Re: [Patch V4 01/42] x86, irq: update high address field when updating affinity for MSI IRQ

[Jiang Liu]

On 2014/6/10 7:46, Yinghai Lu wrote:
> On Mon, Jun 9, 2014 at 1:19 AM, Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx> wrote:
>> If x2apic is enabled, the MSI high address field should also be aslo
>> updated when setting affinity for MSI IRQ, otherwise the MSI IRQ may
>> target wrong APIC IDs.
> 
> Do you have any test case to reveal the problem?
Just by code inspection.

> 
>>
>> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx
>> ---
>>  arch/x86/kernel/apic/io_apic.c |    4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
>> index 9d0a9795a0f8..2de992501a1b 100644
>> --- a/arch/x86/kernel/apic/io_apic.c
>> +++ b/arch/x86/kernel/apic/io_apic.c
>> @@ -3007,6 +3007,10 @@ msi_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
>>
>>         __get_cached_msi_msg(data->msi_desc, &msg);
>>
>> +       msg.address_hi = MSI_ADDR_BASE_HI;
>> +       if (x2apic_enabled())
>> +               msg.address_hi |= MSI_ADDR_EXT_DEST_ID(dest);
>> +
>>         msg.data &= ~MSI_DATA_VECTOR_MASK;
>>         msg.data |= MSI_DATA_VECTOR(cfg->vector);
>>         msg.address_lo &= ~MSI_ADDR_DEST_ID_MASK;
> 
> No. This change is not needed.
> 
> When x2apic is used, and apicid > 255, irq remapping is used.
> 
> msi_chip.irq_set_affinity will be changed from msi_set_affinity to
> x86_io_apic_ops.set_affinity (aka intel_setup_ioapic_entry),  via
> irq_remap_modify_chip_defaults().
Thanks for explanation, will drop this patch.
Gerry
> 
> Thanks
> 
> Yinghai
> 
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