3.0-stable review patch. If anyone has any objections, please let me know.
------------------ From: Boris Ostrovsky <boris.ostrov...@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.ostrov...@oracle.com> Link: http://lkml.kernel.org/r/1364045796-10720-2-git-send-email-konrad.w...@oracle.com Tested-by: Josh Boyer <jwbo...@redhat.com> Tested-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> Acked-by: Borislav Petkov <b...@suse.de> Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> Signed-off-by: H. Peter Anvin <h...@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gre...@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 @@ -731,7 +731,10 @@ 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 @@ -85,6 +85,7 @@ 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 { @@ -673,6 +674,7 @@ 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 @@ -253,6 +253,18 @@ 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()); @@ -282,18 +294,6 @@ 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, @@ -462,6 +462,7 @@ 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 @@ -1309,6 +1309,7 @@ __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 @@ -2011,6 +2011,7 @@ 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 linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
