| Message ID | 1581988104-16628-2-git-send-email-wanpengli@tencent.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RESEND,v2,1/2] KVM: Introduce pv check helpers | expand |
ping, On Tue, 18 Feb 2020 at 09:12, Wanpeng Li <kernellwp@gmail.com> 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> > Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.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 >
(putting Paolo in To: field, in case email filters are to blame. Vitaly, maybe you could ping Paolo internally?) On Mon, Feb 24, 2020 at 11:55 PM Wanpeng Li <kernellwp@gmail.com> wrote: > > ping, > On Tue, 18 Feb 2020 at 09:12, Wanpeng Li <kernellwp@gmail.com> 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> > > Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.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 > >
Nick Desaulniers <ndesaulniers@google.com> writes: > (putting Paolo in To: field, in case email filters are to blame. > Vitaly, maybe you could ping Paolo internally?) > I could, but the only difference from what I'm doing right now would proabbly be the absence of non-@redaht.com emails in To/Cc: fields of this email :-) Do we want this fix for one of the last 5.6 RCs or 5.7 would be fine? Personally, I'd say we're not in a great hurry and 5.7 is OK.
On 26/02/20 14:10, Vitaly Kuznetsov wrote: > Nick Desaulniers <ndesaulniers@google.com> writes: > >> (putting Paolo in To: field, in case email filters are to blame. >> Vitaly, maybe you could ping Paolo internally?) >> > > I could, but the only difference from what I'm doing right now would > proabbly be the absence of non-@redaht.com emails in To/Cc: fields of > this email :-) > > Do we want this fix for one of the last 5.6 RCs or 5.7 would be fine? > Personally, I'd say we're not in a great hurry and 5.7 is OK. I think we can do it for 5.6, but we're not in a great hurry. :) The rc4 pull request was already going to be relatively large and I had just been scolded by Linus so I postponed this, but I am going to include it this week. Paolo
On Wed, Feb 26, 2020 at 5:27 AM Paolo Bonzini <pbonzini@redhat.com> wrote: > > On 26/02/20 14:10, Vitaly Kuznetsov wrote: > > Nick Desaulniers <ndesaulniers@google.com> writes: > > > >> (putting Paolo in To: field, in case email filters are to blame. > >> Vitaly, maybe you could ping Paolo internally?) > >> > > > > I could, but the only difference from what I'm doing right now would > > proabbly be the absence of non-@redaht.com emails in To/Cc: fields of > > this email :-) > > > > Do we want this fix for one of the last 5.6 RCs or 5.7 would be fine? > > Personally, I'd say we're not in a great hurry and 5.7 is OK. > > I think we can do it for 5.6, but we're not in a great hurry. :) The > rc4 pull request was already going to be relatively large and I had just > been scolded by Linus so I postponed this, but I am going to include it > this week. No rush; soak time is good.
On 18/02/20 02:08, 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> > Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.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 > > Queued now, thanks. Paolo
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