From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Matlack Date: Tue, 28 Sep 2021 22:12:50 +0000 Subject: Re: [PATCH 13/14] KVM: x86: Directly block (instead of "halting") UNINITIALIZED vCPUs Message-Id: List-Id: References: <20210925005528.1145584-1-seanjc@google.com> <20210925005528.1145584-14-seanjc@google.com> In-Reply-To: <20210925005528.1145584-14-seanjc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Sean Christopherson Cc: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Christian Borntraeger , Janosch Frank , Paolo Bonzini , James Morse , Alexandru Elisei , Suzuki K Poulose , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, Jing Zhang On Fri, Sep 24, 2021 at 05:55:27PM -0700, Sean Christopherson wrote: > Go directly to kvm_vcpu_block() when handling the case where userspace > attempts to run an UNINITIALIZED vCPU. The vCPU isn't halted and its time > spent in limbo arguably should not be factored into halt-polling as the > behavior of the VM at this point is not at all indicative of the behavior > of the VM once it is up and running, i.e. executing HLT in idle tasks. > > Note, because this case is encountered only on the first run of an AP vCPU, > vcpu->halt_poll_ns is guaranteed to be '0', and so KVM will not attempt > halt-polling, i.e. this really only affects the post-block bookkeeping. > > Signed-off-by: Sean Christopherson Reviewed-by: David Matlack > --- > arch/x86/kvm/x86.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 0d71c73a61bb..b444f9315766 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10127,7 +10127,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) > r = -EINTR; > goto out; > } > - kvm_vcpu_halt(vcpu); > + kvm_vcpu_block(vcpu); > if (kvm_apic_accept_events(vcpu) < 0) { > r = 0; > goto out; > -- > 2.33.0.685.g46640cef36-goog >