On Thu, 8 Dec 2022 18:05:02 +0100
Thomas Huth <thuth@xxxxxxxxxx> wrote:
> We recently discovered a bug with the time management in nested scenarios
> which got fixed by kernel commit "KVM: s390: vsie: Fix the initialization
> of the epoch extension (epdx) field". This adds a simple test for this
> bug so that it is easier to determine whether the host kernel of a machine
> has already been fixed or not.
>
> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> ---
> v2: Remove the spurious "2" from the diag 44 opcode
>
> s390x/sie.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/s390x/sie.c b/s390x/sie.c
> index 87575b29..cd3cea10 100644
> --- a/s390x/sie.c
> +++ b/s390x/sie.c
> @@ -58,6 +58,33 @@ static void test_diags(void)
> }
> }
>
> +static void test_epoch_ext(void)
> +{
> + u32 instr[] = {
> + 0xb2780000, /* STCKE 0 */
> + 0x83000044 /* DIAG 0x44 to intercept */
> + };
> +
> + if (!test_facility(139)) {
> + report_skip("epdx: Multiple Epoch Facility is not available");
> + return;
> + }
> +
> + guest[0] = 0x00;
> + memcpy(guest_instr, instr, sizeof(instr));
> +
> + vm.sblk->gpsw.addr = PAGE_SIZE * 2;
> + vm.sblk->gpsw.mask = PSW_MASK_64;
> +
> + vm.sblk->ecd |= ECD_MEF;
> + vm.sblk->epdx = 0x47; /* Setting the epoch extension here ... */
> +
> + sie(&vm);
> +
> + /* ... should result in the same epoch extension here: */
> + report(guest[0] == 0x47, "epdx: different epoch is visible in the guest");
> +}
> +
> static void setup_guest(void)
> {
> setup_vm();
> @@ -80,6 +107,7 @@ int main(void)
>
> setup_guest();
> test_diags();
> + test_epoch_ext();
> sie_guest_destroy(&vm);
>
> done:
