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([2a01:e0a:9e2:9000:bed7:42c6:fb19:d12e]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6b7ac7bd2a7sm36253976d6.20.2024.07.22.08.13.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 22 Jul 2024 08:13:33 -0700 (PDT) Message-ID: <51012898-c535-4fb1-b101-3d613d46fc30@redhat.com> Date: Mon, 22 Jul 2024 17:13:30 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 12/13] vfio/migration: Don't block migration device dirty tracking is unsupported To: Joao Martins , qemu-devel@nongnu.org Cc: Yi Liu , Eric Auger , Zhenzhong Duan , Alex Williamson , Jason Gunthorpe , Avihai Horon References: <20240719120501.81279-1-joao.m.martins@oracle.com> <20240719120501.81279-13-joao.m.martins@oracle.com> <1304a8c4-be47-4b47-88dd-328a8f167e54@oracle.com> <967952f0-e3bd-4c86-b4a8-4906e6b3e248@redhat.com> <103a2101-3f9e-46da-b45b-b8a4eaa7d6e7@oracle.com> Content-Language: en-US, fr From: =?UTF-8?Q?C=C3=A9dric_Le_Goater?= In-Reply-To: <103a2101-3f9e-46da-b45b-b8a4eaa7d6e7@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.133, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 7/22/24 17:01, Joao Martins wrote: > On 22/07/2024 15:53, Cédric Le Goater wrote: >> On 7/19/24 19:26, Joao Martins wrote: >>> On 19/07/2024 15:24, Joao Martins wrote: >>>> On 19/07/2024 15:17, Cédric Le Goater wrote: >>>>> On 7/19/24 14:05, Joao Martins wrote: >>>>>> By default VFIO migration is set to auto, which will support live >>>>>> migration if the migration capability is set *and* also dirty page >>>>>> tracking is supported. >>>>>> >>>>>> For testing purposes one can force enable without dirty page tracking >>>>>> via enable-migration=on, but that option is generally left for testing >>>>>> purposes. >>>>>> >>>>>> So starting with IOMMU dirty tracking it can use to accomodate the lack of >>>>>> VF dirty page tracking allowing us to minimize the VF requirements for >>>>>> migration and thus enabling migration by default for those too. >>>>>> >>>>>> While at it change the error messages to mention IOMMU dirty tracking as >>>>>> well. >>>>>> >>>>>> Signed-off-by: Joao Martins >>>>>> --- >>>>>>    include/hw/vfio/vfio-common.h |  1 + >>>>>>    hw/vfio/iommufd.c             |  2 +- >>>>>>    hw/vfio/migration.c           | 11 ++++++----- >>>>>>    3 files changed, 8 insertions(+), 6 deletions(-) >>>>>> >>>>>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h >>>>>> index 7e530c7869dc..00b9e933449e 100644 >>>>>> --- a/include/hw/vfio/vfio-common.h >>>>>> +++ b/include/hw/vfio/vfio-common.h >>>>>> @@ -299,6 +299,7 @@ int vfio_devices_query_dirty_bitmap(const >>>>>> VFIOContainerBase *bcontainer, >>>>>>                    VFIOBitmap *vbmap, hwaddr iova, hwaddr size, Error **errp); >>>>>>    int vfio_get_dirty_bitmap(const VFIOContainerBase *bcontainer, uint64_t >>>>>> iova, >>>>>>                              uint64_t size, ram_addr_t ram_addr, Error >>>>>> **errp); >>>>>> +bool iommufd_hwpt_dirty_tracking(VFIOIOASHwpt *hwpt); >>>>>>      /* Returns 0 on success, or a negative errno. */ >>>>>>    bool vfio_device_get_name(VFIODevice *vbasedev, Error **errp); >>>>>> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c >>>>>> index 7dd5d43ce06a..a998e8578552 100644 >>>>>> --- a/hw/vfio/iommufd.c >>>>>> +++ b/hw/vfio/iommufd.c >>>>>> @@ -111,7 +111,7 @@ static void iommufd_cdev_unbind_and_disconnect(VFIODevice >>>>>> *vbasedev) >>>>>>        iommufd_backend_disconnect(vbasedev->iommufd); >>>>>>    } >>>>>>    -static bool iommufd_hwpt_dirty_tracking(VFIOIOASHwpt *hwpt) >>>>>> +bool iommufd_hwpt_dirty_tracking(VFIOIOASHwpt *hwpt) >>>>>>    { >>>>>>        return hwpt && hwpt->hwpt_flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING; >>>>>>    } >>>>>> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c >>>>>> index 34d4be2ce1b1..63ffa46c9652 100644 >>>>>> --- a/hw/vfio/migration.c >>>>>> +++ b/hw/vfio/migration.c >>>>>> @@ -1036,16 +1036,17 @@ bool vfio_migration_realize(VFIODevice *vbasedev, >>>>>> Error **errp) >>>>>>            return !vfio_block_migration(vbasedev, err, errp); >>>>>>        } >>>>>>    -    if (!vbasedev->dirty_pages_supported) { >>>>>> +    if (!vbasedev->dirty_pages_supported && >>>>>> +        !iommufd_hwpt_dirty_tracking(vbasedev->hwpt)) { >>>>> >>>>> >>>>> Some platforms do not have IOMMUFD support and this call will need >>>>> some kind of abstract wrapper to reflect dirty tracking support in >>>>> the IOMMU backend. >>>>> >>>> >>>> This was actually on purpose because only IOMMUFD presents a view of hardware >>>> whereas type1 supporting dirty page tracking is not used as means to 'migration >>>> is supported'. >>>> >>>> The hwpt is nil in type1 and the helper checks that, so it should return false. >>>> >>> >>> Oh wait, maybe you're talking about CONFIG_IOMMUFD=n which I totally didn't >>> consider. Maybe this would be a elegant way to address it? Looks to pass my >>> build with CONFIG_IOMMUFD=n >>> >>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h >>> index 61dd48e79b71..422ad4a5bdd1 100644 >>> --- a/include/hw/vfio/vfio-common.h >>> +++ b/include/hw/vfio/vfio-common.h >>> @@ -300,7 +300,14 @@ int vfio_devices_query_dirty_bitmap(const VFIOContainerBase >>> *bcontainer, >>>                   VFIOBitmap *vbmap, hwaddr iova, hwaddr size, Error **errp); >>>   int vfio_get_dirty_bitmap(const VFIOContainerBase *bcontainer, uint64_t iova, >>>                             uint64_t size, ram_addr_t ram_addr, Error **errp); >>> +#ifdef CONFIG_IOMMUFD >>>   bool iommufd_hwpt_dirty_tracking(VFIOIOASHwpt *hwpt); >>> +#else >>> +static inline bool iommufd_hwpt_dirty_tracking(VFIOIOASHwpt *hwpt) >>> +{ >>> +    return false; >>> +} >>> +#endif >>> >>>   /* Returns 0 on success, or a negative errno. */ >>>   bool vfio_device_get_name(VFIODevice *vbasedev, Error **errp); >>> >> >> hmm, no. You will need to introduce a new Host IOMMU device capability, >> something like : >> >>    HOST_IOMMU_DEVICE_CAP_DIRTY_TRACKING, >> >> Then, introduce an helper routine to check the capability  : >> >>    return hiodc->get_cap( ... HOST_IOMMU_DEVICE_CAP_DIRTY_TRACKING...) >> >> and replace the iommufd_hwpt_dirty_tracking call with it. >> >> Yeah I know, it's cumbersome but it's cleaner ! >> > > Funny you mention it, because that's what I did in v3: > > https://lore.kernel.org/qemu-devel/20240708143420.16953-9-joao.m.martins@oracle.com/ > > But it was suggested to drop (I am assuming to avoid complexity) my bad if I did :/ we will need an helper such as : bool vfio_device_dirty_tracking(VFIODevice *vbasedev) { HostIOMMUDevice *hiod = vbasedev->hiod ; HostIOMMUDeviceClass *hiodc = HOST_IOMMU_DEVICE_GET_CLASS(hiod); return hiodc->get_cap && hiodc->get_cap(hiod, HOST_IOMMU_DEVICE_CAP_DIRTY_TRACKING, NULL) == 1; } and something like, static int hiod_iommufd_vfio_get_cap(HostIOMMUDevice *hiod, int cap, Error **errp) { switch (cap) { case HOST_IOMMU_DEVICE_CAP_DIRTY_TRACKING: return !!(hiod->caps.hw_caps & IOMMU_HW_CAP_DIRTY_TRACKING); default: error_setg(errp, "%s: unsupported capability %x", hiod->name, cap); return -EINVAL; } } Feel free to propose your own implementation, Thanks, C. > >> That's not a major problem in the series. I can address it at the end >> to avoid a resend. First, let's get a R-b on all other patches. >> >> Thanks, >> >> C. >> >> >