| Message ID | 20201112220520.48159-1-john.stultz@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RESEND,1/2] arm-smmu-qcom: Ensure the qcom_scm driver has finished probing | expand |
On 2020-11-12 22:05, John Stultz wrote: > Robin Murphy pointed out that if the arm-smmu driver probes before > the qcom_scm driver, we may call qcom_scm_qsmmu500_wait_safe_toggle() > before the __scm is initialized. > > Now, getting this to happen is a bit contrived, as in my efforts it > required enabling asynchronous probing for both drivers, moving the > firmware dts node to the end of the dtsi file, as well as forcing a > long delay in the qcom_scm_probe function. > > With those tweaks we ran into the following crash: > [ 2.631040] arm-smmu 15000000.iommu: Stage-1: 48-bit VA -> 48-bit IPA > [ 2.633372] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 > ... > [ 2.633402] [0000000000000000] user address but active_mm is swapper > [ 2.633409] Internal error: Oops: 96000005 [#1] PREEMPT SMP > [ 2.633415] Modules linked in: > [ 2.633427] CPU: 5 PID: 117 Comm: kworker/u16:2 Tainted: G W 5.10.0-rc1-mainline-00025-g272a618fc36-dirty #3971 > [ 2.633430] Hardware name: Thundercomm Dragonboard 845c (DT) > [ 2.633448] Workqueue: events_unbound async_run_entry_fn > [ 2.633456] pstate: 80c00005 (Nzcv daif +PAN +UAO -TCO BTYPE=--) > [ 2.633465] pc : qcom_scm_qsmmu500_wait_safe_toggle+0x78/0xb0 > [ 2.633473] lr : qcom_smmu500_reset+0x58/0x78 > [ 2.633476] sp : ffffffc0105a3b60 > ... > [ 2.633567] Call trace: > [ 2.633572] qcom_scm_qsmmu500_wait_safe_toggle+0x78/0xb0 > [ 2.633576] qcom_smmu500_reset+0x58/0x78 > [ 2.633581] arm_smmu_device_reset+0x194/0x270 > [ 2.633585] arm_smmu_device_probe+0xc94/0xeb8 > [ 2.633592] platform_drv_probe+0x58/0xa8 > [ 2.633597] really_probe+0xec/0x398 > [ 2.633601] driver_probe_device+0x5c/0xb8 > [ 2.633606] __driver_attach_async_helper+0x64/0x88 > [ 2.633610] async_run_entry_fn+0x4c/0x118 > [ 2.633617] process_one_work+0x20c/0x4b0 > [ 2.633621] worker_thread+0x48/0x460 > [ 2.633628] kthread+0x14c/0x158 > [ 2.633634] ret_from_fork+0x10/0x18 > [ 2.633642] Code: a9034fa0 d0007f73 29107fa0 91342273 (f9400020) > > To avoid this, this patch adds a check on qcom_scm_is_available() in > the qcom_smmu_impl_init() function, returning -EPROBE_DEFER if its > not ready. > > This allows the driver to try to probe again later after qcom_scm has > finished probing. As well as strict correctness, the other motivation here was that qcom_scm_is_available() should be the place to add the "is the module even loaded yet?" dance to iron out the awkward config dependencies in future. Reviewed-by: Robin Murphy <robin.murphy@arm.com> > Cc: Robin Murphy <robin.murphy@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Andy Gross <agross@kernel.org> > Cc: Maulik Shah <mkshah@codeaurora.org> > Cc: Bjorn Andersson <bjorn.andersson@linaro.org> > Cc: Saravana Kannan <saravanak@google.com> > Cc: Marc Zyngier <maz@kernel.org> > Cc: Lina Iyer <ilina@codeaurora.org> > Cc: iommu@lists.linux-foundation.org > Cc: linux-arm-msm <linux-arm-msm@vger.kernel.org> > Reported-by: Robin Murphy <robin.murphy@arm.com> > Signed-off-by: John Stultz <john.stultz@linaro.org> > --- > drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c > index 66ba4870659f4..ef37ccfa82562 100644 > --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c > @@ -159,6 +159,10 @@ struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu) > { > struct qcom_smmu *qsmmu; > > + /* Check to make sure qcom_scm has finished probing */ > + if (!qcom_scm_is_available()) > + return ERR_PTR(-EPROBE_DEFER); > + > qsmmu = devm_kzalloc(smmu->dev, sizeof(*qsmmu), GFP_KERNEL); > if (!qsmmu) > return ERR_PTR(-ENOMEM); >
On Thu, 12 Nov 2020 22:05:19 +0000, John Stultz wrote: > Robin Murphy pointed out that if the arm-smmu driver probes before > the qcom_scm driver, we may call qcom_scm_qsmmu500_wait_safe_toggle() > before the __scm is initialized. > > Now, getting this to happen is a bit contrived, as in my efforts it > required enabling asynchronous probing for both drivers, moving the > firmware dts node to the end of the dtsi file, as well as forcing a > long delay in the qcom_scm_probe function. > > [...] Applied only the first patch to arm64 (for-next/iommu/fixes), thanks! [1/2] arm-smmu-qcom: Ensure the qcom_scm driver has finished probing https://git.kernel.org/arm64/c/72b55c96f3a5 Cheers,
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c index 66ba4870659f4..ef37ccfa82562 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c @@ -159,6 +159,10 @@ struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu) { struct qcom_smmu *qsmmu; + /* Check to make sure qcom_scm has finished probing */ + if (!qcom_scm_is_available()) + return ERR_PTR(-EPROBE_DEFER); + qsmmu = devm_kzalloc(smmu->dev, sizeof(*qsmmu), GFP_KERNEL); if (!qsmmu) return ERR_PTR(-ENOMEM);
Robin Murphy pointed out that if the arm-smmu driver probes before the qcom_scm driver, we may call qcom_scm_qsmmu500_wait_safe_toggle() before the __scm is initialized. Now, getting this to happen is a bit contrived, as in my efforts it required enabling asynchronous probing for both drivers, moving the firmware dts node to the end of the dtsi file, as well as forcing a long delay in the qcom_scm_probe function. With those tweaks we ran into the following crash: [ 2.631040] arm-smmu 15000000.iommu: Stage-1: 48-bit VA -> 48-bit IPA [ 2.633372] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 ... [ 2.633402] [0000000000000000] user address but active_mm is swapper [ 2.633409] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 2.633415] Modules linked in: [ 2.633427] CPU: 5 PID: 117 Comm: kworker/u16:2 Tainted: G W 5.10.0-rc1-mainline-00025-g272a618fc36-dirty #3971 [ 2.633430] Hardware name: Thundercomm Dragonboard 845c (DT) [ 2.633448] Workqueue: events_unbound async_run_entry_fn [ 2.633456] pstate: 80c00005 (Nzcv daif +PAN +UAO -TCO BTYPE=--) [ 2.633465] pc : qcom_scm_qsmmu500_wait_safe_toggle+0x78/0xb0 [ 2.633473] lr : qcom_smmu500_reset+0x58/0x78 [ 2.633476] sp : ffffffc0105a3b60 ... [ 2.633567] Call trace: [ 2.633572] qcom_scm_qsmmu500_wait_safe_toggle+0x78/0xb0 [ 2.633576] qcom_smmu500_reset+0x58/0x78 [ 2.633581] arm_smmu_device_reset+0x194/0x270 [ 2.633585] arm_smmu_device_probe+0xc94/0xeb8 [ 2.633592] platform_drv_probe+0x58/0xa8 [ 2.633597] really_probe+0xec/0x398 [ 2.633601] driver_probe_device+0x5c/0xb8 [ 2.633606] __driver_attach_async_helper+0x64/0x88 [ 2.633610] async_run_entry_fn+0x4c/0x118 [ 2.633617] process_one_work+0x20c/0x4b0 [ 2.633621] worker_thread+0x48/0x460 [ 2.633628] kthread+0x14c/0x158 [ 2.633634] ret_from_fork+0x10/0x18 [ 2.633642] Code: a9034fa0 d0007f73 29107fa0 91342273 (f9400020) To avoid this, this patch adds a check on qcom_scm_is_available() in the qcom_smmu_impl_init() function, returning -EPROBE_DEFER if its not ready. This allows the driver to try to probe again later after qcom_scm has finished probing. Cc: Robin Murphy <robin.murphy@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Andy Gross <agross@kernel.org> Cc: Maulik Shah <mkshah@codeaurora.org> Cc: Bjorn Andersson <bjorn.andersson@linaro.org> Cc: Saravana Kannan <saravanak@google.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Lina Iyer <ilina@codeaurora.org> Cc: iommu@lists.linux-foundation.org Cc: linux-arm-msm <linux-arm-msm@vger.kernel.org> Reported-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: John Stultz <john.stultz@linaro.org> --- drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 4 ++++ 1 file changed, 4 insertions(+)