From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH V3] drivers/uio/uio_pci_generic.c: allow access for non-privileged processes Date: Wed, 21 Apr 2010 13:30:17 +0300 Message-ID: <20100421103017.GA31433@redhat.com> References: <4bccd3af.M/eSrn9OV22zg0A8%pugs@cisco.com> <20100421093849.GB30855@redhat.com> <20100421103148.GB1995@bluebox.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Tom Lyon , gregkh@suse.de, chrisw@sous-sol.org, joro@8bytes.org, avi@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: "Hans J. Koch" Return-path: Content-Disposition: inline In-Reply-To: <20100421103148.GB1995@bluebox.local> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Wed, Apr 21, 2010 at 12:31:50PM +0200, Hans J. Koch wrote: > On Wed, Apr 21, 2010 at 12:38:49PM +0300, Michael S. Tsirkin wrote: > > > > > + j++; > > > + } > > > + } > > > + for (i = 0, j = 0; i < PCI_STD_RESOURCE_END && > > > + j < MAX_UIO_PORT_REGIONS; i++) { > > > + if (pci_resource_flags(pdev, i) & IORESOURCE_IO) { > > > + name = kmalloc(8, GFP_KERNEL); > > > + if (name == NULL) > > > + break; > > > + sprintf(name, "iobar%d", i); > > > + info->port[j].name = name; > > > + info->port[j].start = pci_resource_start(pdev, i); > > > + info->port[j].size = pci_resource_len(pdev, i); > > > + info->port[j].porttype = UIO_PORT_X86; > > > + j++; > > > > At least on x86, I think io bar can not be mmapped. > > That's right. porttype == UIO_PORT_X86 is only there for information > purposes. Userspace then knows that it cannot map this but has to use > things like inb(), outb() and friends after getting access rights with > ioperm()/iopl(). "start" and "size" gives userspace the information > needed to do this. > > Thanks, > Hans So that fails in the declared purpose of allowing an unpriveledged userspace driver, as inb/outb are priveledged operations. -- MST