[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v5 6/9] ioreq-server: add support for multiple servers
On Tue, 2014-05-06 at 14:28 +0100, Paul Durrant wrote: > > -----Original Message----- > > From: Ian Campbell > > Sent: 06 May 2014 11:46 > > To: Paul Durrant > > Cc: xen-devel@xxxxxxxxxxxxx; Ian Jackson; Stefano Stabellini; Jan Beulich > > Subject: Re: [PATCH v5 6/9] ioreq-server: add support for multiple servers > > > > On Thu, 2014-05-01 at 13:08 +0100, Paul Durrant wrote: > > > NOTE: To prevent emulators running in non-privileged guests from > > > potentially allocating very large amounts of xen heap, the core > > > rangeset code has been modified to introduce a hard limit of 256 > > > ranges per set. > > > > OOI how much RAM does that correspond to? > > Each range is two pointers (list_head) and two unsigned longs (start and > end), so that's 32 bytes - so 256 is two pages worth. Seems reasonable. > > > + } > > > + > > > + arg = xc_hypercall_buffer_alloc(xch, arg, sizeof(*arg)); > > > + if ( arg == NULL ) > > > + return -1; > > > + > > > + hypercall.op = __HYPERVISOR_hvm_op; > > > + hypercall.arg[0] = HVMOP_map_io_range_to_ioreq_server; > > > + hypercall.arg[1] = HYPERCALL_BUFFER_AS_ARG(arg); > > > + > > > + arg->domid = domid; > > > + arg->id = id; > > > + arg->type = HVMOP_IO_RANGE_PCI; > > > + arg->start = arg->end = HVMOP_PCI_SBDF((uint64_t)segment, > > > > Since you have HVMOP_IO_RANGE_PCI do you not want to expose that via > > this interface? > > > > I could have crunched this into the map_range function. I left it > separate because I thought it was more convenient for callers - who I > think will most likely deal with one PCI device at a time. Oh, so the "ranginess" is an existing feature of the hypercall which you are using but doesn't really apply to this use case? (I did think the concept of a range of PCI devices wasn't likely to be very useful, except perhaps in the "all functions of a device" case perhaps). Does the actual hypercall deal with a range? Or does it insist that start == end? Looks like the former, I'm happy with that if the hypervisor side guys are. Not sure if it is worth a comment somewhere? > > > @@ -502,6 +505,31 @@ static int setup_guest(xc_interface *xch, > > > special_pfn(SPECIALPAGE_SHARING)); > > > > > > /* > > > + * Allocate and clear additional ioreq server pages. The default > > > + * server will use the IOREQ and BUFIOREQ special pages above. > > > + */ > > > + for ( i = 0; i < NR_IOREQ_SERVER_PAGES; i++ ) > > > + { > > > + xen_pfn_t pfn = ioreq_server_pfn(i); > > > + > > > + rc = xc_domain_populate_physmap_exact(xch, dom, 1, 0, 0, &pfn); > > > + if ( rc != 0 ) > > > + { > > > + PERROR("Could not allocate %d'th ioreq server page.", i); > > > > This will say things like "1'th". "Could not allocate ioreq server page > > %d" avoids that. > > Ok. It was a cut'n'paste from the special_pfn code just above. I'll > fix that while I'm in the neighbourhood. Thanks! _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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