From: Balbir Singh <bsingharora@gmail.com>
To: Alistair Popple <alistair@popple.id.au>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
Jason Wang <jasowang@redhat.com>,
Mark Hairgrove <mhairgrove@nvidia.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Peter Xu <peterx@redhat.com>, Jerome Glisse <jglisse@redhat.com>,
Paul Mackerras <paulus@samba.org>,
"open list:LINUX FOR POWERPC \(32-BIT AND 64-BIT\)"
<linuxppc-dev@lists.ozlabs.org>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH] powerpc/powernv/npu: Remove redundant change_pte() hook
Date: Wed, 6 Feb 2019 13:55:49 +1100 [thread overview]
Message-ID: <CAKTCnzmC74fQ_NCGvvXY3sv--hp-C094jVy8JfCUYqwp_wcBAg@mail.gmail.com> (raw)
In-Reply-To: <3013350.qntrAZtlsQ@townsend>
On Tue, Feb 5, 2019 at 2:52 PM Alistair Popple <alistair@popple.id.au> wrote:
>
> On Thursday, 31 January 2019 12:11:06 PM AEDT Andrea Arcangeli wrote:
> > On Thu, Jan 31, 2019 at 06:30:22PM +0800, Peter Xu wrote:
> > > The change_pte() notifier was designed to use as a quick path to
> > > update secondary MMU PTEs on write permission changes or PFN changes.
> > > For KVM, it could reduce the vm-exits when vcpu faults on the pages
> > > that was touched up by KSM. It's not used to do cache invalidations,
> > > for example, if we see the notifier will be called before the real PTE
> > > update after all (please see set_pte_at_notify that set_pte_at was
> > > called later).
>
> Thanks for the fixup. I didn't realise that invalidate_range() always gets
> called but I now see that is the case so this change looks good to me as well.
>
> Reviewed-by: Alistair Popple <alistair@popple.id.au>
>
I checked the three callers of set_pte_at_notify and the assumption
seems correct
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
next prev parent reply other threads:[~2019-02-06 2:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-31 10:30 [PATCH] powerpc/powernv/npu: Remove redundant change_pte() hook Peter Xu
2019-01-31 17:11 ` Andrea Arcangeli
2019-02-05 3:52 ` Alistair Popple
2019-02-06 2:55 ` Balbir Singh [this message]
2019-02-22 9:47 ` Michael Ellerman
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