Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-10 22:21:40 +00:00
Code Issues Packages Projects Releases Wiki Activity

iommu/vt-d: Remove unnecessary locking in intel_irq_remapping_alloc()

Browse Source 
The global rwsem dmar_global_lock was introduced by commit 3a5670e8ac
("iommu/vt-d: Introduce a rwsem to protect global data structures"). It
is used to protect DMAR related global data from DMAR hotplug operations.

Using dmar_global_lock in intel_irq_remapping_alloc() is unnecessary as
the DMAR global data structures are not touched there. Remove it to avoid
below lockdep warning.

 ======================================================
 WARNING: possible circular locking dependency detected
 6.3.0-rc2 #468 Not tainted
 ------------------------------------------------------
 swapper/0/1 is trying to acquire lock:
 ff1db4cb40178698 (&domain->mutex){+.+.}-{3:3},
   at: __irq_domain_alloc_irqs+0x3b/0xa0

 but task is already holding lock:
 ffffffffa0c1cdf0 (dmar_global_lock){++++}-{3:3},
   at: intel_iommu_init+0x58e/0x880

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 (dmar_global_lock){++++}-{3:3}:
        lock_acquire+0xd6/0x320
        down_read+0x42/0x180
        intel_irq_remapping_alloc+0xad/0x750
        mp_irqdomain_alloc+0xb8/0x2b0
        irq_domain_alloc_irqs_locked+0x12f/0x2d0
        __irq_domain_alloc_irqs+0x56/0xa0
        alloc_isa_irq_from_domain.isra.7+0xa0/0xe0
        mp_map_pin_to_irq+0x1dc/0x330
        setup_IO_APIC+0x128/0x210
        apic_intr_mode_init+0x67/0x110
        x86_late_time_init+0x24/0x40
        start_kernel+0x41e/0x7e0
        secondary_startup_64_no_verify+0xe0/0xeb

 -> #0 (&domain->mutex){+.+.}-{3:3}:
        check_prevs_add+0x160/0xef0
        __lock_acquire+0x147d/0x1950
        lock_acquire+0xd6/0x320
        __mutex_lock+0x9c/0xfc0
        __irq_domain_alloc_irqs+0x3b/0xa0
        dmar_alloc_hwirq+0x9e/0x120
        iommu_pmu_register+0x11d/0x200
        intel_iommu_init+0x5de/0x880
        pci_iommu_init+0x12/0x40
        do_one_initcall+0x65/0x350
        kernel_init_freeable+0x3ca/0x610
        kernel_init+0x1a/0x140
        ret_from_fork+0x29/0x50

 other info that might help us debug this:

 Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(dmar_global_lock);
                                lock(&domain->mutex);
                                lock(dmar_global_lock);
   lock(&domain->mutex);

                *** DEADLOCK ***

Fixes: 9dbb8e3452 ("irqdomain: Switch to per-domain locking")
Reviewed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Tested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20230314051836.23817-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20230329134721.469447-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Lu Baolu 2023-03-29 21:47:19 +08:00 committed by Joerg Roedel
parent f91bf3272a
commit c7d624520c
1 changed files with 0 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/iommu/intel/irq_remapping.c
View File

@ -311,14 +311,12 @@ static int set_ioapic_sid(struct irte *irte, int apic)
if (!irte)
return -1;
down_read(&dmar_global_lock);
for (i = 0; i < MAX_IO_APICS; i++) {
if (ir_ioapic[i].iommu && ir_ioapic[i].id == apic) {
sid = (ir_ioapic[i].bus << 8) | ir_ioapic[i].devfn;
break;
}
}
up_read(&dmar_global_lock);
if (sid == 0) {
pr_warn("Failed to set source-id of IOAPIC (%d)\n", apic);
@ -338,14 +336,12 @@ static int set_hpet_sid(struct irte *irte, u8 id)
if (!irte)
return -1;
down_read(&dmar_global_lock);
for (i = 0; i < MAX_HPET_TBS; i++) {
if (ir_hpet[i].iommu && ir_hpet[i].id == id) {
sid = (ir_hpet[i].bus << 8) | ir_hpet[i].devfn;
break;
}
}
up_read(&dmar_global_lock);
if (sid == 0) {
pr_warn("Failed to set source-id of HPET block (%d)\n", id);
@ -1339,9 +1335,7 @@ static int intel_irq_remapping_alloc(struct irq_domain *domain,
if (!data)
goto out_free_parent;
down_read(&dmar_global_lock);
index = alloc_irte(iommu, &data->irq_2_iommu, nr_irqs);
up_read(&dmar_global_lock);
if (index < 0) {
pr_warn("Failed to allocate IRTE\n");
kfree(data);