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.
[ 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>