From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Roman Kagan <rkagan@virtuozzo.com>,
Suleiman Souhlal <suleiman@google.com>,
pbonzini@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de,
john.stultz@linaro.org, sboyd@kernel.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
ssouhlal@freebsd.org, tfiga@chromium.org, vkuznets@redhat.com
Subject: Re: [RFC v2 0/2] kvm: Use host timekeeping in guest.
Date: Fri, 11 Oct 2019 14:50:50 -0400 [thread overview]
Message-ID: <20191011185050.GJ691@char.us.oracle.com> (raw)
In-Reply-To: <20191010103939.GA12088@rkaganb.sw.ru>
.snip..
> I wonder how feasible it is to map the host's vdso into the guest and
> thus make the guest use the *same* (as opposed to "synchronized") clock
> as the host's userspace? Another benefit is that it's essentially an
> ABI so is not changed as liberally as internal structures like
> timekeeper, etc. There is probably certain complication in handling the
> syscall fallback in the vdso when used in the guest kernel, though.
>
> You'll also need to ensure neither tsc scaling and nor offsetting is
> applied to the VM once this clock is enabled.
This is how Xen does it - you can register the hypervisor to timestamp
your vDSO regions if you want it. See xen_setup_vsyscall_time_info
>
> Roman.
next prev parent reply other threads:[~2019-10-11 18:48 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 7:30 [RFC v2 0/2] kvm: Use host timekeeping in guest Suleiman Souhlal
2019-10-10 7:30 ` [RFC v2 1/2] kvm: Mechanism to copy host timekeeping parameters into guest Suleiman Souhlal
2019-10-10 8:31 ` Vitaly Kuznetsov
2019-10-10 10:50 ` Paolo Bonzini
2019-10-10 7:30 ` [RFC v2 2/2] x86/kvmclock: Introduce kvm-hostclock clocksource Suleiman Souhlal
2019-10-10 8:37 ` Vitaly Kuznetsov
2019-10-10 10:55 ` Paolo Bonzini
2019-10-15 8:39 ` Suleiman Souhlal
2019-10-15 8:59 ` Paolo Bonzini
2019-10-10 10:39 ` [RFC v2 0/2] kvm: Use host timekeeping in guest Roman Kagan
2019-10-11 18:50 ` Konrad Rzeszutek Wilk [this message]
2019-10-15 5:08 ` Suleiman Souhlal
2019-10-10 10:43 ` Paolo Bonzini
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