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Date: Tue, 17 Dec 2013 10:54:47 +0100
From: Fabio Fantoni <fabio.fantoni@....biz>
To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>, axboe@...nel.dk,
stefano.stabellini@...citrix.com, ian.campbell@...rix.com,
xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
boris.ostrovsky@...cle.com, david.vrabel@...rix.com,
leosilva@...ux.vnet.ibm.com, ashley@...leylai.com,
peterhuewe@....de, mail@...jiv.net, tpmdd@...horst.net,
dmitry.torokhov@...il.com, bhelgaas@...gle.com,
plagnioj@...osoft.com, tomi.valkeinen@...com,
tpmdd-devel@...ts.sourceforge.net, linux-input@...r.kernel.org,
netdev@...r.kernel.org, linux-pci@...r.kernel.org,
linux-fbdev@...r.kernel.org
Subject: Re: [Xen-devel] [PATCH v3 1/2] xen/pvhvm: If xen_platform_pci=0 is
set don't blow up (v3).
Il 16/12/2013 16:04, Konrad Rzeszutek Wilk ha scritto:
> 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:[<ffffffff813ddc40>] [<ffffffff813ddc40>] get_free_entries+0x2e0/0x300
> Call Trace:
> [<ffffffff8150d9a3>] ? evdev_connect+0x1e3/0x240
> [<ffffffff813ddd0e>] gnttab_grant_foreign_access+0x2e/0x70
> [<ffffffffa0010081>] xenkbd_connect_backend+0x41/0x290 [xen_kbdfront]
> [<ffffffffa0010a12>] xenkbd_probe+0x2f2/0x324 [xen_kbdfront]
> [<ffffffff813e5757>] xenbus_dev_probe+0x77/0x130
> [<ffffffff813e7217>] xenbus_frontend_dev_probe+0x47/0x50
> [<ffffffff8145e9a9>] driver_probe_device+0x89/0x230
> [<ffffffff8145ebeb>] __driver_attach+0x9b/0xa0
> [<ffffffff8145eb50>] ? driver_probe_device+0x230/0x230
> [<ffffffff8145eb50>] ? driver_probe_device+0x230/0x230
> [<ffffffff8145cf1c>] bus_for_each_dev+0x8c/0xb0
> [<ffffffff8145e7d9>] driver_attach+0x19/0x20
> [<ffffffff8145e260>] bus_add_driver+0x1a0/0x220
> [<ffffffff8145f1ff>] driver_register+0x5f/0xf0
> [<ffffffff813e55c5>] xenbus_register_driver_common+0x15/0x20
> [<ffffffff813e76b3>] xenbus_register_frontend+0x23/0x40
> [<ffffffffa0015000>] ? 0xffffffffa0014fff
> [<ffffffffa001502b>] xenkbd_init+0x2b/0x1000 [xen_kbdfront]
> [<ffffffff81002049>] 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 any 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.
> - (v2) if running in HVM, and if the user wanted 'xen_emul_unplug=disks',
> then bail out for all PV devices _except_ the block one.
> Ditto for the network one ('nics').
> - (v2) if running in HVM, and if the user wanted 'xen_emul_unplug=unnecessary'
> then load block PV driver, and also setup the legacy IDE paths.
> In (v3) make it actually load PV drivers.
>
> Reported-by: Sander Eikelenboom <linux@...elenboom.it
> Reported-by: Anthony PERARD <anthony.perard@...rix.com>
> Reported-by: Fabio Fantoni <fabio.fantoni@....biz>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> [v2: Add extra logic to handle the myrid ways 'xen_emul_unplug'
> can be used per Ian and Stefano suggestion]
> [v3: Make the unnecessary case work properly]
> Reviewed-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
I tested this patch with all possible cases that I know, no crash or
calltrace found.
I don't understand the utility of 'xen_emul_unplug=unnecessary' but
probably it is working correctly, it shows both pv and not pv for blocks
and nics.
About 'xen_emul_unplug=disks' and 'xen_emul_unplug=nics' probably there
is something wrong.
With 'xen_emul_unplug=nics' it shows pv nic (this should be correct) and
about disks it shows the same disk twice, as pv and not pv (xvda and
sda) with different device number.
With 'xen_emul_unplug=disks' it shows pv block (this should be correct)
and it seems to show the pv nic too (this should be wrong).
Thanks for any reply.
> ---
> arch/x86/xen/platform-pci-unplug.c | 74 ++++++++++++++++++++++++++++++
> drivers/block/xen-blkfront.c | 4 +-
> 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 | 23 ++++++++++
> 9 files changed, 117 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/xen/platform-pci-unplug.c b/arch/x86/xen/platform-pci-unplug.c
> index 0a78524..ab84ac1 100644
> --- a/arch/x86/xen/platform-pci-unplug.c
> +++ b/arch/x86/xen/platform-pci-unplug.c
> @@ -69,6 +69,80 @@ static int check_platform_magic(void)
> return 0;
> }
>
> +bool xen_has_pv_devices()
> +{
> + if (!xen_domain())
> + return false;
> +
> + /* PV domains always have them. */
> + if (xen_pv_domain())
> + return true;
> +
> + /* And user has xen_platform_pci=0 set in guest config as
> + * driver did not modify the value. */
> + if (xen_platform_pci_unplug == 0)
> + return false;
> +
> + if (xen_platform_pci_unplug & XEN_UNPLUG_NEVER)
> + return false;
> +
> + if (xen_platform_pci_unplug & XEN_UNPLUG_ALL)
> + return true;
> +
> + /* This is an odd one - we are going to run legacy
> + * and PV drivers at the same time. */
> + if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
> + return true;
> +
> + /* And the caller has to follow with xen_pv_{disk,nic}_devices
> + * to be certain which driver can load. */
> + return false;
> +}
> +EXPORT_SYMBOL_GPL(xen_has_pv_devices);
> +
> +static bool __xen_has_pv_device(int state)
> +{
> + /* HVM domains might or might not */
> + if (xen_hvm_domain() && (xen_platform_pci_unplug & state))
> + return true;
> +
> + return xen_has_pv_devices();
> +}
> +
> +bool xen_has_pv_nic_devices(void)
> +{
> + return __xen_has_pv_device(XEN_UNPLUG_ALL_NICS | XEN_UNPLUG_ALL);
> +}
> +EXPORT_SYMBOL_GPL(xen_has_pv_nic_devices);
> +
> +bool xen_has_pv_disk_devices(void)
> +{
> + return __xen_has_pv_device(XEN_UNPLUG_ALL_IDE_DISKS |
> + XEN_UNPLUG_AUX_IDE_DISKS | XEN_UNPLUG_ALL);
> +}
> +EXPORT_SYMBOL_GPL(xen_has_pv_disk_devices);
> +
> +/*
> + * This one is odd - it determines whether you want to run PV _and_
> + * legacy (IDE) drivers together. This combination is only possible
> + * under HVM.
> + */
> +bool xen_has_pv_and_legacy_disk_devices(void)
> +{
> + if (!xen_domain())
> + return false;
> +
> + /* N.B. This is only ever used in HVM mode */
> + if (xen_pv_domain())
> + return false;
> +
> + if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
> + return true;
> +
> + return false;
> +}
> +EXPORT_SYMBOL_GPL(xen_has_pv_and_legacy_disk_devices);
> +
> void xen_unplug_emulated_devices(void)
> {
> int r;
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index a4660bb..ed88b3c 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -1278,7 +1278,7 @@ static int blkfront_probe(struct xenbus_device *dev,
> char *type;
> int len;
> /* no unplug has been done: do not hook devices != xen vbds */
> - if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
> + if (xen_has_pv_and_legacy_disk_devices()) {
> int major;
>
> if (!VDEV_IS_EXTENDED(vdevice))
> @@ -2022,7 +2022,7 @@ static int __init xlblk_init(void)
> if (!xen_domain())
> return -ENODEV;
>
> - if (xen_hvm_domain() && !xen_platform_pci_unplug)
> + if (!xen_has_pv_disk_devices())
> return -ENODEV;
>
> if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
> diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
> index 06189e5..9c2cbd1 100644
> --- a/drivers/char/tpm/xen-tpmfront.c
> +++ b/drivers/char/tpm/xen-tpmfront.c
> @@ -16,6 +16,7 @@
> #include <xen/xenbus.h>
> #include <xen/page.h>
> #include "tpm.h"
> +#include <xen/platform_pci.h>
>
> struct tpm_private {
> struct tpm_chip *chip;
> @@ -422,6 +423,9 @@ static int __init xen_tpmfront_init(void)
> if (!xen_domain())
> return -ENODEV;
>
> + if (!xen_has_pv_devices())
> + return -ENODEV;
> +
> return xenbus_register_frontend(&tpmfront_driver);
> }
> module_init(xen_tpmfront_init);
> diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
> index e21c181..fbfdc10 100644
> --- a/drivers/input/misc/xen-kbdfront.c
> +++ b/drivers/input/misc/xen-kbdfront.c
> @@ -29,6 +29,7 @@
> #include <xen/interface/io/fbif.h>
> #include <xen/interface/io/kbdif.h>
> #include <xen/xenbus.h>
> +#include <xen/platform_pci.h>
>
> struct xenkbd_info {
> struct input_dev *kbd;
> @@ -380,6 +381,9 @@ static int __init xenkbd_init(void)
> if (xen_initial_domain())
> return -ENODEV;
>
> + if (!xen_has_pv_devices())
> + return -ENODEV;
> +
> return xenbus_register_frontend(&xenkbd_driver);
> }
>
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index 36808bf..eea2392 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -2106,7 +2106,7 @@ static int __init netif_init(void)
> if (!xen_domain())
> return -ENODEV;
>
> - if (xen_hvm_domain() && !xen_platform_pci_unplug)
> + if (!xen_has_pv_nic_devices())
> return -ENODEV;
>
> pr_info("Initialising Xen virtual ethernet driver\n");
> diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
> index f7197a7..eae7cd9 100644
> --- a/drivers/pci/xen-pcifront.c
> +++ b/drivers/pci/xen-pcifront.c
> @@ -20,6 +20,7 @@
> #include <linux/workqueue.h>
> #include <linux/bitops.h>
> #include <linux/time.h>
> +#include <xen/platform_pci.h>
>
> #include <asm/xen/swiotlb-xen.h>
> #define INVALID_GRANT_REF (0)
> @@ -1138,6 +1139,9 @@ static int __init pcifront_init(void)
> if (!xen_pv_domain() || xen_initial_domain())
> return -ENODEV;
>
> + if (!xen_has_pv_devices())
> + return -ENODEV;
> +
> pci_frontend_registrar(1 /* enable */);
>
> return xenbus_register_frontend(&xenpci_driver);
> diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c
> index cd005c2..4b2d3ab 100644
> --- a/drivers/video/xen-fbfront.c
> +++ b/drivers/video/xen-fbfront.c
> @@ -35,6 +35,7 @@
> #include <xen/interface/io/fbif.h>
> #include <xen/interface/io/protocols.h>
> #include <xen/xenbus.h>
> +#include <xen/platform_pci.h>
>
> struct xenfb_info {
> unsigned char *fb;
> @@ -699,6 +700,9 @@ static int __init xenfb_init(void)
> if (xen_initial_domain())
> return -ENODEV;
>
> + if (!xen_has_pv_devices())
> + return -ENODEV;
> +
> return xenbus_register_frontend(&xenfb_driver);
> }
>
> diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
> index 34b20bf..6244f9c 100644
> --- a/drivers/xen/xenbus/xenbus_probe_frontend.c
> +++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
> @@ -496,7 +496,7 @@ subsys_initcall(xenbus_probe_frontend_init);
> #ifndef MODULE
> static int __init boot_wait_for_devices(void)
> {
> - if (xen_hvm_domain() && !xen_platform_pci_unplug)
> + if (!xen_has_pv_devices())
> return -ENODEV;
>
> ready_to_wait_for_devices = 1;
> diff --git a/include/xen/platform_pci.h b/include/xen/platform_pci.h
> index 438c256..b49eeab 100644
> --- a/include/xen/platform_pci.h
> +++ b/include/xen/platform_pci.h
> @@ -48,4 +48,27 @@ static inline int xen_must_unplug_disks(void) {
>
> extern int xen_platform_pci_unplug;
>
> +#if defined(CONFIG_XEN_PVHVM)
> +extern bool xen_has_pv_devices(void);
> +extern bool xen_has_pv_disk_devices(void);
> +extern bool xen_has_pv_nic_devices(void);
> +extern bool xen_has_pv_and_legacy_disk_devices(void);
> +#else
> +static inline bool xen_has_pv_devices(void)
> +{
> + return IS_ENABLED(CONFIG_XEN);
> +}
> +static inline bool xen_has_pv_disk_devices(void)
> +{
> + return IS_ENABLED(CONFIG_XEN);
> +}
> +static inline bool xen_has_pv_nic_devices(void)
> +{
> + return IS_ENABLED(CONFIG_XEN);
> +}
> +static inline bool xen_has_pv_and_legacy_disk_devices(void)
> +{
> + return false;
> +}
> +#endif
> #endif /* _XEN_PLATFORM_PCI_H */
--
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