3.2.44-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> 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@xxxxxxxxxx> Link: http://lkml.kernel.org/r/1364045796-10720-2-git-send-email-konrad.wilk@xxxxxxxxxx Tested-by: Josh Boyer <jwboyer@xxxxxxxxxx> Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Acked-by: Borislav Petkov <bp@xxxxxxx> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- 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 @@ -740,7 +740,10 @@ 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 { @@ -680,6 +681,7 @@ 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 @@ -261,6 +261,18 @@ 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()); @@ -290,18 +302,6 @@ enum paravirt_lazy_mode paravirt_get_laz return percpu_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 @@ -1328,6 +1328,7 @@ __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 @@ -2079,6 +2079,7 @@ 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, -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html