[PATCH 0/3] MIPS: Enhancements on usage and documentation of parameters

[PATCH 0/3] MIPS: Enhancements on usage and documentation of parameters

[Jiaxun Yang]

Hi all

This patchset is to enhance the usage and documentation of some parameters.

Please review.
Thanks
- Jiaxun

Jiaxun Yang (3):
  MIPS: Rework smt cmdline parameters
  MIPS: Select CONFIG_GENERIC_IDLE_POLL_SETUP
  Documentation: kernel-parameters: Add some MIPS parameters

 .../admin-guide/kernel-parameters.txt         | 37 +++++++++++++++++--
 arch/mips/Kconfig                             |  1 +
 arch/mips/include/asm/smp.h                   |  2 +
 arch/mips/kernel/smp-cps.c                    | 13 +------
 arch/mips/kernel/smp-mt.c                     |  3 +-
 arch/mips/kernel/smp.c                        | 18 +++++++++
 6 files changed, 57 insertions(+), 17 deletions(-)

-- 
2.39.2 (Apple Git-143)

[PATCH 1/3] MIPS: Rework smt cmdline parameters

[Jiaxun Yang]

Provide a generic smt parameters interface aligned with s390
to allow users to limit smt usage and threads per core.

It replaced previous undocumented "nothreads" parameter for
smp-cps which is ambiguous and does not cover smp-mt.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
 .../admin-guide/kernel-parameters.txt          |  4 ++--
 arch/mips/include/asm/smp.h                    |  2 ++
 arch/mips/kernel/smp-cps.c                     | 13 +------------
 arch/mips/kernel/smp-mt.c                      |  3 ++-
 arch/mips/kernel/smp.c                         | 18 ++++++++++++++++++
 5 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 91963d3f0d5c..515cd1f88ea2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3830,7 +3830,7 @@
 	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
 			and disable the IO APIC.  legacy for "maxcpus=0".
 
-	nosmt		[KNL,S390] Disable symmetric multithreading (SMT).
+	nosmt		[KNL,MIPS,S390] Disable symmetric multithreading (SMT).
 			Equivalent to smt=1.
 
 			[KNL,X86] Disable symmetric multithreading (SMT).
@@ -5743,7 +5743,7 @@
 				1: Fast pin select (default)
 				2: ATC IRMode
 
-	smt=		[KNL,S390] Set the maximum number of threads (logical
+	smt=		[KNL,MIPS,S390] Set the maximum number of threads (logical
 			CPUs) to use per physical CPU on systems capable of
 			symmetric multithreading (SMT). Will be capped to the
 			actual hardware limit.
diff --git a/arch/mips/include/asm/smp.h b/arch/mips/include/asm/smp.h
index aab8981bc32c..a40d8c0e4b87 100644
--- a/arch/mips/include/asm/smp.h
+++ b/arch/mips/include/asm/smp.h
@@ -57,6 +57,8 @@ extern int __cpu_logical_map[NR_CPUS];
 /* Mask of CPUs which are currently definitely operating coherently */
 extern cpumask_t cpu_coherent_mask;
 
+extern unsigned int smp_max_threads __initdata;
+
 extern asmlinkage void smp_bootstrap(void);
 
 extern void calculate_cpu_foreign_map(void);
diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
index d7fdbec232da..474318bc08cb 100644
--- a/arch/mips/kernel/smp-cps.c
+++ b/arch/mips/kernel/smp-cps.c
@@ -25,24 +25,13 @@
 #include <asm/time.h>
 #include <asm/uasm.h>
 
-static bool threads_disabled;
 static DECLARE_BITMAP(core_power, NR_CPUS);
 
 struct core_boot_config *mips_cps_core_bootcfg;
 
-static int __init setup_nothreads(char *s)
-{
-	threads_disabled = true;
-	return 0;
-}
-early_param("nothreads", setup_nothreads);
-
 static unsigned core_vpe_count(unsigned int cluster, unsigned core)
 {
-	if (threads_disabled)
-		return 1;
-
-	return mips_cps_numvps(cluster, core);
+	return min(smp_max_threads, mips_cps_numvps(cluster, core));
 }
 
 static void __init cps_smp_setup(void)
diff --git a/arch/mips/kernel/smp-mt.c b/arch/mips/kernel/smp-mt.c
index 5f04a0141068..7729cc733421 100644
--- a/arch/mips/kernel/smp-mt.c
+++ b/arch/mips/kernel/smp-mt.c
@@ -46,7 +46,8 @@ static void __init smvp_copy_vpe_config(void)
 static unsigned int __init smvp_vpe_init(unsigned int tc, unsigned int mvpconf0,
 	unsigned int ncpu)
 {
-	if (tc > ((mvpconf0 & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT))
+	if (tc >= smp_max_threads ||
+		(tc > ((mvpconf0 & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT)))
 		return ncpu;
 
 	/* Deactivate all but VPE 0 */
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 90c71d800b59..8fbef537fb88 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -73,6 +73,24 @@ static cpumask_t cpu_core_setup_map;
 
 cpumask_t cpu_coherent_mask;
 
+unsigned int smp_max_threads __initdata = UINT_MAX;
+
+static int __init early_nosmt(char *s)
+{
+	smp_max_threads = 1;
+	return 0;
+}
+early_param("nosmt", early_nosmt);
+
+static int __init early_smt(char *s)
+{
+	get_option(&s, &smp_max_threads);
+	/* Ensure at least one thread is available */
+	smp_max_threads = clamp_val(smp_max_threads, 1U, UINT_MAX);
+	return 0;
+}
+early_param("smt", early_smt);
+
 #ifdef CONFIG_GENERIC_IRQ_IPI
 static struct irq_desc *call_desc;
 static struct irq_desc *sched_desc;
-- 
2.39.2 (Apple Git-143)

Re: [PATCH 1/3] MIPS: Rework smt cmdline parameters

[Thomas Bogendoerfer]

On Sun, May 21, 2023 at 11:31:22PM +0100, Jiaxun Yang wrote:
> Provide a generic smt parameters interface aligned with s390
> to allow users to limit smt usage and threads per core.
> 
> It replaced previous undocumented "nothreads" parameter for
> smp-cps which is ambiguous and does not cover smp-mt.
> 
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
>  .../admin-guide/kernel-parameters.txt          |  4 ++--
>  arch/mips/include/asm/smp.h                    |  2 ++
>  arch/mips/kernel/smp-cps.c                     | 13 +------------
>  arch/mips/kernel/smp-mt.c                      |  3 ++-
>  arch/mips/kernel/smp.c                         | 18 ++++++++++++++++++
>  5 files changed, 25 insertions(+), 15 deletions(-)

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]

[PATCH 2/3] MIPS: Select CONFIG_GENERIC_IDLE_POLL_SETUP

[Jiaxun Yang]

hlt,nohlt paramaters are useful when debugging cpuidle
related issues.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 4 ++--
 arch/mips/Kconfig                               | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 515cd1f88ea2..9c502d3aa0cd 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3694,8 +3694,8 @@
 
 	nohibernate	[HIBERNATION] Disable hibernation and resume.
 
-	nohlt		[ARM,ARM64,MICROBLAZE,SH] Forces the kernel to busy wait
-			in do_idle() and not use the arch_cpu_idle()
+	nohlt		[ARM,ARM64,MICROBLAZE,MIPS,SH] Forces the kernel to
+			busy wait in do_idle() and not use the arch_cpu_idle()
 			implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP
 			to be effective. This is useful on platforms where the
 			sleep(SH) or wfi(ARM,ARM64) instructions do not work
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 5f52bdecb4c9..e437bf43ecfc 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -45,6 +45,7 @@ config MIPS
 	select GENERIC_LIB_UCMPDI2
 	select GENERIC_SCHED_CLOCK if !CAVIUM_OCTEON_SOC
 	select GENERIC_SMP_IDLE_THREAD
+	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_TIME_VSYSCALL
 	select GUP_GET_PXX_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
 	select HAS_IOPORT if !NO_IOPORT_MAP || ISA
-- 
2.39.2 (Apple Git-143)

Re: [PATCH 2/3] MIPS: Select CONFIG_GENERIC_IDLE_POLL_SETUP

[Thomas Bogendoerfer]

On Sun, May 21, 2023 at 11:31:23PM +0100, Jiaxun Yang wrote:
> hlt,nohlt paramaters are useful when debugging cpuidle
> related issues.
> 
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 4 ++--
>  arch/mips/Kconfig                               | 1 +
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 515cd1f88ea2..9c502d3aa0cd 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3694,8 +3694,8 @@
>  
>  	nohibernate	[HIBERNATION] Disable hibernation and resume.
>  
> -	nohlt		[ARM,ARM64,MICROBLAZE,SH] Forces the kernel to busy wait
> -			in do_idle() and not use the arch_cpu_idle()
> +	nohlt		[ARM,ARM64,MICROBLAZE,MIPS,SH] Forces the kernel to
> +			busy wait in do_idle() and not use the arch_cpu_idle()
>  			implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP
>  			to be effective. This is useful on platforms where the
>  			sleep(SH) or wfi(ARM,ARM64) instructions do not work
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 5f52bdecb4c9..e437bf43ecfc 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -45,6 +45,7 @@ config MIPS
>  	select GENERIC_LIB_UCMPDI2
>  	select GENERIC_SCHED_CLOCK if !CAVIUM_OCTEON_SOC
>  	select GENERIC_SMP_IDLE_THREAD
> +	select GENERIC_IDLE_POLL_SETUP
>  	select GENERIC_TIME_VSYSCALL
>  	select GUP_GET_PXX_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
>  	select HAS_IOPORT if !NO_IOPORT_MAP || ISA
> -- 
> 2.39.2 (Apple Git-143)

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]

[PATCH 3/3] Documentation: kernel-parameters: Add some MIPS parameters

[Jiaxun Yang]

Those parameters lives in MIPS kernel since very start.
Document them for convenience.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
 .../admin-guide/kernel-parameters.txt         | 29 +++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9c502d3aa0cd..67a0c3f7eca3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -713,6 +713,8 @@
 			Sets the size of memory pool for coherent, atomic dma
 			allocations, by default set to 256K.
 
+	coherentio	[KNL,MIPS] Force enable hardware DMA cache coherency.
+
 	com20020=	[HW,NET] ARCnet - COM20020 chipset
 			Format:
 			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
@@ -3626,6 +3628,8 @@
 
 	nocache		[ARM]
 
+	nocoherentio	[KNL,MIPS] Force enable software DMA cache coherency.
+
 	no_console_suspend
 			[HW] Never suspend the console
 			Disable suspending of consoles during suspend and
@@ -3645,6 +3649,7 @@
 			[KNL] Disable object debugging
 
 	nodsp		[SH] Disable hardware DSP at boot time.
+			[MIPS] Disable DSP ASE at boot time.
 
 	noefi		Disable EFI runtime services support.
 
@@ -3667,6 +3672,8 @@
 
 	nofsgsbase	[X86] Disables FSGSBASE instructions.
 
+	noftlb		[MIPS] Disable Fixed TLB at boot time.
+
 	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
 			register save and restore. The kernel will only save
 			legacy floating-point registers on task switch.
@@ -3678,6 +3685,8 @@
 			in certain environments such as networked servers or
 			real-time systems.
 
+	nohtw		[MIPS] Disable hardware page table walker at boot time.
+
 	no_hash_pointers
 			Force pointers printed to the console or buffers to be
 			unhashed.  By default, when a pointer is printed via %p
@@ -3758,6 +3767,8 @@
 
 	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
 
+	noulri          [MIPS] Disable RDHWR ULR access for user space.
+
 	nomca		[IA-64] Disable machine check abort handling
 
 	nomce		[X86-32] Disable Machine Check Exception
@@ -3882,6 +3893,8 @@
 			[X86,PV_OPS] Disable paravirtualized VMware scheduler
 			clock and use the default one.
 
+	nowait		[MIPS] Disable the wait instruction for idle.
+
 	nowatchdog	[KNL] Disable both lockup detectors, i.e.
 			soft-lockup and NMI watchdog (hard-lockup).
 
@@ -3893,6 +3906,8 @@
 			LEGACY_XAPIC_DISABLED bit set in the
 			IA32_XAPIC_DISABLE_STATUS MSR.
 
+	noxpa		[MIPS] Disable XPA (eXtended Physical Addressing) ASE.
+
 	noxsave		[BUGS=X86] Disables x86 extended register state save
 			and restore using xsave. The kernel will fallback to
 			enabling legacy floating-point and sse state.
@@ -3936,6 +3951,8 @@
 
 	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
 
+	ntlb=		[MIPS] Override max number of TLB entries.
+
 	numa=off 	[KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only
 			set up a single NUMA node spanning all memory.
 
@@ -5273,6 +5290,18 @@
 	rcupdate.rcu_self_test= [KNL]
 			Run the RCU early boot self tests
 
+	rd_size=	[KNL,MIPS]
+			Specify size of initrd in memory.
+			Need to be used with rd_start.
+
+	rd_start=	[KNL,MIPS]
+			Specify a virtual address from which to load the initrd.
+			Must in KSEG0 or XKPHYS space.
+			Need to be used with rd_size.
+
+	rdhwr_noopt	[MIPS] Disable optimization of trap and emulation for
+			"RDHWR v1, $29" instruction.
+
 	rdinit=		[KNL]
 			Format: <full_path>
 			Run specified binary instead of /init from the ramdisk,
-- 
2.39.2 (Apple Git-143)

Re: [PATCH 3/3] Documentation: kernel-parameters: Add some MIPS parameters

[Randy Dunlap]

Hi--

A few of these new entries are out of place, i.e., not in
sorted order. See below.


On 5/21/23 15:31, Jiaxun Yang wrote:
> Those parameters lives in MIPS kernel since very start.
> Document them for convenience.
> 
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
>  .../admin-guide/kernel-parameters.txt         | 29 +++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 9c502d3aa0cd..67a0c3f7eca3 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -713,6 +713,8 @@
>  			Sets the size of memory pool for coherent, atomic dma
>  			allocations, by default set to 256K.
>  
> +	coherentio	[KNL,MIPS] Force enable hardware DMA cache coherency.
> +

This one should be just above "coherent_pool".

>  	com20020=	[HW,NET] ARCnet - COM20020 chipset
>  			Format:
>  			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
> @@ -3626,6 +3628,8 @@
>  
>  	nocache		[ARM]
>  
> +	nocoherentio	[KNL,MIPS] Force enable software DMA cache coherency.
> +

OK.

>  	no_console_suspend
>  			[HW] Never suspend the console
>  			Disable suspending of consoles during suspend and
> @@ -3645,6 +3649,7 @@
>  			[KNL] Disable object debugging
>  
>  	nodsp		[SH] Disable hardware DSP at boot time.
> +			[MIPS] Disable DSP ASE at boot time.
>  
>  	noefi		Disable EFI runtime services support.
>  
> @@ -3667,6 +3672,8 @@
>  
>  	nofsgsbase	[X86] Disables FSGSBASE instructions.
>  
> +	noftlb		[MIPS] Disable Fixed TLB at boot time.

OK.

> +
>  	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
>  			register save and restore. The kernel will only save
>  			legacy floating-point registers on task switch.
> @@ -3678,6 +3685,8 @@
>  			in certain environments such as networked servers or
>  			real-time systems.
>  
> +	nohtw		[MIPS] Disable hardware page table walker at boot time.
> +

nohtw should be immediately after "nohlt".

>  	no_hash_pointers
>  			Force pointers printed to the console or buffers to be
>  			unhashed.  By default, when a pointer is printed via %p
> @@ -3758,6 +3767,8 @@
>  
>  	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
>  
> +	noulri          [MIPS] Disable RDHWR ULR access for user space.
> +
This should be just after "no_uaccess_flush".

>  	nomca		[IA-64] Disable machine check abort handling
>  
>  	nomce		[X86-32] Disable Machine Check Exception
> @@ -3882,6 +3893,8 @@
>  			[X86,PV_OPS] Disable paravirtualized VMware scheduler
>  			clock and use the default one.
>  
> +	nowait		[MIPS] Disable the wait instruction for idle.
> +

OK.

>  	nowatchdog	[KNL] Disable both lockup detectors, i.e.
>  			soft-lockup and NMI watchdog (hard-lockup).
>  
> @@ -3893,6 +3906,8 @@
>  			LEGACY_XAPIC_DISABLED bit set in the
>  			IA32_XAPIC_DISABLE_STATUS MSR.
>  
> +	noxpa		[MIPS] Disable XPA (eXtended Physical Addressing) ASE.
> +

OK.

>  	noxsave		[BUGS=X86] Disables x86 extended register state save
>  			and restore using xsave. The kernel will fallback to
>  			enabling legacy floating-point and sse state.
> @@ -3936,6 +3951,8 @@
>  
>  	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
>  
> +	ntlb=		[MIPS] Override max number of TLB entries.
> +

OK.

>  	numa=off 	[KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only
>  			set up a single NUMA node spanning all memory.
>  
> @@ -5273,6 +5290,18 @@
>  	rcupdate.rcu_self_test= [KNL]
>  			Run the RCU early boot self tests
>  
> +	rd_size=	[KNL,MIPS]
> +			Specify size of initrd in memory.
> +			Need to be used with rd_start.
> +
> +	rd_start=	[KNL,MIPS]
> +			Specify a virtual address from which to load the initrd.
> +			Must in KSEG0 or XKPHYS space.
> +			Need to be used with rd_size.
> +

rd_size and rd_start should be just after "rdrand".

> +	rdhwr_noopt	[MIPS] Disable optimization of trap and emulation for
> +			"RDHWR v1, $29" instruction.
> +

OK.

>  	rdinit=		[KNL]
>  			Format: <full_path>
>  			Run specified binary instead of /init from the ramdisk,

thanks.
-- 
~Randy