From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Frederic Barrat <fbarrat@linux.vnet.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org, andrew.donnellan@au1.ibm.com,
clombard@linux.vnet.ibm.com, vaibhav@linux.vnet.ibm.com
Cc: alistair@popple.id.au
Subject: Re: [PATCH v2 1/3] powerpc/mm: Export flush_all_mm()
Date: Thu, 31 Aug 2017 07:01:11 +1000 [thread overview]
Message-ID: <1504126871.4974.23.camel@kernel.crashing.org> (raw)
In-Reply-To: <77b082b9-0e6e-ed38-3a4e-af7797990ef3@linux.vnet.ibm.com>
On Wed, 2017-08-30 at 15:59 +0200, Frederic Barrat wrote:
> > It's not clear why it makes sense for these to be empty. Either for the
> > general idea of the "flush_all_mm()" API, or for your intended use by
> > CXL.
>
> I was not too sure what to do for hash, but the idea is that the new
> flush_all_mm() is really the equivalent of the old flush_tlb_mm() from
> before Ben's optimizations for radix, and that was/still is an empty
> operation on hash, so I kept it that way.
>
> We don't support hash for capi2 yet. Adding it will definitely require
> some work in that area, as the current approach (use count on the driver
> and all TLBIs becoming global when the driver is in use) won't hold much
> longer.
Why not ? It would work fine on hash, but you do need a way to flush
the TLB when decreasing the count indeed and that's missing for hash.
Cheers,
Ben.
next prev parent reply other threads:[~2017-08-30 21:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-30 10:15 [PATCH v2 1/3] powerpc/mm: Export flush_all_mm() Frederic Barrat
2017-08-30 10:15 ` [PATCH v2 2/3] cxl: Fix driver use count Frederic Barrat
2017-08-30 13:18 ` Michael Ellerman
2017-08-31 11:36 ` [v2,2/3] " Michael Ellerman
2017-08-30 10:15 ` [PATCH v2 3/3] cxl: Enable global TLBIs for cxl contexts Frederic Barrat
2017-08-30 13:17 ` [PATCH v2 1/3] powerpc/mm: Export flush_all_mm() Michael Ellerman
2017-08-30 13:59 ` Frederic Barrat
2017-08-30 21:01 ` Benjamin Herrenschmidt [this message]
2017-08-31 9:13 ` Frederic Barrat
2017-08-30 21:00 ` Benjamin Herrenschmidt
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