From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@samba.org>,
Sethi Varun-B16395 <B16395@freescale.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [PATCH] vfio powerpc: enabled and supported on powernv platform
Date: Tue, 27 Nov 2012 11:21:41 +1100 [thread overview]
Message-ID: <1353975701.2179.18.camel@pasglop> (raw)
In-Reply-To: <1353953070.1809.103.camel@bling.home>
On Mon, 2012-11-26 at 11:04 -0700, Alex Williamson wrote:
> Ok, I see tces are put on shutdown via tce_iommu_detach_group, so you're
> more concerned about the guest simply mapping over top of it's own
> mappings. Is that common? Is it common enough for every multi-page
> mapping to assume it will happen? I know this is a performance
> sensitive path for you and it seems like a map-only w/ fallback to
> unmap, remap would be better in the general case.
>
> On x86 we do exactly that, but we do the unmap, remap from userspace
> when we get an EBUSY. Thanks,
Right, Linux as guest at least will never map "over" an existing
mapping. It will always unmap first. IE. The only transition we do on
H_PUT_TCE are 0 -> valid and valid -> 0.
So it would be fine to simplify the code and keep the "map over map" as
a slow fallback. I can't tell for other operating systems but we don't
care about those at this point :-)
Cheers,
Ben.
next prev parent reply other threads:[~2012-11-27 0:22 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20121113033832.GW4696@truffula.fritz.box>
2012-11-20 0:48 ` [PATCH] vfio powerpc: enabled and supported on powernv platform Alexey Kardashevskiy
2012-11-20 18:19 ` Alex Williamson
2012-11-22 11:56 ` Sethi Varun-B16395
2012-11-23 2:02 ` Alexey Kardashevskiy
2012-11-26 15:18 ` Alex Williamson
2012-11-26 18:04 ` Alex Williamson
2012-11-27 0:21 ` Benjamin Herrenschmidt [this message]
2012-11-27 3:28 ` Alexey Kardashevskiy
2012-11-27 4:23 ` Alex Williamson
2012-11-26 15:08 ` Alex Williamson
2012-11-23 9:03 ` [PATCH 0/2] vfio powerpc: implemented and enabled Alexey Kardashevskiy
2012-11-23 9:03 ` [PATCH 1/2] vfio powerpc: implemented IOMMU driver for VFIO Alexey Kardashevskiy
2012-11-26 18:20 ` Alex Williamson
2012-11-27 4:06 ` Alexey Kardashevskiy
2012-11-27 4:29 ` Alex Williamson
2012-11-27 4:58 ` Alexey Kardashevskiy
2012-11-27 5:06 ` David Gibson
2012-11-27 5:07 ` Alex Williamson
2012-11-28 7:21 ` [PATCH] " Alexey Kardashevskiy
2012-11-28 21:01 ` Alex Williamson
2012-11-29 3:51 ` Alexey Kardashevskiy
2012-11-23 9:03 ` [PATCH 2/2] vfio powerpc: enabled on powernv platform Alexey Kardashevskiy
2012-11-27 4:41 ` Alex Williamson
2012-11-28 7:18 ` [PATCH] " Alexey Kardashevskiy
2012-11-28 21:30 ` Alex Williamson
2012-11-29 3:53 ` Alexey Kardashevskiy
2012-11-29 4:20 ` Alex Williamson
2012-11-30 6:14 ` Alexey Kardashevskiy
2012-11-30 16:48 ` Alex Williamson
2012-12-01 0:14 ` Alexey Kardashevskiy
2012-11-30 6:16 ` Alexey Kardashevskiy
2012-12-03 2:52 ` [PATCH 0/2] vfio on power: yet another try Alexey Kardashevskiy
2012-12-03 2:52 ` [PATCH 1/2] vfio powerpc: enabled on powernv platform Alexey Kardashevskiy
2012-12-03 17:35 ` Alex Williamson
2012-12-04 8:12 ` Alexey Kardashevskiy
2012-12-04 15:51 ` Alex Williamson
2012-12-07 7:35 ` [PATCH] " Alexey Kardashevskiy
2012-12-07 17:38 ` Alex Williamson
2012-12-12 6:14 ` Alexey Kardashevskiy
2012-12-12 14:34 ` Alex Williamson
2012-12-13 2:29 ` Benjamin Herrenschmidt
2012-12-13 6:27 ` Alexey Kardashevskiy
2012-12-12 12:34 ` Alexey Kardashevskiy
2012-12-12 12:38 ` Alexey Kardashevskiy
2012-12-12 23:30 ` Alex Williamson
2012-12-13 2:24 ` Alexey Kardashevskiy
2012-12-13 2:39 ` Benjamin Herrenschmidt
2012-12-13 2:57 ` Benjamin Herrenschmidt
2012-12-13 3:22 ` Alex Williamson
2012-12-03 2:52 ` [PATCH 2/2] vfio powerpc: implemented IOMMU driver for VFIO Alexey Kardashevskiy
2012-12-03 17:53 ` Alex Williamson
2012-12-07 7:34 ` [PATCH] " Alexey Kardashevskiy
2012-12-07 17:01 ` Alex Williamson
2012-12-12 6:59 ` Alexey Kardashevskiy
2012-12-12 14:36 ` Alex Williamson
2012-12-12 12:35 ` Alexey Kardashevskiy
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