[Skiboot] [PATCH] asm/head.S: set POWER9 radix HID bit at entry

[Nicholas Piggin]

Nicholas Piggin's on April 12, 2019 2:05 pm:
> When running in virtual memory mode, the radix MMU hid bit should not
> be changed, so set this in the initial boot SPR setup.
> 
> As a side effect, fast reboot also has HID0:RADIX bit set by the
> shared spr init, so no need for an explicit call.

I guess that's not a good changelog outside the vmm series.

Better point is that the HID0[RADIX] bit is no more special than
any other HID bit, exactly equivalent to HID0[HILE] really. So no
need for this special case.

Thanks,
Nick

> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
>  asm/head.S    |  3 +++
>  core/cpu.c    | 18 ++----------------
>  core/init.c   |  3 ---
>  include/cpu.h |  1 -
>  4 files changed, 5 insertions(+), 20 deletions(-)
> 
> diff --git a/asm/head.S b/asm/head.S
> index 0ed1acddd..916b22c51 100644
> --- a/asm/head.S
> +++ b/asm/head.S
> @@ -766,9 +766,12 @@ init_shared_sprs:
>  	mtspr	SPR_TSCR, %r3
>  	/* HID0: Clear bit 5 (enable core recovery)
>  	 *       Clear bit 4 (HILE)
> +	 *       Set bit 8 (radix)
>  	 */
>  	mfspr	%r3,SPR_HID0
>  	li	%r0,1
> +	sldi	%r4,%r0,(63-8)
> +	or	%r3,%r3,%r4
>  	sldi	%r4,%r0,(63-5)
>  	sldi	%r5,%r0,(63-4)
>  	or	%r0,%r4,%r5
> diff --git a/core/cpu.c b/core/cpu.c
> index d9d471337..62c020174 100644
> --- a/core/cpu.c
> +++ b/core/cpu.c
> @@ -1433,20 +1433,6 @@ static int64_t cpu_change_all_hid0(struct hid0_change_req *req)
>  	return OPAL_SUCCESS;
>  }
>  
> -void cpu_set_radix_mode(void)
> -{
> -	struct hid0_change_req req;
> -
> -	if (!radix_supported)
> -		return;
> -
> -	req.clr_bits = 0;
> -	req.set_bits = SPR_HID0_POWER9_RADIX;
> -	cleanup_global_tlb();
> -	current_radix_mode = true;
> -	cpu_change_all_hid0(&req);
> -}
> -
>  static void cpu_cleanup_one(void *param __unused)
>  {
>  	mtspr(SPR_AMR, 0);
> @@ -1488,8 +1474,8 @@ void cpu_fast_reboot_complete(void)
>  	/* Fast reboot will have cleared HID0:HILE */
>  	current_hile_mode = false;
>  
> -	/* On P9, restore radix mode */
> -	cpu_set_radix_mode();
> +	/* and set HID0:RADIX */
> +	current_radix_mode = true;
>  }
>  
>  static int64_t opal_reinit_cpus(uint64_t flags)
> diff --git a/core/init.c b/core/init.c
> index eeee2d9e9..0fe6c1682 100644
> --- a/core/init.c
> +++ b/core/init.c
> @@ -1282,9 +1282,6 @@ void __noreturn __nomcount main_cpu_entry(const void *fdt)
>  
>  	prd_register_reserved_memory();
>  
> -	/* On P9, switch to radix mode by default */
> -	cpu_set_radix_mode();
> -
>  	checksum_romem();
>  
>  	load_and_boot_kernel(false);
> diff --git a/include/cpu.h b/include/cpu.h
> index 39071a191..011b12bb9 100644
> --- a/include/cpu.h
> +++ b/include/cpu.h
> @@ -313,7 +313,6 @@ extern unsigned long __attrconst cpu_emergency_stack_top(unsigned int pir);
>  extern void cpu_idle_job(void);
>  extern void cpu_idle_delay(unsigned long delay);
>  
> -extern void cpu_set_radix_mode(void);
>  extern void cpu_fast_reboot_complete(void);
>  
>  int dctl_set_special_wakeup(struct cpu_thread *t);
> -- 
> 2.20.1
> 
>