| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <2faaf564-ab1c-0a21-4b41-48ed657e4ee6@redhat.com>
Date: Sat, 17 Apr 2021 14:34:09 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org
Cc: Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v2 1/3] x86/kvm: Don't bother __pv_cpu_mask when
!CONFIG_SMP
On 09/04/21 06:18, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@...cent.com>
>
> Enable PV TLB shootdown when !CONFIG_SMP doesn't make sense. Let's
> move it inside CONFIG_SMP. In addition, we can avoid define and
> alloc __pv_cpu_mask when !CONFIG_SMP and get rid of 'alloc' variable
> in kvm_alloc_cpumask.
>
> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> ---
> v1 -> v2:
> * shuffle things around a bit more
>
> arch/x86/kernel/kvm.c | 118 +++++++++++++++++++++++---------------------------
> 1 file changed, 55 insertions(+), 63 deletions(-)
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 5e78e01..224a7a1 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -451,6 +451,10 @@ static void __init sev_map_percpu_data(void)
> }
> }
>
> +#ifdef CONFIG_SMP
> +
> +static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
> +
> static bool pv_tlb_flush_supported(void)
> {
> return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
> @@ -458,10 +462,6 @@ 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)
> {
> return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI);
> @@ -574,6 +574,49 @@ static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
> }
> }
>
> +static void kvm_flush_tlb_others(const struct cpumask *cpumask,
> + const struct flush_tlb_info *info)
> +{
> + u8 state;
> + int cpu;
> + struct kvm_steal_time *src;
> + struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
> +
> + cpumask_copy(flushmask, cpumask);
> + /*
> + * We have to call flush only on online vCPUs. And
> + * queue flush_on_enter for pre-empted vCPUs
> + */
> + for_each_cpu(cpu, flushmask) {
> + src = &per_cpu(steal_time, cpu);
> + state = READ_ONCE(src->preempted);
> + if ((state & KVM_VCPU_PREEMPTED)) {
> + if (try_cmpxchg(&src->preempted, &state,
> + state | KVM_VCPU_FLUSH_TLB))
> + __cpumask_clear_cpu(cpu, flushmask);
> + }
> + }
> +
> + native_flush_tlb_others(flushmask, info);
> +}
> +
> +static __init int kvm_alloc_cpumask(void)
> +{
> + int cpu;
> +
> + if (!kvm_para_available() || nopv)
> + return 0;
> +
> + if (pv_tlb_flush_supported() || pv_ipi_supported())
> + for_each_possible_cpu(cpu) {
> + zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
> + GFP_KERNEL, cpu_to_node(cpu));
> + }
> +
> + return 0;
> +}
> +arch_initcall(kvm_alloc_cpumask);
> +
> static void __init kvm_smp_prepare_boot_cpu(void)
> {
> /*
> @@ -611,33 +654,8 @@ static int kvm_cpu_down_prepare(unsigned int cpu)
> local_irq_enable();
> return 0;
> }
> -#endif
> -
> -static void kvm_flush_tlb_others(const struct cpumask *cpumask,
> - const struct flush_tlb_info *info)
> -{
> - u8 state;
> - int cpu;
> - struct kvm_steal_time *src;
> - struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
> -
> - cpumask_copy(flushmask, cpumask);
> - /*
> - * We have to call flush only on online vCPUs. And
> - * queue flush_on_enter for pre-empted vCPUs
> - */
> - for_each_cpu(cpu, flushmask) {
> - src = &per_cpu(steal_time, cpu);
> - state = READ_ONCE(src->preempted);
> - if ((state & KVM_VCPU_PREEMPTED)) {
> - if (try_cmpxchg(&src->preempted, &state,
> - state | KVM_VCPU_FLUSH_TLB))
> - __cpumask_clear_cpu(cpu, flushmask);
> - }
> - }
>
> - native_flush_tlb_others(flushmask, info);
> -}
> +#endif
>
> static void __init kvm_guest_init(void)
> {
> @@ -653,12 +671,6 @@ static void __init kvm_guest_init(void)
> pv_ops.time.steal_clock = kvm_steal_clock;
> }
>
> - 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))
> apic_set_eoi_write(kvm_guest_apic_eoi_write);
>
> @@ -668,6 +680,12 @@ static void __init kvm_guest_init(void)
> }
>
> #ifdef CONFIG_SMP
> + 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");
> + }
> +
> smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
> if (pv_sched_yield_supported()) {
> smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
> @@ -734,7 +752,7 @@ static uint32_t __init kvm_detect(void)
>
> static void __init kvm_apic_init(void)
> {
> -#if defined(CONFIG_SMP)
> +#ifdef CONFIG_SMP
> if (pv_ipi_supported())
> kvm_setup_pv_ipi();
> #endif
> @@ -794,32 +812,6 @@ static __init int activate_jump_labels(void)
> }
> arch_initcall(activate_jump_labels);
>
> -static __init int kvm_alloc_cpumask(void)
> -{
> - int cpu;
> - bool alloc = false;
> -
> - if (!kvm_para_available() || nopv)
> - return 0;
> -
> - 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_cpu_mask, cpu),
> - GFP_KERNEL, cpu_to_node(cpu));
> - }
> -
> - return 0;
> -}
> -arch_initcall(kvm_alloc_cpumask);
> -
> #ifdef CONFIG_PARAVIRT_SPINLOCKS
>
> /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
>
Queued all three, thanks.
Paolo
Powered by blists - more mailing lists