From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bhushan Bharat-R65777 <R65777@freescale.com>
Cc: Wood Scott-B07421 <B07421@freescale.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"agraf@suse.de" <agraf@suse.de>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH 6/6 v2] kvm: powerpc: use caching attributes as per linux pte
Date: Sat, 03 Aug 2013 14:25:38 +1000 [thread overview]
Message-ID: <1375503938.15999.82.camel@pasglop> (raw)
In-Reply-To: <6A3DF150A5B70D4F9B66A25E3F7C888D070F8FE9@039-SN2MPN1-012.039d.mgd.msft.net>
On Sat, 2013-08-03 at 03:11 +0000, Bhushan Bharat-R65777 wrote:
>
> >
> > Could you explain why we need to set dirty/referenced on the PTE, when we didn't
> > need to do that before? All we're getting from the PTE is wimg.
> > We have MMU notifiers to take care of the page being unmapped, and we've already
> > marked the page itself as dirty if the TLB entry is writeable.
>
> I pulled this code from book3s.
>
> Ben, can you describe why we need this on book3s ?
If you let the guest write to the page you must set the dirty bit on the PTE
(or the struct page, at least one of them), similar with accessed on any access.
If you don't, the VM might swap the page out without writing it back to disk
for example, assuming it contains no modified data.
Cheers,
Ben.
next prev parent reply other threads:[~2013-08-03 4:25 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-01 11:12 [PATCH 0/6 v2] kvm: powerpc: use cache attributes from linux pte Bharat Bhushan
2013-08-01 11:12 ` [PATCH 1/6 v2] powerpc: book3e: _PAGE_LENDIAN must be _PAGE_ENDIAN Bharat Bhushan
2013-08-01 11:12 ` [PATCH 2/6 v2] kvm: powerpc: allow guest control "E" attribute in mas2 Bharat Bhushan
2013-08-01 11:12 ` [PATCH 3/6 v2] kvm: powerpc: allow guest control "G" " Bharat Bhushan
2013-08-02 6:39 ` "“tiejun.chen”"
2013-08-01 11:12 ` [PATCH 4/6 v2] powerpc: move linux pte/hugepte search to more generic file Bharat Bhushan
2013-08-01 11:12 ` [PATCH 5/6 v2] kvm: powerpc: booke: Add linux pte lookup like booke3s Bharat Bhushan
2013-08-02 6:37 ` "“tiejun.chen”"
2013-08-02 22:58 ` Scott Wood
2013-08-02 23:16 ` Benjamin Herrenschmidt
2013-08-03 2:58 ` Bhushan Bharat-R65777
2013-08-03 4:24 ` Benjamin Herrenschmidt
2013-08-05 14:27 ` Bhushan Bharat-R65777
2013-08-05 19:19 ` Scott Wood
2013-08-06 1:12 ` Bhushan Bharat-R65777
2013-08-06 7:02 ` Bhushan Bharat-R65777
2013-08-07 0:24 ` Paul Mackerras
2013-08-07 1:11 ` Scott Wood
2013-08-07 1:47 ` Paul Mackerras
2013-08-06 14:46 ` Bhushan Bharat-R65777
2013-08-01 11:12 ` [PATCH 6/6 v2] kvm: powerpc: use caching attributes as per linux pte Bharat Bhushan
2013-08-02 6:24 ` "“tiejun.chen”"
2013-08-02 23:34 ` Scott Wood
2013-08-03 3:11 ` Bhushan Bharat-R65777
2013-08-03 4:25 ` Benjamin Herrenschmidt [this message]
2013-08-05 16:28 ` Scott Wood
2013-08-05 16:30 ` Scott Wood
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