riscv: mm: Use mmu-type from FDT as SATP mode limit

[PATCH 1/2] riscv: mm: Return intended SATP mode for noXlvl options

Posted by Junhui Liu 2 months, 2 weeks ago

Change the return value of match_noXlvl() to return the SATP mode that
will be used, rather than the mode being disabled. This enables unified
logic for return value judgement with the function that obtains mmu-type
from the fdt, avoiding extra conversion. This only changes the naming,
with no functional impact.

Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
---
 arch/riscv/kernel/pi/cmdline_early.c | 4 ++--
 arch/riscv/mm/init.c                 | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/kernel/pi/cmdline_early.c b/arch/riscv/kernel/pi/cmdline_early.c
index fbcdc9e4e14322af0cedd31343aeb9403ba2dd14..389d086a071876dde2fd57ee6f6661e65c38b7c4 100644
--- a/arch/riscv/kernel/pi/cmdline_early.c
+++ b/arch/riscv/kernel/pi/cmdline_early.c
@@ -41,9 +41,9 @@ static char *get_early_cmdline(uintptr_t dtb_pa)
 static u64 match_noXlvl(char *cmdline)
 {
 	if (strstr(cmdline, "no4lvl"))
-		return SATP_MODE_48;
+		return SATP_MODE_39;
 	else if (strstr(cmdline, "no5lvl"))
-		return SATP_MODE_57;
+		return SATP_MODE_48;
 
 	return 0;
 }
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 8d0374d7ce8ed72320f58e4cea212d0e2bce8fd4..d03e02a92379f2338a4f4df0ab797a7859b83dfc 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -864,9 +864,9 @@ static __init void set_satp_mode(uintptr_t dtb_pa)
 
 	kernel_map.page_offset = PAGE_OFFSET_L5;
 
-	if (satp_mode_cmdline == SATP_MODE_57) {
+	if (satp_mode_cmdline == SATP_MODE_48) {
 		disable_pgtable_l5();
-	} else if (satp_mode_cmdline == SATP_MODE_48) {
+	} else if (satp_mode_cmdline == SATP_MODE_39) {
 		disable_pgtable_l5();
 		disable_pgtable_l4();
 		return;

-- 
2.50.1

Re: [PATCH 1/2] riscv: mm: Return intended SATP mode for noXlvl options

Posted by Alexandre Ghiti 2 months, 1 week ago

Hi Junhui,

On 7/21/25 18:53, Junhui Liu wrote:
> Change the return value of match_noXlvl() to return the SATP mode that
> will be used, rather than the mode being disabled. This enables unified
> logic for return value judgement with the function that obtains mmu-type
> from the fdt, avoiding extra conversion. This only changes the naming,
> with no functional impact.
>
> Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
> ---
>   arch/riscv/kernel/pi/cmdline_early.c | 4 ++--
>   arch/riscv/mm/init.c                 | 4 ++--
>   2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/kernel/pi/cmdline_early.c b/arch/riscv/kernel/pi/cmdline_early.c
> index fbcdc9e4e14322af0cedd31343aeb9403ba2dd14..389d086a071876dde2fd57ee6f6661e65c38b7c4 100644
> --- a/arch/riscv/kernel/pi/cmdline_early.c
> +++ b/arch/riscv/kernel/pi/cmdline_early.c
> @@ -41,9 +41,9 @@ static char *get_early_cmdline(uintptr_t dtb_pa)
>   static u64 match_noXlvl(char *cmdline)
>   {
>   	if (strstr(cmdline, "no4lvl"))
> -		return SATP_MODE_48;
> +		return SATP_MODE_39;
>   	else if (strstr(cmdline, "no5lvl"))
> -		return SATP_MODE_57;
> +		return SATP_MODE_48;
>   
>   	return 0;
>   }
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 8d0374d7ce8ed72320f58e4cea212d0e2bce8fd4..d03e02a92379f2338a4f4df0ab797a7859b83dfc 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -864,9 +864,9 @@ static __init void set_satp_mode(uintptr_t dtb_pa)
>   
>   	kernel_map.page_offset = PAGE_OFFSET_L5;
>   
> -	if (satp_mode_cmdline == SATP_MODE_57) {
> +	if (satp_mode_cmdline == SATP_MODE_48) {
>   		disable_pgtable_l5();
> -	} else if (satp_mode_cmdline == SATP_MODE_48) {
> +	} else if (satp_mode_cmdline == SATP_MODE_39) {
>   		disable_pgtable_l5();
>   		disable_pgtable_l4();
>   		return;
>

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex

Re: [PATCH 1/2] riscv: mm: Return intended SATP mode for noXlvl options

Posted by Nutty Liu 2 months, 2 weeks ago

On 7/22/2025 12:53 AM, Junhui Liu wrote:
> Change the return value of match_noXlvl() to return the SATP mode that
> will be used, rather than the mode being disabled. This enables unified
> logic for return value judgement with the function that obtains mmu-type
> from the fdt, avoiding extra conversion. This only changes the naming,
> with no functional impact.
>
> Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
> ---
>   arch/riscv/kernel/pi/cmdline_early.c | 4 ++--
>   arch/riscv/mm/init.c                 | 4 ++--
>   2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/kernel/pi/cmdline_early.c b/arch/riscv/kernel/pi/cmdline_early.c
> index fbcdc9e4e14322af0cedd31343aeb9403ba2dd14..389d086a071876dde2fd57ee6f6661e65c38b7c4 100644
> --- a/arch/riscv/kernel/pi/cmdline_early.c
> +++ b/arch/riscv/kernel/pi/cmdline_early.c
> @@ -41,9 +41,9 @@ static char *get_early_cmdline(uintptr_t dtb_pa)
>   static u64 match_noXlvl(char *cmdline)
>   {
>   	if (strstr(cmdline, "no4lvl"))
> -		return SATP_MODE_48;
> +		return SATP_MODE_39;
>   	else if (strstr(cmdline, "no5lvl"))
> -		return SATP_MODE_57;
> +		return SATP_MODE_48;
>   
>   	return 0;
>   }
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 8d0374d7ce8ed72320f58e4cea212d0e2bce8fd4..d03e02a92379f2338a4f4df0ab797a7859b83dfc 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -864,9 +864,9 @@ static __init void set_satp_mode(uintptr_t dtb_pa)
>   
>   	kernel_map.page_offset = PAGE_OFFSET_L5;
>   
> -	if (satp_mode_cmdline == SATP_MODE_57) {
> +	if (satp_mode_cmdline == SATP_MODE_48) {
>   		disable_pgtable_l5();
> -	} else if (satp_mode_cmdline == SATP_MODE_48) {
> +	} else if (satp_mode_cmdline == SATP_MODE_39) {
>   		disable_pgtable_l5();
>   		disable_pgtable_l4();
>   		return;

Nice, this change is a good idea. It's more readable.

Reviewed-by: Nutty Liu <liujingqi@lanxincomputing.com>

Thanks,
Nutty