Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush
Date	2017-08-11 18:30 +0200
Message-ID	<udkYX-5NJ-39@gated-at.bofh.it> (permalink)
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On Fri, Aug 11, 2017 at 09:16:29AM -0700, Linus Torvalds wrote:
> On Fri, Aug 11, 2017 at 2:03 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > I'm sure we talked about using HAVE_RCU_TABLE_FREE for x86 (and yes that
> > would make it work again), but this was some years ago and I cannot
> > readily find those emails.
> 
> I think the only time we really talked about HAVE_RCU_TABLE_FREE for
> x86 (at least that I was cc'd on) was not because of RCU freeing, but
> because we just wanted to use the generic page table lookup code on
> x86 *despite* not using RCU freeing.
> 
> And we just ended up renaming HAVE_GENERIC_RCU_GUP as HAVE_GENERIC_GUP.
> 
> There was only passing mention of maybe making x86 use RCU, but the
> discussion was really about why the IF flag meant that x86 didn't need
> to, iirc.
> 
> I don't recall us ever discussing *really* making x86 use RCU.

Google finds me this:

  https://lwn.net/Articles/500188/

Which includes:

  http://www.mail-archive.com/kvm@vger.kernel.org/msg72918.html

which does as was suggested here, selects HAVE_RCU_TABLE_FREE for
PARAVIRT_TLB_FLUSH.

But yes, this is very much virt specific nonsense, native would never
need this.

Thread

[PATCH v10 0/9] Hyper-V: paravirtualized remote TLB flushing and hypercall improvements Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:10 +0200
  [PATCH v10 1/9] x86/hyper-v: include hyperv/ only when CONFIG_HYPERV is set Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:10 +0200
    [tip:x86/platform] x86/hyper-v: Include hyperv/ only when  CONFIG_HYPERV is set tip-bot for Vitaly Kuznetsov <tipbot@zytor.com> - 2017-08-10 18:50 +0200
  [PATCH v10 3/9] x86/hyper-v: fast hypercall implementation Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:10 +0200
    [tip:x86/platform] x86/hyper-v: Introduce fast hypercall  implementation tip-bot for Vitaly Kuznetsov <tipbot@zytor.com> - 2017-08-10 18:50 +0200
  [PATCH v10 7/9] x86/hyper-v: use hypercall for remote TLB flush Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:20 +0200
    [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush tip-bot for Vitaly Kuznetsov <tipbot@zytor.com> - 2017-08-10 18:50 +0200
    [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush tip-bot for Vitaly Kuznetsov <tipbot@zytor.com> - 2017-08-10 20:30 +0200
      Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Peter Zijlstra <peterz@infradead.org> - 2017-08-10 21:00 +0200
        Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Peter Zijlstra <peterz@infradead.org> - 2017-08-10 21:30 +0200
          Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Peter Zijlstra <peterz@infradead.org> - 2017-08-11 11:10 +0200
            Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-08-11 13:30 +0200
            Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush Linus Torvalds <torvalds@linux-foundation.org> - 2017-08-11 18:20 +0200
              Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Peter Zijlstra <peterz@infradead.org> - 2017-08-11 18:30 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-14 15:30 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-16 18:50 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-08-16 23:50 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-17 10:00 +0200
          Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB flush Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-11 11:30 +0200
            Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Peter Zijlstra <peterz@infradead.org> - 2017-08-11 13:00 +0200
              Re: [Xen-devel] [tip:x86/platform] x86/hyper-v: Use hypercall for  remote TLB flush Andrew Cooper <andrew.cooper3@citrix.com> - 2017-08-11 13:10 +0200
                Re: [Xen-devel] [tip:x86/platform] x86/hyper-v: Use hypercall for  remote TLB flush Peter Zijlstra <peterz@infradead.org> - 2017-08-11 14:10 +0200
                Re: [Xen-devel] [tip:x86/platform] x86/hyper-v: Use hypercall for  remote TLB flush Steven Rostedt <rostedt@goodmis.org> - 2017-08-16 02:10 +0200
              Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Juergen Gross <jgross@suse.com> - 2017-08-11 14:30 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Peter Zijlstra <peterz@infradead.org> - 2017-08-11 14:40 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Juergen Gross <jgross@suse.com> - 2017-08-11 14:50 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Peter Zijlstra <peterz@infradead.org> - 2017-08-11 15:00 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Juergen Gross <jgross@suse.com> - 2017-08-11 15:10 +0200
                Re: [tip:x86/platform] x86/hyper-v: Use hypercall for remote TLB  flush Peter Zijlstra <peterz@infradead.org> - 2017-08-11 15:50 +0200
  [PATCH v10 4/9] hyper-v: use fast hypercall for HVCALL_SIGNAL_EVENT Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:20 +0200
    [tip:x86/platform] hyper-v: Use fast hypercall for  HVCALL_SIGNAL_EVENT tip-bot for Vitaly Kuznetsov <tipbot@zytor.com> - 2017-08-10 18:50 +0200
  [PATCH v10 5/9] x86/hyper-v: implement rep hypercalls Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:20 +0200
    [tip:x86/platform] x86/hyper-v: Implement rep hypercalls tip-bot for Vitaly Kuznetsov <tipbot@zytor.com> - 2017-08-10 18:50 +0200
  [PATCH v10 8/9] x86/hyper-v: support extended CPU ranges for TLB flush hypercalls Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:20 +0200
  [PATCH v10 9/9] tracing/hyper-v: trace hyperv_mmu_flush_tlb_others() Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:20 +0200
  [PATCH v10 6/9] hyper-v: globalize vp_index Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-02 18:20 +0200
    [tip:x86/platform] hyper-v: Globalize vp_index tip-bot for Vitaly Kuznetsov <tipbot@zytor.com> - 2017-08-10 18:50 +0200
  Re: [PATCH v10 0/9] Hyper-V: paravirtualized remote TLB flushing and hypercall improvements Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-10 14:00 +0200
    Re: [PATCH v10 0/9] Hyper-V: paravirtualized remote TLB flushing and  hypercall improvements Ingo Molnar <mingo@kernel.org> - 2017-08-10 17:20 +0200
      Re: [PATCH v10 0/9] Hyper-V: paravirtualized remote TLB flushing and hypercall improvements Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-10 17:20 +0200
  Re: [PATCH v10 0/9] Hyper-V: paravirtualized remote TLB flushing and hypercall improvements Vitaly Kuznetsov <vkuznets@redhat.com> - 2017-08-10 19:10 +0200

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