[PATCH v2] lib:firmware: Select preferred boot hart for cold boot.

[Xiang W]

在 2024-01-24星期三的 23:27 +0800，Cheng Yang写道：
> We now use the boot hart in struct fw_dynamic_info to do
> relocate, but use a lottery algorithm when selecting the
> cold boot hart. This may result in using a hart other
> than the preferred boot hart to boot the next stage
> firmware.
> 
> sbi_platform_cold_boot_allowed seems to be able to solve
> this problem, but for most platforms all hartids are
> allowed to cold boot. In this case, we still cannot
> guarantee that the hart consistent with the preferred boot
> hart will be used for cold boot.
> 
> Therefore, we should also save the preferred boot hart
> information in scratch, so that we can select it first when
> making cold start core selection. If no preferred boot hart
> is specified then the lottery algorithm is used as before.
> 
> Signed-off-by: Cheng Yang <yangcheng.work at foxmail.com>
LGTM

Reviewed-by: Xiang W <wxjstz at 126.com>
> ---
> Changes v1 -> v2:
>   - Replace -1 with -1UL.
>   - If the preferred hart does not allow cold boot will enter sbi_hart_hang.
> 
>  firmware/fw_base.S        |  5 +++++
>  include/sbi/sbi_scratch.h | 11 ++++++++++-
>  lib/sbi/sbi_init.c        | 21 +++++++++++++++------
>  3 files changed, 30 insertions(+), 7 deletions(-)
> 
> diff --git a/firmware/fw_base.S b/firmware/fw_base.S
> index f7763f4..88abd45 100644
> --- a/firmware/fw_base.S
> +++ b/firmware/fw_base.S
> @@ -333,6 +333,11 @@ _scratch_init:
>  #endif
>  	REG_S	a0, SBI_SCRATCH_OPTIONS_OFFSET(tp)
>  	MOV_3R	a0, s0, a1, s1, a2, s2
> +	/* Store boot hart in scratch space */
> +	MOV_3R	s0, a0, s1, a1, s2, a2
> +	call	fw_boot_hart
> +	REG_S	a0, SBI_SCRATCH_BOOT_HART_OFFSET(tp)
> +	MOV_3R	a0, s0, a1, s1, a2, s2
>  	/* Move to next scratch space */
>  	add	t1, t1, t2
>  	blt	t1, s7, _scratch_init
> diff --git a/include/sbi/sbi_scratch.h b/include/sbi/sbi_scratch.h
> index e6a33ba..1cf2b5e 100644
> --- a/include/sbi/sbi_scratch.h
> +++ b/include/sbi/sbi_scratch.h
> @@ -42,8 +42,10 @@
>  #define SBI_SCRATCH_TMP0_OFFSET			(12 * __SIZEOF_POINTER__)
>  /** Offset of options member in sbi_scratch */
>  #define SBI_SCRATCH_OPTIONS_OFFSET		(13 * __SIZEOF_POINTER__)
> +/** Offset of boot_hart member in sbi_scratch */
> +#define SBI_SCRATCH_BOOT_HART_OFFSET		(14 * __SIZEOF_POINTER__)
>  /** Offset of extra space in sbi_scratch */
> -#define SBI_SCRATCH_EXTRA_SPACE_OFFSET		(14 * __SIZEOF_POINTER__)
> +#define SBI_SCRATCH_EXTRA_SPACE_OFFSET		(15 * __SIZEOF_POINTER__)
>  /** Maximum size of sbi_scratch (4KB) */
>  #define SBI_SCRATCH_SIZE			(0x1000)
>  
> @@ -83,6 +85,8 @@ struct sbi_scratch {
>  	unsigned long tmp0;
>  	/** Options for OpenSBI library */
>  	unsigned long options;
> +	/** Preferred boot HART id */
> +	unsigned long boot_hart;
>  };
>  
>  /**
> @@ -144,6 +148,11 @@ _Static_assert(
>  		== SBI_SCRATCH_OPTIONS_OFFSET,
>  	"struct sbi_scratch definition has changed, please redefine "
>  	"SBI_SCRATCH_OPTIONS_OFFSET");
> +_Static_assert(
> +	offsetof(struct sbi_scratch, boot_hart)
> +		== SBI_SCRATCH_BOOT_HART_OFFSET,
> +	"struct sbi_scratch definition has changed, please redefine "
> +	"SBI_SCRATCH_BOOT_HART_OFFSET");
>  
>  /** Possible options for OpenSBI library */
>  enum sbi_scratch_options {
> diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
> index 804b01c..42eec2d 100644
> --- a/lib/sbi/sbi_init.c
> +++ b/lib/sbi/sbi_init.c
> @@ -573,14 +573,23 @@ void __noreturn sbi_init(struct sbi_scratch *scratch)
>  	 * HART because the coldboot HART will be directly jumping to
>  	 * the next booting stage.
>  	 *
> -	 * We use a lottery mechanism to select coldboot HART among
> -	 * HARTs which satisfy above condition.
> +	 * We select coldboot HART among HARTs which satisfy above condition.
> +	 * If the preferred boot hart is not specified, we use a lottery
> +	 * algorithm to select a cold boot hart, otherwise the preferred 
> +	 * boot core is selected.
>  	 */
>  
> -	if (sbi_platform_cold_boot_allowed(plat, hartid)) {
> -		if (next_mode_supported &&
> -		    atomic_xchg(&coldboot_lottery, 1) == 0)
> -			coldboot = true;
> +	if (scratch->boot_hart != -1UL && !sbi_platform_cold_boot_allowed(plat, hartid))
> +		sbi_hart_hang();
> +
> +	if (sbi_platform_cold_boot_allowed(plat, hartid) && next_mode_supported) {
> +		if (scratch->boot_hart == -1UL) {
> +			if (atomic_xchg(&coldboot_lottery, 1) == 0)
> +				coldboot = true;
> +		} else {
> +			if (scratch->boot_hart == hartid)
> +				coldboot = true;
> +		}
>  	}
>  
>  	/*
> -- 
> 2.34.1
> 
>