Re: [Qemu-devel] [PATCH 00/10] Fix versatile_pci (and break versatilepb linux guests!)

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Mar 24, 2013 at 04:58:37PM +0100, Aurelien Jarno wrote:
> On Sun, Mar 24, 2013 at 11:32:30AM +0000, Peter Maydell wrote:
> > This patch series fixes a number of serious bugs in our emulation of
> > the PCI controller found on VersatilePB and the early Realview boards:
> >  * our interrupt mapping was totally wrong
> >  * we weren't implementing the PCI memory windows
> >  * the I/O window wasn't mapped on VersatilePB
> >  * realview mapped things at the wrong addresses
> >  * we didn't implement the controller's registers at all
> > It also updates to some reasonable approximation to QOM best practice,
> > including subclassing pci_host rather than doing everything by hand.
> > 
> > I haven't implemented support for the SMAP registers (which control
> > how the controller converts accesses made by bus-mastering PCI
> > devices into system addresses). For the moment we rely on the fact
> > that Linux always maps things 1:1. (It wouldn't be too hard to add
> > SMAP support but it requires changing QEMU's pci code to allow a
> > controller to pass in a MemoryRegion* for DMA to use instead of
> > the system address space, so I prefer to leave that for another series.)
> > 
> > Patchset tested on both versatilepb and realview, using a set of
> > Linux kernel patches written by Arnd Bergmann:
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2010-October/029040.html
> > which were in turn tested against real PB926 and PB1176 hardware.
> > 
> > 
> >  * WARNING WARNING *
> > 
> > This patchset will break any use of PCI (including the default SCSI
> > card) on versatilepb with current Linux kernels, because those kernels
> 
> Do you mean Versatile/PB and not Versatile/AB, or actually both?
> 
> > have the matching bug in interrupt mapping to old QEMU.
> 
> How is real hardware working with this bug?
> 
> > I've provided a property for enabling the old broken IRQ mapping;
> > this can be enabled with the command line option:
> >       -global versatile_pci.broken-irq-mapping=1
> > 
> > (If anybody wants to suggest a better way of handling this please do.)
> 
> Do you have a pointer to the corresponding kernel patch? Is it possible
> to get the kernel to detect if it should use the correct or the broken 
> IRQ mapping?

Alternatively, or additionally, how about detecting the correct or
the incorrect kernel and updating the mapping?
For example, maybe we could do this using the
IRQ value written into the device pci config register?

If we can't find anything, maybe add our own register
so the same qemu config can support old and new kernels?

> 
> > Peter Maydell (10):
> >   versatile_pci: Fix hardcoded tabs
> >   versatile_pci: Expose PCI I/O region on Versatile PB
> >   versatile_pci: Update to realize and instance init functions
> >   versatile_pci: Change to subclassing TYPE_PCI_HOST_BRIDGE
> >   versatile_pci: Use separate PCI I/O space rather than system I/O space
> >   versatile_pci: Put the host bridge PCI device at slot 29
> >   versatile_pci: Implement the correct PCI IRQ mapping
> >   versatile_pci: Implement the PCI controller's control registers
> >   arm/realview: Fix mapping of PCI regions
> >   versatile_pci: Expose PCI memory space to system
> > 
> >  hw/arm/realview.c    |   22 +--
> >  hw/arm/versatilepb.c |   11 +-
> >  hw/versatile_pci.c   |  368 ++++++++++++++++++++++++++++++++++++++++++++------
> >  3 files changed, 344 insertions(+), 57 deletions(-)
> > 
> > -- 
> > 1.7.9.5
> > 
> > 
> > 
> 
> -- 
> Aurelien Jarno	                        GPG: 1024D/F1BCDB73
> aurelien@aurel32.net                 http://www.aurel32.net