| Message ID | CANRm+CxGOeGQ0vV9ueBgjUDvkzH29EQWLe4GQGDvOhm3idM6NQ@mail.gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/2] KVM: Introduce pv check helpers | expand |
Wanpeng Li <kernellwp@gmail.com> writes: > From: Wanpeng Li <wanpengli@tencent.com> > > Nick Desaulniers Reported: > > When building with: > $ make CC=clang arch/x86/ CFLAGS=-Wframe-larger-than=1000 > The following warning is observed: > arch/x86/kernel/kvm.c:494:13: warning: stack frame size of 1064 bytes in > function 'kvm_send_ipi_mask_allbutself' [-Wframe-larger-than=] > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int > vector) > ^ > Debugging with: > https://github.com/ClangBuiltLinux/frame-larger-than > via: > $ python3 frame_larger_than.py arch/x86/kernel/kvm.o \ > kvm_send_ipi_mask_allbutself > points to the stack allocated `struct cpumask newmask` in > `kvm_send_ipi_mask_allbutself`. The size of a `struct cpumask` is > potentially large, as it's CONFIG_NR_CPUS divided by BITS_PER_LONG for > the target architecture. CONFIG_NR_CPUS for X86_64 can be as high as > 8192, making a single instance of a `struct cpumask` 1024 B. > > This patch fixes it by pre-allocate 1 cpumask variable per cpu and use it for > both pv tlb and pv ipis.. > > Reported-by: Nick Desaulniers <ndesaulniers@google.com> > Acked-by: Nick Desaulniers <ndesaulniers@google.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > --- > v1 -> v2: > * remove '!alloc' check > * use new pv check helpers > > arch/x86/kernel/kvm.c | 33 +++++++++++++++++++++------------ > 1 file changed, 21 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index 76ea8c4..377b224 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -432,6 +432,8 @@ static bool pv_tlb_flush_supported(void) > kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); > } > > +static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); > + > #ifdef CONFIG_SMP > > static bool pv_ipi_supported(void) > @@ -510,12 +512,12 @@ static void kvm_send_ipi_mask(const struct > cpumask *mask, int vector) > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, > int vector) > { > unsigned int this_cpu = smp_processor_id(); > - struct cpumask new_mask; > + struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); > const struct cpumask *local_mask; > > - cpumask_copy(&new_mask, mask); > - cpumask_clear_cpu(this_cpu, &new_mask); > - local_mask = &new_mask; > + cpumask_copy(new_mask, mask); > + cpumask_clear_cpu(this_cpu, new_mask); > + local_mask = new_mask; > __send_ipi_mask(local_mask, vector); > } > > @@ -595,7 +597,6 @@ static void __init kvm_apf_trap_init(void) > update_intr_gate(X86_TRAP_PF, async_page_fault); > } > > -static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask); > > static void kvm_flush_tlb_others(const struct cpumask *cpumask, > const struct flush_tlb_info *info) > @@ -603,7 +604,7 @@ static void kvm_flush_tlb_others(const struct > cpumask *cpumask, > u8 state; > int cpu; > struct kvm_steal_time *src; > - struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask); > + struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); > > cpumask_copy(flushmask, cpumask); > /* > @@ -642,6 +643,7 @@ static void __init kvm_guest_init(void) > if (pv_tlb_flush_supported()) { > pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others; > pv_ops.mmu.tlb_remove_table = tlb_remove_table; > + pr_info("KVM setup pv remote TLB flush\n"); Nit: to be consistent with __send_ipi_mask() the message should be somthing like "KVM: switch to using PV TLB flush" > } > > if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) > @@ -748,24 +750,31 @@ static __init int activate_jump_labels(void) > } > arch_initcall(activate_jump_labels); > > -static __init int kvm_setup_pv_tlb_flush(void) > +static __init int kvm_alloc_cpumask(void) > { > int cpu; > + bool alloc = false; > > if (!kvm_para_available() || nopv) > return 0; > > - if (pv_tlb_flush_supported()) { > + if (pv_tlb_flush_supported()) > + alloc = true; > + > +#if defined(CONFIG_SMP) > + if (pv_ipi_supported()) > + alloc = true; > +#endif > + > + if (alloc) > for_each_possible_cpu(cpu) { > - zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu), > + zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), > GFP_KERNEL, cpu_to_node(cpu)); > } > - pr_info("KVM setup pv remote TLB flush\n"); > - } > > return 0; > } > -arch_initcall(kvm_setup_pv_tlb_flush); > +arch_initcall(kvm_alloc_cpumask); > > #ifdef CONFIG_PARAVIRT_SPINLOCKS > > -- > 2.7.4 > Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
On Mon, 17 Feb 2020 at 20:46, Vitaly Kuznetsov <vkuznets@redhat.com> wrote: > > Wanpeng Li <kernellwp@gmail.com> writes: > > > From: Wanpeng Li <wanpengli@tencent.com> > > > > Nick Desaulniers Reported: > > > > When building with: > > $ make CC=clang arch/x86/ CFLAGS=-Wframe-larger-than=1000 > > The following warning is observed: > > arch/x86/kernel/kvm.c:494:13: warning: stack frame size of 1064 bytes in > > function 'kvm_send_ipi_mask_allbutself' [-Wframe-larger-than=] > > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int > > vector) > > ^ > > Debugging with: > > https://github.com/ClangBuiltLinux/frame-larger-than > > via: > > $ python3 frame_larger_than.py arch/x86/kernel/kvm.o \ > > kvm_send_ipi_mask_allbutself > > points to the stack allocated `struct cpumask newmask` in > > `kvm_send_ipi_mask_allbutself`. The size of a `struct cpumask` is > > potentially large, as it's CONFIG_NR_CPUS divided by BITS_PER_LONG for > > the target architecture. CONFIG_NR_CPUS for X86_64 can be as high as > > 8192, making a single instance of a `struct cpumask` 1024 B. > > > > This patch fixes it by pre-allocate 1 cpumask variable per cpu and use it for > > both pv tlb and pv ipis.. > > > > Reported-by: Nick Desaulniers <ndesaulniers@google.com> > > Acked-by: Nick Desaulniers <ndesaulniers@google.com> > > Cc: Peter Zijlstra <peterz@infradead.org> > > Cc: Nick Desaulniers <ndesaulniers@google.com> > > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > > --- > > v1 -> v2: > > * remove '!alloc' check > > * use new pv check helpers > > > > arch/x86/kernel/kvm.c | 33 +++++++++++++++++++++------------ > > 1 file changed, 21 insertions(+), 12 deletions(-) > > > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > > index 76ea8c4..377b224 100644 > > --- a/arch/x86/kernel/kvm.c > > +++ b/arch/x86/kernel/kvm.c > > @@ -432,6 +432,8 @@ static bool pv_tlb_flush_supported(void) > > kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); > > } > > > > +static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); > > + > > #ifdef CONFIG_SMP > > > > static bool pv_ipi_supported(void) > > @@ -510,12 +512,12 @@ static void kvm_send_ipi_mask(const struct > > cpumask *mask, int vector) > > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, > > int vector) > > { > > unsigned int this_cpu = smp_processor_id(); > > - struct cpumask new_mask; > > + struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); > > const struct cpumask *local_mask; > > > > - cpumask_copy(&new_mask, mask); > > - cpumask_clear_cpu(this_cpu, &new_mask); > > - local_mask = &new_mask; > > + cpumask_copy(new_mask, mask); > > + cpumask_clear_cpu(this_cpu, new_mask); > > + local_mask = new_mask; > > __send_ipi_mask(local_mask, vector); > > } > > > > @@ -595,7 +597,6 @@ static void __init kvm_apf_trap_init(void) > > update_intr_gate(X86_TRAP_PF, async_page_fault); > > } > > > > -static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask); > > > > static void kvm_flush_tlb_others(const struct cpumask *cpumask, > > const struct flush_tlb_info *info) > > @@ -603,7 +604,7 @@ static void kvm_flush_tlb_others(const struct > > cpumask *cpumask, > > u8 state; > > int cpu; > > struct kvm_steal_time *src; > > - struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask); > > + struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); > > > > cpumask_copy(flushmask, cpumask); > > /* > > @@ -642,6 +643,7 @@ static void __init kvm_guest_init(void) > > if (pv_tlb_flush_supported()) { > > pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others; > > pv_ops.mmu.tlb_remove_table = tlb_remove_table; > > + pr_info("KVM setup pv remote TLB flush\n"); > > Nit: to be consistent with __send_ipi_mask() the message should be > somthing like > > "KVM: switch to using PV TLB flush" There is a lot of native ops we replace by pv ops in kvm.c, I use "KVM setup xxx" there, like pv ipis, pv tlb flush, pv sched yield, should we keep consistent as before? Wanpeng > > > } > > > > if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) > > @@ -748,24 +750,31 @@ static __init int activate_jump_labels(void) > > } > > arch_initcall(activate_jump_labels); > > > > -static __init int kvm_setup_pv_tlb_flush(void) > > +static __init int kvm_alloc_cpumask(void) > > { > > int cpu; > > + bool alloc = false; > > > > if (!kvm_para_available() || nopv) > > return 0; > > > > - if (pv_tlb_flush_supported()) { > > + if (pv_tlb_flush_supported()) > > + alloc = true; > > + > > +#if defined(CONFIG_SMP) > > + if (pv_ipi_supported()) > > + alloc = true; > > +#endif > > + > > + if (alloc) > > for_each_possible_cpu(cpu) { > > - zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu), > > + zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), > > GFP_KERNEL, cpu_to_node(cpu)); > > } > > - pr_info("KVM setup pv remote TLB flush\n"); > > - } > > > > return 0; > > } > > -arch_initcall(kvm_setup_pv_tlb_flush); > > +arch_initcall(kvm_alloc_cpumask); > > > > #ifdef CONFIG_PARAVIRT_SPINLOCKS > > > > -- > > 2.7.4 > > > > Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> > > -- > Vitaly >
Wanpeng Li <kernellwp@gmail.com> writes: > On Mon, 17 Feb 2020 at 20:46, Vitaly Kuznetsov <vkuznets@redhat.com> wrote: >> >> Wanpeng Li <kernellwp@gmail.com> writes: >> >> > From: Wanpeng Li <wanpengli@tencent.com> >> > >> > Nick Desaulniers Reported: >> > >> > When building with: >> > $ make CC=clang arch/x86/ CFLAGS=-Wframe-larger-than=1000 >> > The following warning is observed: >> > arch/x86/kernel/kvm.c:494:13: warning: stack frame size of 1064 bytes in >> > function 'kvm_send_ipi_mask_allbutself' [-Wframe-larger-than=] >> > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int >> > vector) >> > ^ >> > Debugging with: >> > https://github.com/ClangBuiltLinux/frame-larger-than >> > via: >> > $ python3 frame_larger_than.py arch/x86/kernel/kvm.o \ >> > kvm_send_ipi_mask_allbutself >> > points to the stack allocated `struct cpumask newmask` in >> > `kvm_send_ipi_mask_allbutself`. The size of a `struct cpumask` is >> > potentially large, as it's CONFIG_NR_CPUS divided by BITS_PER_LONG for >> > the target architecture. CONFIG_NR_CPUS for X86_64 can be as high as >> > 8192, making a single instance of a `struct cpumask` 1024 B. >> > >> > This patch fixes it by pre-allocate 1 cpumask variable per cpu and use it for >> > both pv tlb and pv ipis.. >> > >> > Reported-by: Nick Desaulniers <ndesaulniers@google.com> >> > Acked-by: Nick Desaulniers <ndesaulniers@google.com> >> > Cc: Peter Zijlstra <peterz@infradead.org> >> > Cc: Nick Desaulniers <ndesaulniers@google.com> >> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> >> > --- >> > v1 -> v2: >> > * remove '!alloc' check >> > * use new pv check helpers >> > >> > arch/x86/kernel/kvm.c | 33 +++++++++++++++++++++------------ >> > 1 file changed, 21 insertions(+), 12 deletions(-) >> > >> > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c >> > index 76ea8c4..377b224 100644 >> > --- a/arch/x86/kernel/kvm.c >> > +++ b/arch/x86/kernel/kvm.c >> > @@ -432,6 +432,8 @@ static bool pv_tlb_flush_supported(void) >> > kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); >> > } >> > >> > +static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); >> > + >> > #ifdef CONFIG_SMP >> > >> > static bool pv_ipi_supported(void) >> > @@ -510,12 +512,12 @@ static void kvm_send_ipi_mask(const struct >> > cpumask *mask, int vector) >> > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, >> > int vector) >> > { >> > unsigned int this_cpu = smp_processor_id(); >> > - struct cpumask new_mask; >> > + struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); >> > const struct cpumask *local_mask; >> > >> > - cpumask_copy(&new_mask, mask); >> > - cpumask_clear_cpu(this_cpu, &new_mask); >> > - local_mask = &new_mask; >> > + cpumask_copy(new_mask, mask); >> > + cpumask_clear_cpu(this_cpu, new_mask); >> > + local_mask = new_mask; >> > __send_ipi_mask(local_mask, vector); >> > } >> > >> > @@ -595,7 +597,6 @@ static void __init kvm_apf_trap_init(void) >> > update_intr_gate(X86_TRAP_PF, async_page_fault); >> > } >> > >> > -static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask); >> > >> > static void kvm_flush_tlb_others(const struct cpumask *cpumask, >> > const struct flush_tlb_info *info) >> > @@ -603,7 +604,7 @@ static void kvm_flush_tlb_others(const struct >> > cpumask *cpumask, >> > u8 state; >> > int cpu; >> > struct kvm_steal_time *src; >> > - struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask); >> > + struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); >> > >> > cpumask_copy(flushmask, cpumask); >> > /* >> > @@ -642,6 +643,7 @@ static void __init kvm_guest_init(void) >> > if (pv_tlb_flush_supported()) { >> > pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others; >> > pv_ops.mmu.tlb_remove_table = tlb_remove_table; >> > + pr_info("KVM setup pv remote TLB flush\n"); >> >> Nit: to be consistent with __send_ipi_mask() the message should be >> somthing like >> >> "KVM: switch to using PV TLB flush" > > There is a lot of native ops we replace by pv ops in kvm.c, I use "KVM > setup xxx" there, like pv ipis, pv tlb flush, pv sched yield, should > we keep consistent as before? > Oh, I see, it's either one or another :-) Personally, I prefer when subsystem is delimited with ':' so if we were to change them all I'd prefer the "KVM: switch to using PV TLB flush" (__send_ipi_mask() style). But this looks more like a separate patch idea, we can discuss our personal preferences there :-)
On 10/02/20 07:38, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > Nick Desaulniers Reported: > > When building with: > $ make CC=clang arch/x86/ CFLAGS=-Wframe-larger-than=1000 > The following warning is observed: > arch/x86/kernel/kvm.c:494:13: warning: stack frame size of 1064 bytes in > function 'kvm_send_ipi_mask_allbutself' [-Wframe-larger-than=] > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int > vector) > ^ > Debugging with: > https://github.com/ClangBuiltLinux/frame-larger-than > via: > $ python3 frame_larger_than.py arch/x86/kernel/kvm.o \ > kvm_send_ipi_mask_allbutself > points to the stack allocated `struct cpumask newmask` in > `kvm_send_ipi_mask_allbutself`. The size of a `struct cpumask` is > potentially large, as it's CONFIG_NR_CPUS divided by BITS_PER_LONG for > the target architecture. CONFIG_NR_CPUS for X86_64 can be as high as > 8192, making a single instance of a `struct cpumask` 1024 B. > > This patch fixes it by pre-allocate 1 cpumask variable per cpu and use it for > both pv tlb and pv ipis.. > > Reported-by: Nick Desaulniers <ndesaulniers@google.com> > Acked-by: Nick Desaulniers <ndesaulniers@google.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > --- > v1 -> v2: > * remove '!alloc' check > * use new pv check helpers > > arch/x86/kernel/kvm.c | 33 +++++++++++++++++++++------------ > 1 file changed, 21 insertions(+), 12 deletions(-) > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > index 76ea8c4..377b224 100644 > --- a/arch/x86/kernel/kvm.c > +++ b/arch/x86/kernel/kvm.c > @@ -432,6 +432,8 @@ static bool pv_tlb_flush_supported(void) > kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); > } > > +static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); > + > #ifdef CONFIG_SMP > > static bool pv_ipi_supported(void) > @@ -510,12 +512,12 @@ static void kvm_send_ipi_mask(const struct > cpumask *mask, int vector) > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, > int vector) > { > unsigned int this_cpu = smp_processor_id(); > - struct cpumask new_mask; > + struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); > const struct cpumask *local_mask; > > - cpumask_copy(&new_mask, mask); > - cpumask_clear_cpu(this_cpu, &new_mask); > - local_mask = &new_mask; > + cpumask_copy(new_mask, mask); > + cpumask_clear_cpu(this_cpu, new_mask); > + local_mask = new_mask; > __send_ipi_mask(local_mask, vector); > } > > @@ -595,7 +597,6 @@ static void __init kvm_apf_trap_init(void) > update_intr_gate(X86_TRAP_PF, async_page_fault); > } > > -static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask); > > static void kvm_flush_tlb_others(const struct cpumask *cpumask, > const struct flush_tlb_info *info) > @@ -603,7 +604,7 @@ static void kvm_flush_tlb_others(const struct > cpumask *cpumask, > u8 state; > int cpu; > struct kvm_steal_time *src; > - struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask); > + struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); > > cpumask_copy(flushmask, cpumask); > /* > @@ -642,6 +643,7 @@ static void __init kvm_guest_init(void) > if (pv_tlb_flush_supported()) { > pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others; > pv_ops.mmu.tlb_remove_table = tlb_remove_table; > + pr_info("KVM setup pv remote TLB flush\n"); > } > > if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) > @@ -748,24 +750,31 @@ static __init int activate_jump_labels(void) > } > arch_initcall(activate_jump_labels); > > -static __init int kvm_setup_pv_tlb_flush(void) > +static __init int kvm_alloc_cpumask(void) > { > int cpu; > + bool alloc = false; > > if (!kvm_para_available() || nopv) > return 0; > > - if (pv_tlb_flush_supported()) { > + if (pv_tlb_flush_supported()) > + alloc = true; > + > +#if defined(CONFIG_SMP) > + if (pv_ipi_supported()) > + alloc = true; > +#endif > + > + if (alloc) > for_each_possible_cpu(cpu) { > - zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu), > + zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), > GFP_KERNEL, cpu_to_node(cpu)); > } > - pr_info("KVM setup pv remote TLB flush\n"); > - } > > return 0; > } > -arch_initcall(kvm_setup_pv_tlb_flush); > +arch_initcall(kvm_alloc_cpumask); > > #ifdef CONFIG_PARAVIRT_SPINLOCKS > > -- > 2.7.4 > Also has messed up whitespace, can you resend please? Paolo
On Tue, 18 Feb 2020 at 01:11, Paolo Bonzini <pbonzini@redhat.com> wrote: > > On 10/02/20 07:38, Wanpeng Li wrote: > > From: Wanpeng Li <wanpengli@tencent.com> > > > > Nick Desaulniers Reported: > > > > When building with: > > $ make CC=clang arch/x86/ CFLAGS=-Wframe-larger-than=1000 > > The following warning is observed: > > arch/x86/kernel/kvm.c:494:13: warning: stack frame size of 1064 bytes in > > function 'kvm_send_ipi_mask_allbutself' [-Wframe-larger-than=] > > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int > > vector) > > ^ > > Debugging with: > > https://github.com/ClangBuiltLinux/frame-larger-than > > via: > > $ python3 frame_larger_than.py arch/x86/kernel/kvm.o \ > > kvm_send_ipi_mask_allbutself > > points to the stack allocated `struct cpumask newmask` in > > `kvm_send_ipi_mask_allbutself`. The size of a `struct cpumask` is > > potentially large, as it's CONFIG_NR_CPUS divided by BITS_PER_LONG for > > the target architecture. CONFIG_NR_CPUS for X86_64 can be as high as > > 8192, making a single instance of a `struct cpumask` 1024 B. > > > > This patch fixes it by pre-allocate 1 cpumask variable per cpu and use it for > > both pv tlb and pv ipis.. > > > > Reported-by: Nick Desaulniers <ndesaulniers@google.com> > > Acked-by: Nick Desaulniers <ndesaulniers@google.com> > > Cc: Peter Zijlstra <peterz@infradead.org> > > Cc: Nick Desaulniers <ndesaulniers@google.com> > > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > > --- > > v1 -> v2: > > * remove '!alloc' check > > * use new pv check helpers > > > > arch/x86/kernel/kvm.c | 33 +++++++++++++++++++++------------ > > 1 file changed, 21 insertions(+), 12 deletions(-) > > > > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > > index 76ea8c4..377b224 100644 > > --- a/arch/x86/kernel/kvm.c > > +++ b/arch/x86/kernel/kvm.c > > @@ -432,6 +432,8 @@ static bool pv_tlb_flush_supported(void) > > kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); > > } > > > > +static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); > > + > > #ifdef CONFIG_SMP > > > > static bool pv_ipi_supported(void) > > @@ -510,12 +512,12 @@ static void kvm_send_ipi_mask(const struct > > cpumask *mask, int vector) > > static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, > > int vector) > > { > > unsigned int this_cpu = smp_processor_id(); > > - struct cpumask new_mask; > > + struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); > > const struct cpumask *local_mask; > > > > - cpumask_copy(&new_mask, mask); > > - cpumask_clear_cpu(this_cpu, &new_mask); > > - local_mask = &new_mask; > > + cpumask_copy(new_mask, mask); > > + cpumask_clear_cpu(this_cpu, new_mask); > > + local_mask = new_mask; > > __send_ipi_mask(local_mask, vector); > > } > > > > @@ -595,7 +597,6 @@ static void __init kvm_apf_trap_init(void) > > update_intr_gate(X86_TRAP_PF, async_page_fault); > > } > > > > -static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask); > > > > static void kvm_flush_tlb_others(const struct cpumask *cpumask, > > const struct flush_tlb_info *info) > > @@ -603,7 +604,7 @@ static void kvm_flush_tlb_others(const struct > > cpumask *cpumask, > > u8 state; > > int cpu; > > struct kvm_steal_time *src; > > - struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask); > > + struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); > > > > cpumask_copy(flushmask, cpumask); > > /* > > @@ -642,6 +643,7 @@ static void __init kvm_guest_init(void) > > if (pv_tlb_flush_supported()) { > > pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others; > > pv_ops.mmu.tlb_remove_table = tlb_remove_table; > > + pr_info("KVM setup pv remote TLB flush\n"); > > } > > > > if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) > > @@ -748,24 +750,31 @@ static __init int activate_jump_labels(void) > > } > > arch_initcall(activate_jump_labels); > > > > -static __init int kvm_setup_pv_tlb_flush(void) > > +static __init int kvm_alloc_cpumask(void) > > { > > int cpu; > > + bool alloc = false; > > > > if (!kvm_para_available() || nopv) > > return 0; > > > > - if (pv_tlb_flush_supported()) { > > + if (pv_tlb_flush_supported()) > > + alloc = true; > > + > > +#if defined(CONFIG_SMP) > > + if (pv_ipi_supported()) > > + alloc = true; > > +#endif > > + > > + if (alloc) > > for_each_possible_cpu(cpu) { > > - zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu), > > + zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu), > > GFP_KERNEL, cpu_to_node(cpu)); > > } > > - pr_info("KVM setup pv remote TLB flush\n"); > > - } > > > > return 0; > > } > > -arch_initcall(kvm_setup_pv_tlb_flush); > > +arch_initcall(kvm_alloc_cpumask); > > > > #ifdef CONFIG_PARAVIRT_SPINLOCKS > > > > -- > > 2.7.4 > > > > Also has messed up whitespace, can you resend please? My fault, just resend all of them. Wanpeng
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 76ea8c4..377b224 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -432,6 +432,8 @@ static bool pv_tlb_flush_supported(void) kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); } +static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); + #ifdef CONFIG_SMP static bool pv_ipi_supported(void) @@ -510,12 +512,12 @@ static void kvm_send_ipi_mask(const struct cpumask *mask, int vector) static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) { unsigned int this_cpu = smp_processor_id(); - struct cpumask new_mask; + struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask); const struct cpumask *local_mask; - cpumask_copy(&new_mask, mask); - cpumask_clear_cpu(this_cpu, &new_mask); - local_mask = &new_mask; + cpumask_copy(new_mask, mask); + cpumask_clear_cpu(this_cpu, new_mask); + local_mask = new_mask; __send_ipi_mask(local_mask, vector);