Re: [kvm-unit-tests PATCH v7 2/8] s390x: add function to set DAT mode for all interrupts

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

On Fri,  3 Nov 2023 10:29:31 +0100
Nico Boehr <nrb@linux.ibm.com> wrote:

> When toggling DAT or switch address space modes, it is likely that
> interrupts should be handled in the same DAT or address space mode.
> 
> Add a function which toggles DAT and address space mode for all
> interruptions, except restart interrupts.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  lib/s390x/asm/arch_def.h  | 10 ++++++----
>  lib/s390x/asm/interrupt.h |  2 ++
>  lib/s390x/interrupt.c     | 35 +++++++++++++++++++++++++++++++++++
>  lib/s390x/mmu.c           |  5 +++--
>  4 files changed, 46 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
> index f629b6d0a17f..5beaf15b57e7 100644
> --- a/lib/s390x/asm/arch_def.h
> +++ b/lib/s390x/asm/arch_def.h
> @@ -84,10 +84,12 @@ struct cpu {
>  	bool in_interrupt_handler;
>  };
>  
> -#define AS_PRIM				0
> -#define AS_ACCR				1
> -#define AS_SECN				2
> -#define AS_HOME				3
> +enum address_space {
> +	AS_PRIM = 0,
> +	AS_ACCR = 1,
> +	AS_SECN = 2,
> +	AS_HOME = 3
> +};
>  
>  #define PSW_MASK_DAT			0x0400000000000000UL
>  #define PSW_MASK_IO			0x0200000000000000UL
> diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h
> index 35c1145f0349..d01f8a89641a 100644
> --- a/lib/s390x/asm/interrupt.h
> +++ b/lib/s390x/asm/interrupt.h
> @@ -83,6 +83,8 @@ void expect_ext_int(void);
>  uint16_t clear_pgm_int(void);
>  void check_pgm_int_code(uint16_t code);
>  
> +void irq_set_dat_mode(bool use_dat, enum address_space as);
> +
>  /* Activate low-address protection */
>  static inline void low_prot_enable(void)
>  {
> diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
> index 3f993a363ae2..e0a1713349f6 100644
> --- a/lib/s390x/interrupt.c
> +++ b/lib/s390x/interrupt.c
> @@ -9,6 +9,7 @@
>   */
>  #include <libcflat.h>
>  #include <asm/barrier.h>
> +#include <asm/mem.h>
>  #include <asm/asm-offsets.h>
>  #include <sclp.h>
>  #include <interrupt.h>
> @@ -104,6 +105,40 @@ void register_ext_cleanup_func(void (*f)(struct stack_frame_int *))
>  	THIS_CPU->ext_cleanup_func = f;
>  }
>  
> +/**
> + * irq_set_dat_mode - Set the DAT mode of all interrupt handlers, except for
> + * restart.

(here)

> + * This will update the DAT mode and address space mode of all interrupt new
> + * PSWs.
> + *
> + * Since enabling DAT needs initialized CRs and the restart new PSW is often used
> + * to initialize CRs, the restart new PSW is never touched to avoid the chicken
> + * and egg situation.
> + *
> + * @use_dat specifies whether to use DAT or not
> + * @as specifies the address space mode to use. Not set if use_dat is false.

add the colon

 * @use_dat: 
 * @as: 

and move them up there ^

with that fixed:

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> + */
> +void irq_set_dat_mode(bool use_dat, enum address_space as)
> +{
> +	struct psw* irq_psws[] = {
> +		OPAQUE_PTR(GEN_LC_EXT_NEW_PSW),
> +		OPAQUE_PTR(GEN_LC_SVC_NEW_PSW),
> +		OPAQUE_PTR(GEN_LC_PGM_NEW_PSW),
> +		OPAQUE_PTR(GEN_LC_MCCK_NEW_PSW),
> +		OPAQUE_PTR(GEN_LC_IO_NEW_PSW),
> +	};
> +	struct psw *psw;
> +
> +	assert(as == AS_PRIM || as == AS_ACCR || as == AS_SECN || as == AS_HOME);
> +
> +	for (size_t i = 0; i < ARRAY_SIZE(irq_psws); i++) {
> +		psw = irq_psws[i];
> +		psw->dat = use_dat;
> +		if (use_dat)
> +			psw->as = as;
> +	}
> +}
> +
>  static void fixup_pgm_int(struct stack_frame_int *stack)
>  {
>  	/* If we have an error on SIE we directly move to sie_exit */
> diff --git a/lib/s390x/mmu.c b/lib/s390x/mmu.c
> index b474d7021d3f..9a179d6b8ec5 100644
> --- a/lib/s390x/mmu.c
> +++ b/lib/s390x/mmu.c
> @@ -12,6 +12,7 @@
>  #include <asm/pgtable.h>
>  #include <asm/arch_def.h>
>  #include <asm/barrier.h>
> +#include <asm/interrupt.h>
>  #include <vmalloc.h>
>  #include "mmu.h"
>  
> @@ -41,8 +42,8 @@ static void mmu_enable(pgd_t *pgtable)
>  	/* enable dat (primary == 0 set as default) */
>  	enable_dat();
>  
> -	/* we can now also use DAT unconditionally in our PGM handler */
> -	lowcore.pgm_new_psw.mask |= PSW_MASK_DAT;
> +	/* we can now also use DAT in all interrupt handlers */
> +	irq_set_dat_mode(true, AS_PRIM);
>  }
>  
>  /*