Re: [kvm-unit-tests PATCH v7 5/8] s390x: lib: sie: don't reenter SIE on pgm int

[Janosch Frank <frankja@linux.ibm.com>]

On 11/3/23 10:29, Nico Boehr 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.
> 
> In sie(), check whether a pgm int code is set in lowcore. If it has,
> exit the loop so the test can react to the interrupt. Add a new function
> read_pgm_int_code() to obtain the interrupt code.
> 
> Note that this introduces a slight oddity with sie and pgm int in
> certain cases: If a PGM int occurs between a expect_pgm_int() and sie(),
> we will now never enter SIE until the pgm_int_code is cleared by e.g.
> clear_pgm_int().

Is there any use in NOT having an assert(!read_pgm_int_code()) before 
entering the loop?