On 17/05/2019 15.03, Laurent Vivier wrote:
> From: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
>
> Currently the handler for a decrementer exception will simply reload the
> maximum value (0x7FFFFFFF), which will take ~4 seconds to expire again.
> This means that if a vcpu cedes, it will be ~4 seconds between wakeups.
>
> The h_cede_tm test is testing a known breakage when a guest cedes while
> suspended. To be sure we cede 500 times to check for the bug. However
> since it takes ~4 seconds to be woken up once we've ceded, we only get
> through ~20 iterations before we reach the 90 seconds timeout and the
> test appears to fail.
>
> Add an option when registering the decrementer handler to specify the
> value which should be reloaded by the handler, allowing the timeout to be
> chosen.
>
> Modify the spr test to use the max timeout to preserve existing
> behaviour.
> Modify the h_cede_tm test to use a 10ms timeout to ensure we can perform
> 500 iterations before hitting the 90 second time limit for a test.
>
> This means the h_cede_tm test now succeeds rather than timing out.
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
> Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
> Reviewed-by: Laurent Vivier <lvivier@xxxxxxxxxx>
> [lv: reset initial value to 0x3FFFFFFF]
Looks like something went wrong here? There is still the 0x7FFFFFFF in
the hunk below...
> diff --git a/powerpc/sprs.c b/powerpc/sprs.c
> index 6744bd8d8049..3c2d98c9ca99 100644
> --- a/powerpc/sprs.c
> +++ b/powerpc/sprs.c
> @@ -253,6 +253,7 @@ int main(int argc, char **argv)
> 0x1234567890ABCDEFULL, 0xFEDCBA0987654321ULL,
> -1ULL,
> };
> + static uint64_t decr = 0x7FFFFFFF; /* Max value */
>
> for (i = 1; i < argc; i++) {
> if (!strcmp(argv[i], "-w")) {
> @@ -288,7 +289,7 @@ int main(int argc, char **argv)
> (void) getchar();
> } else {
> puts("Sleeping...\n");
> - handle_exception(0x900, &dec_except_handler, NULL);
> + handle_exception(0x900, &dec_except_handler, &decr);
> asm volatile ("mtdec %0" : : "r" (0x3FFFFFFF));
> hcall(H_CEDE);
> }
Thomas
