* [PATCH] x86/kvm: Don't alloc __pv_cpu_mask when !CONFIG_SMP
@ 2021-04-07 8:53 Wanpeng Li
2021-04-08 20:20 ` Sean Christopherson
0 siblings, 1 reply; 3+ messages in thread
From: Wanpeng Li @ 2021-04-07 8:53 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
From: Wanpeng Li <wanpengli@tencent.com>
Enable PV TLB shootdown when !CONFIG_SMP doesn't make sense. Let's move
it inside CONFIG_SMP. In addition, we can avoid alloc __pv_cpu_mask when
!CONFIG_SMP and get rid of 'alloc' variable in kvm_alloc_cpumask.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kernel/kvm.c | 79 +++++++++++++++++++++++++--------------------------
1 file changed, 39 insertions(+), 40 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01..202e1f0 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -451,6 +451,11 @@ static void __init sev_map_percpu_data(void)
}
}
+
+static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
+
+#ifdef CONFIG_SMP
+
static bool pv_tlb_flush_supported(void)
{
return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
@@ -458,10 +463,6 @@ 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 +575,32 @@ 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 void __init kvm_smp_prepare_boot_cpu(void)
{
/*
@@ -611,33 +638,16 @@ 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);
+#else
- 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);
- }
- }
+static bool pv_tlb_flush_supported(void) { return false; }
+static bool pv_ipi_supported(void) { return false; }
+static void kvm_flush_tlb_others(const struct cpumask *cpumask,
+ const struct flush_tlb_info *info) { }
+static void kvm_setup_pv_ipi(void) { }
- native_flush_tlb_others(flushmask, info);
-}
+#endif
static void __init kvm_guest_init(void)
{
@@ -734,10 +744,8 @@ static uint32_t __init kvm_detect(void)
static void __init kvm_apic_init(void)
{
-#if defined(CONFIG_SMP)
if (pv_ipi_supported())
kvm_setup_pv_ipi();
-#endif
}
static bool __init kvm_msi_ext_dest_id(void)
@@ -797,20 +805,11 @@ 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)
+ 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));
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/kvm: Don't alloc __pv_cpu_mask when !CONFIG_SMP
2021-04-07 8:53 [PATCH] x86/kvm: Don't alloc __pv_cpu_mask when !CONFIG_SMP Wanpeng Li
@ 2021-04-08 20:20 ` Sean Christopherson
2021-04-09 3:03 ` Wanpeng Li
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2021-04-08 20:20 UTC (permalink / raw)
To: Wanpeng Li
Cc: linux-kernel, kvm, Paolo Bonzini, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
On Wed, Apr 07, 2021, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> Enable PV TLB shootdown when !CONFIG_SMP doesn't make sense. Let's move
> it inside CONFIG_SMP. In addition, we can avoid alloc __pv_cpu_mask when
> !CONFIG_SMP and get rid of 'alloc' variable in kvm_alloc_cpumask.
...
> +static bool pv_tlb_flush_supported(void) { return false; }
> +static bool pv_ipi_supported(void) { return false; }
> +static void kvm_flush_tlb_others(const struct cpumask *cpumask,
> + const struct flush_tlb_info *info) { }
> +static void kvm_setup_pv_ipi(void) { }
If you shuffle things around a bit more, you can avoid these stubs, and hide the
definition of __pv_cpu_mask behind CONFIG_SMP, too.
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01ca3b4..13c6b1c7c01b 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -451,6 +451,8 @@ static void __init sev_map_percpu_data(void)
}
}
+#ifdef CONFIG_SMP
+
static bool pv_tlb_flush_supported(void)
{
return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
@@ -460,8 +462,6 @@ static bool pv_tlb_flush_supported(void)
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);
@@ -574,45 +574,6 @@ static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
}
}
-static void __init kvm_smp_prepare_boot_cpu(void)
-{
- /*
- * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
- * shares the guest physical address with the hypervisor.
- */
- sev_map_percpu_data();
-
- kvm_guest_cpu_init();
- native_smp_prepare_boot_cpu();
- kvm_spinlock_init();
-}
-
-static void kvm_guest_cpu_offline(void)
-{
- kvm_disable_steal_time();
- if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
- wrmsrl(MSR_KVM_PV_EOI_EN, 0);
- kvm_pv_disable_apf();
- apf_task_wake_all();
-}
-
-static int kvm_cpu_online(unsigned int cpu)
-{
- local_irq_disable();
- kvm_guest_cpu_init();
- local_irq_enable();
- return 0;
-}
-
-static int kvm_cpu_down_prepare(unsigned int cpu)
-{
- local_irq_disable();
- kvm_guest_cpu_offline();
- local_irq_enable();
- return 0;
-}
-#endif
-
static void kvm_flush_tlb_others(const struct cpumask *cpumask,
const struct flush_tlb_info *info)
{
@@ -639,6 +600,63 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
native_flush_tlb_others(flushmask, info);
}
+static void __init kvm_smp_prepare_boot_cpu(void)
+{
+ /*
+ * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
+ * shares the guest physical address with the hypervisor.
+ */
+ sev_map_percpu_data();
+
+ kvm_guest_cpu_init();
+ native_smp_prepare_boot_cpu();
+ kvm_spinlock_init();
+}
+
+static void kvm_guest_cpu_offline(void)
+{
+ kvm_disable_steal_time();
+ if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
+ wrmsrl(MSR_KVM_PV_EOI_EN, 0);
+ kvm_pv_disable_apf();
+ apf_task_wake_all();
+}
+
+static int kvm_cpu_online(unsigned int cpu)
+{
+ local_irq_disable();
+ kvm_guest_cpu_init();
+ local_irq_enable();
+ return 0;
+}
+
+static int kvm_cpu_down_prepare(unsigned int cpu)
+{
+ local_irq_disable();
+ kvm_guest_cpu_offline();
+ local_irq_enable();
+ return 0;
+}
+
+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);
+
+#endif
+
static void __init kvm_guest_init(void)
{
int i;
@@ -653,21 +671,21 @@ static void __init kvm_guest_init(void)
pv_ops.time.steal_clock = kvm_steal_clock;
}
+ if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
+ apic_set_eoi_write(kvm_guest_apic_eoi_write);
+
+ if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
+ static_branch_enable(&kvm_async_pf_enabled);
+ alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
+ }
+
+#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");
}
- if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
- apic_set_eoi_write(kvm_guest_apic_eoi_write);
-
- if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
- static_branch_enable(&kvm_async_pf_enabled);
- alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
- }
-
-#ifdef CONFIG_SMP
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
@@ -794,31 +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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/kvm: Don't alloc __pv_cpu_mask when !CONFIG_SMP
2021-04-08 20:20 ` Sean Christopherson
@ 2021-04-09 3:03 ` Wanpeng Li
0 siblings, 0 replies; 3+ messages in thread
From: Wanpeng Li @ 2021-04-09 3:03 UTC (permalink / raw)
To: Sean Christopherson
Cc: LKML, kvm, Paolo Bonzini, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
On Fri, 9 Apr 2021 at 04:20, Sean Christopherson <seanjc@google.com> wrote:
>
> On Wed, Apr 07, 2021, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@tencent.com>
> >
> > Enable PV TLB shootdown when !CONFIG_SMP doesn't make sense. Let's move
> > it inside CONFIG_SMP. In addition, we can avoid alloc __pv_cpu_mask when
> > !CONFIG_SMP and get rid of 'alloc' variable in kvm_alloc_cpumask.
>
> ...
>
> > +static bool pv_tlb_flush_supported(void) { return false; }
> > +static bool pv_ipi_supported(void) { return false; }
> > +static void kvm_flush_tlb_others(const struct cpumask *cpumask,
> > + const struct flush_tlb_info *info) { }
> > +static void kvm_setup_pv_ipi(void) { }
>
> If you shuffle things around a bit more, you can avoid these stubs, and hide the
> definition of __pv_cpu_mask behind CONFIG_SMP, too.
Thanks, I will move around.
Wanpeng
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-04-07 8:53 [PATCH] x86/kvm: Don't alloc __pv_cpu_mask when !CONFIG_SMP Wanpeng Li
2021-04-08 20:20 ` Sean Christopherson
2021-04-09 3:03 ` Wanpeng Li
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