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    Subject[patch 14/17] add flush_tlb_others paravirt_op
    This patch adds a pv_op for flush_tlb_others.  Linux running on native
    hardware uses cross-CPU IPIs to flush the TLB on any CPU which may
    have a particular mm's pagetable entries cached in its TLB. This is
    inefficient in a paravirtualized environment, since the hypervisor
    knows which real CPUs actually contain cached mappings, which may be a
    small subset of a guest's VCPUs.

    Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>

    ---
    arch/i386/kernel/paravirt.c | 1 +
    arch/i386/kernel/smp.c | 15 ++++++++-------
    include/asm-i386/paravirt.h | 9 +++++++++
    include/asm-i386/tlbflush.h | 19 +++++++++++++++++--
    4 files changed, 35 insertions(+), 9 deletions(-)

    ===================================================================
    --- a/arch/i386/kernel/paravirt.c
    +++ b/arch/i386/kernel/paravirt.c
    @@ -301,6 +301,7 @@ struct paravirt_ops paravirt_ops = {
    .flush_tlb_user = native_flush_tlb,
    .flush_tlb_kernel = native_flush_tlb_global,
    .flush_tlb_single = native_flush_tlb_single,
    + .flush_tlb_others = native_flush_tlb_others,

    .map_pt_hook = paravirt_nop,

    ===================================================================
    --- a/arch/i386/kernel/smp.c
    +++ b/arch/i386/kernel/smp.c
    @@ -256,7 +256,6 @@ static struct mm_struct * flush_mm;
    static struct mm_struct * flush_mm;
    static unsigned long flush_va;
    static DEFINE_SPINLOCK(tlbstate_lock);
    -#define FLUSH_ALL 0xffffffff

    /*
    * We cannot call mmdrop() because we are in interrupt context,
    @@ -338,7 +337,7 @@ fastcall void smp_invalidate_interrupt(s

    if (flush_mm == per_cpu(cpu_tlbstate, cpu).active_mm) {
    if (per_cpu(cpu_tlbstate, cpu).state == TLBSTATE_OK) {
    - if (flush_va == FLUSH_ALL)
    + if (flush_va == TLB_FLUSH_ALL)
    local_flush_tlb();
    else
    __flush_tlb_one(flush_va);
    @@ -353,9 +352,11 @@ out:
    put_cpu_no_resched();
    }

    -static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm,
    - unsigned long va)
    -{
    +void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
    + unsigned long va)
    +{
    + cpumask_t cpumask = *cpumaskp;
    +
    /*
    * A couple of (to be removed) sanity checks:
    *
    @@ -417,7 +418,7 @@ void flush_tlb_current_task(void)

    local_flush_tlb();
    if (!cpus_empty(cpu_mask))
    - flush_tlb_others(cpu_mask, mm, FLUSH_ALL);
    + flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);
    preempt_enable();
    }

    @@ -436,7 +437,7 @@ void flush_tlb_mm (struct mm_struct * mm
    leave_mm(smp_processor_id());
    }
    if (!cpus_empty(cpu_mask))
    - flush_tlb_others(cpu_mask, mm, FLUSH_ALL);
    + flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);

    preempt_enable();
    }
    ===================================================================
    --- a/include/asm-i386/paravirt.h
    +++ b/include/asm-i386/paravirt.h
    @@ -15,6 +15,7 @@

    #ifndef __ASSEMBLY__
    #include <linux/types.h>
    +#include <linux/cpumask.h>

    struct thread_struct;
    struct Xgt_desc_struct;
    @@ -125,6 +126,8 @@ struct paravirt_ops
    void (*flush_tlb_user)(void);
    void (*flush_tlb_kernel)(void);
    void (*flush_tlb_single)(unsigned long addr);
    + void (*flush_tlb_others)(const cpumask_t *cpus, struct mm_struct *mm,
    + unsigned long va);

    void (*map_pt_hook)(int type, pte_t *va, u32 pfn);

    @@ -731,6 +734,12 @@ static inline void __flush_tlb_single(un
    PVOP_VCALL1(flush_tlb_single, addr);
    }

    +static inline void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm,
    + unsigned long va)
    +{
    + PVOP_VCALL3(flush_tlb_others, &cpumask, mm, va);
    +}
    +
    static inline void paravirt_map_pt_hook(int type, pte_t *va, u32 pfn)
    {
    PVOP_VCALL3(map_pt_hook, type, va, pfn);
    ===================================================================
    --- a/include/asm-i386/tlbflush.h
    +++ b/include/asm-i386/tlbflush.h
    @@ -79,10 +79,14 @@
    * - flush_tlb_range(vma, start, end) flushes a range of pages
    * - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
    * - flush_tlb_pgtables(mm, start, end) flushes a range of page tables
    + * - flush_tlb_others(cpumask, mm, va) flushes a TLBs on other cpus
    *
    * ..but the i386 has somewhat limited tlb flushing capabilities,
    * and page-granular flushes are available only on i486 and up.
    */
    +
    +#define TLB_FLUSH_ALL 0xffffffff
    +

    #ifndef CONFIG_SMP

    @@ -110,7 +114,12 @@ static inline void flush_tlb_range(struc
    __flush_tlb();
    }

    -#else
    +static inline void native_flush_tlb_others(const cpumask_t *cpumask,
    + struct mm_struct *mm, unsigned long va)
    +{
    +}
    +
    +#else /* SMP */

    #include <asm/smp.h>

    @@ -129,6 +138,9 @@ static inline void flush_tlb_range(struc
    flush_tlb_mm(vma->vm_mm);
    }

    +void native_flush_tlb_others(const cpumask_t *cpumask, struct mm_struct *mm,
    + unsigned long va);
    +
    #define TLBSTATE_OK 1
    #define TLBSTATE_LAZY 2

    @@ -139,8 +151,11 @@ struct tlb_state
    char __cacheline_padding[L1_CACHE_BYTES-8];
    };
    DECLARE_PER_CPU(struct tlb_state, cpu_tlbstate);
    +#endif /* SMP */

    -
    +#ifndef CONFIG_PARAVIRT
    +#define flush_tlb_others(mask, mm, va) \
    + native_flush_tlb_others(&mask, mm, va)
    #endif

    #define flush_tlb_kernel_range(start, end) flush_tlb_all()
    --

    -
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