From: Peter Zijlstra <peterz@infradead.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Paul Mackerras <paulus@ozlabs.org>,
akpm@linux-foundation.org, npiggin@gmail.com, will@kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org,
Scott Wood <oss@buserror.net>
Subject: Re: [PATCH v2 2/3] mm/mmu_gather: Invalidate TLB correctly on batch allocation failure and flush
Date: Wed, 18 Dec 2019 15:15:01 +0100 [thread overview]
Message-ID: <20191218141501.GT2844@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <87v9qdn5df.fsf@mpe.ellerman.id.au>
On Thu, Dec 19, 2019 at 12:13:48AM +1100, Michael Ellerman wrote:
> >> I'm a little confused though; if nohash is a software TLB fill, why do
> >> you need a TLBI for tables?
> >>
> >
> > nohash (AKA book3e) has different mmu modes. I don't follow all the
> > details w.r.t book3e. Paul or Michael might be able to explain the need
> > for table flush with book3e.
>
> Some of the Book3E CPUs have a partial hardware table walker. The IBM one (A2)
> did, before we ripped that support out. And the Freescale (NXP) e6500
> does, see eg:
>
> 28efc35fe68d ("powerpc/e6500: TLB miss handler with hardware tablewalk support")
>
> They only support walking one level IIRC, ie. you can create a TLB entry
> that points to a PTE page, and the hardware will dereference that to get
> a PTE and load that into the TLB.
Shiny!, all the embedded goodness. Thanks for the info.
next prev parent reply other threads:[~2019-12-18 14:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 5:35 [PATCH v2 1/3] powerpc/mmu_gather: Enable RCU_TABLE_FREE even for !SMP case Aneesh Kumar K.V
2019-12-18 5:35 ` [PATCH v2 2/3] mm/mmu_gather: Invalidate TLB correctly on batch allocation failure and flush Aneesh Kumar K.V
2019-12-18 9:17 ` Peter Zijlstra
2019-12-18 11:37 ` Aneesh Kumar K.V
2019-12-18 13:13 ` Michael Ellerman
2019-12-18 14:15 ` Peter Zijlstra [this message]
2019-12-18 5:35 ` [PATCH v2 3/3] asm-generic/tlb: Avoid potential double flush Aneesh Kumar K.V
2019-12-18 9:19 ` Peter Zijlstra
2019-12-18 9:14 ` [PATCH v2 1/3] powerpc/mmu_gather: Enable RCU_TABLE_FREE even for !SMP case Peter Zijlstra
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