[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: Bug in pci-detach (Was: Re: [Xen-devel] Re: VT-d HowTo Update)
On Wed, Apr 22, 2009 at 11:44:50AM +1000, Simon Horman wrote: > On Wed, Apr 22, 2009 at 09:11:58AM +1000, Simon Horman wrote: > > On Tue, Apr 21, 2009 at 05:16:14PM +0800, Cui, Dexuan wrote: > > > Simon Horman wrote: > > > > Hi, > > > > > > > > in preparation for 3.4.0 I have made a number of updates to the VT-d > > > > Howto. I have tried to retain the original information while > > > > reorganising things a bit. I have also added information on recent > > > > work I have done in this area. > > > > > > > > Apologies in advance for any errors, accidental deletions, etc... > > > > > > > > http://wiki.xensource.com/xenwiki/VTdHowTo > > > > > > Hi Simon, > > > There is a bug: we can't pci-detach a statically-assigned (I mean: use > > > the pci string in hvm config file) devices for hvm guest. > > > Accordong my limited experience, after a device is assigned to hvm guest, > > > ioemu does write the correct vslots value into xenstore, but looks xend > > > can't get the correct value somwhow. > > > Could you help to have a look? Thanks! > > > > Sure, I can look into that. Do you have a version that you are worried > > about? It did seem to work the last time that I checked. > > Hi Dexuan, > > I am seeing this bug too. I'll try and get a fix ASAP. Hi, I've poked a little further into this and the problem is partly a missunderstanding on my part. In the case where a function is specified in the hvm.conf in the form BUS:DEV:FUNC (e.g. 00:1d.0), then there is a check inside xm that prevents the function from subsequently being hot-unplugged. The check is that the vslot number is set to auto-select. And presumably the idea was that statically assigned devices couldn't be hot-unplugged, which to be honest was my initial assumption of how things work. If, however, the function in the hvm.conf is of the form BUS:DEV:FUNC@VSLOT (e.g. 00:1d.00@1e) which I added recently, then the check is bypassed, because vslot is set to 1e not auto. This is how I was doing my tests. I assumed this was the behaviour for all cases, and documented it as such. This leaves us with 3 choices: 1. Leave the inconsistency, which seems like a bad idea. 2. Add a check to make sure both forms can't be hot-unplugged This is more work than; 3. Remove the check and allow statically assigned devies to be removed. This seems like a good option, and if there is consensus I can fix this up into a propper patch. diff -r 6ba4e34d21d3 tools/python/xen/xend/XendDomainInfo.py --- a/tools/python/xen/xend/XendDomainInfo.py Tue Apr 21 16:31:26 2009 +0100 +++ b/tools/python/xen/xend/XendDomainInfo.py Wed Apr 22 12:42:58 2009 +1000 @@ -1092,9 +1092,6 @@ if devnum >= pci_len: raise VmError("Device @ vslot 0x%x doesn't exist." % (vslot)) - if vslot == AUTO_PHP_SLOT: - raise VmError("Device @ vslot 0x%x doesn't support hotplug." % (vslot)) - # Check the co-assignment. # To pci-detach a device D from domN, we should ensure: for each DD in the # list of D's co-assignment devices, DD is not assigned (to domN). _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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