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Re: [RFC XEN PATCH 6/6] tools/libs/light: pci: translate irq to gsi

  • To: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>
  • From: "Chen, Jiqian" <Jiqian.Chen@xxxxxxx>
  • Date: Mon, 31 Jul 2023 16:40:35 +0000
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  • Cc: "Huang, Ray" <Ray.Huang@xxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "Deucher, Alexander" <Alexander.Deucher@xxxxxxx>, "Koenig, Christian" <Christian.Koenig@xxxxxxx>, "Hildebrand, Stewart" <Stewart.Hildebrand@xxxxxxx>, Xenia Ragiadakou <burzalodowa@xxxxxxxxx>, "Huang, Honglei1" <Honglei1.Huang@xxxxxxx>, "Zhang, Julia" <Julia.Zhang@xxxxxxx>, "Chen, Jiqian" <Jiqian.Chen@xxxxxxx>
  • Delivery-date: Mon, 31 Jul 2023 16:40:52 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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  • Thread-topic: [RFC XEN PATCH 6/6] tools/libs/light: pci: translate irq to gsi
Hi,

On 2023/3/18 04:55, Stefano Stabellini wrote:
> On Fri, 17 Mar 2023, Roger Pau Monné wrote:
>> On Fri, Mar 17, 2023 at 11:15:37AM -0700, Stefano Stabellini wrote:
>>> On Fri, 17 Mar 2023, Roger Pau Monné wrote:
>>>> On Fri, Mar 17, 2023 at 09:39:52AM +0100, Jan Beulich wrote:
>>>>> On 17.03.2023 00:19, Stefano Stabellini wrote:
>>>>>> On Thu, 16 Mar 2023, Jan Beulich wrote:
>>>>>>> So yes, it then all boils down to that Linux-
>>>>>>> internal question.
>>>>>>
>>>>>> Excellent question but we'll have to wait for Ray as he is the one with
>>>>>> access to the hardware. But I have this data I can share in the
>>>>>> meantime:
>>>>>>
>>>>>> [    1.260378] IRQ to pin mappings:
>>>>>> [    1.260387] IRQ1 -> 0:1
>>>>>> [    1.260395] IRQ2 -> 0:2
>>>>>> [    1.260403] IRQ3 -> 0:3
>>>>>> [    1.260410] IRQ4 -> 0:4
>>>>>> [    1.260418] IRQ5 -> 0:5
>>>>>> [    1.260425] IRQ6 -> 0:6
>>>>>> [    1.260432] IRQ7 -> 0:7
>>>>>> [    1.260440] IRQ8 -> 0:8
>>>>>> [    1.260447] IRQ9 -> 0:9
>>>>>> [    1.260455] IRQ10 -> 0:10
>>>>>> [    1.260462] IRQ11 -> 0:11
>>>>>> [    1.260470] IRQ12 -> 0:12
>>>>>> [    1.260478] IRQ13 -> 0:13
>>>>>> [    1.260485] IRQ14 -> 0:14
>>>>>> [    1.260493] IRQ15 -> 0:15
>>>>>> [    1.260505] IRQ106 -> 1:8
>>>>>> [    1.260513] IRQ112 -> 1:4
>>>>>> [    1.260521] IRQ116 -> 1:13
>>>>>> [    1.260529] IRQ117 -> 1:14
>>>>>> [    1.260537] IRQ118 -> 1:15
>>>>>> [    1.260544] .................................... done.
>>>>>
>>>>> And what does Linux think are IRQs 16 ... 105? Have you compared with
>>>>> Linux running baremetal on the same hardware?
>>>>
>>>> So I have some emails from Ray from he time he was looking into this,
>>>> and on Linux dom0 PVH dmesg there is:
>>>>
>>>> [    0.065063] IOAPIC[0]: apic_id 33, version 17, address 0xfec00000, GSI 
>>>> 0-23
>>>> [    0.065096] IOAPIC[1]: apic_id 34, version 17, address 0xfec01000, GSI 
>>>> 24-55
>>>>
>>>> So it seems the vIO-APIC data provided by Xen to dom0 is at least
>>>> consistent.
>>>>  
>>>>>> And I think Ray traced the point in Linux where Linux gives us an IRQ ==
>>>>>> 112 (which is the one causing issues):
>>>>>>
>>>>>> __acpi_register_gsi->
>>>>>>         acpi_register_gsi_ioapic->
>>>>>>                 mp_map_gsi_to_irq->
>>>>>>                         mp_map_pin_to_irq->
>>>>>>                                 __irq_resolve_mapping()
>>>>>>
>>>>>>         if (likely(data)) {
>>>>>>                 desc = irq_data_to_desc(data);
>>>>>>                 if (irq)
>>>>>>                         *irq = data->irq;
>>>>>>                 /* this IRQ is 112, IO-APIC-34 domain */
>>>>>>         }
>>>>
>>>>
>>>> Could this all be a result of patch 4/5 in the Linux series ("[RFC
>>>> PATCH 4/5] x86/xen: acpi registers gsi for xen pvh"), where a different
>>>> __acpi_register_gsi hook is installed for PVH in order to setup GSIs
>>>> using PHYSDEV ops instead of doing it natively from the IO-APIC?
>>>>
>>>> FWIW, the introduced function in that patch
>>>> (acpi_register_gsi_xen_pvh()) seems to unconditionally call
>>>> acpi_register_gsi_ioapic() without checking if the GSI is already
>>>> registered, which might lead to multiple IRQs being allocated for the
>>>> same underlying GSI?
>>>
>>> I understand this point and I think it needs investigating.
>>>
>>>
>>>> As I commented there, I think that approach is wrong.  If the GSI has
>>>> not been mapped in Xen (because dom0 hasn't unmasked the respective
>>>> IO-APIC pin) we should add some logic in the toolstack to map it
>>>> before attempting to bind.
>>>
>>> But this statement confuses me. The toolstack doesn't get involved in
>>> IRQ setup for PCI devices for HVM guests?
>>
>> It does for GSI interrupts AFAICT, see pci_add_dm_done() and the call
>> to xc_physdev_map_pirq().  I'm not sure whether that's a remnant that
>> cold be removed (maybe for qemu-trad only?) or it's also required by
>> QEMU upstream, I would have to investigate more.
> 
> You are right. I am not certain, but it seems like a mistake in the
> toolstack to me. In theory, pci_add_dm_done should only be needed for PV
> guests, not for HVM guests. I am not sure. But I can see the call to
> xc_physdev_map_pirq you were referring to now.
> 
> 
>> It's my understanding it's in pci_add_dm_done() where Ray was getting
>> the mismatched IRQ vs GSI number.
> 
> I think the mismatch was actually caused by the xc_physdev_map_pirq call
> from QEMU, which makes sense because in any case it should happen before
> the same call done by pci_add_dm_done (pci_add_dm_done is called after
> sending the pci passthrough QMP command to QEMU). So the first to hit
> the IRQ!=GSI problem would be QEMU.


Sorry for replying to you so late. And thank you all for review. I realized 
that your questions mainly focus on the following points: 1. Why irq is not 
equal with gsi? 2. Why I do the translations between irq and gsi? 3. Why I call 
PHYSDEVOP_map_pirq in acpi_register_gsi_xen_pvh()? 4. Why I call 
PHYSDEVOP_setup_gsi in acpi_register_gsi_xen_pvh()? 
Please forgive me for making a summary response first. And I am looking forward 
to your comments.

1. Why irq is not equal with gsi?
As far as I know, irq is dynamically allocated according to gsi, they are not 
necessarily equal.
When I run "sudo xl pci-assignable-add 03:00.0" to assign passthrough 
device(Taking dGPU on my environment as an example, which gsi is 28). It will 
call into acpi_register_gsi_ioapic to get irq, the callstack is: 
acpi_register_gsi_ioapic
        mp_map_gsi_to_irq
                mp_map_pin_to_irq
                        irq_find_mapping(if gsi has been mapped to an irq 
before, it will return corresponding irq here)
                        alloc_irq_from_domain
                                __irq_domain_alloc_irqs
                                        irq_domain_alloc_descs
                                                __irq_alloc_descs

If you add some printings like below:
---------------------------------------------------------------------------------------------------------------------------------------------
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index a868b76cd3d4..970fd461be7a 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1067,6 +1067,8 @@ static int mp_map_pin_to_irq(u32 gsi, int idx, int 
ioapic, int pin,
                }
        }
        mutex_unlock(&ioapic_mutex);
+       printk("cjq_debug mp_map_pin_to_irq gsi: %u, irq: %d, idx: %d, ioapic: 
%d, pin: %d\n",
+                       gsi, irq, idx, ioapic, pin);

        return irq;
 }
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 5db0230aa6b5..4e9613abbe96 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -786,6 +786,8 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int 
cnt, int node,
        start = bitmap_find_next_zero_area(allocated_irqs, IRQ_BITMAP_BITS,
                                           from, cnt, 0);
        ret = -EEXIST;
+       printk("cjq_debug __irq_alloc_descs irq: %d, from: %u, cnt: %u, node: 
%d, start: %d, nr_irqs: %d\n",
+                       irq, from, cnt, node, start, nr_irqs);
        if (irq >=0 && start != irq)
                goto unlock;
---------------------------------------------------------------------------------------------------------------------------------------------
You will get output on PVH dom0:

[    0.181560] cjq_debug __irq_alloc_descs irq: 1, from: 1, cnt: 1, node: -1, 
start: 1, nr_irqs: 1096
[    0.181639] cjq_debug mp_map_pin_to_irq gsi: 1, irq: 1, idx: 2, ioapic: 0, 
pin: 1
[    0.181641] cjq_debug __irq_alloc_descs irq: 2, from: 2, cnt: 1, node: -1, 
start: 2, nr_irqs: 1096
[    0.181682] cjq_debug mp_map_pin_to_irq gsi: 2, irq: 2, idx: 0, ioapic: 0, 
pin: 2
[    0.181683] cjq_debug __irq_alloc_descs irq: 3, from: 3, cnt: 1, node: -1, 
start: 3, nr_irqs: 1096
[    0.181715] cjq_debug mp_map_pin_to_irq gsi: 3, irq: 3, idx: 3, ioapic: 0, 
pin: 3
[    0.181716] cjq_debug __irq_alloc_descs irq: 4, from: 4, cnt: 1, node: -1, 
start: 4, nr_irqs: 1096
[    0.181751] cjq_debug mp_map_pin_to_irq gsi: 4, irq: 4, idx: 4, ioapic: 0, 
pin: 4
[    0.181752] cjq_debug __irq_alloc_descs irq: 5, from: 5, cnt: 1, node: -1, 
start: 5, nr_irqs: 1096
[    0.181783] cjq_debug mp_map_pin_to_irq gsi: 5, irq: 5, idx: 5, ioapic: 0, 
pin: 5
[    0.181784] cjq_debug __irq_alloc_descs irq: 6, from: 6, cnt: 1, node: -1, 
start: 6, nr_irqs: 1096
[    0.181813] cjq_debug mp_map_pin_to_irq gsi: 6, irq: 6, idx: 6, ioapic: 0, 
pin: 6
[    0.181814] cjq_debug __irq_alloc_descs irq: 7, from: 7, cnt: 1, node: -1, 
start: 7, nr_irqs: 1096
[    0.181856] cjq_debug mp_map_pin_to_irq gsi: 7, irq: 7, idx: 7, ioapic: 0, 
pin: 7
[    0.181857] cjq_debug __irq_alloc_descs irq: 8, from: 8, cnt: 1, node: -1, 
start: 8, nr_irqs: 1096
[    0.181888] cjq_debug mp_map_pin_to_irq gsi: 8, irq: 8, idx: 8, ioapic: 0, 
pin: 8
[    0.181889] cjq_debug __irq_alloc_descs irq: 9, from: 9, cnt: 1, node: -1, 
start: 9, nr_irqs: 1096
[    0.181918] cjq_debug mp_map_pin_to_irq gsi: 9, irq: 9, idx: 1, ioapic: 0, 
pin: 9
[    0.181919] cjq_debug __irq_alloc_descs irq: 10, from: 10, cnt: 1, node: -1, 
start: 10, nr_irqs: 1096
[    0.181950] cjq_debug mp_map_pin_to_irq gsi: 10, irq: 10, idx: 9, ioapic: 0, 
pin: 10
[    0.181951] cjq_debug __irq_alloc_descs irq: 11, from: 11, cnt: 1, node: -1, 
start: 11, nr_irqs: 1096
[    0.181977] cjq_debug mp_map_pin_to_irq gsi: 11, irq: 11, idx: 10, ioapic: 
0, pin: 11
[    0.181979] cjq_debug __irq_alloc_descs irq: 12, from: 12, cnt: 1, node: -1, 
start: 12, nr_irqs: 1096
[    0.182006] cjq_debug mp_map_pin_to_irq gsi: 12, irq: 12, idx: 11, ioapic: 
0, pin: 12
[    0.182007] cjq_debug __irq_alloc_descs irq: 13, from: 13, cnt: 1, node: -1, 
start: 13, nr_irqs: 1096
[    0.182034] cjq_debug mp_map_pin_to_irq gsi: 13, irq: 13, idx: 12, ioapic: 
0, pin: 13
[    0.182035] cjq_debug __irq_alloc_descs irq: 14, from: 14, cnt: 1, node: -1, 
start: 14, nr_irqs: 1096
[    0.182066] cjq_debug mp_map_pin_to_irq gsi: 14, irq: 14, idx: 13, ioapic: 
0, pin: 14
[    0.182067] cjq_debug __irq_alloc_descs irq: 15, from: 15, cnt: 1, node: -1, 
start: 15, nr_irqs: 1096
[    0.182095] cjq_debug mp_map_pin_to_irq gsi: 15, irq: 15, idx: 14, ioapic: 
0, pin: 15
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 24, nr_irqs: 1096
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 25, nr_irqs: 1096
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 26, nr_irqs: 1096
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 27, nr_irqs: 1096
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 28, nr_irqs: 1096
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 29, nr_irqs: 1096
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 30, nr_irqs: 1096
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 31, nr_irqs: 1096
[    0.186111] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 32, nr_irqs: 1096
[    0.188491] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 33, nr_irqs: 1096
[    0.188491] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 34, nr_irqs: 1096
[    0.188491] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 35, nr_irqs: 1096
[    0.188491] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 36, nr_irqs: 1096
[    0.188491] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 37, nr_irqs: 1096
[    0.192282] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 38, nr_irqs: 1096
[    0.192282] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 39, nr_irqs: 1096
[    0.192282] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 40, nr_irqs: 1096
[    0.192282] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 41, nr_irqs: 1096
[    0.192282] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 42, nr_irqs: 1096
[    0.196208] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 43, nr_irqs: 1096
[    0.196208] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 44, nr_irqs: 1096
[    0.196208] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 45, nr_irqs: 1096
[    0.196208] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 46, nr_irqs: 1096
[    0.196208] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 47, nr_irqs: 1096
[    0.198199] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 48, nr_irqs: 1096
[    0.198416] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 49, nr_irqs: 1096
[    0.198460] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 50, nr_irqs: 1096
[    0.198489] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 51, nr_irqs: 1096
[    0.198523] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 52, nr_irqs: 1096
[    0.201315] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 53, nr_irqs: 1096
[    0.202174] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 54, nr_irqs: 1096
[    0.202225] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 55, nr_irqs: 1096
[    0.202259] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 56, nr_irqs: 1096
[    0.202291] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 57, nr_irqs: 1096
[    0.205239] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 58, nr_irqs: 1096
[    0.205239] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 59, nr_irqs: 1096
[    0.205239] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 60, nr_irqs: 1096
[    0.205239] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 61, nr_irqs: 1096
[    0.205239] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 62, nr_irqs: 1096
[    0.208653] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 63, nr_irqs: 1096
[    0.208653] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 64, nr_irqs: 1096
[    0.208653] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 65, nr_irqs: 1096
[    0.208653] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 66, nr_irqs: 1096
[    0.208653] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 67, nr_irqs: 1096
[    0.210169] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 68, nr_irqs: 1096
[    0.210322] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 69, nr_irqs: 1096
[    0.210370] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 70, nr_irqs: 1096
[    0.210403] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 71, nr_irqs: 1096
[    0.210436] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 72, nr_irqs: 1096
[    0.213190] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 73, nr_irqs: 1096
[    0.213190] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 74, nr_irqs: 1096
[    0.213190] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 75, nr_irqs: 1096
[    0.213190] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 76, nr_irqs: 1096
[    0.214151] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 77, nr_irqs: 1096
[    0.217075] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 78, nr_irqs: 1096
[    0.217075] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 79, nr_irqs: 1096
[    0.217075] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 80, nr_irqs: 1096
[    0.217075] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 81, nr_irqs: 1096
[    0.217075] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 82, nr_irqs: 1096
[    0.220389] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 83, nr_irqs: 1096
[    0.220389] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 84, nr_irqs: 1096
[    0.220389] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 85, nr_irqs: 1096
[    0.220389] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 86, nr_irqs: 1096
[    0.220389] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 87, nr_irqs: 1096
[    0.222215] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 88, nr_irqs: 1096
[    0.222366] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 89, nr_irqs: 1096
[    0.222410] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 90, nr_irqs: 1096
[    0.222447] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 91, nr_irqs: 1096
[    0.222478] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 92, nr_irqs: 1096
[    0.225490] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 93, nr_irqs: 1096
[    0.226225] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 94, nr_irqs: 1096
[    0.226268] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 95, nr_irqs: 1096
[    0.226300] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 96, nr_irqs: 1096
[    0.226329] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 97, nr_irqs: 1096
[    0.229057] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 98, nr_irqs: 1096
[    0.229057] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 99, nr_irqs: 1096
[    0.229057] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 100, nr_irqs: 1096
[    0.229057] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 101, nr_irqs: 1096
[    0.229057] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 102, nr_irqs: 1096
[    0.232399] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 103, nr_irqs: 1096
[    0.248854] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 104, nr_irqs: 1096
[    0.250609] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 105, nr_irqs: 1096
[    0.372343] cjq_debug mp_map_pin_to_irq gsi: 9, irq: 9, idx: 1, ioapic: 0, 
pin: 9
[    0.720950] cjq_debug mp_map_pin_to_irq gsi: 8, irq: 8, idx: 8, ioapic: 0, 
pin: 8
[    0.721052] cjq_debug mp_map_pin_to_irq gsi: 13, irq: 13, idx: 12, ioapic: 
0, pin: 13
[    1.254825] cjq_debug mp_map_pin_to_irq gsi: 7, irq: -16, idx: 7, ioapic: 0, 
pin: 7
[    1.333081] cjq_debug mp_map_pin_to_irq gsi: 1, irq: 1, idx: 2, ioapic: 0, 
pin: 1
[    1.375882] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 106, nr_irqs: 1096
[    1.375951] cjq_debug mp_map_pin_to_irq gsi: 32, irq: 106, idx: -1, ioapic: 
1, pin: 8
[    1.376072] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 107, nr_irqs: 1096
[    1.376121] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 107, idx: -1, ioapic: 
1, pin: 13
[    1.472551] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 107, idx: -1, ioapic: 
1, pin: 13
[    1.472697] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 107, nr_irqs: 1096
[    1.472751] cjq_debug mp_map_pin_to_irq gsi: 38, irq: 107, idx: -1, ioapic: 
1, pin: 14
[    1.484290] cjq_debug mp_map_pin_to_irq gsi: 38, irq: 107, idx: -1, ioapic: 
1, pin: 14
[    1.768163] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 107, nr_irqs: 1096
[    1.768627] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 108, nr_irqs: 1096
[    1.769059] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 109, nr_irqs: 1096
[    1.769694] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 110, nr_irqs: 1096
[    1.770169] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 111, nr_irqs: 1096
[    1.770697] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 112, nr_irqs: 1096
[    1.770738] cjq_debug mp_map_pin_to_irq gsi: 28, irq: 112, idx: -1, ioapic: 
1, pin: 4
[    1.770789] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 113, nr_irqs: 1096
[    1.771230] cjq_debug mp_map_pin_to_irq gsi: 28, irq: 112, idx: -1, ioapic: 
1, pin: 4
[    1.771278] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 114, nr_irqs: 1096
[    2.127884] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 115, nr_irqs: 1096
[    3.207419] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 116, nr_irqs: 1096
[    3.207730] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 116, idx: -1, ioapic: 
1, pin: 13
[    3.208120] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 117, nr_irqs: 1096
[    3.208475] cjq_debug mp_map_pin_to_irq gsi: 36, irq: 117, idx: -1, ioapic: 
1, pin: 12
[    3.208478] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 118, nr_irqs: 1096
[    3.208861] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 116, idx: -1, ioapic: 
1, pin: 13
[    3.208933] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 119, nr_irqs: 1096
[    3.209127] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 120, nr_irqs: 1096
[    3.209383] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 121, nr_irqs: 1096
[    3.209863] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 122, nr_irqs: 1096
[    3.211439] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 123, nr_irqs: 1096
[    3.211833] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 124, nr_irqs: 1096
[    3.212873] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 125, nr_irqs: 1096
[    3.243514] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 126, nr_irqs: 1096
[    3.243689] cjq_debug mp_map_pin_to_irq gsi: 38, irq: 126, idx: -1, ioapic: 
1, pin: 14
[    3.244293] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 127, nr_irqs: 1096
[    3.244534] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 128, nr_irqs: 1096
[    3.244714] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 129, nr_irqs: 1096
[    3.244911] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 130, nr_irqs: 1096
[    3.245096] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 131, nr_irqs: 1096
[    3.245633] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 132, nr_irqs: 1096
[    3.247890] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 133, nr_irqs: 1096
[    3.248192] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 134, nr_irqs: 1096
[    3.271093] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 135, nr_irqs: 1096
[    3.307045] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 136, nr_irqs: 1096
[    3.307162] cjq_debug mp_map_pin_to_irq gsi: 48, irq: 136, idx: -1, ioapic: 
1, pin: 24
[    3.307223] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 137, nr_irqs: 1096
[    3.331183] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 137, nr_irqs: 1096
[    3.331295] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 138, nr_irqs: 1096
[    3.331366] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 139, nr_irqs: 1096
[    3.331438] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 140, nr_irqs: 1096
[    3.331511] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 141, nr_irqs: 1096
[    3.331579] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 142, nr_irqs: 1096
[    3.331646] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 143, nr_irqs: 1096
[    3.331713] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 144, nr_irqs: 1096
[    3.331780] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 145, nr_irqs: 1096
[    3.331846] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 146, nr_irqs: 1096
[    3.331913] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 147, nr_irqs: 1096
[    3.331984] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 148, nr_irqs: 1096
[    3.332051] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 149, nr_irqs: 1096
[    3.332118] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 150, nr_irqs: 1096
[    3.332183] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 151, nr_irqs: 1096
[    3.332252] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 152, nr_irqs: 1096
[    3.332319] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 153, nr_irqs: 1096
[    8.010370] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 116, idx: -1, ioapic: 
1, pin: 13
[    9.545439] cjq_debug mp_map_pin_to_irq gsi: 36, irq: 117, idx: -1, ioapic: 
1, pin: 12
[    9.545713] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 154, nr_irqs: 1096
[    9.546034] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 155, nr_irqs: 1096
[    9.687796] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 156, nr_irqs: 1096
[    9.687979] cjq_debug mp_map_pin_to_irq gsi: 39, irq: 156, idx: -1, ioapic: 
1, pin: 15
[    9.688057] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 157, nr_irqs: 1096
[    9.921038] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 158, nr_irqs: 1096
[    9.921210] cjq_debug mp_map_pin_to_irq gsi: 29, irq: 158, idx: -1, ioapic: 
1, pin: 5
[    9.921403] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 159, nr_irqs: 1096
[    9.926373] cjq_debug mp_map_pin_to_irq gsi: 39, irq: 156, idx: -1, ioapic: 
1, pin: 15
[    9.926747] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 160, nr_irqs: 1096
[    9.928201] cjq_debug mp_map_pin_to_irq gsi: 36, irq: 117, idx: -1, ioapic: 
1, pin: 12
[    9.928488] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 161, nr_irqs: 1096
[   10.653915] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 162, nr_irqs: 1096
[   10.656257] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 163, nr_irqs: 1096

You can find that the allocation of irq is not always based on the value of 
gsi. It follows the principle of requesting first, distributing first, like gsi 
32 get 106 but gsi 28 get 112. And not only acpi_register_gsi_ioapic() will 
call into __irq_alloc_descs, but other functions will call, even earlier.
Above output is like baremetal. So, we can get conclusion irq != gsi. See below 
output on linux:

[    0.105053] cjq_debug mp_map_pin_to_irq gsi: 1, irq: 1, idx: 2, ioapic: 0, 
pin: 1
[    0.105061] cjq_debug mp_map_pin_to_irq gsi: 2, irq: 0, idx: 0, ioapic: 0, 
pin: 2
[    0.105069] cjq_debug mp_map_pin_to_irq gsi: 3, irq: 3, idx: 3, ioapic: 0, 
pin: 3
[    0.105078] cjq_debug mp_map_pin_to_irq gsi: 4, irq: 4, idx: 4, ioapic: 0, 
pin: 4
[    0.105086] cjq_debug mp_map_pin_to_irq gsi: 5, irq: 5, idx: 5, ioapic: 0, 
pin: 5
[    0.105094] cjq_debug mp_map_pin_to_irq gsi: 6, irq: 6, idx: 6, ioapic: 0, 
pin: 6
[    0.105103] cjq_debug mp_map_pin_to_irq gsi: 7, irq: 7, idx: 7, ioapic: 0, 
pin: 7
[    0.105111] cjq_debug mp_map_pin_to_irq gsi: 8, irq: 8, idx: 8, ioapic: 0, 
pin: 8
[    0.105119] cjq_debug mp_map_pin_to_irq gsi: 9, irq: 9, idx: 1, ioapic: 0, 
pin: 9
[    0.105127] cjq_debug mp_map_pin_to_irq gsi: 10, irq: 10, idx: 9, ioapic: 0, 
pin: 10
[    0.105136] cjq_debug mp_map_pin_to_irq gsi: 11, irq: 11, idx: 10, ioapic: 
0, pin: 11
[    0.105144] cjq_debug mp_map_pin_to_irq gsi: 12, irq: 12, idx: 11, ioapic: 
0, pin: 12
[    0.105152] cjq_debug mp_map_pin_to_irq gsi: 13, irq: 13, idx: 12, ioapic: 
0, pin: 13
[    0.105160] cjq_debug mp_map_pin_to_irq gsi: 14, irq: 14, idx: 13, ioapic: 
0, pin: 14
[    0.105169] cjq_debug mp_map_pin_to_irq gsi: 15, irq: 15, idx: 14, ioapic: 
0, pin: 15
[    0.398134] cjq_debug mp_map_pin_to_irq gsi: 9, irq: 9, idx: 1, ioapic: 0, 
pin: 9
[    1.169293] cjq_debug mp_map_pin_to_irq gsi: 8, irq: 8, idx: 8, ioapic: 0, 
pin: 8
[    1.169394] cjq_debug mp_map_pin_to_irq gsi: 13, irq: 13, idx: 12, ioapic: 
0, pin: 13
[    1.323132] cjq_debug mp_map_pin_to_irq gsi: 7, irq: 7, idx: 7, ioapic: 0, 
pin: 7
[    1.345425] cjq_debug mp_map_pin_to_irq gsi: 1, irq: 1, idx: 2, ioapic: 0, 
pin: 1
[    1.375502] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 24, nr_irqs: 1096
[    1.375575] cjq_debug mp_map_pin_to_irq gsi: 32, irq: 24, idx: -1, ioapic: 
1, pin: 8
[    1.375661] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 25, nr_irqs: 1096
[    1.375705] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 25, idx: -1, ioapic: 
1, pin: 13
[    1.442277] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 25, idx: -1, ioapic: 
1, pin: 13
[    1.442393] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 25, nr_irqs: 1096
[    1.442450] cjq_debug mp_map_pin_to_irq gsi: 38, irq: 25, idx: -1, ioapic: 
1, pin: 14
[    1.453893] cjq_debug mp_map_pin_to_irq gsi: 38, irq: 25, idx: -1, ioapic: 
1, pin: 14
[    1.456127] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 25, nr_irqs: 1096
[    1.734065] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 26, nr_irqs: 1096
[    1.734165] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 27, nr_irqs: 1096
[    1.734253] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 28, nr_irqs: 1096
[    1.734344] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 29, nr_irqs: 1096
[    1.734426] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 30, nr_irqs: 1096
[    1.734512] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 31, nr_irqs: 1096
[    1.734597] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 32, nr_irqs: 1096
[    1.734643] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 33, nr_irqs: 1096
[    1.734687] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 34, nr_irqs: 1096
[    1.734728] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 35, nr_irqs: 1096
[    1.735017] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 36, nr_irqs: 1096
[    1.735252] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 37, nr_irqs: 1096
[    1.735467] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 38, nr_irqs: 1096
[    1.735799] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 39, nr_irqs: 1096
[    1.736024] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 40, nr_irqs: 1096
[    1.736364] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 41, nr_irqs: 1096
[    1.736406] cjq_debug mp_map_pin_to_irq gsi: 28, irq: 41, idx: -1, ioapic: 
1, pin: 4
[    1.736434] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 42, nr_irqs: 1096
[    1.736701] cjq_debug mp_map_pin_to_irq gsi: 28, irq: 41, idx: -1, ioapic: 
1, pin: 4
[    1.736724] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 43, nr_irqs: 1096
[    3.037123] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 44, nr_irqs: 1096
[    3.037313] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 44, idx: -1, ioapic: 
1, pin: 13
[    3.037515] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 44, idx: -1, ioapic: 
1, pin: 13
[    3.037738] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 45, nr_irqs: 1096
[    3.037959] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 46, nr_irqs: 1096
[    3.038073] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 47, nr_irqs: 1096
[    3.038154] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 48, nr_irqs: 1096
[    3.038179] cjq_debug mp_map_pin_to_irq gsi: 36, irq: 47, idx: -1, ioapic: 
1, pin: 12
[    3.038277] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 49, nr_irqs: 1096
[    3.038399] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 50, nr_irqs: 1096
[    3.038525] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 51, nr_irqs: 1096
[    3.038657] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 52, nr_irqs: 1096
[    3.038852] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 53, nr_irqs: 1096
[    3.052377] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 54, nr_irqs: 1096
[    3.052479] cjq_debug mp_map_pin_to_irq gsi: 38, irq: 54, idx: -1, ioapic: 
1, pin: 14
[    3.052730] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 55, nr_irqs: 1096
[    3.052840] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 56, nr_irqs: 1096
[    3.052918] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 57, nr_irqs: 1096
[    3.052987] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 58, nr_irqs: 1096
[    3.053069] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 59, nr_irqs: 1096
[    3.053139] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 60, nr_irqs: 1096
[    3.053201] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 61, nr_irqs: 1096
[    3.053260] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 62, nr_irqs: 1096
[    3.089128] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 63, nr_irqs: 1096
[    3.089310] cjq_debug mp_map_pin_to_irq gsi: 48, irq: 63, idx: -1, ioapic: 
1, pin: 24
[    3.089376] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 64, nr_irqs: 1096
[    3.103435] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 65, nr_irqs: 1096
[    3.114190] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 64, nr_irqs: 1096
[    3.114346] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 66, nr_irqs: 1096
[    3.121215] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 67, nr_irqs: 1096
[    3.121350] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 68, nr_irqs: 1096
[    3.121479] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 69, nr_irqs: 1096
[    3.121612] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 70, nr_irqs: 1096
[    3.121726] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 71, nr_irqs: 1096
[    3.121841] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 72, nr_irqs: 1096
[    3.121955] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 73, nr_irqs: 1096
[    3.122025] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 74, nr_irqs: 1096
[    3.122093] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 75, nr_irqs: 1096
[    3.122148] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 76, nr_irqs: 1096
[    3.122203] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 77, nr_irqs: 1096
[    3.122265] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 78, nr_irqs: 1096
[    3.122322] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 79, nr_irqs: 1096
[    3.122378] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 80, nr_irqs: 1096
[    3.122433] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: 0, 
start: 81, nr_irqs: 1096
[    7.838753] cjq_debug mp_map_pin_to_irq gsi: 37, irq: 44, idx: -1, ioapic: 
1, pin: 13
[    9.619174] cjq_debug mp_map_pin_to_irq gsi: 36, irq: 47, idx: -1, ioapic: 
1, pin: 12
[    9.619556] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 82, nr_irqs: 1096
[    9.622038] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 83, nr_irqs: 1096
[    9.634900] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 84, nr_irqs: 1096
[    9.635316] cjq_debug mp_map_pin_to_irq gsi: 39, irq: 84, idx: -1, ioapic: 
1, pin: 15
[    9.635405] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 85, nr_irqs: 1096
[   10.006686] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 86, nr_irqs: 1096
[   10.006823] cjq_debug mp_map_pin_to_irq gsi: 29, irq: 86, idx: -1, ioapic: 
1, pin: 5
[   10.007009] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 87, nr_irqs: 1096
[   10.008723] cjq_debug mp_map_pin_to_irq gsi: 39, irq: 84, idx: -1, ioapic: 
1, pin: 15
[   10.009853] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 88, nr_irqs: 1096
[   10.010786] cjq_debug mp_map_pin_to_irq gsi: 36, irq: 47, idx: -1, ioapic: 
1, pin: 12
[   10.010858] cjq_debug __irq_alloc_descs irq: -1, from: 24, cnt: 1, node: -1, 
start: 89, nr_irqs: 1096

2. Why I do the translations between irq and gsi?

After answering question 1, we get irq != gsi. And I found, in QEMU, 
(pci_qdev_realize->xen_pt_realize->xen_host_pci_device_get->xen_host_pci_get_hex_value)
 will get the irq number, but later, 
pci_qdev_realize->xen_pt_realize->xc_physdev_map_pirq requires us to pass into 
gsi, it will call into Xen physdev_map_pirq-> allocate_and_map_gsi_pirq to 
allocate pirq for gsi. And then the error occurred.
Not only that, the callback function pci_add_dm_done-> xc_physdev_map_pirq also 
need gsi.

So, I added the function xc_physdev_map_pirq() to translate irq to gsi, for 
QEMU.

And I didn't find similar functions in existing linux codes, and I think only 
"QEMU passthrough for Xen" need this translation, so I added it into privcmd. 
If you guys know any other similar functions or other more suitable places, 
please feel free to tell me.

3. Why I call PHYSDEVOP_map_pirq in acpi_register_gsi_xen_pvh()?

Because if you want to map a gsi for domU, it must have a mapping in dom0. See 
QEMU code:
pci_add_dm_done
        xc_physdev_map_pirq
        xc_domain_irq_permission
                XEN_DOMCTL_irq_permission
                        pirq_access_permitted
xc_physdev_map_pirq will get the pirq which mapped from gsi, and 
xc_domain_irq_permission will use pirq and call into Xen. If we don't do 
PHYSDEVOP_map_pirq for passthrough devices on PVH dom0, then 
pirq_access_permitted will get a NULL irq from dom0 and get failed.

So, I added PHYSDEVOP_map_pirq for PVH dom0. But I think it is only necessary 
for passthrough devices to do that, instead of all devices which call 
__acpi_register_gsi. In next version patch, I will restrain that only 
passthrough devices can do PHYSDEVOP_map_pirq.

4. Why I call PHYSDEVOP_setup_gsi in acpi_register_gsi_xen_pvh()?

Like Roger's comments, the gsi of passthrough device doesn't be unmasked and 
registered(I added printings in vioapic_hwdom_map_gsi(), and I found that it 
never be called for dGPU with gsi 28 in my environment).
So, I called PHYSDEVOP_setup_gsi to register gsi.
But I agree with Roger and Jan's opinion, it is wrong to do PHYSDEVOP_setup_gsi 
for all devices.
So, in next version patch, I will also restrain that only passthrough devices 
can do PHYSDEVOP_setup_gsi.

-- 
Best regards,
Jiqian Chen.

 

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