From: Paolo Bonzini <pbonzini@redhat.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH] KVM: x86: update master clock before computing kvmclock_offset
Date: Wed, 17 May 2017 02:56:01 -0400 (EDT) [thread overview]
Message-ID: <1466623738.8419146.1495004161792.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20170516205000.5436-1-rkrcmar@redhat.com>
> I regret not pressing harder when we sanctified this frequency
> difference ... too late to make kvm clock follow the boot clock? :)
> ---
> arch/x86/kvm/x86.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b54125b590e8..b8aad0969690 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4180,9 +4180,15 @@ long kvm_arch_vm_ioctl(struct file *filp,
> goto out;
>
> r = 0;
> + /*
> + * TODO: userspace has to take care of races with VCPU_RUN, so
> + * kvm_gen_update_masterclock() can be cut down to locked
> + * pvclock_update_vm_gtod_copy().
> + */
> + kvm_gen_update_masterclock(kvm);
> now_ns = get_kvmclock_ns(kvm);
> kvm->arch.kvmclock_offset += user_ns.clock - now_ns;
> - kvm_gen_update_masterclock(kvm);
> + kvm_make_all_cpus_request(kvm, KVM_REQ_CLOCK_UPDATE);
> break;
Looks good, though I'd still prefer to do what the TODO says... I'll
try to put together a patch today.
Paolo
next prev parent reply other threads:[~2017-05-17 6:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-16 20:50 [PATCH] KVM: x86: update master clock before computing kvmclock_offset Radim Krčmář
2017-05-17 6:56 ` Paolo Bonzini [this message]
2017-05-30 13:12 ` Marcelo Tosatti
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