Messages in this thread | | | Date | Thu, 23 Feb 2023 09:03:08 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH mm-unstable v1 3/5] kvm/arm64: add kvm_arch_test_clear_young() |
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On Thu, 23 Feb 2023 03:58:47 +0000, Yu Zhao <yuzhao@google.com> wrote: > > On Fri, Feb 17, 2023 at 2:00 AM Marc Zyngier <maz@kernel.org> wrote: > > > > On Fri, 17 Feb 2023 04:21:28 +0000, > > Yu Zhao <yuzhao@google.com> wrote: > > > > > > On Thu, Feb 16, 2023 at 9:12 PM Yu Zhao <yuzhao@google.com> wrote: > > > > > > > > This patch adds kvm_arch_test_clear_young() for the vast majority of > > > > VMs that are not pKVM and run on hardware that sets the accessed bit > > > > in KVM page tables. > > > > I'm really interested in how you can back this statement. 90% of the > > HW I have access to is not FEAT_HWAFDB capable, either because it > > predates the feature or because the feature is too buggy to be useful. > > This is my expericen too -- most devices are pre v8.2.
And yet you have no issue writing the above. Puzzling.
> > > Do you have numbers? > > Let's do a quick market survey by segment. The following only applies > to ARM CPUs: > > 1. Phones: none of the major Android phone vendors sell phones running > VMs; no other major Linux phone vendors.
Maybe you should have a reality check and look at what your own employer is shipping.
> 2. Laptops: only a very limited number of Chromebooks run VMs, namely > ACRVM. No other major Linux laptop vendors.
Again, your employer disagree.
> 3. Desktops: no major Linux desktop vendors.
My desktop disagree (I send this from my arm64 desktop VM ).
> 4. Embedded/IoT/Router: no major Linux vendors run VMs (Android Auto > can be a VM guest on QNX host).
This email is brought to you via a router VM on an arm64 box.
> 5. Cloud: this is where the vast majority VMs come from. Among the > vendors available to the general public, Ampere is the biggest player. > Here [1] is a list of its customers. The A-bit works well even on its > EVT products (Neoverse cores).
Just the phone stuff dwarfs the number of cloud hosts.
Hopefully your patches are better than your market analysis...
M.
-- Without deviation from the norm, progress is not possible.
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