From mboxrd@z Thu Jan  1 00:00:00 1970
From: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Date: Thu, 20 Jun 2019 01:45:16 +0000
Subject: Re: [PATCH 0/2] Fix handling of h_set_dawr
Message-Id: <1560995116.4771.1.camel@gmail.com>
List-Id: <kvm-ppc.vger.kernel.org>
References: <20190617071619.19360-1-sjitindarsingh@gmail.com>
 <87e219c8-1db7-9976-03ce-5a566a8df7ab@kaod.org>
In-Reply-To: <87e219c8-1db7-9976-03ce-5a566a8df7ab@kaod.org>
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To: =?ISO-8859-1?Q?C=E9dric?= Le Goater <clg@kaod.org>, linuxppc-dev@lists.ozlabs.org
Cc: mikey@neuling.org, kvm-ppc@vger.kernel.org

On Mon, 2019-06-17 at 11:06 +0200, C=C3=A9dric Le Goater wrote:
> On 17/06/2019 09:16, Suraj Jitindar Singh wrote:
> > Series contains 2 patches to fix the host in kernel handling of the
> > hcall
> > h_set_dawr.
> >=20
> > First patch from Michael Neuling is just a resend added here for
> > clarity.
> >=20
> > Michael Neuling (1):
> >   KVM: PPC: Book3S HV: Fix r3 corruption in h_set_dabr()
> >=20
> > Suraj Jitindar Singh (1):
> >   KVM: PPC: Book3S HV: Only write DAWR[X] when handling h_set_dawr
> > in
> >     real mode
>=20
>=20
>=20
> Reviewed-by: C=C3=A9dric Le Goater <clg@kaod.org>
>=20
> and=20
>=20
> Tested-by: C=C3=A9dric Le Goater <clg@kaod.org>
>=20
>=20
> but I see slowdowns in nested as if the IPIs were not delivered. Have
> we
> touch this part in 5.2 ?=20

Hi,

I've seen the same and tracked it down to decrementer exceptions not
being delivered when the guest is using large decrementer. I've got a
patch I'm about to send so I'll CC you.

Another option is to disable the large decrementer with:
-machine pseries,cap-large-decr=FAlse

Thanks,
Suraj

>=20
> Thanks,
>=20
> C.
>=20