From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:55009) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Rz6vk-0007VZ-RE for qemu-devel@nongnu.org; Sun, 19 Feb 2012 08:35:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Rz6vj-0006j2-7b for qemu-devel@nongnu.org; Sun, 19 Feb 2012 08:35:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52960) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Rz6vi-0006in-T6 for qemu-devel@nongnu.org; Sun, 19 Feb 2012 08:35:55 -0500 Date: Sun, 19 Feb 2012 15:35:49 +0200 From: "Michael S. Tsirkin" Message-ID: <20120219133549.GB16160@redhat.com> References: <1329498525-8454-1-git-send-email-anthony.perard@citrix.com> <1329498525-8454-7-git-send-email-anthony.perard@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1329498525-8454-7-git-send-email-anthony.perard@citrix.com> Subject: Re: [Qemu-devel] [PATCH V7 06/11] pci.c: Add pci_check_bar_overlap List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony PERARD Cc: Yuji Shimada , Xen Devel , QEMU-devel , Stefano Stabellini On Fri, Feb 17, 2012 at 05:08:40PM +0000, Anthony PERARD wrote: > From: Yuji Shimada > > This function helps Xen PCI Passthrough device to check for overlap. > > Signed-off-by: Yuji Shimada > Signed-off-by: Anthony PERARD As far as I can see, this scans the bus a specific device is on, looking for devices who have conflicting BARs. Returns 1 if found, 0 if not. Not sure what would devices do with this information, really: patches posted just print out a warning which does not seem too useful. Just FYI, if you decided to e.g. disable device in such a case that would be wrong: it is legal to have overlapping BARs as long as there are no accesses. So a legal thing for a guest to do is: Assign BAR1 = abcde Assign BAR2 = abcde <- overlaps temporarily Assign BAR1 = 12345 And this means that you can't just check your device has no conflicts when your device is touched: it needs to be checked each time mappings are updated. > --- > hw/pci.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ > hw/pci.h | 3 +++ > 2 files changed, 50 insertions(+), 0 deletions(-) > > diff --git a/hw/pci.c b/hw/pci.c > index 678a8c1..75d6529 100644 > --- a/hw/pci.c > +++ b/hw/pci.c > @@ -1985,6 +1985,53 @@ MemoryRegion *pci_address_space_io(PCIDevice *dev) > return dev->bus->address_space_io; > } > > +int pci_check_bar_overlap(PCIDevice *dev, > + pcibus_t addr, pcibus_t size, uint8_t type) This lacks comments documentng what this does, parameters, return values, etc. > +{ > + PCIBus *bus = dev->bus; > + PCIDevice *devices = NULL; > + PCIIORegion *r; > + int i, j; > + int rc = 0; > + > + /* check Overlapped to Base Address */ Weird use of upper case. Intentional? Also - what does this comment mean? > + for (i = 0; i < ARRAY_SIZE(bus->devices); i++) { > + devices = bus->devices[i]; > + if (!devices) { > + continue; > + } > + > + /* skip itself */ itself? > + if (devices->devfn == dev->devfn) { > + continue; > + } > + > + for (j = 0; j < PCI_NUM_REGIONS; j++) { This ignores bridges. > + r = &devices->io_regions[j]; > + > + /* skip different resource type, but don't skip when > + * prefetch and non-prefetch memory are compared. > + */ > + if (type != r->type) { > + if (type & PCI_BASE_ADDRESS_SPACE_IO || > + r->type & PCI_BASE_ADDRESS_SPACE_IO) { Do you mean type & PCI_BASE_ADDRESS_SPACE_IO != r->type & PCI_BASE_ADDRESS_SPACE_IO ? This would not need a comment then. > + continue; > + } > + } > + > + if ((addr < (r->addr + r->size)) && ((addr + size) > r->addr)) { Can ranges_overlap be used? > + printf("Overlapped to device[%02x:%02x.%x][Region:%d]" > + "[Address:%"PRIx64"h][Size:%"PRIx64"h]\n", > + pci_bus_num(bus), PCI_SLOT(devices->devfn), > + PCI_FUNC(devices->devfn), j, r->addr, r->size); That's not how one should report errors. > + rc = 1; > + } > + } > + } > + > + return rc; > +} > + > static void pci_device_class_init(ObjectClass *klass, void *data) > { > DeviceClass *k = DEVICE_CLASS(klass); > diff --git a/hw/pci.h b/hw/pci.h > index 33b0b18..f05fda5 100644 > --- a/hw/pci.h > +++ b/hw/pci.h > @@ -566,4 +566,7 @@ extern const VMStateDescription vmstate_pci_device; > .offset = vmstate_offset_pointer(_state, _field, PCIDevice), \ > } > > +int pci_check_bar_overlap(PCIDevice *dev, > + pcibus_t addr, pcibus_t size, uint8_t type); > + > #endif > -- > Anthony PERARD