| Message ID | 1435257911-9715-4-git-send-email-drjones@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 25/06/2015 20:45, Andrew Jones wrote: > spinlock torture tests made it clear that checking mmu_enabled() > every time we call spin_lock is a bad idea. As most tests will > want the MMU enabled the entire time, then we can inline a light > weight "nobody disabled the mmu" check, and bail out early. > > Adding a light weight inlined check vs. a compile-time flag > suggested by Paolo. > > Signed-off-by: Andrew Jones <drjones@redhat.com> > --- > lib/arm/asm/mmu-api.h | 7 ++++++- > lib/arm/mmu.c | 9 +++++++-- > 2 files changed, 13 insertions(+), 3 deletions(-) > > diff --git a/lib/arm/asm/mmu-api.h b/lib/arm/asm/mmu-api.h > index 12fdc57918c27..b2fc900a30add 100644 > --- a/lib/arm/asm/mmu-api.h > +++ b/lib/arm/asm/mmu-api.h > @@ -1,7 +1,12 @@ > #ifndef __ASMARM_MMU_API_H_ > #define __ASMARM_MMU_API_H_ > extern pgd_t *mmu_idmap; > -extern bool mmu_enabled(void); > +extern unsigned int mmu_disabled_cpu_count; > +extern bool __mmu_enabled(void); > +static inline bool mmu_enabled(void) > +{ > + return mmu_disabled_cpu_count == 0 || __mmu_enabled(); > +} > 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 ad558e177dd1c..e661d4f26e4b7 100644 > --- a/lib/arm/mmu.c > +++ b/lib/arm/mmu.c > @@ -15,8 +15,9 @@ extern unsigned long etext; > pgd_t *mmu_idmap; > > static cpumask_t mmu_disabled_cpumask; > +unsigned int mmu_disabled_cpu_count; > > -bool mmu_enabled(void) > +bool __mmu_enabled(void) > { > int cpu = current_thread_info()->cpu; > > @@ -30,7 +31,9 @@ void mmu_enable(pgd_t *pgtable) > > asm_mmu_enable(__pa(pgtable)); > flush_tlb_all(); > - cpumask_clear_cpu(cpu, &mmu_disabled_cpumask); > + > + if (cpumask_test_and_clear_cpu(cpu, &mmu_disabled_cpumask)) > + --mmu_disabled_cpu_count; > } > > extern void asm_mmu_disable(void); > @@ -39,6 +42,8 @@ void mmu_disable(void) > int cpu = current_thread_info()->cpu; > > cpumask_set_cpu(cpu, &mmu_disabled_cpumask); > + ++mmu_disabled_cpu_count; > + > asm_mmu_disable(); > } > > Applied, thanks. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/lib/arm/asm/mmu-api.h b/lib/arm/asm/mmu-api.h index 12fdc57918c27..b2fc900a30add 100644 --- a/lib/arm/asm/mmu-api.h +++ b/lib/arm/asm/mmu-api.h @@ -1,7 +1,12 @@ #ifndef __ASMARM_MMU_API_H_ #define __ASMARM_MMU_API_H_ extern pgd_t *mmu_idmap; -extern bool mmu_enabled(void); +extern unsigned int mmu_disabled_cpu_count; +extern bool __mmu_enabled(void); +static inline bool mmu_enabled(void) +{ + return mmu_disabled_cpu_count == 0 || __mmu_enabled(); +} 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 ad558e177dd1c..e661d4f26e4b7 100644 --- a/lib/arm/mmu.c +++ b/lib/arm/mmu.c @@ -15,8 +15,9 @@ extern unsigned long etext; pgd_t *mmu_idmap; static cpumask_t mmu_disabled_cpumask; +unsigned int mmu_disabled_cpu_count; -bool mmu_enabled(void) +bool __mmu_enabled(void) { int cpu = current_thread_info()->cpu; @@ -30,7 +31,9 @@ void mmu_enable(pgd_t *pgtable) asm_mmu_enable(__pa(pgtable)); flush_tlb_all(); - cpumask_clear_cpu(cpu, &mmu_disabled_cpumask); + + if (cpumask_test_and_clear_cpu(cpu, &mmu_disabled_cpumask)) + --mmu_disabled_cpu_count; } extern void asm_mmu_disable(void); @@ -39,6 +42,8 @@ void mmu_disable(void) int cpu = current_thread_info()->cpu; cpumask_set_cpu(cpu, &mmu_disabled_cpumask); + ++mmu_disabled_cpu_count; + asm_mmu_disable(); }
spinlock torture tests made it clear that checking mmu_enabled() every time we call spin_lock is a bad idea. As most tests will want the MMU enabled the entire time, then we can inline a light weight "nobody disabled the mmu" check, and bail out early. Adding a light weight inlined check vs. a compile-time flag suggested by Paolo. Signed-off-by: Andrew Jones <drjones@redhat.com> --- lib/arm/asm/mmu-api.h | 7 ++++++- lib/arm/mmu.c | 9 +++++++-- 2 files changed, 13 insertions(+), 3 deletions(-)