From: Andrea Arcangeli <aarcange@redhat.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>
Subject: [PATCH 13/14] KVM: retpolines: x86: eliminate retpoline from svm.c exit handlers
Date: Sat, 28 Sep 2019 13:23:22 -0400 [thread overview]
Message-ID: <20190928172323.14663-14-aarcange@redhat.com> (raw)
In-Reply-To: <20190928172323.14663-1-aarcange@redhat.com>
It's enough to check the exit value and issue a direct call to avoid
the retpoline for all the common vmexit reasons.
After this commit is applied, here the most common retpolines executed
under a high resolution timer workload in the guest on a SVM host:
[..]
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
ktime_get_update_offsets_now+70
hrtimer_interrupt+131
smp_apic_timer_interrupt+106
apic_timer_interrupt+15
start_sw_timer+359
restart_apic_timer+85
kvm_set_msr_common+1497
msr_interception+142
vcpu_enter_guest+684
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 1940
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_r12+33
force_qs_rnp+217
rcu_gp_kthread+1270
kthread+268
ret_from_fork+34
]: 4644
@[]: 25095
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
lapic_next_event+28
clockevents_program_event+148
hrtimer_start_range_ns+528
start_sw_timer+356
restart_apic_timer+85
kvm_set_msr_common+1497
msr_interception+142
vcpu_enter_guest+684
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 41474
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
clockevents_program_event+148
hrtimer_start_range_ns+528
start_sw_timer+356
restart_apic_timer+85
kvm_set_msr_common+1497
msr_interception+142
vcpu_enter_guest+684
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 41474
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
ktime_get+58
clockevents_program_event+84
hrtimer_start_range_ns+528
start_sw_timer+356
restart_apic_timer+85
kvm_set_msr_common+1497
msr_interception+142
vcpu_enter_guest+684
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 41887
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
lapic_next_event+28
clockevents_program_event+148
hrtimer_try_to_cancel+168
hrtimer_cancel+21
kvm_set_lapic_tscdeadline_msr+43
kvm_set_msr_common+1497
msr_interception+142
vcpu_enter_guest+684
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 42723
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
clockevents_program_event+148
hrtimer_try_to_cancel+168
hrtimer_cancel+21
kvm_set_lapic_tscdeadline_msr+43
kvm_set_msr_common+1497
msr_interception+142
vcpu_enter_guest+684
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 42766
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
ktime_get+58
clockevents_program_event+84
hrtimer_try_to_cancel+168
hrtimer_cancel+21
kvm_set_lapic_tscdeadline_msr+43
kvm_set_msr_common+1497
msr_interception+142
vcpu_enter_guest+684
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 42848
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
ktime_get+58
start_sw_timer+279
restart_apic_timer+85
kvm_set_msr_common+1497
msr_interception+142
vcpu_enter_guest+684
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 499845
@total: 1780243
SVM has no TSC based programmable preemption timer so it is invoking
ktime_get() frequently.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
arch/x86/kvm/svm.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 50c57112c0ce..4d8370fcd212 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4989,6 +4989,20 @@ int kvm_x86_handle_exit(struct kvm_vcpu *vcpu)
return 0;
}
+#ifdef CONFIG_RETPOLINE
+ if (exit_code == SVM_EXIT_MSR)
+ return msr_interception(svm);
+ else if (exit_code == SVM_EXIT_VINTR)
+ return interrupt_window_interception(svm);
+ else if (exit_code == SVM_EXIT_INTR)
+ return intr_interception(svm);
+ else if (exit_code == SVM_EXIT_HLT)
+ return halt_interception(svm);
+ else if (exit_code == SVM_EXIT_NPF)
+ return npf_interception(svm);
+ else if (exit_code == SVM_EXIT_CPUID)
+ return cpuid_interception(svm);
+#endif
return svm_exit_handlers[exit_code](svm);
}
next prev parent reply other threads:[~2019-09-28 17:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-28 17:23 [PATCH 00/14] KVM monolithic v2 Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 01/14] KVM: monolithic: x86: remove kvm.ko Andrea Arcangeli
2019-10-15 1:31 ` Sean Christopherson
2019-10-15 3:18 ` Sean Christopherson
2019-10-15 8:32 ` Paolo Bonzini
2019-09-28 17:23 ` [PATCH 02/14] KVM: monolithic: x86: disable linking vmx and svm at the same time into the kernel Andrea Arcangeli
2019-10-15 3:16 ` Sean Christopherson
2019-10-15 8:21 ` Paolo Bonzini
2019-10-15 15:23 ` Sean Christopherson
2019-09-28 17:23 ` [PATCH 03/14] KVM: monolithic: x86: convert the kvm_x86_ops and kvm_pmu_ops methods to external functions Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 04/14] KVM: monolithic: x86: handle the request_immediate_exit variation Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 05/14] KVM: monolithic: add more section prefixes in the KVM common code Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 06/14] KVM: monolithic: x86: remove __exit section prefix from machine_unsetup Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 07/14] KVM: monolithic: x86: remove __init section prefix from kvm_x86_cpu_has_kvm_support Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 08/14] KVM: monolithic: x86: remove exports Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 09/14] KVM: monolithic: remove exports from KVM common code Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 10/14] KVM: monolithic: x86: drop the kvm_pmu_ops structure Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 11/14] KVM: x86: optimize more exit handlers in vmx.c Andrea Arcangeli
2019-09-28 17:23 ` [PATCH 12/14] KVM: retpolines: x86: eliminate retpoline from vmx.c exit handlers Andrea Arcangeli
2019-10-15 8:28 ` Paolo Bonzini
2019-10-15 16:49 ` Andrea Arcangeli
2019-10-15 19:46 ` Paolo Bonzini
2019-10-15 20:35 ` Andrea Arcangeli
2019-10-15 22:22 ` Paolo Bonzini
2019-10-15 23:42 ` Andrea Arcangeli
2019-10-16 7:07 ` Paolo Bonzini
2019-10-16 16:50 ` Andrea Arcangeli
2019-10-16 17:01 ` Paolo Bonzini
2019-09-28 17:23 ` Andrea Arcangeli [this message]
2019-09-28 17:23 ` [PATCH 14/14] x86: retpolines: eliminate retpoline from msr event handlers Andrea Arcangeli
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