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authorWanpeng Li <wanpengli@tencent.com>2018-07-23 14:39:54 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2018-08-06 17:59:20 +0200
commit4180bf1b655a791a0a6ef93a2ffffc762722c782 (patch)
treeb15142899c6343af5a3adf015d0528277820748c /arch
parent74fec5b9dbaa5e6fe776f6c73e6c00fb23dca844 (diff)
downloadlinux-4180bf1b655a791a0a6ef93a2ffffc762722c782.tar.bz2
KVM: X86: Implement "send IPI" hypercall
Using hypercall to send IPIs by one vmexit instead of one by one for xAPIC/x2APIC physical mode and one vmexit per-cluster for x2APIC cluster mode. Intel guest can enter x2apic cluster mode when interrupt remmaping is enabled in qemu, however, latest AMD EPYC still just supports xapic mode which can get great improvement by Exit-less IPIs. This patchset lets a guest send multicast IPIs, with at most 128 destinations per hypercall in 64-bit mode and 64 vCPUs per hypercall in 32-bit mode. Hardware: Xeon Skylake 2.5GHz, 2 sockets, 40 cores, 80 threads, the VM is 80 vCPUs, IPI microbenchmark(https://lkml.org/lkml/2017/12/19/141): x2apic cluster mode, vanilla Dry-run: 0, 2392199 ns Self-IPI: 6907514, 15027589 ns Normal IPI: 223910476, 251301666 ns Broadcast IPI: 0, 9282161150 ns Broadcast lock: 0, 8812934104 ns x2apic cluster mode, pv-ipi Dry-run: 0, 2449341 ns Self-IPI: 6720360, 15028732 ns Normal IPI: 228643307, 255708477 ns Broadcast IPI: 0, 7572293590 ns => 22% performance boost Broadcast lock: 0, 8316124651 ns x2apic physical mode, vanilla Dry-run: 0, 3135933 ns Self-IPI: 8572670, 17901757 ns Normal IPI: 226444334, 255421709 ns Broadcast IPI: 0, 19845070887 ns Broadcast lock: 0, 19827383656 ns x2apic physical mode, pv-ipi Dry-run: 0, 2446381 ns Self-IPI: 6788217, 15021056 ns Normal IPI: 219454441, 249583458 ns Broadcast IPI: 0, 7806540019 ns => 154% performance boost Broadcast lock: 0, 9143618799 ns Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/kvm_host.h4
-rw-r--r--arch/x86/kvm/cpuid.c3
-rw-r--r--arch/x86/kvm/lapic.c40
-rw-r--r--arch/x86/kvm/x86.c3
4 files changed, 49 insertions, 1 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 150937e64f63..c18958ef17d2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1457,6 +1457,10 @@ int kvm_cpu_get_interrupt(struct kvm_vcpu *v);
void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event);
void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu);
+int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low,
+ unsigned long ipi_bitmap_high, int min,
+ unsigned long icr, int op_64_bit);
+
void kvm_define_shared_msr(unsigned index, u32 msr);
int kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 7e042e3d47fd..7bcfa61375c0 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -621,7 +621,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
(1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
(1 << KVM_FEATURE_PV_UNHALT) |
(1 << KVM_FEATURE_PV_TLB_FLUSH) |
- (1 << KVM_FEATURE_ASYNC_PF_VMEXIT);
+ (1 << KVM_FEATURE_ASYNC_PF_VMEXIT) |
+ (1 << KVM_FEATURE_PV_SEND_IPI);
if (sched_info_on())
entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index b5cd8465d44f..f0d693122c24 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -547,6 +547,46 @@ int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
irq->level, irq->trig_mode, dest_map);
}
+int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low,
+ unsigned long ipi_bitmap_high, int min,
+ unsigned long icr, int op_64_bit)
+{
+ int i;
+ struct kvm_apic_map *map;
+ struct kvm_vcpu *vcpu;
+ struct kvm_lapic_irq irq = {0};
+ int cluster_size = op_64_bit ? 64 : 32;
+ int count = 0;
+
+ irq.vector = icr & APIC_VECTOR_MASK;
+ irq.delivery_mode = icr & APIC_MODE_MASK;
+ irq.level = (icr & APIC_INT_ASSERT) != 0;
+ irq.trig_mode = icr & APIC_INT_LEVELTRIG;
+
+ if (icr & APIC_DEST_MASK)
+ return -KVM_EINVAL;
+ if (icr & APIC_SHORT_MASK)
+ return -KVM_EINVAL;
+
+ rcu_read_lock();
+ map = rcu_dereference(kvm->arch.apic_map);
+
+ /* Bits above cluster_size are masked in the caller. */
+ for_each_set_bit(i, &ipi_bitmap_low, BITS_PER_LONG) {
+ vcpu = map->phys_map[min + i]->vcpu;
+ count += kvm_apic_set_irq(vcpu, &irq, NULL);
+ }
+
+ min += cluster_size;
+ for_each_set_bit(i, &ipi_bitmap_high, BITS_PER_LONG) {
+ vcpu = map->phys_map[min + i]->vcpu;
+ count += kvm_apic_set_irq(vcpu, &irq, NULL);
+ }
+
+ rcu_read_unlock();
+ return count;
+}
+
static int pv_eoi_put_user(struct kvm_vcpu *vcpu, u8 val)
{
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6b974802cadb..3c83711c0ebe 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6802,6 +6802,9 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
case KVM_HC_CLOCK_PAIRING:
ret = kvm_pv_clock_pairing(vcpu, a0, a1);
break;
+ case KVM_HC_SEND_IPI:
+ ret = kvm_pv_send_ipi(vcpu->kvm, a0, a1, a2, a3, op_64_bit);
+ break;
#endif
default:
ret = -KVM_ENOSYS;