[PATCH] lib: sbi: Respect boot hart setting in "dynamic" boot mode

[Xiang W]

在 2024-06-04星期二的 18:33 +0800，Inochi Amaoto写道：
> In "dynamic" boot mode, the boot hart is only used for the early
> initialization, but not for the coldboot even if it is available.
> This make the boot hart configuration in the dynamic mode
> meaningless.
> 
> To solve this, add extra check for coldboot detection and fallback
> to the lottery if the boot hart does not support coldboot.
> 
> Signed-off-by: Inochi Amaoto <inochiama at outlook.com>

It seems that someone has submitted a similar patch. But this is not
necessary, see the comment of fw_dynamic_info.hartid:

	/**
	 * Preferred boot HART id
	 *
	 * It is possible that the previous booting stage uses same link
	 * address as the FW_DYNAMIC firmware. In this case, the relocation
	 * lottery mechanism can potentially overwrite the previous booting
	 * stage while other HARTs are still running in the previous booting
	 * stage leading to boot-time crash. To avoid this boot-time crash,
	 * the previous booting stage can specify last HART that will jump
	 * to the FW_DYNAMIC firmware as the preferred boot HART.
	 *
	 * To avoid specifying a preferred boot HART, the previous booting
	 * stage can set it to -1UL which will force the FW_DYNAMIC firmware
	 * to use the relocation lottery mechanism.
	 */

If you need to specify the cold boot hart, you can set cold-boot-harts through dt.

Regards,
Xiang W

> ---
>  firmware/fw_dynamic.S  |  4 +---
>  include/sbi/sbi_init.h |  2 ++
>  lib/sbi/sbi_init.c     | 14 +++++++++++++-
>  3 files changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/firmware/fw_dynamic.S b/firmware/fw_dynamic.S
> index 5ee2883..c08ba5f 100644
> --- a/firmware/fw_dynamic.S
> +++ b/firmware/fw_dynamic.S
> @@ -66,7 +66,7 @@ fw_save_info:
>  	li	a4, FW_DYNAMIC_INFO_VERSION_2
>  	REG_L	a3, FW_DYNAMIC_INFO_VERSION_OFFSET(a2)
>  	blt	a3, a4, 2f
> -	lla	a4, _dynamic_boot_hart
> +	lla	a4, sbi_boot_hart
>  	REG_L	a3, FW_DYNAMIC_INFO_BOOT_HART_OFFSET(a2)
>  	REG_S	a3, (a4)
>  2:
> @@ -133,5 +133,3 @@ _dynamic_next_mode:
>  	RISCV_PTR PRV_S
>  _dynamic_options:
>  	RISCV_PTR 0x0
> -_dynamic_boot_hart:
> -	RISCV_PTR -1
> diff --git a/include/sbi/sbi_init.h b/include/sbi/sbi_init.h
> index 9640fee..dd88c23 100644
> --- a/include/sbi/sbi_init.h
> +++ b/include/sbi/sbi_init.h
> @@ -22,4 +22,6 @@ unsigned long sbi_init_count(u32 hartid);
>  
>  void __noreturn sbi_exit(struct sbi_scratch *scratch);
>  
> +extern long sbi_boot_hart;
> +
>  #endif
> diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
> index 389172a..70ff4d7 100644
> --- a/lib/sbi/sbi_init.c
> +++ b/lib/sbi/sbi_init.c
> @@ -18,6 +18,7 @@
>  #include <sbi/sbi_hartmask.h>
>  #include <sbi/sbi_heap.h>
>  #include <sbi/sbi_hsm.h>
> +#include <sbi/sbi_init.h>
>  #include <sbi/sbi_ipi.h>
>  #include <sbi/sbi_irqchip.h>
>  #include <sbi/sbi_platform.h>
> @@ -479,6 +480,8 @@ static void __noreturn init_warmboot(struct sbi_scratch *scratch, u32 hartid)
>  
>  static atomic_t coldboot_lottery = ATOMIC_INITIALIZER(0);
>  
> +long sbi_boot_hart = -1;
> +
>  /**
>   * Initialize OpenSBI library for current HART and jump to next
>   * booting stage.
> @@ -532,9 +535,18 @@ void __noreturn sbi_init(struct sbi_scratch *scratch)
>  	 *
>  	 * We use a lottery mechanism to select coldboot HART among
>  	 * HARTs which satisfy above condition.
> +	 *
> +	 * If user set the boot HART, we will check whether it supports
> +	 * coldboot, and boot the system with the selected one if the
> +	 * check success. Otherwise, we fall back to any supported HART
> +	 * selected from the lottery mechanism.
>  	 */
>  
> -	if (sbi_platform_cold_boot_allowed(plat, hartid)) {
> +	if (sbi_boot_hart != -1 &&
> +	    sbi_platform_cold_boot_allowed(plat, sbi_boot_hart)) {
> +		if (sbi_boot_hart == hartid)
> +			coldboot = true;
> +	} else if (sbi_platform_cold_boot_allowed(plat, hartid)) {
>  		if (next_mode_supported &&
>  		    atomic_xchg(&coldboot_lottery, 1) == 0)
>  			coldboot = true;
> -- 
> 2.45.2
> 
>