From: Sean Christopherson <seanjc@google.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: "Ankur Arora" <ankur.a.arora@oracle.com>,
"Joao Martins" <joao.m.martins@oracle.com>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH RFC 03/39] KVM: x86/xen: register shared_info page
Date: Fri, 4 Dec 2020 09:30:02 -0800 [thread overview]
Message-ID: <X8pyGiVDuBGJmazJ@google.com> (raw)
In-Reply-To: <8c92b2f3a8e8829ec85d22091b2fe84794f12f78.camel@infradead.org>
On Thu, Dec 03, 2020, David Woodhouse wrote:
> On Wed, 2020-12-02 at 12:32 -0800, Ankur Arora wrote:
> > > On IRC, Paolo told me that permanent pinning causes problems for memory
> > > hotplug, and pointed me at the trick we do with an MMU notifier and
> > > kvm_vcpu_reload_apic_access_page().
> >
> > Okay that answers my question. Thanks for clearing that up.
> >
> > Not sure of a good place to document this but it would be good to
> > have this written down somewhere. Maybe kvm_map_gfn()?
>
> Trying not to get too distracted by polishing this part, so I can
> continue with making more things actually work. But I took a quick look
> at the reload_apic_access_page() thing.
>
> AFAICT it works because the access is only from *within* the vCPU, in
> guest mode.
>
> So all the notifier has to do is kick all CPUs, which happens when it
> calls kvm_make_all_cpus_request(). Thus we are guaranteed that all CPUs
> are *out* of guest mode by the time...
>
> ...er... maybe not by the time the notifier returns, because all
> we've done is *send* the IPI and we don't know the other CPUs have
> actually stopped running the guest yet?
>
> Maybe there's some explanation of why the actual TLB shootdown
> truly *will* occur before the page goes away, and some ordering
> rules which mean our reschedule IPI will happen first? Something
> like that ideally would have been in a comment in in MMU notifier.
KVM_REQ_APIC_PAGE_RELOAD is tagged with KVM_REQUEST_WAIT, which means that
kvm_kick_many_cpus() and thus smp_call_function_many() will have @wait=true,
i.e. the sender will wait for the SMP function call to finish on the target CPUs.
next prev parent reply other threads:[~2020-12-04 17:31 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 20:15 [PATCH RFC 00/39] x86/KVM: Xen HVM guest support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 01/39] KVM: x86: fix Xen hypercall page msr handling Joao Martins
2019-02-22 1:30 ` Sean Christopherson
2019-02-22 11:47 ` Joao Martins
2019-02-22 12:51 ` Paolo Bonzini
2020-11-30 10:39 ` David Woodhouse
2020-11-30 11:03 ` Paolo Bonzini
2020-11-30 11:27 ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 02/39] KVM: x86/xen: intercept xen hypercalls if enabled Joao Martins
2019-02-21 18:29 ` Sean Christopherson
2019-02-21 20:56 ` Joao Martins
2019-02-22 0:30 ` Sean Christopherson
2019-02-22 12:50 ` Paolo Bonzini
2020-12-01 9:48 ` David Woodhouse
2020-12-01 11:19 ` David Woodhouse
2020-12-02 11:17 ` Joao Martins
2020-12-02 12:12 ` David Woodhouse
2020-12-02 5:19 ` Ankur Arora
2020-12-02 8:03 ` David Woodhouse
2020-12-02 18:20 ` Ankur Arora
2019-02-20 20:15 ` [PATCH RFC 03/39] KVM: x86/xen: register shared_info page Joao Martins
2020-12-01 13:07 ` David Woodhouse
2020-12-02 0:40 ` Ankur Arora
2020-12-02 1:26 ` David Woodhouse
2020-12-02 5:17 ` Ankur Arora
2020-12-02 10:50 ` Joao Martins
2020-12-02 10:44 ` Joao Martins
2020-12-02 12:20 ` David Woodhouse
2020-12-02 20:32 ` Ankur Arora
2020-12-03 10:16 ` David Woodhouse
2020-12-04 17:30 ` Sean Christopherson [this message]
2020-12-02 20:33 ` Ankur Arora
2020-12-12 12:07 ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 04/39] KVM: x86/xen: setup pvclock updates Joao Martins
2019-02-20 20:15 ` [PATCH RFC 05/39] KVM: x86/xen: update wallclock region Joao Martins
2019-02-20 20:15 ` [PATCH RFC 06/39] KVM: x86/xen: register vcpu info Joao Martins
2019-02-20 20:15 ` [PATCH RFC 07/39] KVM: x86/xen: register vcpu time info region Joao Martins
2019-02-20 20:15 ` [PATCH RFC 08/39] KVM: x86/xen: register steal clock Joao Martins
2019-02-20 20:15 ` [PATCH RFC 09/39] KVM: x86: declare Xen HVM guest capability Joao Martins
2019-02-20 20:15 ` [PATCH RFC 10/39] KVM: x86/xen: support upcall vector Joao Martins
2020-12-02 11:17 ` David Woodhouse
2020-12-02 13:12 ` Joao Martins
2020-12-02 16:47 ` David Woodhouse
2020-12-02 18:34 ` Joao Martins
2020-12-02 19:02 ` David Woodhouse
2020-12-02 20:12 ` Joao Martins
2020-12-02 20:37 ` David Woodhouse
2020-12-03 1:08 ` Ankur Arora
2020-12-08 16:08 ` David Woodhouse
2020-12-09 6:35 ` Ankur Arora
2020-12-09 10:27 ` David Woodhouse
2020-12-09 10:51 ` Joao Martins
2020-12-09 11:39 ` David Woodhouse
2020-12-09 13:26 ` Joao Martins
2020-12-09 15:41 ` David Woodhouse
2020-12-09 16:12 ` Joao Martins
2021-01-01 14:33 ` David Woodhouse
2021-01-05 12:11 ` Joao Martins
2021-01-05 13:23 ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 11/39] KVM: x86/xen: evtchn signaling via eventfd Joao Martins
2020-11-30 9:41 ` David Woodhouse
2020-11-30 12:17 ` Joao Martins
2020-11-30 12:55 ` David Woodhouse
2020-11-30 15:08 ` Joao Martins
2020-11-30 16:48 ` David Woodhouse
2020-11-30 17:15 ` Joao Martins
2020-11-30 18:01 ` David Woodhouse
2020-11-30 18:41 ` Joao Martins
2020-11-30 19:04 ` David Woodhouse
2020-11-30 19:25 ` Joao Martins
2021-11-23 13:15 ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 12/39] KVM: x86/xen: store virq when assigning evtchn Joao Martins
[not found] ` <b750291466f3c89e0a393e48079c087704b217a5.camel@amazon.co.uk>
2022-02-10 12:17 ` Joao Martins
2022-02-10 15:23 ` [EXTERNAL] " David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 13/39] KVM: x86/xen: handle PV timers oneshot mode Joao Martins
2019-02-20 20:15 ` [PATCH RFC 14/39] KVM: x86/xen: handle PV IPI vcpu yield Joao Martins
2019-02-20 20:15 ` [PATCH RFC 15/39] KVM: x86/xen: handle PV spinlocks slowpath Joao Martins
2022-02-08 12:36 ` David Woodhouse
2022-02-10 12:17 ` Joao Martins
2022-02-10 14:11 ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 16/39] KVM: x86: declare Xen HVM evtchn offload capability Joao Martins
2019-02-20 20:15 ` [PATCH RFC 17/39] x86/xen: export vcpu_info and shared_info Joao Martins
2019-02-20 20:15 ` [PATCH RFC 18/39] x86/xen: make hypercall_page generic Joao Martins
2019-02-20 20:15 ` [PATCH RFC 19/39] xen/xenbus: xenbus uninit support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 20/39] xen-blkback: module_exit support Joao Martins
2019-02-25 18:57 ` Konrad Rzeszutek Wilk
2019-02-26 11:20 ` Joao Martins
2019-02-20 20:15 ` [PATCH RFC 21/39] KVM: x86/xen: domid allocation Joao Martins
2019-02-20 20:15 ` [PATCH RFC 22/39] KVM: x86/xen: grant table init Joao Martins
2019-02-20 20:15 ` [PATCH RFC 23/39] KVM: x86/xen: grant table grow support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 24/39] KVM: x86/xen: backend hypercall support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 25/39] KVM: x86/xen: grant map support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 26/39] KVM: x86/xen: grant unmap support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 27/39] KVM: x86/xen: grant copy support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 28/39] KVM: x86/xen: interdomain evtchn support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 29/39] KVM: x86/xen: evtchn unmask support Joao Martins
2019-02-20 20:16 ` [PATCH RFC 30/39] KVM: x86/xen: add additional evtchn ops Joao Martins
2019-02-20 20:16 ` [PATCH RFC 31/39] xen-shim: introduce shim domain driver Joao Martins
2019-02-20 20:16 ` [PATCH RFC 32/39] xen/balloon: xen_shim_domain() support Joao Martins
2019-02-20 20:16 ` [PATCH RFC 33/39] xen/grant-table: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 34/39] xen/gntdev: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 35/39] xen/xenbus: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 36/39] drivers/xen: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 37/39] xen-netback: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 38/39] xen-blkback: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 39/39] KVM: x86: declare Xen HVM Dom0 capability Joao Martins
2019-02-20 21:09 ` [PATCH RFC 00/39] x86/KVM: Xen HVM guest support Paolo Bonzini
2019-02-21 0:29 ` Ankur Arora
2019-02-21 11:45 ` Joao Martins
2019-02-22 16:59 ` Paolo Bonzini
2019-03-12 17:14 ` Joao Martins
2019-04-08 6:44 ` Juergen Gross
2019-04-08 10:36 ` Joao Martins
2019-04-08 10:42 ` Juergen Gross
2019-04-08 17:31 ` Joao Martins
2019-04-09 0:35 ` Stefano Stabellini
2019-04-10 5:50 ` [Xen-devel] " Ankur Arora
2019-04-10 20:45 ` Stefano Stabellini
2019-04-09 5:04 ` Juergen Gross
2019-04-10 6:55 ` Ankur Arora
2019-04-10 7:14 ` Juergen Gross
2019-02-20 23:39 ` [Xen-devel] " Marek Marczykowski-Górecki
2019-02-21 0:31 ` Ankur Arora
2019-02-21 7:57 ` Juergen Gross
2019-02-21 12:00 ` Joao Martins
2019-02-21 11:55 ` Joao Martins
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