| From 511ba86e1d386f671084b5d0e6f110bb30b8eeb2 Mon Sep 17 00:00:00 2001 |
| From: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| Date: Sat, 23 Mar 2013 09:36:36 -0400 |
| Subject: x86, mm: Patch out arch_flush_lazy_mmu_mode() when running on bare metal |
| |
| From: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| |
| commit 511ba86e1d386f671084b5d0e6f110bb30b8eeb2 upstream. |
| |
| Invoking arch_flush_lazy_mmu_mode() results in calls to |
| preempt_enable()/disable() which may have performance impact. |
| |
| Since lazy MMU is not used on bare metal we can patch away |
| arch_flush_lazy_mmu_mode() so that it is never called in such |
| environment. |
| |
| [ hpa: the previous patch "Fix vmalloc_fault oops during lazy MMU |
| updates" may cause a minor performance regression on |
| bare metal. This patch resolves that performance regression. It is |
| somewhat unclear to me if this is a good -stable candidate. ] |
| |
| Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| Link: http://lkml.kernel.org/r/1364045796-10720-2-git-send-email-konrad.wilk@oracle.com |
| Tested-by: Josh Boyer <jwboyer@redhat.com> |
| Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> |
| Acked-by: Borislav Petkov <bp@suse.de> |
| Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> |
| Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/x86/include/asm/paravirt.h | 5 ++++- |
| arch/x86/include/asm/paravirt_types.h | 2 ++ |
| arch/x86/kernel/paravirt.c | 25 +++++++++++++------------ |
| arch/x86/lguest/boot.c | 1 + |
| arch/x86/xen/mmu.c | 1 + |
| 5 files changed, 21 insertions(+), 13 deletions(-) |
| |
| --- a/arch/x86/include/asm/paravirt.h |
| +++ b/arch/x86/include/asm/paravirt.h |
| @@ -703,7 +703,10 @@ static inline void arch_leave_lazy_mmu_m |
| PVOP_VCALL0(pv_mmu_ops.lazy_mode.leave); |
| } |
| |
| -void arch_flush_lazy_mmu_mode(void); |
| +static inline void arch_flush_lazy_mmu_mode(void) |
| +{ |
| + PVOP_VCALL0(pv_mmu_ops.lazy_mode.flush); |
| +} |
| |
| static inline void __set_fixmap(unsigned /* enum fixed_addresses */ idx, |
| phys_addr_t phys, pgprot_t flags) |
| --- a/arch/x86/include/asm/paravirt_types.h |
| +++ b/arch/x86/include/asm/paravirt_types.h |
| @@ -91,6 +91,7 @@ struct pv_lazy_ops { |
| /* Set deferred update mode, used for batching operations. */ |
| void (*enter)(void); |
| void (*leave)(void); |
| + void (*flush)(void); |
| }; |
| |
| struct pv_time_ops { |
| @@ -679,6 +680,7 @@ void paravirt_end_context_switch(struct |
| |
| void paravirt_enter_lazy_mmu(void); |
| void paravirt_leave_lazy_mmu(void); |
| +void paravirt_flush_lazy_mmu(void); |
| |
| void _paravirt_nop(void); |
| u32 _paravirt_ident_32(u32); |
| --- a/arch/x86/kernel/paravirt.c |
| +++ b/arch/x86/kernel/paravirt.c |
| @@ -263,6 +263,18 @@ void paravirt_leave_lazy_mmu(void) |
| leave_lazy(PARAVIRT_LAZY_MMU); |
| } |
| |
| +void paravirt_flush_lazy_mmu(void) |
| +{ |
| + preempt_disable(); |
| + |
| + if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { |
| + arch_leave_lazy_mmu_mode(); |
| + arch_enter_lazy_mmu_mode(); |
| + } |
| + |
| + preempt_enable(); |
| +} |
| + |
| void paravirt_start_context_switch(struct task_struct *prev) |
| { |
| BUG_ON(preemptible()); |
| @@ -292,18 +304,6 @@ enum paravirt_lazy_mode paravirt_get_laz |
| return this_cpu_read(paravirt_lazy_mode); |
| } |
| |
| -void arch_flush_lazy_mmu_mode(void) |
| -{ |
| - preempt_disable(); |
| - |
| - if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { |
| - arch_leave_lazy_mmu_mode(); |
| - arch_enter_lazy_mmu_mode(); |
| - } |
| - |
| - preempt_enable(); |
| -} |
| - |
| struct pv_info pv_info = { |
| .name = "bare hardware", |
| .paravirt_enabled = 0, |
| @@ -475,6 +475,7 @@ struct pv_mmu_ops pv_mmu_ops = { |
| .lazy_mode = { |
| .enter = paravirt_nop, |
| .leave = paravirt_nop, |
| + .flush = paravirt_nop, |
| }, |
| |
| .set_fixmap = native_set_fixmap, |
| --- a/arch/x86/lguest/boot.c |
| +++ b/arch/x86/lguest/boot.c |
| @@ -1333,6 +1333,7 @@ __init void lguest_init(void) |
| 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_mmu_mode; |
| + pv_mmu_ops.lazy_mode.flush = paravirt_flush_lazy_mmu; |
| pv_mmu_ops.pte_update = lguest_pte_update; |
| pv_mmu_ops.pte_update_defer = lguest_pte_update; |
| |
| --- a/arch/x86/xen/mmu.c |
| +++ b/arch/x86/xen/mmu.c |
| @@ -2190,6 +2190,7 @@ static const struct pv_mmu_ops xen_mmu_o |
| .lazy_mode = { |
| .enter = paravirt_enter_lazy_mmu, |
| .leave = xen_leave_lazy_mmu, |
| + .flush = paravirt_flush_lazy_mmu, |
| }, |
| |
| .set_fixmap = xen_set_fixmap, |