Subject: Re: [kvm-unit-tests PATCH v2 4/4] arm64: split its-migrate-unmapped-collection into KVM and TCG variants

From: Alex Bennée <[email-masked]>
Date: Tue, 01 Jun 2021 17:49:01 +0100

Auger Eric <[email-masked]> writes:

> Hi Alex,
>
> On 5/25/21 7:26 PM, Alex Bennée wrote:
>> When running the test in TCG we are basically running on bare metal so
>> don't rely on having a particular kernel errata applied.
>> 
>> You might wonder why we handle this with a totally new test name
>> instead of adjusting the append to take an extra parameter? Well the
>> run_migration shell script uses eval "$@" which unwraps the -append
>> leading to any second parameter being split and leaving QEMU very
>> confused and the test hanging. This seemed simpler than re-writing all
>> the test running logic in something sane ;-)
>
> there is
> lib/s390x/vm.h:bool vm_is_tcg(void)
>
> but I don't see any particular ID we could use to differentiate both the
> KVM and the TCG mode, do you?

For -cpu max we do:

        /*
         * Reset MIDR so the guest doesn't mistake our 'max' CPU type for a real
         * one and try to apply errata workarounds or use impdef features we
         * don't provide.
         * An IMPLEMENTER field of 0 means "reserved for software use";
         * ARCHITECTURE must be 0xf indicating "v7 or later, check ID registers
         * to see which features are present";
         * the VARIANT, PARTNUM and REVISION fields are all implementation
         * defined and we choose to define PARTNUM just in case guest
         * code needs to distinguish this QEMU CPU from other software
         * implementations, though this shouldn't be needed.
         */
        t = FIELD_DP64(0, MIDR_EL1, IMPLEMENTER, 0);
        t = FIELD_DP64(t, MIDR_EL1, ARCHITECTURE, 0xf);
        t = FIELD_DP64(t, MIDR_EL1, PARTNUM, 'Q');
        t = FIELD_DP64(t, MIDR_EL1, VARIANT, 0);
        t = FIELD_DP64(t, MIDR_EL1, REVISION, 0);
        cpu->midr = t;

However for the default -cpu cortex-a57 we aim to look just like the
real thing - only without any annoying micro-architecture bugs ;-)

>
> without a more elegant solution,

I'll look into the suggestion made by Richard.

> Reviewed-by: Eric Auger <[email-masked]>
>
> Thanks
>
> Eric
>
>
>> 
>> Signed-off-by: Alex Bennée <[email-masked]>
>> Cc: Shashi Mallela <[email-masked]>
>> ---
>>  arm/gic.c         |  8 +++++++-
>>  arm/unittests.cfg | 10 +++++++++-
>>  2 files changed, 16 insertions(+), 2 deletions(-)
>> 
>> diff --git a/arm/gic.c b/arm/gic.c
>> index bef061a..0fce2a4 100644
>> --- a/arm/gic.c
>> +++ b/arm/gic.c
>> @@ -36,6 +36,7 @@ static struct gic *gic;
>>  static int acked[NR_CPUS], spurious[NR_CPUS];
>>  static int irq_sender[NR_CPUS], irq_number[NR_CPUS];
>>  static cpumask_t ready;
>> +static bool under_tcg;
>>  
>>  static void nr_cpu_check(int nr)
>>  {
>> @@ -834,7 +835,7 @@ static void test_migrate_unmapped_collection(void)
>>  		goto do_migrate;
>>  	}
>>  
>> -	if (!errata(ERRATA_UNMAPPED_COLLECTIONS)) {
>> +	if (!errata(ERRATA_UNMAPPED_COLLECTIONS) && !under_tcg) {
>>  		report_skip("Skipping test, as this test hangs without the fix. "
>>  			    "Set %s=y to enable.", ERRATA_UNMAPPED_COLLECTIONS);
>>  		test_skipped = true;
>> @@ -1005,6 +1006,11 @@ int main(int argc, char **argv)
>>  		report_prefix_push(argv[1]);
>>  		test_migrate_unmapped_collection();
>>  		report_prefix_pop();
>> +	} else if (!strcmp(argv[1], "its-migrate-unmapped-collection-tcg")) {
>> +		under_tcg = true;
>> +		report_prefix_push(argv[1]);
>> +		test_migrate_unmapped_collection();
>> +		report_prefix_pop();
>>  	} else if (strcmp(argv[1], "its-introspection") == 0) {
>>  		report_prefix_push(argv[1]);
>>  		test_its_introspection();
>> diff --git a/arm/unittests.cfg b/arm/unittests.cfg
>> index 1a39428..adc1bbf 100644
>> --- a/arm/unittests.cfg
>> +++ b/arm/unittests.cfg
>> @@ -205,7 +205,7 @@ extra_params = -machine gic-version=3 -append 'its-pending-migration'
>>  groups = its migration
>>  arch = arm64
>>  
>> -[its-migrate-unmapped-collection]
>> +[its-migrate-unmapped-collection-kvm]
>>  file = gic.flat
>>  smp = $MAX_SMP
>>  accel = kvm
>> @@ -213,6 +213,14 @@ extra_params = -machine gic-version=3 -append 'its-migrate-unmapped-collection'
>>  groups = its migration
>>  arch = arm64
>>  
>> +[its-migrate-unmapped-collection-tcg]
>> +file = gic.flat
>> +smp = $MAX_SMP
>> +accel = tcg
>> +extra_params = -machine gic-version=3 -append 'its-migrate-unmapped-collection-tcg'
>> +groups = its migration
>> +arch = arm64
>> +
>>  # Test PSCI emulation
>>  [psci]
>>  file = psci.flat
>> 

-- 
Alex Bennée

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