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Fri, 20 Nov 2020 16:53:48 +0000 Received: from lhreml710-chm.china.huawei.com ([169.254.81.184]) by lhreml710-chm.china.huawei.com ([169.254.81.184]) with mapi id 15.01.1913.007; Fri, 20 Nov 2020 16:53:48 +0000 From: Shameerali Kolothum Thodi To: Robin Murphy , Will Deacon Subject: RE: [PATCH] iommu: Check return of __iommu_attach_device() Thread-Topic: [PATCH] iommu: Check return of __iommu_attach_device() Thread-Index: AQHWvpWDFOlCvhbm1kiI932Tcvk2j6nQ358AgAAwKACAACcb8A== Date: Fri, 20 Nov 2020 16:53:47 +0000 Message-ID: <6375e8511bcb48209fffa0c02833e27b@huawei.com> References: <20201119165846.34180-1-shameerali.kolothum.thodi@huawei.com> <20201120111503.GB6151@willie-the-truck> <337ffd34-a606-4fb1-adb0-49367c136170@arm.com> In-Reply-To: <337ffd34-a606-4fb1-adb0-49367c136170@arm.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.210.172.192] MIME-Version: 1.0 X-CFilter-Loop: Reflected Cc: "iommu@lists.linux-foundation.org" , Linuxarm , "linux-arm-kernel@lists.infradead.org" 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" > -----Original Message----- > From: Robin Murphy [mailto:robin.murphy@arm.com] > Sent: 20 November 2020 14:07 > To: Will Deacon ; Shameerali Kolothum Thodi > > Cc: linux-arm-kernel@lists.infradead.org; iommu@lists.linux-foundation.org; > Linuxarm > Subject: Re: [PATCH] iommu: Check return of __iommu_attach_device() > > On 2020-11-20 11:15, Will Deacon wrote: > > On Thu, Nov 19, 2020 at 04:58:46PM +0000, Shameer Kolothum wrote: > >> Currently iommu_create_device_direct_mappings() is called > >> without checking the return of __iommu_attach_device(). This > >> may result in failures in iommu driver if dev attach returns > >> error. > >> > >> Fixes: ce574c27ae27("iommu: Move > iommu_group_create_direct_mappings() out of iommu_group_add_device()") > >> Signed-off-by: Shameer Kolothum > > >> --- > >> Crash log: > >> [ 31.353605] hns3 0000:7d:00.3: Adding to iommu group 10 > >> [ 31.358822] Unable to handle kernel NULL pointer dereference at virtual > address 0000000000000018 > >> [ 31.367567] Mem abort info: > >> [ 31.370350] ESR = 0x96000004 > >> [ 31.373391] EC = 0x25: DABT (current EL), IL = 32 bits > >> [ 31.378680] SET = 0, FnV = 0 > >> [ 31.381720] EA = 0, S1PTW = 0 > >> [ 31.384847] Data abort info: > >> [ 31.387716] ISV = 0, ISS = 0x00000004 > >> [ 31.391535] CM = 0, WnR = 0 > >> [ 31.394491] [0000000000000018] user address but active_mm is > swapper > >> [ 31.400818] Internal error: Oops: 96000004 [#1] PREEMPT SMP > >> [ 31.406365] Modules linked in: > >> [ 31.409409] CPU: 21 PID: 1 Comm: swapper/0 Not tainted > 5.10.0-rc4-00008-gdd5aba9d719-dirty #79 > >> [ 31.417980] Hardware name: Huawei TaiShan 200 (Model > 2280)/BC82AMDD, BIOS 2280-V2 CS V3.B220.01 03/19/2020 > >> [ 31.427588] pstate: 00c00009 (nzcv daif +PAN +UAO -TCO BTYPE=--) > >> [ 31.433566] pc : arm_smmu_tlb_inv_range+0x178/0x1f0 > >> [ 31.438422] lr : arm_smmu_tlb_inv_range+0x5c/0x1f0 > >> [ 31.443190] sp : ffff80001043b4e0 > >> ... > >> [ 31.531175] Call trace: > >> [ 31.533613] arm_smmu_tlb_inv_range+0x178/0x1f0 > >> [ 31.538122] arm_smmu_iotlb_sync+0x2c/0x38 > >> [ 31.542200] iommu_unmap+0x60/0x90 > >> [ 31.545585] __iommu_map+0x110/0x1f0 > >> [ 31.549144] > iommu_create_device_direct_mappings.isra.34+0x1ac/0x250 > >> [ 31.555468] iommu_probe_device+0x6c/0x110 > >> [ 31.559551] iort_iommu_configure_id+0x114/0x218 > >> [ 31.564148] acpi_dma_configure_id+0x94/0xe0 > >> [ 31.568402] pci_dma_configure+0xc8/0xf0 > >> [ 31.572310] really_probe+0xd4/0x3e0 > >> [ 31.575871] driver_probe_device+0x5c/0xc0 > >> > >> --- > >> drivers/iommu/iommu.c | 10 ++++++---- > >> 1 file changed, 6 insertions(+), 4 deletions(-) > >> > >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > >> index b53446bb8c6b..0f4dc25d46c9 100644 > >> --- a/drivers/iommu/iommu.c > >> +++ b/drivers/iommu/iommu.c > >> @@ -264,16 +264,18 @@ int iommu_probe_device(struct device *dev) > >> */ > >> iommu_alloc_default_domain(group, dev); > >> > >> - if (group->default_domain) > >> + if (group->default_domain) { > >> ret = __iommu_attach_device(group->default_domain, dev); > >> + if (ret) { > >> + iommu_group_put(group); > >> + goto err_release; > >> + } > >> + } > > > > This looks sensible to me, but what I don't understand is where that > > NULL pointer is coming from in the first place. iommu_map() operates > > on the domain, so why does it matter if the attach fails? What is being > > accessed at arm_smmu_tlb_inv_range+0x178/0x1f0 ? > > Probably because the domain is a hollow fake until the first successful > attach - even TLB maintenance depends on having decided a pagetable format. I think, in this particular instance, what happens is, dev reports RMR regions (IOMMU_RESV_DIRECT) but attach_dev() fails early without setting, smmu_domain->smmu = smmu. iommu_probe_device() __iommu_attach_dev() -->return err, but carries on. iommu_create_device_direct_mappings() iommu_get_resv_regions() --> dev has IOMMU_RESV_DIRECT regions iommu_map() __iommu_map() arm_smmu_map() -->return err iommu_unmap() --> unroll on map failure __iommu_unmap() --> size is zero. So returns. iommu_iotlb_sync() arm_smmu_iotlb_sync() arm_smmu_tlb_inv_range() --> smmu is NULL Thanks, Shameer _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu