Subject: Re: [kvm-unit-tests PATCH 7/7] common: add memory dirtying vs migration test

From: "Nicholas Piggin" <[email-masked]>
Date: Tue, 05 Mar 2024 12:50:18 +1000

On Mon Mar 4, 2024 at 4:22 PM AEST, Thomas Huth wrote:
> On 26/02/2024 10.38, Nicholas Piggin wrote:
> > This test stores to a bunch of pages and verifies previous stores,
> > while being continually migrated. This can fail due to a QEMU TCG
> > physical memory dirty bitmap bug.
>
> Good idea, but could we then please drop "continuous" test from 
> selftest-migration.c again? ... having two common tests to exercise the 
> continuous migration that take quite a bunch of seconds to finish sounds 
> like a waste of time in the long run to me.

Yeah if you like. I could shorten them up a bit. I did want to have
the selftests for just purely testing the harness with as little
"test" code as possible.

>
> > Signed-off-by: Nicholas Piggin <[email-masked]>
> > ---
> >   common/memory-verify.c  | 48 +++++++++++++++++++++++++++++++++++++++++
> >   powerpc/Makefile.common |  1 +
> >   powerpc/memory-verify.c |  1 +
> >   powerpc/unittests.cfg   |  7 ++++++
> >   s390x/Makefile          |  1 +
> >   s390x/memory-verify.c   |  1 +
> >   s390x/unittests.cfg     |  6 ++++++
> >   7 files changed, 65 insertions(+)
> >   create mode 100644 common/memory-verify.c
> >   create mode 120000 powerpc/memory-verify.c
> >   create mode 120000 s390x/memory-verify.c
> > 
> > diff --git a/common/memory-verify.c b/common/memory-verify.c
> > new file mode 100644
> > index 000000000..7c4ec087b
> > --- /dev/null
> > +++ b/common/memory-verify.c
> > @@ -0,0 +1,48 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Simple memory verification test, used to exercise dirty memory migration.
> > + *
> > + */
> > +#include <libcflat.h>
> > +#include <migrate.h>
> > +#include <alloc.h>
> > +#include <asm/page.h>
> > +#include <asm/time.h>
> > +
> > +#define NR_PAGES 32
> > +
> > +int main(int argc, char **argv)
> > +{
> > +	void *mem = malloc(NR_PAGES*PAGE_SIZE);
> > +	bool success = true;
> > +	uint64_t ms;
> > +	long i;
> > +
> > +	report_prefix_push("memory");
> > +
> > +	memset(mem, 0, NR_PAGES*PAGE_SIZE);
> > +
> > +	migrate_begin_continuous();
> > +	ms = get_clock_ms();
> > +	i = 0;
> > +	do {
> > +		int j;
> > +
> > +		for (j = 0; j < NR_PAGES*PAGE_SIZE; j += PAGE_SIZE) {
> > +			if (*(volatile long *)(mem + j) != i) {
> > +				success = false;
> > +				goto out;
> > +			}
> > +			*(volatile long *)(mem + j) = i + 1;
> > +		}
> > +		i++;
> > +	} while (get_clock_ms() - ms < 5000);
>
> Maybe add a parameter so that the user can use different values for the 
> runtime than always doing 5 seconds?

Sure.

Thanks,
Nick