Re: [Patch v1] x86: Fix the logical destination mode test

Nitesh Narayan Lal
2020-03-16T22:34:11Z

On 3/10/20 10:03 AM, Marcelo Tosatti wrote:
> On Mon, Mar 09, 2020 at 07:15:50PM -0400, Nitesh Narayan Lal wrote:
>> There are following issues with the ioapic logical destination mode test:
>>
>> - A race condition that is triggered when the interrupt handler
>>   ioapic_isr_86() is called at the same time by multiple vCPUs. Due to this
>> the g_isr_86 is not correctly incremented. To prevent this a spinlock is
>> added around ‘g_isr_86++’.
>>
>> - On older QEMU versions initial x2APIC ID is not set, that is why
>>   the local APIC IDs of each vCPUs are not configured. Hence the logical
>>   destination mode test fails/hangs. Adding ‘+x2apic’ to the qemu -cpu params
>>   ensures that the local APICs are configured every time, irrespective of the
>>   QEMU version.
>>
>> - With ‘-machine kernel_irqchip=split’ included in the ioapic test
>>   test_ioapic_self_reconfigure() always fails and somehow leads to a state where
>>   after submitting IOAPIC fixed delivery - logical destination mode request we
>>   never receive an interrupt back. For now, the physical and logical destination
>>   mode tests are moved above test_ioapic_self_reconfigure().
>>
>> Fixes: b2a1ee7e ("kvm-unit-test: x86: ioapic: Test physical and logical destination mode")
>> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com>
> Looks good to me.

Hi,

I just wanted to follow up and see if there are any more suggestions for me to
improve this patch before it can be merged.

>
>> ---
>> x86/ioapic.c | 11 +++++++----
>> x86/unittests.cfg | 2 +-
>> 2 files changed, 8 insertions(+), 5 deletions(-)
>>
>> diff --git a/x86/ioapic.c b/x86/ioapic.c
>> index 742c711..3106531 100644
>> --- a/x86/ioapic.c
>> +++ b/x86/ioapic.c
>> @@ -432,10 +432,13 @@ static void test_ioapic_physical_destination_mode(void)
>> }
>>
>> static volatile int g_isr_86;
>> +struct spinlock ioapic_lock;
>>
>> static void ioapic_isr_86(isr_regs_t *regs)
>> {
>> + spin_lock(&ioapic_lock);
>> ++g_isr_86;
>> + spin_unlock(&ioapic_lock);
>> set_irq_line(0x0e, 0);
>> eoi();
>> }
>> @@ -501,6 +504,10 @@ int main(void)
>> test_ioapic_level_tmr(true);
>> test_ioapic_edge_tmr(true);
>>
>> + test_ioapic_physical_destination_mode();
>> + if (cpu_count() > 3)
>> + test_ioapic_logical_destination_mode();
>> +
>> if (cpu_count() > 1) {
>> test_ioapic_edge_tmr_smp(false);
>> test_ioapic_level_tmr_smp(false);
>> @@ -508,11 +515,7 @@ int main(void)
>> test_ioapic_edge_tmr_smp(true);
>>
>> test_ioapic_self_reconfigure();
>> - test_ioapic_physical_destination_mode();
>> }
>>
>> - if (cpu_count() > 3)
>> - test_ioapic_logical_destination_mode();
>> -
>> return report_summary();
>> }
>> diff --git a/x86/unittests.cfg b/x86/unittests.cfg
>> index f2401eb..d658bc8 100644
>> --- a/x86/unittests.cfg
>> +++ b/x86/unittests.cfg
>> @@ -46,7 +46,7 @@ timeout = 30
>> [ioapic]
>> file = ioapic.flat
>> smp = 4
>> -extra_params = -cpu qemu64
>> +extra_params = -cpu qemu64,+x2apic
>> arch = x86_64
>>
>> [cmpxchg8b]
>> --
>> 1.8.3.1

--
Nitesh