> -----Original Message----- > From: Roger Pau Monne > Sent: 24 April 2017 10:42 > To: Paul Durrant <paul.durr...@citrix.com> > Cc: xen-de...@lists.xenproject.org; konrad.w...@oracle.com; > boris.ostrov...@oracle.com; Ian Jackson <ian.jack...@citrix.com>; Wei Liu > <wei.l...@citrix.com>; Jan Beulich <jbeul...@suse.com>; Andrew Cooper > <andrew.coop...@citrix.com> > Subject: Re: [PATCH v2 1/9] xen/vpci: introduce basic handlers to trap > accesses to the PCI config space > > On Fri, Apr 21, 2017 at 05:23:34PM +0100, Paul Durrant wrote: > > > -----Original Message----- > > > From: Roger Pau Monne [mailto:roger....@citrix.com] > [...] > > > +int xen_vpci_read(unsigned int seg, unsigned int bus, unsigned int > devfn, > > > + unsigned int reg, uint32_t size, uint32_t *data) > > > +{ > > > + struct domain *d = current->domain; > > > + struct pci_dev *pdev; > > > + const struct vpci_register *r; > > > + union vpci_val val = { .double_word = 0 }; > > > + unsigned int data_rshift = 0, data_lshift = 0, data_size; > > > + uint32_t tmp_data; > > > + int rc; > > > + > > > + ASSERT(vpci_locked(d)); > > > + > > > + *data = 0; > > > + > > > + /* Find the PCI dev matching the address. */ > > > + pdev = pci_get_pdev_by_domain(d, seg, bus, devfn); > > > + if ( !pdev ) > > > + goto passthrough; > > > > I hope this can eventually be generalised so I wonder what your intention is > regarding co-existence between Xen emulated PCI config space, pass- > through and PCI devices emulated externally. We already have a framework > for registering PCI devices by SBDF but this code seems to make no use of it, > which I suspect is likely to cause future conflict. > > Yes, the long term aim is to use this code in order to implement > PCI-passthrough for PVH and HVM DomUs also. > > TBH, I didn't know we already had such code (I assume you mean the IOREQ > related PCI code). As it is, I see a couple of issues with that, the first one > is that this code expects a ioreq client on the other end, and the code I'm > adding here is all inside of the hypervisor. The second issue is that the > IOREQ > code ATM only allows for local PCI accesses, which means I should extend it > to > also deal with ECAM/MMCFG areas. > > I completely agree that at some point this should be made to work together, > but > I'm not sure if it would be better to do that once we want to also use vPCI > for > DomUs, so that the Dom0 side is not delayed further.
BTW, that's also an argument for forgetting about the r-b scheme for handler registration since, if this really is for dom0 only, 8 pages worth of direct map is not a lot. Paul > > Roger. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
