[PATCH] i386: PARAVIRT: 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>
Signed-off-by: Andi Kleen <ak@suse.de>

2 files changed, 26 insertions, 2 deletions

diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index 4b3d50858670..f880b06d6d56 100644
--- 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;
@@ -165,6 +166,8 @@ 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);
 
@@ -853,6 +856,12 @@ static inline void __flush_tlb_single(unsigned long addr)
         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);
diff --git a/include/asm-i386/tlbflush.h b/include/asm-i386/tlbflush.h
index 4dd82840d53b..db7f77eacfa0 100644
--- a/include/asm-i386/tlbflush.h
+++ b/include/asm-i386/tlbflush.h
@@ -79,11 +79,15 @@
  *  - 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
 
 #define flush_tlb() __flush_tlb()
@@ -110,7 +114,12 @@ static inline void flush_tlb_range(struct vm_area_struct *vma,
                 __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(struct vm_area_struct * vma, unsigned long st
         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()