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From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	benh@kernel.crashing.org, paulus@samba.org
Cc: linuxppc-dev@lists.ozlabs.org,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: powerpc/mm/hash: Properly mask the ESID bits when building proto-VSID
Date: Wed,  1 Feb 2017 12:05:32 +1100 (AEDT)	[thread overview]
Message-ID: <3vClL46b5vz9tk1@ozlabs.org> (raw)
In-Reply-To: <20170128154840.32468-1-aneesh.kumar@linux.vnet.ibm.com>

On Sat, 2017-01-28 at 15:48:40 UTC, "Aneesh Kumar K.V" wrote:
> proto-vsid is built using both mmu context id and ESID. We should not have
> overlapping bits between those. That will result in us having vsid
> collision. With the current code we missed masking the top bits of effective
> address. This implies for kernel address we ended up using the top 4 bits
> as part of proto-vsid, which is wrong. For the kernel we should have the
> below mapping
> 
> 0xf000000000000000 -> 0x7ffff  (19 bits context + 6 bits ESID ).
> 
> Without the patch we endup with
> 0xf000000000000000 ->  0xf7ffff (0x7ffff | 0xf00000)
> 
> We didn't observe any issues till now possibly because we never end up
> using a context value which could map to the same  VSID as kernel.
> 
> Fixes: c60ac5693c4 ("powerpc: Update kernel VSID range")
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/79270e0a3fd124388a0407f9edbd6a

cheers

      parent reply	other threads:[~2017-02-01  1:05 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-28 15:48 [PATCH] powerpc/mm/hash: Properly mask the ESID bits when building proto-VSID Aneesh Kumar K.V
2017-01-30  4:44 ` Michael Ellerman
2017-02-01  1:05 ` Michael Ellerman [this message]

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