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From: Paolo Bonzini <pbonzini@redhat.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: "Liu Ping Fan" <pingfank@linux.vnet.ibm.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	"Alexander Graf" <agraf@suse.de>,
	"Hervé Poussineau" <hpoussin@reactos.org>,
	"Jan Kiszka" <jan.kiszka@web.de>,
	"Andreas Färber" <afaerber@suse.de>
Subject: Re: [Qemu-devel] [PATCH v3 11/14] ioport: Switch dispatching to memory core layer
Date: Sun, 14 Jul 2013 08:15:50 +0200	[thread overview]
Message-ID: <51E24216.4050406@redhat.com> (raw)
In-Reply-To: <CA+aC4ks0PUZVbeMw6Mo5K9AEr5GA3m+kbDP=Ri+Wn4y7r47=3Q@mail.gmail.com>

Il 13/07/2013 17:22, Anthony Liguori ha scritto:
> 1) MMIO request goes to sPAPR PIO area, the vCPU was in BE mode but by
> the time the handler is called, the value is in host byte order.
> 
> 2) sPAPR (incorrectly) byte swaps by marking the region as little
> endian (data is now garbage)
> 
> 3) The portio layer (incorrectly) byte swaps because it is marked as
> little endian (data is now good)
> 
> 4) Dispatch happens to VGA device which (incorrectly) byte swaps
> because it is marked as little endian (data is now bad)
> 
> (2), (3), and (4) are all wrong.  By removing either (2) or (3) we can
> "fix" the regression but that's just because two wrongs make a right
> in this situation.
> 
> We should remove *all* of the LE markings from ISA devices, remove the
> portio mark, and the sPAPR mark.  That's the right fix.

So the bug here is that we have multiple levels of dispatch.  Byte
swapping in the dispatch level only works as long as every dispatch is
merged, which is not the case.

However, I do suspect that you have broken PREP again, because PREP has
1/3/4 but not 2.  Removing (2) IIUC amounts to re-applying commit
a178274efabcbbc5d44805b51def874e47051325, and I think that's a better fix.

Also, what devices exactly would have a non-native byte order?!?  I'm
confused...

Paolo

  parent reply	other threads:[~2013-07-14  6:16 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-22  6:06 [Qemu-devel] [PATCH v3 00/14] Refactor portio dispatching Jan Kiszka
2013-06-22  6:06 ` [Qemu-devel] [PATCH v3 01/14] adlib: replace register_ioport* Jan Kiszka
2013-06-22  6:06 ` [Qemu-devel] [PATCH v3 02/14] applesmc: " Jan Kiszka
2013-06-22  6:06 ` [Qemu-devel] [PATCH v3 03/14] wdt_ib700: " Jan Kiszka
2013-06-22  6:06 ` [Qemu-devel] [PATCH v3 04/14] i82374: " Jan Kiszka
2013-06-22  6:06 ` [Qemu-devel] [PATCH v3 05/14] prep: " Jan Kiszka
2013-06-22  6:06 ` [Qemu-devel] [PATCH v3 06/14] vt82c686: " Jan Kiszka
2013-06-22  6:07 ` [Qemu-devel] [PATCH v3 07/14] Privatize register_ioport_read/write Jan Kiszka
2013-06-22  6:07 ` [Qemu-devel] [PATCH v3 08/14] isa: implement isa_is_ioport_assigned via memory_region_find Jan Kiszka
2013-06-22  6:07 ` [Qemu-devel] [PATCH v3 09/14] vmware-vga: Accept unaligned I/O accesses Jan Kiszka
2013-06-22  6:07 ` [Qemu-devel] [PATCH v3 10/14] xen: Mark fixed platform I/O as unaligned Jan Kiszka
2013-06-22  6:07 ` [Qemu-devel] [PATCH v3 11/14] ioport: Switch dispatching to memory core layer Jan Kiszka
2013-06-23 20:50   ` Hervé Poussineau
2013-06-24  6:07     ` Jan Kiszka
2013-07-11 12:29       ` Alexander Graf
2013-07-11 12:34         ` Alexander Graf
2013-07-11 12:46           ` Andreas Färber
2013-07-11 12:48             ` Alexander Graf
2013-07-11 13:28               ` Alexander Graf
2013-07-11 13:35                 ` Alexander Graf
2013-07-11 22:30                 ` [Qemu-devel] [Qemu-ppc] " Benjamin Herrenschmidt
2013-07-11 22:32                 ` Benjamin Herrenschmidt
2013-07-12  3:18                   ` Alexander Graf
2013-07-12 11:35                     ` Benjamin Herrenschmidt
2013-07-12 17:04                       ` Hervé Poussineau
2013-07-12 19:06                         ` Anthony Liguori
2013-07-12 22:59                           ` Benjamin Herrenschmidt
2013-07-12 22:39                         ` Benjamin Herrenschmidt
2013-07-12 17:49                       ` Anthony Liguori
2013-07-12 18:26                         ` Peter Maydell
2013-07-12 22:50                           ` Benjamin Herrenschmidt
2013-07-12 23:10                             ` Peter Maydell
2013-07-12 23:49                               ` Benjamin Herrenschmidt
2013-07-15 14:01                               ` Anthony Liguori
2013-07-15 14:10                                 ` Peter Maydell
2013-07-15 14:16                                 ` Benjamin Herrenschmidt
2013-07-12 22:44                         ` Benjamin Herrenschmidt
2013-07-13 14:38             ` [Qemu-devel] " Paolo Bonzini
2013-07-13 15:22               ` Anthony Liguori
2013-07-13 18:11                 ` Hervé Poussineau
2013-07-14  6:15                 ` Paolo Bonzini [this message]
2013-07-14 13:05                   ` Anthony Liguori
2013-07-14 14:58                     ` Peter Maydell
2013-07-14 15:18                       ` Anthony Liguori
2013-07-14 16:50                         ` Peter Maydell
2013-07-16  7:18                         ` Jan Kiszka
2013-07-16  7:33                           ` Paolo Bonzini
2013-07-16 16:59                             ` Hervé Poussineau
2013-07-16 17:12                               ` Paolo Bonzini
2013-07-12 12:56           ` Anthony Liguori
2013-07-12 14:30             ` Alexander Graf
2013-07-19 11:09         ` [Qemu-devel] BUG: " Alexey Kardashevskiy
2013-07-19 12:49           ` Paolo Bonzini
2013-07-19 15:48             ` Alexey Kardashevskiy
2013-07-20  0:55               ` Alexey Kardashevskiy
2013-07-20  1:11                 ` Alexey Kardashevskiy
2013-07-20 10:11                   ` Paolo Bonzini
2013-07-20 20:53                     ` Edgar E. Iglesias
2013-07-21 15:13                     ` Hervé Poussineau
2013-07-22 10:25                       ` Paolo Bonzini
2013-06-24  8:45     ` [Qemu-devel] [PATCH v4 " Jan Kiszka
2013-07-12 19:36     ` [Qemu-devel] [PATCH v3 " Anthony Liguori
2013-06-22  6:07 ` [Qemu-devel] [PATCH v3 12/14] ioport: Remove unused old dispatching services Jan Kiszka
2013-06-22  6:07 ` [Qemu-devel] [PATCH v3 13/14] vmport: Disentangle read handler type from portio Jan Kiszka
2013-06-22  6:07 ` [Qemu-devel] [PATCH v3 14/14] ioport: Move portio types to ioport.h Jan Kiszka
2013-06-23 20:45 ` [Qemu-devel] [PATCH v3 00/14] Refactor portio dispatching Hervé Poussineau

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