Hi, > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On Behalf Of Zheng, > Lv > Subject: RE: 174cc7187e6f ACPICA: Tables: Back port acpi_get_table_with_size() and > early_acpi_os_unmap_memory() from Linux kernel > > Hi, > > > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On Behalf Of > Borislav > > Petkov > > Subject: Re: 174cc7187e6f ACPICA: Tables: Back port acpi_get_table_with_size() and > > early_acpi_os_unmap_memory() from Linux kernel > > > > On Sun, Jan 08, 2017 at 03:20:20AM +0100, Rafael J. Wysocki wrote: > > > drivers/iommu/amd_iommu_init.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > Index: linux-pm/drivers/iommu/amd_iommu_init.c > > > =================================================================== > > > --- linux-pm.orig/drivers/iommu/amd_iommu_init.c > > > +++ linux-pm/drivers/iommu/amd_iommu_init.c > > > @@ -2230,7 +2230,7 @@ static int __init early_amd_iommu_init(v > > > */ > > > ret = check_ivrs_checksum(ivrs_base); > > > if (ret) > > > - return ret; > > > + goto out; > > > > > > amd_iommu_target_ivhd_type = get_highest_supported_ivhd_type(ivrs_base); > > > DUMP_printk("Using IVHD type %#x\n", amd_iommu_target_ivhd_type); > > > > Good catch, this one needs to be applied regardless. > > > > However, it doesn't fix my issue though. > > > > But I think I have it - I went and applied the well-proven debugging > > technique of sprinkling printks around. Here's what I'm seeing: > > > > early_amd_iommu_init() > > |-> acpi_put_table(ivrs_base); > > |-> acpi_tb_put_table(table_desc); > > |-> acpi_tb_invalidate_table(table_desc); > > |-> acpi_tb_release_table(...) > > |-> acpi_os_unmap_memory > > |-> acpi_os_unmap_iomem > > |-> acpi_os_map_cleanup > > |-> synchronize_rcu_expedited <-- the kernel/rcu/tree_exp.h version with CONFIG_PREEMPT_RCU=y > > > > Now that function goes and sends IPIs, i.e., schedule_work() > > but this is too early - we haven't even done workqueue_init(). > > Actually, from looking at the callstack, we do > > kernel_init_freeable->native_smp_prepare_cpus() and workqueue_init() > > comes next. > > > > And this makes sense because the splat rIP points to __queue_work() but > > we haven't done that yet. > > > > So that acpi_put_table() is happening too early. Looks like AMD IOMMU > > should not put the table but WTH do I know?! > > > > In any case, commenting out: > > > > acpi_put_table(ivrs_base); > > ivrs_base = NULL; > > > > and the end of early_amd_iommu_init() makes the box boot again. > > So please help to comment out these 2 lines (with descriptions and do not delete them). > Until acpi_os_unmap_memory() is able to handle such an early case. IMO, synchronize_rcu_expedited() should be improved: If rcu_init() isn't called or there is nothing to synchronize, schedule_work() shouldn't be invoked. Thanks and best regards Lv > > Thanks and best regards > Lv > > > > > -- > > Regards/Gruss, > > Boris. > > > > Good mailing practices for 400: avoid top-posting and trim the reply. ��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
