >> +================================+================================== >> ===+ >>> + * | @format | @data[] | >>> + * >> +================================+================================== >> ===+ >>> + * | IOMMU_PASID_FORMAT_INTEL_VTD | struct iommu_nesting_info_vtd | >>> + * +--------------------------------+-------------------------------------+ >>> + * >>> + */ >>> +struct iommu_nesting_info { >>> + __u32 argsz; >>> + __u32 flags; >>> + __u32 format; >>> +#define IOMMU_NESTING_FEAT_SYSWIDE_PASID (1 << 0) >>> +#define IOMMU_NESTING_FEAT_BIND_PGTBL (1 << 1) >>> +#define IOMMU_NESTING_FEAT_CACHE_INVLD (1 << 2) >>> + __u32 features; >>> + __u16 addr_width; >>> + __u16 pasid_bits; >>> + __u32 padding; >>> + __u8 data[]; >>> +}; >> As opposed to other IOMMU UAPI structs there is no union member at the >> end. > > nice catch. do you think it would be better to adding a union and > put the struct iommu_nesting_info_vtd in it? Yes I think so. At least it would be consistent with the rest of the API and with the guidelines. > >> Also this struct is not documented in [PATCH v7 1/7] docs: IOMMU >> user API. Shouldn't we align. >> You may also consider to move this patch in Jacob's series for >> consistency, thoughts? > > this was talked one time between Jacob and me. It was put in this > series as the major user of nesting_info is in this series. e.g. > vfio checks the SYSWIDE_PASID. but I'm open to merge it with Jacob's > series if it would make the merge easier. Yep I think it would make sense to move in Jacob's series to have a general understanding of the uapi Thanks Eric > > Thanks, > Yi Liu > >>> + >>> +/* >>> + * struct iommu_nesting_info_vtd - Intel VT-d specific nesting info. >>> + * >>> + * @flags: VT-d specific flags. Currently reserved for future >>> + * extension. must be set to 0. >>> + * @cap_reg: Describe basic capabilities as defined in VT-d capability >>> + * register. >>> + * @ecap_reg: Describe the extended capabilities as defined in VT-d >>> + * extended capability register. >>> + */ >>> +struct iommu_nesting_info_vtd { >>> + __u32 flags; >>> + __u32 padding; >>> + __u64 cap_reg; >>> + __u64 ecap_reg; >>> +}; >>> + >>> #endif /* _UAPI_IOMMU_H */ >>> >> >> Thanks >> >> Eric >> > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu