Re: [PATCH 2/3] arm/arm64: drop mmu_set_enabled

[Paolo Bonzini <pbonzini@redhat.com>]

On 25/06/2015 20:45, Andrew Jones wrote:
> The mmu is enabled automatically for all cpus, they must disable it
> themselves if they don't want it on. Switch from managing a cpumask
> of enabled cpus to one of disabled cpus. This allows us to remove
> the mmu_set_enabled call from secondary_cinit, and the function all
> together.
> 
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
>  lib/arm/asm/mmu-api.h |  1 -
>  lib/arm/mmu.c         | 21 ++++++++++-----------
>  lib/arm/smp.c         |  1 -
>  3 files changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/arm/asm/mmu-api.h b/lib/arm/asm/mmu-api.h
> index c46c4b08b14cc..12fdc57918c27 100644
> --- a/lib/arm/asm/mmu-api.h
> +++ b/lib/arm/asm/mmu-api.h
> @@ -2,7 +2,6 @@
>  #define __ASMARM_MMU_API_H_
>  extern pgd_t *mmu_idmap;
>  extern bool mmu_enabled(void);
> -extern void mmu_set_enabled(void);
>  extern void mmu_enable(pgd_t *pgtable);
>  extern void mmu_disable(void);
>  extern void mmu_enable_idmap(void);
> diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c
> index 5966b408cb455..ad558e177dd1c 100644
> --- a/lib/arm/mmu.c
> +++ b/lib/arm/mmu.c
> @@ -14,32 +14,31 @@ extern unsigned long etext;
>  
>  pgd_t *mmu_idmap;
>  
> -static cpumask_t mmu_enabled_cpumask;
> +static cpumask_t mmu_disabled_cpumask;
> +
>  bool mmu_enabled(void)
>  {
> -	struct thread_info *ti = current_thread_info();
> -	return cpumask_test_cpu(ti->cpu, &mmu_enabled_cpumask);
> -}
> +	int cpu = current_thread_info()->cpu;
>  
> -void mmu_set_enabled(void)
> -{
> -	struct thread_info *ti = current_thread_info();
> -	cpumask_set_cpu(ti->cpu, &mmu_enabled_cpumask);
> +	return !cpumask_test_cpu(cpu, &mmu_disabled_cpumask);
>  }
>  
>  extern void asm_mmu_enable(phys_addr_t pgtable);
>  void mmu_enable(pgd_t *pgtable)
>  {
> +	int cpu = current_thread_info()->cpu;
> +
>  	asm_mmu_enable(__pa(pgtable));
>  	flush_tlb_all();
> -	mmu_set_enabled();
> +	cpumask_clear_cpu(cpu, &mmu_disabled_cpumask);
>  }
>  
>  extern void asm_mmu_disable(void);
>  void mmu_disable(void)
>  {
> -	struct thread_info *ti = current_thread_info();
> -	cpumask_clear_cpu(ti->cpu, &mmu_enabled_cpumask);
> +	int cpu = current_thread_info()->cpu;
> +
> +	cpumask_set_cpu(cpu, &mmu_disabled_cpumask);
>  	asm_mmu_disable();
>  }
>  
> diff --git a/lib/arm/smp.c b/lib/arm/smp.c
> index f389ba6598faa..ca435dcd5f4a2 100644
> --- a/lib/arm/smp.c
> +++ b/lib/arm/smp.c
> @@ -23,7 +23,6 @@ secondary_entry_fn secondary_cinit(void)
>  	secondary_entry_fn entry;
>  
>  	thread_info_init(ti, 0);
> -	mmu_set_enabled();
>  
>  	/*
>  	 * Save secondary_data.entry locally to avoid opening a race
> 

This is needed too on a Cubietruck:

diff --git a/lib/arm/asm/mmu-api.h b/lib/arm/asm/mmu-api.h
index 12fdc57..73bac70 100644
--- a/lib/arm/asm/mmu-api.h
+++ b/lib/arm/asm/mmu-api.h
@@ -3,6 +3,7 @@
 extern pgd_t *mmu_idmap;
 extern bool mmu_enabled(void);
 extern void mmu_enable(pgd_t *pgtable);
+extern void mmu_mark_disabled(int cpu);
 extern void mmu_disable(void);
 extern void mmu_enable_idmap(void);
 extern void mmu_init_io_sect(pgd_t *pgtable, unsigned long virt_offset);
diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c
index ad558e1..8ff659b 100644
--- a/lib/arm/mmu.c
+++ b/lib/arm/mmu.c
@@ -14,7 +14,8 @@ extern unsigned long etext;

 pgd_t *mmu_idmap;

-static cpumask_t mmu_disabled_cpumask;
+/* CPU 0 starts with disabled MMU */
+static cpumask_t mmu_disabled_cpumask = { {1} };

 bool mmu_enabled(void)
 {
@@ -33,6 +34,11 @@ void mmu_enable(pgd_t *pgtable)
 	cpumask_clear_cpu(cpu, &mmu_disabled_cpumask);
 }

+void mmu_mark_disabled(int cpu)
+{
+	cpumask_set_cpu(cpu, &mmu_disabled_cpumask);
+}
+
 extern void asm_mmu_disable(void);
 void mmu_disable(void)
 {
diff --git a/lib/arm/psci.c b/lib/arm/psci.c
index aca8885..c4469c9 100644
--- a/lib/arm/psci.c
+++ b/lib/arm/psci.c
@@ -9,6 +9,7 @@
 #include <asm/psci.h>
 #include <asm/setup.h>
 #include <asm/page.h>
+#include <asm/mmu-api.h>

 #define T PSCI_INVOKE_ARG_TYPE
 __attribute__((noinline))
@@ -29,6 +30,7 @@ int psci_cpu_on(unsigned long cpuid, unsigned long
entry_point)
 extern void secondary_entry(void);
 int cpu_psci_cpu_boot(unsigned int cpu)
 {
+	mmu_mark_disabled(cpu);
 	int err = psci_cpu_on(cpus[cpu], __pa(secondary_entry));
 	if (err)
 		printf("failed to boot CPU%d (%d)\n", cpu, err);