Re: [kvm-unit-tests PATCH v2 1/2] lib/s390x: move TOD clock related functions to library

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

On Tue, 11 Oct 2022 17:14:32 +0200
Nico Boehr <nrb@linux.ibm.com> wrote:

> The TOD-clock related functions can be useful for other tests beside the
> sck test, hence move them to the library.
> 
> While at it, add a wrapper for stckf and express get_clock_us() with
> stck() to reduce code duplication.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>  lib/s390x/asm/time.h | 50 +++++++++++++++++++++++++++++++++++++++++++-
>  s390x/sck.c          | 32 ----------------------------
>  2 files changed, 49 insertions(+), 33 deletions(-)
> 
> diff --git a/lib/s390x/asm/time.h b/lib/s390x/asm/time.h
> index d8d91d68a667..c5e1797fd29e 100644
> --- a/lib/s390x/asm/time.h
> +++ b/lib/s390x/asm/time.h
> @@ -18,11 +18,59 @@
>  
>  #define CPU_TIMER_SHIFT_US	S390_CLOCK_SHIFT_US
>  
> +static inline int sck(uint64_t *time)
> +{
> +	int cc;
> +
> +	asm volatile(
> +		"	sck %[time]\n"
> +		"	ipm %[cc]\n"
> +		"	srl %[cc],28\n"
> +		: [cc] "=d"(cc)
> +		: [time] "Q"(*time)
> +		: "cc"
> +	);
> +
> +	return cc;
> +}
> +
> +static inline int stck(uint64_t *time)
> +{
> +	int cc;
> +
> +	asm volatile(
> +		"	stck %[time]\n"
> +		"	ipm %[cc]\n"
> +		"	srl %[cc],28\n"
> +		: [cc] "=d" (cc), [time] "=Q" (*time)
> +		:
> +		: "cc", "memory"

why do you need "memory" ?

(I know it was in the old code, but probably it should not have)

> +	);
> +
> +	return cc;
> +}
> +
> +static inline int stckf(uint64_t *time)
> +{
> +	int cc;
> +
> +	asm volatile(
> +		"	stckf %[time]\n"
> +		"	ipm %[cc]\n"
> +		"	srl %[cc],28\n"
> +		: [cc] "=d" (cc), [time] "=Q" (*time)
> +		:
> +		: "cc", "memory"

same here

> +	);
> +
> +	return cc;
> +}
> +
>  static inline uint64_t get_clock_us(void)
>  {
>  	uint64_t clk;
>  
> -	asm volatile(" stck %0 " : : "Q"(clk) : "memory");
> +	stck(&clk);
>  
>  	return clk >> STCK_SHIFT_US;
>  }
> diff --git a/s390x/sck.c b/s390x/sck.c
> index 88d52b74a586..dff496187602 100644
> --- a/s390x/sck.c
> +++ b/s390x/sck.c
> @@ -12,38 +12,6 @@
>  #include <asm/interrupt.h>
>  #include <asm/time.h>
>  
> -static inline int sck(uint64_t *time)
> -{
> -	int cc;
> -
> -	asm volatile(
> -		"	sck %[time]\n"
> -		"	ipm %[cc]\n"
> -		"	srl %[cc],28\n"
> -		: [cc] "=d"(cc)
> -		: [time] "Q"(*time)
> -		: "cc"
> -	);
> -
> -	return cc;
> -}
> -
> -static inline int stck(uint64_t *time)
> -{
> -	int cc;
> -
> -	asm volatile(
> -		"	stck %[time]\n"
> -		"	ipm %[cc]\n"
> -		"	srl %[cc],28\n"
> -		: [cc] "=d" (cc), [time] "=Q" (*time)
> -		:
> -		: "cc", "memory"
> -	);
> -
> -	return cc;
> -}
> -
>  static void test_priv(void)
>  {
>  	uint64_t time_to_set_privileged = 0xfacef00dcafe0000,