From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Nicholas Piggin <npiggin@gmail.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: paulus@samba.org, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org
Subject: Re: [for-4.8, 1/2] powerpc/mm: Switch user slb fault handling to translation enabled
Date: Fri, 22 Jul 2016 23:40:43 +1000 [thread overview]
Message-ID: <1469194843.8568.179.camel@kernel.crashing.org> (raw)
In-Reply-To: <20160722223738.62a27fed@roar.ozlabs.ibm.com>
On Fri, 2016-07-22 at 22:37 +1000, Nicholas Piggin wrote:
> > We also handle fault with proper stack initialized. This enable us
> to
> > callout to C in fault handling routines. We don't do this for
> kernel
> > mapping, because of the possibility of taking recursive fault if
> > kernel stack in not yet mapped by an slb entry.
> >
> > This enable us to handle Power9 slb fault better. We will add
> bolted
> > entries for the entire kernel mapping in segment table and user slb
> > entries we take fault and insert on demand. With translation on, we
> > should be able to access segment table from fault handler.
>
> What does this cost on P8? Is that a problem? Might need to do
> feature bits.
Also what is the need ?
The segment table is only for Nest MMU clients, we should probably
handle it separately.
Cheers,
Ben.
next prev parent reply other threads:[~2016-07-22 13:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-13 9:40 [PATCH for-4.8_set4 0/2] Segment table support Aneesh Kumar K.V
2016-07-13 9:40 ` [PATCH for-4.8 1/2] powerpc/mm: Switch user slb fault handling to translation enabled Aneesh Kumar K.V
2016-07-22 12:37 ` [for-4.8, " Nicholas Piggin
2016-07-22 13:40 ` Benjamin Herrenschmidt [this message]
2016-07-13 9:40 ` [PATCH for-4.8 2/2] powerpc/mm: Support segment table for Power9 Aneesh Kumar K.V
2016-07-13 12:04 ` [PATCH for-4.8_set4 0/2] Segment table support Benjamin Herrenschmidt
2016-07-13 14:02 ` Aneesh Kumar K.V
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