diff options
| -rw-r--r-- | arch/i386/kernel/paravirt.c | 1 | ||||
| -rw-r--r-- | arch/i386/kernel/process.c | 25 | ||||
| -rw-r--r-- | include/asm-generic/pgtable.h | 13 | ||||
| -rw-r--r-- | include/asm-i386/paravirt.h | 15 | ||||
| -rw-r--r-- | kernel/sched.c | 7 |
5 files changed, 53 insertions, 8 deletions
diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c index 7329ec9..4dfdac4 100644 --- a/arch/i386/kernel/paravirt.c +++ b/arch/i386/kernel/paravirt.c @@ -545,6 +545,7 @@ struct paravirt_ops paravirt_ops = { .apic_write_atomic = native_apic_write_atomic, .apic_read = native_apic_read, #endif + .set_lazy_mode = (void *)native_nop, .flush_tlb_user = native_flush_tlb, .flush_tlb_kernel = native_flush_tlb_global, diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index 23ae198..cfae587 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -670,14 +670,6 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas load_TLS(next, cpu); /* - * Restore %gs if needed (which is common) - */ - if (prev->gs | next->gs) - loadsegment(gs, next->gs); - - write_pda(pcurrent, next_p); - - /* * Now maybe handle debug registers and/or IO bitmaps */ if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW) @@ -686,6 +678,15 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas disable_tsc(prev_p, next_p); + /* + * Leave lazy mode, flushing any hypercalls made here. + * This must be done before restoring TLS segments so + * the GDT and LDT are properly updated, and must be + * done before math_state_restore, so the TS bit is up + * to date. + */ + arch_leave_lazy_cpu_mode(); + /* If the task has used fpu the last 5 timeslices, just do a full * restore of the math state immediately to avoid the trap; the * chances of needing FPU soon are obviously high now @@ -693,6 +694,14 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas if (next_p->fpu_counter > 5) math_state_restore(); + /* + * Restore %gs if needed (which is common) + */ + if (prev->gs | next->gs) + loadsegment(gs, next->gs); + + write_pda(pcurrent, next_p); + return prev_p; } diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 9d774d0..00c2343 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -183,6 +183,19 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres #endif /* + * A facility to provide batching of the reload of page tables with the + * actual context switch code for paravirtualized guests. By convention, + * only one of the lazy modes (CPU, MMU) should be active at any given + * time, entry should never be nested, and entry and exits should always + * be paired. This is for sanity of maintaining and reasoning about the + * kernel code. + */ +#ifndef __HAVE_ARCH_ENTER_LAZY_CPU_MODE +#define arch_enter_lazy_cpu_mode() do {} while (0) +#define arch_leave_lazy_cpu_mode() do {} while (0) +#endif + +/* * When walking page tables, get the address of the next boundary, * or the end address of the range if that comes earlier. Although no * vma end wraps to 0, rounded up __boundary may wrap to 0 throughout. diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h index 53da276..38e5164 100644 --- a/include/asm-i386/paravirt.h +++ b/include/asm-i386/paravirt.h @@ -146,6 +146,8 @@ struct paravirt_ops void (fastcall *pmd_clear)(pmd_t *pmdp); #endif + void (fastcall *set_lazy_mode)(int mode); + /* These two are jmp to, not actually called. */ void (fastcall *irq_enable_sysexit)(void); void (fastcall *iret)(void); @@ -386,6 +388,19 @@ static inline void pmd_clear(pmd_t *pmdp) } #endif +/* Lazy mode for batching updates / context switch */ +#define PARAVIRT_LAZY_NONE 0 +#define PARAVIRT_LAZY_MMU 1 +#define PARAVIRT_LAZY_CPU 2 + +#define __HAVE_ARCH_ENTER_LAZY_CPU_MODE +#define arch_enter_lazy_cpu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_CPU) +#define arch_leave_lazy_cpu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_NONE) + +#define __HAVE_ARCH_ENTER_LAZY_MMU_MODE +#define arch_enter_lazy_mmu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_MMU) +#define arch_leave_lazy_mmu_mode() paravirt_ops.set_lazy_mode(PARAVIRT_LAZY_NONE) + /* These all sit in the .parainstructions section to tell us what to patch. */ struct paravirt_patch { u8 *instr; /* original instructions */ diff --git a/kernel/sched.c b/kernel/sched.c index 08f86178..0dc7572 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1853,6 +1853,13 @@ context_switch(struct rq *rq, struct task_struct *prev, struct mm_struct *mm = next->mm; struct mm_struct *oldmm = prev->active_mm; + /* + * For paravirt, this is coupled with an exit in switch_to to + * combine the page table reload and the switch backend into + * one hypercall. + */ + arch_enter_lazy_cpu_mode(); + if (!mm) { next->active_mm = oldmm; atomic_inc(&oldmm->mm_count); |
