From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Date: Wed, 04 Dec 2013 09:37:28 +0000 Subject: Re: [PATCH] xen/pvhvm: If xen_platform_pci=0 is set don't blow up. Message-Id: <1386149848.13256.86.camel@kazak.uk.xensource.com> List-Id: References: <1386105246-14337-1-git-send-email-konrad.wilk@oracle.com> In-Reply-To: <1386105246-14337-1-git-send-email-konrad.wilk@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Konrad Rzeszutek Wilk Cc: stefano.stabellini@eu.citrix.com, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, david.vrabel@citrix.com, leosilva@linux.vnet.ibm.com, ashley@ashleylai.com, peterhuewe@gmx.de, mail@srajiv.net, tpmdd@selhorst.net, tpmdd@sirrix.com, dmitry.torokhov@gmail.com, bhelgaas@google.com, plagnioj@jcrosoft.com, tomi.valkeinen@ti.com, tpmdd-devel@lists.sourceforge.net, linux-input@vger.kernel.org, netdev@vger.kernel.org, linux-pci@vger.kernel.org, linux-fbdev@vger.kernel.org On Tue, 2013-12-03 at 16:14 -0500, Konrad Rzeszutek Wilk wrote: > The user has the option of disabling the platform driver: > 00:02.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device (rev 01) > > which is used to unplug the emulated drivers (IDE, Realtek 8169, etc) > and allow the PV drivers to take over. If the user wishes > to disable that they can set: > > xen_platform_pci=0 > (in the guest config file) > > or > xen_emul_unplug=never > (on the Linux command line) > > except it does not work properly. The PV drivers still try to > load and since the Xen platform driver is not run - and it > has not initialized the grant tables, most of the PV drivers > stumble upon: > > input: Xen Virtual Keyboard as /devices/virtual/input/input5 > input: Xen Virtual Pointer as /devices/virtual/input/input6M > ------------[ cut here ]------------ > kernel BUG at /home/konrad/ssd/konrad/linux/drivers/xen/grant-table.c:1206! > invalid opcode: 0000 [#1] SMP > Modules linked in: xen_kbdfront(+) xenfs xen_privcmd > CPU: 6 PID: 1389 Comm: modprobe Not tainted 3.13.0-rc1upstream-00021-ga6c892b-dirty #1 > Hardware name: Xen HVM domU, BIOS 4.4-unstable 11/26/2013 > RIP: 0010:[] [] get_free_entries+0x2e0/0x300 > Call Trace: > [] ? evdev_connect+0x1e3/0x240 > [] gnttab_grant_foreign_access+0x2e/0x70 > [] xenkbd_connect_backend+0x41/0x290 [xen_kbdfront] > [] xenkbd_probe+0x2f2/0x324 [xen_kbdfront] > [] xenbus_dev_probe+0x77/0x130 > [] xenbus_frontend_dev_probe+0x47/0x50 > [] driver_probe_device+0x89/0x230 > [] __driver_attach+0x9b/0xa0 > [] ? driver_probe_device+0x230/0x230 > [] ? driver_probe_device+0x230/0x230 > [] bus_for_each_dev+0x8c/0xb0 > [] driver_attach+0x19/0x20 > [] bus_add_driver+0x1a0/0x220 > [] driver_register+0x5f/0xf0 > [] xenbus_register_driver_common+0x15/0x20 > [] xenbus_register_frontend+0x23/0x40 > [] ? 0xffffffffa0014fff > [] xenkbd_init+0x2b/0x1000 [xen_kbdfront] > [] do_one_initcall+0x49/0x170 > > .. snip.. > > which is hardly nice. This patch fixes this by having each > PV driver check for: > - if running in PV, then it is fine to execute (as that is their > native environment). > - if running in HVM, check if user wanted 'xen_emul_unplug=never', > in which case bail out and don't load PV drivers. > - if running in HVM, and if PCI device 5853:0001 (xen_platform_pci) > does not exist, then bail out and not load PV drivers. > > P.S. > Ian Campbell suggested getting rid of 'xen_platform_pci_unplug' > but unfortunatly the xen-blkfront driver is using it, so we > cannot do it. It might still be nice to expose a suitable semantic interface (i.e. some relevant predicate) rather than the raw value for blkfront to use. But that can be a future thing I think. > Reported-by: Sander Eikelenboom Reported-by: Anthony PERARD > Reported-by: Fabio Fantoni > --- > arch/x86/xen/platform-pci-unplug.c | 18 ++++++++++++++++++ > drivers/block/xen-blkfront.c | 2 +- > drivers/char/tpm/xen-tpmfront.c | 4 ++++ > drivers/input/misc/xen-kbdfront.c | 4 ++++ > drivers/net/xen-netfront.c | 2 +- > drivers/pci/xen-pcifront.c | 4 ++++ > drivers/video/xen-fbfront.c | 4 ++++ > drivers/xen/xenbus/xenbus_probe_frontend.c | 2 +- > include/xen/platform_pci.h | 13 ++++++++++++- > 9 files changed, 49 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/xen/platform-pci-unplug.c b/arch/x86/xen/platform-pci-unplug.c > index 0a78524..087dfeb 100644 > --- a/arch/x86/xen/platform-pci-unplug.c > +++ b/arch/x86/xen/platform-pci-unplug.c > @@ -69,6 +69,24 @@ static int check_platform_magic(void) > return 0; > } > > +bool xen_has_pv_devices(void) > +{ > + if (!xen_domain()) > + return false; > + > + if (xen_hvm_domain()) { > + /* User requested no unplug, so no PV drivers. */ > + if (xen_emul_unplug & XEN_UNPLUG_NEVER) > + return false; I think you need if (xen_emul_unpug & XEN_UNPLUG_UNNECESSARY) return true; don't you? > + /* And user has xen_platform_pci=0 set in guest config as > + * driver did not modify the value. */ > + if (!xen_platform_pci_unplug) > + return false; > + } > + return true; > +} > +EXPORT_SYMBOL_GPL(xen_has_pv_devices); > + > void xen_unplug_emulated_devices(void) > { > int r;