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x86/paravirt: flush pending mmu updates on context switch

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Impact: allow preemption during lazy mmu updates

If we're in lazy mmu mode when context switching, leave
lazy mmu mode, but remember the task's state in
TIF_LAZY_MMU_UPDATES.  When we resume the task, check this
flag and re-enter lazy mmu mode if its set.

This sets things up for allowing lazy mmu mode while preemptible,
though that won't actually be active until the next change.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
This commit is contained in:
Jeremy Fitzhardinge 2009-02-17 23:46:21 -08:00
parent 7fd7d83d49
commit b407fc57b8
9 changed files with 42 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/paravirt.h
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@ -1418,7 +1418,6 @@ void paravirt_enter_lazy_cpu(void);
void paravirt_leave_lazy_cpu(void);
void paravirt_enter_lazy_mmu(void);
void paravirt_leave_lazy_mmu(void);
void paravirt_leave_lazy(enum paravirt_lazy_mode mode);
#define __HAVE_ARCH_START_CONTEXT_SWITCH
static inline void arch_start_context_switch(void)

2
arch/x86/include/asm/thread_info.h
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@ -94,6 +94,7 @@ struct thread_info {
#define TIF_FORCED_TF 24 /* true if TF in eflags artificially */
#define TIF_DEBUGCTLMSR 25 /* uses thread_struct.debugctlmsr */
#define TIF_DS_AREA_MSR 26 /* uses thread_struct.ds_area_msr */
#define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
@ -115,6 +116,7 @@ struct thread_info {
#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
#define _TIF_DEBUGCTLMSR (1 << TIF_DEBUGCTLMSR)
#define _TIF_DS_AREA_MSR (1 << TIF_DS_AREA_MSR)
#define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES)
/* work to do in syscall_trace_enter() */
#define _TIF_WORK_SYSCALL_ENTRY \

2
arch/x86/kernel/kvm.c
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@ -201,7 +201,7 @@ static void kvm_leave_lazy_mmu(void)
struct kvm_para_state *state = kvm_para_state();
mmu_queue_flush(state);
paravirt_leave_lazy(paravirt_get_lazy_mode());
paravirt_leave_lazy_mmu();
state->mode = paravirt_get_lazy_mode();
}

13
arch/x86/kernel/paravirt.c
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@ -252,7 +252,7 @@ static inline void enter_lazy(enum paravirt_lazy_mode mode)
__get_cpu_var(paravirt_lazy_mode) = mode;
}
void paravirt_leave_lazy(enum paravirt_lazy_mode mode)
static void leave_lazy(enum paravirt_lazy_mode mode)
{
BUG_ON(__get_cpu_var(paravirt_lazy_mode) != mode);
BUG_ON(preemptible());
@ -267,17 +267,24 @@ void paravirt_enter_lazy_mmu(void)
void paravirt_leave_lazy_mmu(void)
{
paravirt_leave_lazy(PARAVIRT_LAZY_MMU);
leave_lazy(PARAVIRT_LAZY_MMU);
}
void paravirt_enter_lazy_cpu(void)
{
if (percpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
arch_leave_lazy_mmu_mode();
set_thread_flag(TIF_LAZY_MMU_UPDATES);
}
enter_lazy(PARAVIRT_LAZY_CPU);
}
void paravirt_leave_lazy_cpu(void)
{
paravirt_leave_lazy(PARAVIRT_LAZY_CPU);
leave_lazy(PARAVIRT_LAZY_CPU);
if (test_and_clear_thread_flag(TIF_LAZY_MMU_UPDATES))
arch_enter_lazy_mmu_mode();
}
enum paravirt_lazy_mode paravirt_get_lazy_mode(void)

14
arch/x86/kernel/vmi_32.c
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@ -473,16 +473,22 @@ static void vmi_enter_lazy_cpu(void)
vmi_ops.set_lazy_mode(2);
}
static void vmi_leave_lazy_cpu(void)
{
vmi_ops.set_lazy_mode(0);
paravirt_leave_lazy_cpu();
}
static void vmi_enter_lazy_mmu(void)
{
paravirt_enter_lazy_mmu();
vmi_ops.set_lazy_mode(1);
}
static void vmi_leave_lazy(void)
static void vmi_leave_lazy_mmu(void)
{
paravirt_leave_lazy(paravirt_get_lazy_mode());
vmi_ops.set_lazy_mode(0);
paravirt_leave_lazy_mmu();
}
static inline int __init check_vmi_rom(struct vrom_header *rom)
@ -718,12 +724,12 @@ static inline int __init activate_vmi(void)
para_wrap(pv_cpu_ops.lazy_mode.enter, vmi_enter_lazy_cpu,
set_lazy_mode, SetLazyMode);
para_wrap(pv_cpu_ops.lazy_mode.leave, vmi_leave_lazy,
para_wrap(pv_cpu_ops.lazy_mode.leave, vmi_leave_lazy_cpu,
set_lazy_mode, SetLazyMode);
para_wrap(pv_mmu_ops.lazy_mode.enter, vmi_enter_lazy_mmu,
set_lazy_mode, SetLazyMode);
para_wrap(pv_mmu_ops.lazy_mode.leave, vmi_leave_lazy,
para_wrap(pv_mmu_ops.lazy_mode.leave, vmi_leave_lazy_mmu,
set_lazy_mode, SetLazyMode);
/* user and kernel flush are just handled with different flags to FlushTLB */

14
arch/x86/lguest/boot.c
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@ -147,10 +147,16 @@ static void lazy_hcall(unsigned long call,
/* When lazy mode is turned off reset the per-cpu lazy mode variable and then
* issue the do-nothing hypercall to flush any stored calls. */
static void lguest_leave_lazy_mode(void)
static void lguest_leave_lazy_mmu_mode(void)
{
paravirt_leave_lazy(paravirt_get_lazy_mode());
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
paravirt_leave_lazy_mmu();
}
static void lguest_leave_lazy_cpu_mode(void)
{
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
paravirt_leave_lazy_cpu();
}
/*G:033
@ -1026,7 +1032,7 @@ __init void lguest_init(void)
pv_cpu_ops.write_idt_entry = lguest_write_idt_entry;
pv_cpu_ops.wbinvd = lguest_wbinvd;
pv_cpu_ops.lazy_mode.enter = paravirt_enter_lazy_cpu;
pv_cpu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
pv_cpu_ops.lazy_mode.leave = lguest_leave_lazy_cpu_mode;
/* pagetable management */
pv_mmu_ops.write_cr3 = lguest_write_cr3;
@ -1039,7 +1045,7 @@ __init void lguest_init(void)
pv_mmu_ops.read_cr2 = lguest_read_cr2;
pv_mmu_ops.read_cr3 = lguest_read_cr3;
pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu;
pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mmu_mode;
#ifdef CONFIG_X86_LOCAL_APIC
/* apic read/write intercepts */

6
arch/x86/xen/enlighten.c
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@ -203,10 +203,10 @@ static unsigned long xen_get_debugreg(int reg)
return HYPERVISOR_get_debugreg(reg);
}
void xen_leave_lazy(void)
static void xen_leave_lazy_cpu(void)
{
paravirt_leave_lazy(paravirt_get_lazy_mode());
xen_mc_flush();
paravirt_leave_lazy_cpu();
}
static unsigned long xen_store_tr(void)
@ -819,7 +819,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
.lazy_mode = {
.enter = paravirt_enter_lazy_cpu,
.leave = xen_leave_lazy,
.leave = xen_leave_lazy_cpu,
},
};

7
arch/x86/xen/mmu.c
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@ -1816,6 +1816,11 @@ __init void xen_post_allocator_init(void)
xen_mark_init_mm_pinned();
}
static void xen_leave_lazy_mmu(void)
{
xen_mc_flush();
paravirt_leave_lazy_mmu();
}
const struct pv_mmu_ops xen_mmu_ops __initdata = {
.pagetable_setup_start = xen_pagetable_setup_start,
@ -1891,7 +1896,7 @@ const struct pv_mmu_ops xen_mmu_ops __initdata = {
.lazy_mode = {
.enter = paravirt_enter_lazy_mmu,
.leave = xen_leave_lazy,
.leave = xen_leave_lazy_mmu,
},
.set_fixmap = xen_set_fixmap,

1
arch/x86/xen/xen-ops.h
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@ -30,7 +30,6 @@ pgd_t *xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn);
void xen_ident_map_ISA(void);
void xen_reserve_top(void);
void xen_leave_lazy(void);
void xen_post_allocator_init(void);
char * __init xen_memory_setup(void);