On Mon, Dec 13, 2010 at 10:04:24PM -0700, Alex Williamson wrote: > On Tue, 2010-12-14 at 06:57 +0200, Michael S. Tsirkin wrote: > > On Mon, Dec 13, 2010 at 09:49:21PM -0700, Alex Williamson wrote: > > > On Tue, 2010-12-14 at 06:46 +0200, Michael S. Tsirkin wrote: > > > > On Mon, Dec 13, 2010 at 01:04:23PM -0700, Alex Williamson wrote: > > > > > On Mon, 2010-11-08 at 13:22 +0200, Michael S. Tsirkin wrote: > > > > > > On Mon, Oct 04, 2010 at 03:53:11PM -0600, Alex Williamson wrote: > > > > > > > pcibus_dev_print() was erroneously retrieving the device bus > > > > > > > number from the secondary bus number offset of the device > > > > > > > instead of the bridge above the device. This ends of landing > > > > > > > in the 2nd byte of the 3rd BAR for devices, which thankfully > > > > > > > is usually zero. pcibus_get_dev_path() copied this code, > > > > > > > inheriting the same bug. pcibus_get_dev_path() is used for > > > > > > > ramblock naming, so changing it can effect migration. However, > > > > > > > I've only seen this byte be non-zero for an assigned device, > > > > > > > which can't migrate anyway, so hopefully we won't run into > > > > > > > any issues. > > > > > > > > > > > > > > Signed-off-by: Alex Williamson <alex.william...@redhat.com> > > > > > > > > > > > > Good catch. Applied. > > > > > > > > > > Um... submitted vs applied: > > > > > > > > > > PCI: Bus number from the bridge, not the device > > > > > > > > > > @@ -6,20 +8,28 @@ > > > > > number from the secondary bus number offset of the device > > > > > instead of the bridge above the device. This ends of landing > > > > > in the 2nd byte of the 3rd BAR for devices, which thankfully > > > > > - is usually zero. pcibus_get_dev_path() copied this code, > > > > > + is usually zero. > > > > > + > > > > > + Note: pcibus_get_dev_path() copied this code, > > > > > inheriting the same bug. pcibus_get_dev_path() is used for > > > > > ramblock naming, so changing it can effect migration. However, > > > > > I've only seen this byte be non-zero for an assigned device, > > > > > which can't migrate anyway, so hopefully we won't run into > > > > > any issues. > > > > > > > > > > + This patch does not touch pcibus_get_dev_path, as > > > > > + bus number is guest assigned for nested buses, > > > > > + so using it for migration is broken anyway. > > > > > + Fix it properly later. > > > > > + > > > > > Signed-off-by: Alex Williamson <alex.william...@redhat.com> > > > > > + Signed-off-by: Michael S. Tsirkin <m...@redhat.com> > > > > > > > > > > diff --git a/hw/pci.c b/hw/pci.c > > > > > -index 6d0934d..15416dd 100644 > > > > > +index 962886e..8f6fcf8 100644 > > > > > --- a/hw/pci.c > > > > > +++ b/hw/pci.c > > > > > -@@ -1940,8 +1940,7 @@ static void pcibus_dev_print(Monitor *mon, > > > > > DeviceState *dev, int indent) > > > > > +@@ -1806,8 +1806,7 @@ static void pcibus_dev_print(Monitor *mon, > > > > > DeviceState *dev, int indent) > > > > > > > > > > monitor_printf(mon, "%*sclass %s, addr %02x:%02x.%x, " > > > > > "pci id %04x:%04x (sub %04x:%04x)\n", > > > > > @@ -29,14 +39,3 @@ > > > > > PCI_SLOT(d->devfn), PCI_FUNC(d->devfn), > > > > > pci_get_word(d->config + PCI_VENDOR_ID), > > > > > pci_get_word(d->config + PCI_DEVICE_ID), > > > > > -@@ -1965,7 +1964,7 @@ static char *pcibus_get_dev_path(DeviceState > > > > > *dev) > > > > > - char path[16]; > > > > > - > > > > > - snprintf(path, sizeof(path), "%04x:%02x:%02x.%x", > > > > > -- pci_find_domain(d->bus), d->config[PCI_SECONDARY_BUS], > > > > > -+ pci_find_domain(d->bus), pci_bus_num(d->bus), > > > > > - PCI_SLOT(d->devfn), PCI_FUNC(d->devfn)); > > > > > - > > > > > - return strdup(path); > > > > > - > > > > > - > > > > > > > > > > So the chunk that fixed the part that I was actually interested in got > > > > > dropped even though the existing code is clearly wrong. Yes, we still > > > > > have issues with nested bridges (not that we have many of those), but > > > > > until the "Fix it properly later" part comes along, can we please > > > > > include the obvious bug fix? Thanks, > > > > > > > > > > Alex > > > > > > > > We can stick 0 in there - would that help? I would much rather not > > > > create a version where we put the bus number there. > > > > > > Yep, 0 is good enough until we solve the nested bridge problem. Thanks, > > > > > > Alex > > > > I'm surprised you see that it matters in practice, but ok. > > Like this? > > I've only ever seen config[PCI_SECONDARY_BUS] be non-zero for an > assigned device, so I'm pretty sure we're not going to hurt migration, > but the code is clearly wrong and I'd like to make sure we don't trip on > a migration failure for a minor device config space change.
Which reminds me: maybe just mark nested bridges as non-migrateable for now? Care writing such a patch? > > diff --git a/hw/pci.c b/hw/pci.c > > index 254647b..81231c5 100644 > > --- a/hw/pci.c > > +++ b/hw/pci.c > > @@ -1952,7 +1952,10 @@ static char *pcibus_get_dev_path(DeviceState *dev) > > char path[16]; > > > > snprintf(path, sizeof(path), "%04x:%02x:%02x.%x", > > - pci_find_domain(d->bus), d->config[PCI_SECONDARY_BUS], > > + pci_find_domain(d->bus), > > + 0 /* TODO: need a persistent path for nested buses. > > + * Note: pci_bus_num(d->bus) is not right as it's guest > > + * assigned. */, > > PCI_SLOT(d->devfn), PCI_FUNC(d->devfn)); > > > > return strdup(path); > > Sure, that's fine. > > Acked-by: Alex Williamson <alex.william...@redhat.com> > > Thanks, > > Alex
