[Xen-devel] [patch 08/26] Xen-paravirt_ops: add hooks to intercept mm creation and destruction

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Add hooks to allow a paravirt implementation to track the lifetime of
an mm.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
---
 arch/i386/kernel/paravirt.c    |    4 ++++
 include/asm-i386/mmu_context.h |    8 ++++++--
 include/asm-i386/paravirt.h    |   24 ++++++++++++++++++++++++
 include/linux/sched.h          |    6 ++++++
 kernel/fork.c                  |    2 ++
 mm/mmap.c                      |    3 +++
 6 files changed, 45 insertions(+), 2 deletions(-)

===================================================================
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -591,6 +591,10 @@ struct paravirt_ops paravirt_ops = {
        .irq_enable_sysexit = native_irq_enable_sysexit,
        .iret = native_iret,
 
+       .dup_mmap = paravirt_nop,
+       .exit_mmap = paravirt_nop,
+       .activate_mm = paravirt_nop,
+
        .startup_ipi_hook = paravirt_nop,
 };
 
===================================================================
--- a/include/asm-i386/mmu_context.h
+++ b/include/asm-i386/mmu_context.h
@@ -5,6 +5,7 @@
 #include <asm/atomic.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
+#include <asm/paravirt.h>
 
 /*
  * Used for LDT copy/destruction.
@@ -65,7 +66,10 @@ static inline void switch_mm(struct mm_s
 #define deactivate_mm(tsk, mm)                 \
        asm("movl %0,%%gs": :"r" (0));
 
-#define activate_mm(prev, next) \
-       switch_mm((prev),(next),NULL)
+#define activate_mm(prev, next)                                \
+       do {                                            \
+               arch_activate_mm(prev, next);           \
+               switch_mm((prev),(next),NULL);          \
+       } while(0);
 
 #endif
===================================================================
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -118,6 +118,12 @@ struct paravirt_ops
        void (*io_delay)(void);
        void (*const_udelay)(unsigned long loops);
 
+       void (*activate_mm)(struct mm_struct *prev,
+                           struct mm_struct *next);
+       void (*dup_mmap)(struct mm_struct *oldmm,
+                        struct mm_struct *mm);
+       void (*exit_mmap)(struct mm_struct *mm);
+
 #ifdef CONFIG_X86_LOCAL_APIC
        void (*apic_write)(unsigned long reg, unsigned long v);
        void (*apic_write_atomic)(unsigned long reg, unsigned long v);
@@ -398,6 +404,24 @@ static inline void startup_ipi_hook(int 
 }
 #endif
 
+#define __HAVE_ARCH_MM_LIFETIME
+static inline void arch_activate_mm(struct mm_struct *prev,
+                                   struct mm_struct *next)
+{
+       paravirt_ops.activate_mm(prev, next);
+}
+
+static inline void arch_dup_mmap(struct mm_struct *oldmm,
+                                struct mm_struct *mm)
+{
+       paravirt_ops.dup_mmap(oldmm, mm);
+}
+
+static inline void arch_exit_mmap(struct mm_struct *mm)
+{
+       paravirt_ops.exit_mmap(mm);
+}
+
 #define __flush_tlb() paravirt_ops.flush_tlb_user()
 #define __flush_tlb_global() paravirt_ops.flush_tlb_kernel()
 #define __flush_tlb_single(addr) paravirt_ops.flush_tlb_single(addr)
===================================================================
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -374,6 +374,12 @@ struct mm_struct {
        rwlock_t                ioctx_list_lock;
        struct kioctx           *ioctx_list;
 };
+
+#ifndef __HAVE_ARCH_MM_LIFETIME
+#define arch_activate_mm(prev, next)   do {} while(0)
+#define arch_dup_mmap(oldmm, mm)       do {} while(0)
+#define arch_exit_mmap(mm)             do {} while(0)
+#endif
 
 struct sighand_struct {
        atomic_t                count;
===================================================================
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -286,6 +286,8 @@ static inline int dup_mmap(struct mm_str
                if (retval)
                        goto out;
        }
+       /* a new mm has just been created */
+       arch_dup_mmap(oldmm, mm);
        retval = 0;
 out:
        up_write(&mm->mmap_sem);
===================================================================
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1976,6 +1976,9 @@ void exit_mmap(struct mm_struct *mm)
        struct vm_area_struct *vma = mm->mmap;
        unsigned long nr_accounted = 0;
        unsigned long end;
+
+       /* mm's last user has gone, and its about to be pulled down */
+       arch_exit_mmap(mm);
 
        lru_add_drain();
        flush_cache_mm(mm);

-- 


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