From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:47523) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1STmz4-0008LJ-IV for qemu-devel@nongnu.org; Mon, 14 May 2012 00:34:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1STmz0-0004Tm-03 for qemu-devel@nongnu.org; Mon, 14 May 2012 00:34:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31655) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1STmyz-0004TS-Oy for qemu-devel@nongnu.org; Mon, 14 May 2012 00:34:05 -0400 Message-ID: <1336970040.6954.43.camel@bling.home> From: Alex Williamson Date: Sun, 13 May 2012 22:34:00 -0600 In-Reply-To: <4FB07AE6.5080009@ozlabs.ru> References: <4FAE0824.4050209@ozlabs.ru> <1336964103.6954.12.camel@bling.home> <4FB07AE6.5080009@ozlabs.ru> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] kernel vfio: PCI ROM size calculation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexey Kardashevskiy Cc: Alex Graf , qemu-devel@nongnu.org, kvm@vger.kernel.org, David Gibson On Mon, 2012-05-14 at 13:24 +1000, Alexey Kardashevskiy wrote: > On 14/05/12 12:55, Alex Williamson wrote: > > On Sat, 2012-05-12 at 16:50 +1000, Alexey Kardashevskiy wrote: > >> The original code calculated the real size of the ROM and passed it to > >> QEMU which tried to do pci_register_bar and failed with error message > >> "ERROR: PCI region size must be pow2". > >> > >> The example card is PCIe Intel E1000E with the ROM size 0x9c00. > >> > >> pci_resource_len seems to be a proper solution. > >> > >> Signed-off-by: Alexey Kardashevskiy > >> --- > >> drivers/vfio/pci/vfio_pci.c | 9 +++------ > >> 1 files changed, 3 insertions(+), 6 deletions(-) > >> > >> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c > >> index b2f1f3a..6d4a783 100644 > >> --- a/drivers/vfio/pci/vfio_pci.c > >> +++ b/drivers/vfio/pci/vfio_pci.c > >> @@ -234,12 +234,9 @@ static long vfio_pci_ioctl(void *device_data, > >> * this gives the user an easy way to determine whether > >> * there's anything here w/o trying to read it. */ > > > > This is actually intentional, but maybe isn't the best way to handle it > > anymore. The cut-off comment above reads: > > > > /* Report the actual ROM size instead of the BAR size, > > * this gives the user an easy way to determine whether > > * there's anything here w/o trying to read it. */ > > > > At the time I added that though, I think we still had a separate ioctl > > to get the BAR size, so one gave the real size, the other the BAR size. > > Do we care to expose that ROMs have real size, maybe zero, that doesn't > > necessarily match pci_resource_len()? Thanks, > > > The guest will still see aligned ROM BAR (not real one) and may try to read behind the real end of > ROM, and it is allowed while it is still within the BAR, right? Yes. > >> if (info.index == VFIO_PCI_ROM_REGION_INDEX) { > >> - void __iomem *io; > >> - size_t size; > >> - > >> - io = pci_map_rom(pdev, &size); > >> - info.size = io ? size : 0; > >> - pci_unmap_rom(pdev, io); > >> + info.size = pci_resource_len(pdev, > >> + PCI_ROM_RESOURCE); > >> + info.flags |= VFIO_PCI_ROM_REGION_INDEX; > >> } else if (flags & IORESOURCE_MEM) { > >> info.size = pci_resource_len(pdev, info.index); > >> info.flags |= (VFIO_REGION_INFO_FLAG_WRITE | > >> > > > > > > > >