On Mon, 27 Mar 2023 10:21:17 +0200
Nico Boehr <nrb@xxxxxxxxxxxxx> wrote:
> At the moment, when a PGM int occurs while in SIE, we will just reenter
> SIE after the interrupt handler was called.
>
> This is because sie() has a loop which checks icptcode and re-enters SIE
> if it is zero.
>
> However, this behaviour is quite undesirable for SIE tests, since it
> doesn't give the host the chance to assert on the PGM int. Instead, we
> will just re-enter SIE, on nullifing conditions even causing the
> exception again.
>
> Add a flag PROG_PGM_IN_SIE set by the pgm int fixup which indicates a
> program interrupt has occured in SIE. Check for the flag in sie() and if
> it's set return from sie() to give the host the ability to react on the
> exception. The host may check if a PGM int has occured in the guest
> using the new function sie_had_pgm_int().
>
> Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
> ---
> lib/s390x/interrupt.c | 6 ++++++
> lib/s390x/sie.c | 10 +++++++++-
> lib/s390x/sie.h | 1 +
> 3 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
> index eb3d6a9b701d..9baf7a003f52 100644
> --- a/lib/s390x/interrupt.c
> +++ b/lib/s390x/interrupt.c
> @@ -106,10 +106,16 @@ void register_ext_cleanup_func(void (*f)(struct stack_frame_int *))
>
> static void fixup_pgm_int(struct stack_frame_int *stack)
> {
> + struct kvm_s390_sie_block *sblk;
> +
> /* If we have an error on SIE we directly move to sie_exit */
> if (lowcore.pgm_old_psw.addr >= (uint64_t)&sie_entry &&
> lowcore.pgm_old_psw.addr <= (uint64_t)&sie_exit) {
> lowcore.pgm_old_psw.addr = (uint64_t)&sie_exit;
> +
> + /* set a marker in sie_block that a PGM int occured */
> + sblk = *((struct kvm_s390_sie_block **)(stack->grs0[13] + __SF_SIE_CONTROL));
> + sblk->prog0c |= PROG_PGM_IN_SIE;
> return;
> }
>
> diff --git a/lib/s390x/sie.c b/lib/s390x/sie.c
> index 22141ded1a90..5e9ae7115c47 100644
> --- a/lib/s390x/sie.c
> +++ b/lib/s390x/sie.c
> @@ -44,6 +44,11 @@ void sie_handle_validity(struct vm *vm)
> vm->validity_expected = false;
> }
>
> +bool sie_had_pgm_int(struct vm *vm)
> +{
> + return vm->sblk->prog0c & PROG_PGM_IN_SIE;
> +}
> +
> void sie(struct vm *vm)
> {
> uint64_t old_cr13;
> @@ -68,7 +73,10 @@ void sie(struct vm *vm)
> lowcore.io_new_psw.mask |= PSW_MASK_DAT_HOME;
> mb();
>
> - while (vm->sblk->icptcode == 0) {
> + /* clear PGM int marker, which might still be set */
> + vm->sblk->prog0c &= ~PROG_PGM_IN_SIE;
> +
> + while (vm->sblk->icptcode == 0 && !sie_had_pgm_int(vm)) {
> sie64a(vm->sblk, &vm->save_area);
> sie_handle_validity(vm);
> }
> diff --git a/lib/s390x/sie.h b/lib/s390x/sie.h
> index 0b00fb709776..8ab755dc9456 100644
> --- a/lib/s390x/sie.h
> +++ b/lib/s390x/sie.h
> @@ -37,6 +37,7 @@ struct kvm_s390_sie_block {
> uint32_t ibc : 12;
> uint8_t reserved08[4]; /* 0x0008 */
> #define PROG_IN_SIE (1<<0)
> +#define PROG_PGM_IN_SIE (1<<1)
please align the body of the macros with tabs, so they are more readable
> uint32_t prog0c; /* 0x000c */
> union {
> uint8_t reserved10[16]; /* 0x0010 */
