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[34.83.46.153]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2bd5c05ffbesm232289015ad.27.2026.05.20.10.24.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 May 2026 10:24:51 -0700 (PDT) Date: Wed, 20 May 2026 17:24:47 +0000 From: Samiullah Khawaja To: Pranjal Shrivastava Cc: David Woodhouse , Lu Baolu , Joerg Roedel , Will Deacon , Jason Gunthorpe , Robin Murphy , Kevin Tian , Alex Williamson , Shuah Khan , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Saeed Mahameed , Adithya Jayachandran , Parav Pandit , Leon Romanovsky , William Tu , Pratyush Yadav , Pasha Tatashin , David Matlack , Andrew Morton , Chris Li , Vipin Sharma , YiFei Zhu Subject: Re: [PATCH v2 08/16] iommu: Add APIs to get iommu and device preserved state Message-ID: References: <20260427175633.1978233-1-skhawaja@google.com> <20260427175633.1978233-9-skhawaja@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: On Tue, May 19, 2026 at 03:52:43PM +0000, Pranjal Shrivastava wrote: >On Mon, Apr 27, 2026 at 05:56:25PM +0000, Samiullah Khawaja wrote: >> The preserved state of the device and IOMMU needs to be fetched during >> shutdown and boot in the next kernel. Add APIs that can be used to fetch >> the preserved state of a device and IOMMU. The APIs will only be used >> during shutdown and after liveupdate so no locking needed. >> >> Signed-off-by: Samiullah Khawaja >> --- >> drivers/iommu/liveupdate.c | 57 ++++++++++++++++++++++++++++++++ >> include/linux/iommu-liveupdate.h | 31 +++++++++++++++++ >> 2 files changed, 88 insertions(+) >> >> diff --git a/drivers/iommu/liveupdate.c b/drivers/iommu/liveupdate.c >> index 765d042e22e3..60ee29b0c6bd 100644 >> --- a/drivers/iommu/liveupdate.c >> +++ b/drivers/iommu/liveupdate.c >> @@ -17,6 +17,14 @@ >> #define iommu_max_objs_per_page(_array) \ >> ((PAGE_SIZE - sizeof(struct iommu_array_hdr_ser)) / sizeof((_array)->objects[0])) >> >> +#define iommu_liveupdate_for_each_obj(_arr, _obj, _idx) \ >> + for (; (_arr); \ >> + (_arr) = (_arr)->hdr.next_array_phys ? \ >> + phys_to_virt((_arr)->hdr.next_array_phys) : NULL) \ >> + for ((_idx) = 0, (_obj) = (_arr)->objects; \ >> + (_idx) < (_arr)->hdr.nr_objects; (_idx)++, (_obj)++) \ >> + if (!(_obj)->hdr.deleted) >> + > >Nit: While the usage of this macro is safe right now because we use >goto out; to short-circuit the scan. Such naked nested loops inside an >iterator macro can be a bit of a trap for the future. > >If anyone tries to reuse this macro down the road and uses a break; >statement, it will only break the innermost object loop and continue >scanning subsequent array blocks. > >We could nest two macros or it as a helper fn to prevent such bugs. Agreed on all points. I will change this to two nested macros. > > >> static void *iommu_liveupdate_restore_array(u64 array_phys) >> { >> struct iommu_array_hdr_ser *array_hdr; >> @@ -201,6 +209,55 @@ void iommu_liveupdate_unregister_flb(struct liveupdate_file_handler *handler) >> } >> EXPORT_SYMBOL(iommu_liveupdate_unregister_flb); >> >> +int iommu_for_each_preserved_device(iommu_preserved_device_iter_fn fn, >> + void *arg) >> +{ >> + struct iommu_flb_obj *flb_obj; >> + struct iommu_device_array_ser *array; >> + struct iommu_device_ser *device_ser; >> + int ret, idx; >> + >> + ret = liveupdate_flb_get_incoming(&iommu_flb, (void **)&flb_obj); >> + if (ret) >> + return -ENOENT; >> + >> + array = phys_to_virt(flb_obj->ser->device_array_phys); > >Nit: phys_to_virt doesn't return an error for NULL. While we shouldn't >be in a case where serialized ptrs are NULL. I'm wondering how painful >catching such bugs would be.. should we check for NULL phys_addr here? >(and at other places) Agreed. Will update. > >> + iommu_liveupdate_for_each_obj(array, device_ser, idx) { >> + ret = fn(device_ser, arg); >> + if (ret) >> + goto out; >> + } >> + >> +out: >> + liveupdate_flb_put_incoming(&iommu_flb); >> + return ret; >> +} >> +EXPORT_SYMBOL(iommu_for_each_preserved_device); >> + > >With those two nits, > >Reviewed-by: Pranjal Shrivastava i Thanks, Sami