Re: [kvm-unit-tests PATCH v7 1/8] lib: s390x: introduce bitfield for PSW mask

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Fri,  3 Nov 2023 10:29:30 +0100
Nico Boehr <nrb@linux.ibm.com> wrote:

> Changing the PSW mask is currently little clumsy, since there is only the
> PSW_MASK_* defines. This makes it hard to change e.g. only the address
> space in the current PSW without a lot of bit fiddling.
> 
> Introduce a bitfield for the PSW mask. This makes this kind of
> modifications much simpler and easier to read.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> ---
>  lib/s390x/asm/arch_def.h | 25 ++++++++++++++++++++++++-
>  s390x/selftest.c         | 34 ++++++++++++++++++++++++++++++++++
>  2 files changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
> index bb26e008cc68..f629b6d0a17f 100644
> --- a/lib/s390x/asm/arch_def.h
> +++ b/lib/s390x/asm/arch_def.h
> @@ -37,9 +37,32 @@ struct stack_frame_int {
>  };
>  
>  struct psw {
> -	uint64_t	mask;
> +	union {
> +		uint64_t	mask;
> +		struct {
> +			uint64_t reserved00:1;
> +			uint64_t per:1;
> +			uint64_t reserved02:3;
> +			uint64_t dat:1;
> +			uint64_t io:1;
> +			uint64_t ext:1;
> +			uint64_t key:4;
> +			uint64_t reserved12:1;
> +			uint64_t mchk:1;
> +			uint64_t wait:1;
> +			uint64_t pstate:1;
> +			uint64_t as:2;
> +			uint64_t cc:2;
> +			uint64_t prg_mask:4;
> +			uint64_t reserved24:7;
> +			uint64_t ea:1;
> +			uint64_t ba:1;
> +			uint64_t reserved33:31;
> +		};
> +	};
>  	uint64_t	addr;
>  };
> +_Static_assert(sizeof(struct psw) == 16, "PSW size");
>  
>  #define PSW(m, a) ((struct psw){ .mask = (m), .addr = (uint64_t)(a) })
>  
> diff --git a/s390x/selftest.c b/s390x/selftest.c
> index 13fd36bc06f8..92ed4e5d35eb 100644
> --- a/s390x/selftest.c
> +++ b/s390x/selftest.c
> @@ -74,6 +74,39 @@ static void test_malloc(void)
>  	report_prefix_pop();
>  }
>  
> +static void test_psw_mask(void)
> +{
> +	uint64_t expected_key = 0xf;
> +	struct psw test_psw = PSW(0, 0);
> +
> +	report_prefix_push("PSW mask");
> +	test_psw.mask = PSW_MASK_DAT;
> +	report(test_psw.dat, "DAT matches expected=0x%016lx actual=0x%016lx", PSW_MASK_DAT, test_psw.mask);
> +
> +	test_psw.mask = PSW_MASK_IO;
> +	report(test_psw.io, "IO matches expected=0x%016lx actual=0x%016lx", PSW_MASK_IO, test_psw.mask);
> +
> +	test_psw.mask = PSW_MASK_EXT;
> +	report(test_psw.ext, "EXT matches expected=0x%016lx actual=0x%016lx", PSW_MASK_EXT, test_psw.mask);
> +
> +	test_psw.mask = expected_key << (63 - 11);
> +	report(test_psw.key == expected_key, "PSW Key matches expected=0x%lx actual=0x%x", expected_key, test_psw.key);
> +
> +	test_psw.mask = 1UL << (63 - 13);
> +	report(test_psw.mchk, "MCHK matches");
> +
> +	test_psw.mask = PSW_MASK_WAIT;
> +	report(test_psw.wait, "Wait matches expected=0x%016lx actual=0x%016lx", PSW_MASK_WAIT, test_psw.mask);
> +
> +	test_psw.mask = PSW_MASK_PSTATE;
> +	report(test_psw.pstate, "Pstate matches expected=0x%016lx actual=0x%016lx", PSW_MASK_PSTATE, test_psw.mask);
> +
> +	test_psw.mask = PSW_MASK_64;
> +	report(test_psw.ea && test_psw.ba, "BA/EA matches expected=0x%016lx actual=0x%016lx", PSW_MASK_64, test_psw.mask);
> +
> +	report_prefix_pop();
> +}
> +
>  int main(int argc, char**argv)
>  {
>  	report_prefix_push("selftest");
> @@ -89,6 +122,7 @@ int main(int argc, char**argv)
>  	test_fp();
>  	test_pgm_int();
>  	test_malloc();
> +	test_psw_mask();
>  
>  	return report_summary();
>  }