[patch 14/17] add flush_tlb_others paravirt_op

Jeremy Fitzhardinge
2007-04-02T06:02:11Z

[-- Attachment #1: paravirt-flush_tlb_others.patch --]
[-- Type: text/plain, Size: 5109 bytes --]

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()

--