[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 24 Sep 2021 17:55:28 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Huacai Chen <chenhuacai@...nel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
Paul Mackerras <paulus@...abs.org>,
Christian Borntraeger <borntraeger@...ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Paolo Bonzini <pbonzini@...hat.com>
Cc: James Morse <james.morse@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
David Hildenbrand <david@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
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>,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
linux-mips@...r.kernel.org, kvm@...r.kernel.org,
kvm-ppc@...r.kernel.org, linux-kernel@...r.kernel.org,
David Matlack <dmatlack@...gle.com>,
Jing Zhang <jingzhangos@...gle.com>
Subject: [PATCH 14/14] KVM: x86: Invoke kvm_vcpu_block() directly for
non-HALTED wait states
Call kvm_vcpu_block() directly for all wait states except HALTED so that
kvm_vcpu_halt() is no longer a misnomer on x86.
Functionally, this means KVM will never attempt halt-polling or adjust
vcpu->halt_poll_ns for INIT_RECEIVED (a.k.a. Wait-For-SIPI (WFS)) or
AP_RESET_HOLD; UNINITIALIZED is handled in kvm_arch_vcpu_ioctl_run(),
and x86 doesn't use any other "wait" states.
As mentioned above, the motivation of this is purely so that "halt" isn't
overloaded on x86, e.g. in KVM's stats. Skipping halt-polling for WFS
(and RESET_HOLD) has no meaningful effect on guest performance as there
are typically single-digit numbers of INIT-SIPI sequences per AP vCPU,
per boot, versus thousands of HLTs just to boot to console.
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
arch/x86/kvm/x86.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b444f9315766..a0f313c4bc49 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9893,7 +9893,10 @@ static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu)
if (!kvm_arch_vcpu_runnable(vcpu) &&
(!kvm_x86_ops.pre_block || static_call(kvm_x86_pre_block)(vcpu) == 0)) {
srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
- kvm_vcpu_halt(vcpu);
+ if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED)
+ kvm_vcpu_halt(vcpu);
+ else
+ kvm_vcpu_block(vcpu);
vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
if (kvm_x86_ops.post_block)
--
2.33.0.685.g46640cef36-goog
Powered by blists - more mailing lists