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Tue, 15 Mar 2022 16:29:04 +0000 (GMT) Message-ID: <5a1c64ac-df10-fb66-ad6d-39adf786f32b@linux.ibm.com> Date: Tue, 15 Mar 2022 12:29:02 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 Subject: Re: [PATCH v4 15/32] vfio: introduce KVM-owned IOMMU type Content-Language: en-US To: Jason Gunthorpe , borntraeger@linux.ibm.com Cc: linux-s390@vger.kernel.org, alex.williamson@redhat.com, cohuck@redhat.com, schnelle@linux.ibm.com, farman@linux.ibm.com, pmorel@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, gerald.schaefer@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com, vneethv@linux.ibm.com, oberpar@linux.ibm.com, freude@linux.ibm.com, thuth@redhat.com, pasic@linux.ibm.com, joro@8bytes.org, will@kernel.org, pbonzini@redhat.com, corbet@lwn.net, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-doc@vger.kernel.org References: <20220314194451.58266-1-mjrosato@linux.ibm.com> <20220314194451.58266-16-mjrosato@linux.ibm.com> <20220314213808.GI11336@nvidia.com> <20220315143858.GY11336@nvidia.com> From: Matthew Rosato In-Reply-To: <20220315143858.GY11336@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: XovYpnHnN8X7XvZsXcj1wbC8jRUcunWF X-Proofpoint-GUID: VyCBJft7M62L1ZwToTemOEV0VPlk6L0Q X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.850,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-03-15_03,2022-03-15_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 mlxlogscore=999 suspectscore=0 phishscore=0 impostorscore=0 spamscore=0 bulkscore=0 clxscore=1015 adultscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2203150102 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/15/22 10:38 AM, Jason Gunthorpe wrote: > On Tue, Mar 15, 2022 at 09:49:01AM -0400, Matthew Rosato wrote: > >> The rationale for splitting steps 1 and 2 are that VFIO_SET_IOMMU doesn't >> have a mechanism for specifying more than the type as an arg, no? Otherwise >> yes, you could specify a kvm fd at this point and it would have some other >> advantages (e.g. skip notifier). But we still can't use the IOMMU for >> mapping until step 3. > > Stuff like this is why I'd be much happier if this could join our > iommfd project so we can have clean modeling of the multiple iommu_domains. > I'd certainly be willing to collaborate so feel free to loop me in on the discussions; but I got the impression that iommufd is not close to ready (maybe I'm wrong?) -- if so I really don't want to completely delay this zPCI support behind it as it has a significant benefit for kvm guests on s390x :(