On Mon, 2023-03-27 at 19:50 -0700, Sathyanarayanan Kuppuswamy wrote:
> Hi Kai,
>
> On 3/27/23 7:38 PM, Huang, Kai wrote:
> > > +/* Reserve an IRQ from x86_vector_domain for TD event notification */
> > > +static int __init tdx_event_irq_init(void)
> > > +{
> > > + struct irq_alloc_info info;
> > > + cpumask_t saved_cpumask;
> > > + struct irq_cfg *cfg;
> > > + int cpu, irq;
> > > +
> > > + if (!cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
> > > + return 0;
> > > +
> > > + init_irq_alloc_info(&info, NULL);
> > > +
> > > + /*
> > > + * Event notification vector will be delivered to the CPU
> > > + * in which TDVMCALL_SETUP_NOTIFY_INTR hypercall is requested.
> > > + * So set the IRQ affinity to the current CPU.
> > > + */
> > > + cpu = get_cpu();
> > > + cpumask_copy(&saved_cpumask, current->cpus_ptr);
> > > + info.mask = cpumask_of(cpu);
> > > + put_cpu();
> > The 'saved_cpumask' related code is ugly. If you move put_cpu() to the end of
> > this function, I think you can remove all related code:
> >
> > cpu = get_cpu();
> >
> > /*
> > * Set @info->mask to local cpu to make sure a valid vector is
> > * pre-allocated when TDX event notification IRQ is allocated
> > * from x86_vector_domain.
> > */
> > init_irq_alloc_info(&info, cpumask_of(cpu));
> >
> > // rest staff: request_irq(), hypercall ...
> >
> > put_cpu();
> >
>
> init_irq_alloc_info() is a sleeping function. Since get_cpu() disables
> preemption, we cannot call sleeping function after it. Initially, I
> have implemented it like you have mentioned. However, I discovered the
> following error.
Oh sorry I forgot this. So I think we should use migrate_disable() instead:
migrate_disable();
init_irq_alloc_info(&info, cpumask_of(smp_processor_id()));
...
migrate_enable();
Or, should we just use early_initcall() so that only BSP is running? IMHO it's
OK to always allocate the vector from BSP.
Anyway, either way is fine to me.
>
> [ 2.400755] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580
> [ 2.404664] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper/0
> [ 2.408671] preempt_count: 1, expected: 0
> [ 2.412650] RCU nest depth: 0, expected: 0
> [ 2.412666] no locks held by swapper/0/1.
> [ 2.416650] Preemption disabled at:
> [ 2.416650] [<ffffffff83b8089f>] tdx_arch_init+0x38/0x117
> [ 2.420670] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.0-rc4-00117-g672ca073d9f9-dirty #2527
> [ 2.424650] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
> [ 2.424650] Call Trace:
> [ 2.424650] <TASK>
> [ 2.424650] dump_stack_lvl+0x6a/0x86
> [ 2.424650] __might_resched.cold+0xf4/0x12f
> [ 2.424650] __mutex_lock+0x50/0x810
> [ 2.424650] ? lock_is_held_type+0xd8/0x130
> [ 2.424650] ? __irq_alloc_descs+0xcf/0x310
> [ 2.424650] ? find_held_lock+0x2b/0x80
> [ 2.424650] ? __irq_alloc_descs+0xcf/0x310
> [ 2.424650] __irq_alloc_descs+0xcf/0x310
> [ 2.424650] irq_domain_alloc_descs.part.0+0x49/0xa0
> [ 2.424650] __irq_domain_alloc_irqs+0x2a0/0x4f0
> [ 2.424650] ? next_arg+0x129/0x1f0
> [ 2.424650] ? tdx_guest_init+0x5b/0x5b
> [ 2.424650] tdx_arch_init+0x8e/0x117
> [ 2.424650] do_one_initcall+0x137/0x2ec
> [ 2.424650] ? rcu_read_lock_sched_held+0x36/0x60
> [ 2.424650] kernel_init_freeable+0x1e3/0x241
> [ 2.424650] ? rest_init+0x1a0/0x1a0
> [ 2.424650] kernel_init+0x17/0x170
> [ 2.424650] ? rest_init+0x1a0/0x1a0
> [ 2.424650] ret_from_fork+0x1f/0x30
> [ 2.424650] </TASK>
