Re: [PATCH] KVM: arm64: Don't eagerly teardown the vgic on init error

[Eric Auger <eauger@redhat.com>]

Hi Mark, Marc,

On 10/25/24 12:54, Mark Brown wrote:
> On Thu, Oct 24, 2024 at 07:05:10PM +0100, Marc Zyngier wrote:
>> Mark Brown <broonie@kernel.org> wrote:
> 
>>> # ==== Test Assertion Failure ====
>>> #   lib/kvm_util.c:724: false
>>> #   pid=1947 tid=1947 errno=5 - Input/output error
>>> #      1	0x0000000000404edb: __vm_mem_region_delete at kvm_util.c:724 (discriminator 5)
>>> #      2	0x0000000000405d0b: kvm_vm_free at kvm_util.c:762 (discriminator 12)
>>> #      3	0x0000000000402d5f: vm_gic_destroy at vgic_init.c:101
>>> #      4	 (inlined by) test_vcpus_then_vgic at vgic_init.c:368
>>> #      5	 (inlined by) run_tests at vgic_init.c:720
>>> #      6	0x0000000000401a6f: main at vgic_init.c:748
>>> #      7	0x0000ffffa7b37543: ?? ??:0
>>> #      8	0x0000ffffa7b37617: ?? ??:0
>>> #      9	0x0000000000401b6f: _start at ??:?
>>> #   KVM killed/bugged the VM, check the kernel log for clues
>>> not ok 10 selftests: kvm: vgic_init # exit=254
> 
>>> which does rather look like a test bug rather than a problem in the
>>> change itself.
> 
>> Well, the test tries to do braindead things, and then the test
>> infrastructure seems surprised that KVM tells it to bugger off...
> 
>> I can paper over it with this (see below), but frankly, someone who
>> actually cares about this crap should take a look (and ownership).
As I am the original contributor of the crap I can definitively have a
look at it and take ownership. Those tests were originally written
because the init sequence was different between kvmtool and qemu and we
had regular regressions when touching the init sequence at some point.
Now this may be not valid anymore ...
> 
> I'm not even sure that's a terrible fix, looking at the changelog I get
> the impression the test is deliberately looking to do problematic things
> with the goal of making sure that the kernel handles them appropriately.
> That's not interacting well with the KVM selftest framework's general
> assert early assert often approach but it's a reasonable thing to want
Can you elaborate on the "assert early assert often approach". What
shall this test rather do according to you?

I am OoO next week but I can have a look afterwards. On which machine is
it failing?

Thanks

Eric


> to test so relaxing the asserts like this is one way of squaring the
> circile.