diff mbox

xen/pvhvm: If xen_platform_pci=0 is set don't blow up.

Message ID 1386105246-14337-1-git-send-email-konrad.wilk@oracle.com (mailing list archive)
State New, archived
Headers show

Commit Message

Konrad Rzeszutek Wilk Dec. 3, 2013, 9:14 p.m. UTC
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 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.

Reported-by: Sander Eikelenboom <linux@eikelenboom.it
Reported-by: Anthony PERARD <anthony.perard@citrix.com>
Reported-by: Fabio Fantoni <fabio.fantoni@m2r.biz>
---
 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(-)

Comments

Matthew Daley Dec. 4, 2013, 12:03 a.m. UTC | #1
On Wed, Dec 4, 2013 at 10:14 AM, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> 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:[<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 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.
>
> Reported-by: Sander Eikelenboom <linux@eikelenboom.it
> Reported-by: Anthony PERARD <anthony.perard@citrix.com>
> Reported-by: Fabio Fantoni <fabio.fantoni@m2r.biz>

I think you forgot your Signed-off-by line.

- Matthew
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Ian Campbell Dec. 4, 2013, 9:37 a.m. UTC | #2
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:[<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 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 <linux@eikelenboom.it
> Reported-by: Anthony PERARD <anthony.perard@citrix.com>
> Reported-by: Fabio Fantoni <fabio.fantoni@m2r.biz>
> ---
>  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;


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Stefano Stabellini Dec. 4, 2013, 10:48 a.m. UTC | #3
On Tue, 3 Dec 2013, Konrad Rzeszutek Wilk wrote:
> 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;

Considering that if (xen_emul_unplug & XEN_UNPLUG_NEVER) we never set
xen_platform_pci_unplug, this check is redundant.


> +		/* 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;
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Stefano Stabellini Dec. 4, 2013, 10:51 a.m. UTC | #4
On Wed, 4 Dec 2013, Ian Campbell wrote:
> > +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?

XEN_UNPLUG_UNNECESSARY was introduced to enable the platform PCI device
even if it didn't respond properly to the unplug protocol.
The corresponding parameter is called "unnecessary" because if you pass
it to the kernel you mean that it is unnecessary to unplug the emulated
devices but you can use the pv devices anyway.

So no, we shouldn't check for XEN_UNPLUG_UNNECESSARY here.



> > +		/* 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;
> 
> 
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Ian Campbell Dec. 4, 2013, 10:59 a.m. UTC | #5
On Wed, 2013-12-04 at 10:51 +0000, Stefano Stabellini wrote:
> On Wed, 4 Dec 2013, Ian Campbell wrote:
> > > +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?
> 
> XEN_UNPLUG_UNNECESSARY was introduced to enable the platform PCI device
> even if it didn't respond properly to the unplug protocol.
> The corresponding parameter is called "unnecessary" because if you pass
> it to the kernel you mean that it is unnecessary to unplug the emulated
> devices but you can use the pv devices anyway.
> 
> So no, we shouldn't check for XEN_UNPLUG_UNNECESSARY here.

Oh, we will eventually fall through to the return true, so it does
actually work out OK.

I'd still be in favour of handling each option explicitly, for clarity.
Which means checking for XEN_UNPLUG_UNNECESSARY.

> > > +		/* 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;

I assume this check doesn't trigger if unnecessary has been specified?

> > > +	}
> > > +	return true;
> > > +}
> > > +EXPORT_SYMBOL_GPL(xen_has_pv_devices);
> > > +
> > >  void xen_unplug_emulated_devices(void)
> > >  {
> > >  	int r;
> > 
> > 


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Stefano Stabellini Dec. 4, 2013, 11:05 a.m. UTC | #6
On Wed, 4 Dec 2013, Ian Campbell wrote:
> On Wed, 2013-12-04 at 10:51 +0000, Stefano Stabellini wrote:
> > On Wed, 4 Dec 2013, Ian Campbell wrote:
> > > > +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?
> > 
> > XEN_UNPLUG_UNNECESSARY was introduced to enable the platform PCI device
> > even if it didn't respond properly to the unplug protocol.
> > The corresponding parameter is called "unnecessary" because if you pass
> > it to the kernel you mean that it is unnecessary to unplug the emulated
> > devices but you can use the pv devices anyway.
> > 
> > So no, we shouldn't check for XEN_UNPLUG_UNNECESSARY here.
> 
> Oh, we will eventually fall through to the return true, so it does
> actually work out OK.
> 
> I'd still be in favour of handling each option explicitly, for clarity.
> Which means checking for XEN_UNPLUG_UNNECESSARY.

I think is wrong to check for any xen_emul_unpug options in this function.
The xen_emul_unpug options should be used to set the right value of
xen_platform_pci_unplug. (See my other reply.)


> > > > +		/* 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;
> 
> I assume this check doesn't trigger if unnecessary has been specified?
 
right
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Ian Campbell Dec. 4, 2013, 11:08 a.m. UTC | #7
On Wed, 2013-12-04 at 11:05 +0000, Stefano Stabellini wrote:
> On Wed, 4 Dec 2013, Ian Campbell wrote:
> > On Wed, 2013-12-04 at 10:51 +0000, Stefano Stabellini wrote:
> > > On Wed, 4 Dec 2013, Ian Campbell wrote:
> > > > > +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?
> > > 
> > > XEN_UNPLUG_UNNECESSARY was introduced to enable the platform PCI device
> > > even if it didn't respond properly to the unplug protocol.
> > > The corresponding parameter is called "unnecessary" because if you pass
> > > it to the kernel you mean that it is unnecessary to unplug the emulated
> > > devices but you can use the pv devices anyway.
> > > 
> > > So no, we shouldn't check for XEN_UNPLUG_UNNECESSARY here.
> > 
> > Oh, we will eventually fall through to the return true, so it does
> > actually work out OK.
> > 
> > I'd still be in favour of handling each option explicitly, for clarity.
> > Which means checking for XEN_UNPLUG_UNNECESSARY.
> 
> I think is wrong to check for any xen_emul_unpug options in this function.
> The xen_emul_unpug options should be used to set the right value of
> xen_platform_pci_unplug. (See my other reply.)

Whichever one we check we should still be checking explicitly for the
"unnecessary" case, for clarity if nothing else.

TBH I think the split between xen_emul_unplug and
xen_platform_pci_unplug is a bit artificial. There should be one value
which is static to platform-pci-unplug.c and accessor functions should
be provided for other code to use. Open coding all those accesses to
xen_platform_pci_unplug in every driver is just too error prone.

Ian.

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Stefano Stabellini Dec. 4, 2013, 11:18 a.m. UTC | #8
On Wed, 4 Dec 2013, Ian Campbell wrote:
> On Wed, 2013-12-04 at 11:05 +0000, Stefano Stabellini wrote:
> > On Wed, 4 Dec 2013, Ian Campbell wrote:
> > > On Wed, 2013-12-04 at 10:51 +0000, Stefano Stabellini wrote:
> > > > On Wed, 4 Dec 2013, Ian Campbell wrote:
> > > > > > +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?
> > > > 
> > > > XEN_UNPLUG_UNNECESSARY was introduced to enable the platform PCI device
> > > > even if it didn't respond properly to the unplug protocol.
> > > > The corresponding parameter is called "unnecessary" because if you pass
> > > > it to the kernel you mean that it is unnecessary to unplug the emulated
> > > > devices but you can use the pv devices anyway.
> > > > 
> > > > So no, we shouldn't check for XEN_UNPLUG_UNNECESSARY here.
> > > 
> > > Oh, we will eventually fall through to the return true, so it does
> > > actually work out OK.
> > > 
> > > I'd still be in favour of handling each option explicitly, for clarity.
> > > Which means checking for XEN_UNPLUG_UNNECESSARY.
> > 
> > I think is wrong to check for any xen_emul_unpug options in this function.
> > The xen_emul_unpug options should be used to set the right value of
> > xen_platform_pci_unplug. (See my other reply.)
> 
> Whichever one we check we should still be checking explicitly for the
> "unnecessary" case, for clarity if nothing else.

Sure, that is OK for me.
In that case should we check for the full list of possible options?

            ide-disks -- unplug primary master IDE devices
			aux-ide-disks -- unplug non-primary-master IDE devices
			nics -- unplug network devices
			all -- unplug all emulated devices (NICs and IDE disks)
			unnecessary -- unplugging emulated devices is
				unnecessary even if the host did not respond to
				the unplug protocol
			never -- do not unplug even if version check succeeds
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Ian Campbell Dec. 4, 2013, 11:23 a.m. UTC | #9
On Wed, 2013-12-04 at 11:18 +0000, Stefano Stabellini wrote:
> On Wed, 4 Dec 2013, Ian Campbell wrote:
> > On Wed, 2013-12-04 at 11:05 +0000, Stefano Stabellini wrote:
> > > On Wed, 4 Dec 2013, Ian Campbell wrote:
> > > > On Wed, 2013-12-04 at 10:51 +0000, Stefano Stabellini wrote:
> > > > > On Wed, 4 Dec 2013, Ian Campbell wrote:
> > > > > > > +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?
> > > > > 
> > > > > XEN_UNPLUG_UNNECESSARY was introduced to enable the platform PCI device
> > > > > even if it didn't respond properly to the unplug protocol.
> > > > > The corresponding parameter is called "unnecessary" because if you pass
> > > > > it to the kernel you mean that it is unnecessary to unplug the emulated
> > > > > devices but you can use the pv devices anyway.
> > > > > 
> > > > > So no, we shouldn't check for XEN_UNPLUG_UNNECESSARY here.
> > > > 
> > > > Oh, we will eventually fall through to the return true, so it does
> > > > actually work out OK.
> > > > 
> > > > I'd still be in favour of handling each option explicitly, for clarity.
> > > > Which means checking for XEN_UNPLUG_UNNECESSARY.
> > > 
> > > I think is wrong to check for any xen_emul_unpug options in this function.
> > > The xen_emul_unpug options should be used to set the right value of
> > > xen_platform_pci_unplug. (See my other reply.)
> > 
> > Whichever one we check we should still be checking explicitly for the
> > "unnecessary" case, for clarity if nothing else.
> 
> Sure, that is OK for me.
> In that case should we check for the full list of possible options?

We probably should. That probably means an extra
xen_has_pv_{disk,nic}_devices() which is the existing one plus the
specific checks?

> 
>             ide-disks -- unplug primary master IDE devices
> 			aux-ide-disks -- unplug non-primary-master IDE devices
> 			nics -- unplug network devices
> 			all -- unplug all emulated devices (NICs and IDE disks)
> 			unnecessary -- unplugging emulated devices is
> 				unnecessary even if the host did not respond to
> 				the unplug protocol
> 			never -- do not unplug even if version check succeeds


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David Vrabel Dec. 4, 2013, 1 p.m. UTC | #10
On 03/12/13 21:14, Konrad Rzeszutek Wilk wrote:
> 
> Ian Campbell suggested getting rid of 'xen_platform_pci_unplug'
> but unfortunatly the xen-blkfront driver is using it, so we
> cannot do it.

I had a look at what blkfront was using this for and it seems dumb.  How
did we end up with the frontend driver working around toolstack bugs?
If HVM Linux guest didn't want (e.g.,) PV CDROM, the toolstack shouldn't
have created one.

And perhaps more importantly, if you actually want a PV CDROM in a HVM
guest, it's not possible.

David
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Ian Campbell Dec. 4, 2013, 1:06 p.m. UTC | #11
On Wed, 2013-12-04 at 13:00 +0000, David Vrabel wrote:
> On 03/12/13 21:14, Konrad Rzeszutek Wilk wrote:
> > 
> > Ian Campbell suggested getting rid of 'xen_platform_pci_unplug'
> > but unfortunatly the xen-blkfront driver is using it, so we
> > cannot do it.
> 
> I had a look at what blkfront was using this for and it seems dumb.  How
> did we end up with the frontend driver working around toolstack bugs?
> If HVM Linux guest didn't want (e.g.,) PV CDROM, the toolstack shouldn't
> have created one.

Note that this cdrom stuff is actually nothing to do with the unplug
variable -- it just happens to be right next to that check.

Not that the use of the unplug var there doesn't also look pretty odd...


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Dmitry Torokhov Dec. 4, 2013, 4:42 p.m. UTC | #12
Hi Konrad,

On Tue, Dec 03, 2013 at 04:14:06PM -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:[<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 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.
> 
> Reported-by: Sander Eikelenboom <linux@eikelenboom.it
> Reported-by: Anthony PERARD <anthony.perard@citrix.com>
> Reported-by: Fabio Fantoni <fabio.fantoni@m2r.biz>

For input:

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

...

> +#if defined(CONFIG_XEN_PVHVM)
> +extern bool xen_has_pv_devices(void);
> +#else
> +static inline bool xen_has_pv_devices(void)
> +{
> +#if defined(CONFIG_XEN)
> +	return true;
> +#else
> +	return false;
> +#endif

	return IS_ENABLED(CONFIG_XEN);

?

Thanks.
Konrad Rzeszutek Wilk Dec. 4, 2013, 4:48 p.m. UTC | #13
> > 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.
> > 
> > Reported-by: Sander Eikelenboom <linux@eikelenboom.it
> > Reported-by: Anthony PERARD <anthony.perard@citrix.com>
> > Reported-by: Fabio Fantoni <fabio.fantoni@m2r.biz>
> 
> For input:
> 
> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thank you. I need to do some extra changes to the other subsystems but
for the fb/kbd itshould be still throught the same function as this
patch has exposed. I will repost it and include your Ack if you are OK
with that?
> 
> ...
> 
> > +#if defined(CONFIG_XEN_PVHVM)
> > +extern bool xen_has_pv_devices(void);
> > +#else
> > +static inline bool xen_has_pv_devices(void)
> > +{
> > +#if defined(CONFIG_XEN)
> > +	return true;
> > +#else
> > +	return false;
> > +#endif
> 
> 	return IS_ENABLED(CONFIG_XEN);
> 
> ?

Oh, awesome!  Thanks!
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Dmitry Torokhov Dec. 4, 2013, 5:08 p.m. UTC | #14
On Wed, Dec 04, 2013 at 11:48:03AM -0500, Konrad Rzeszutek Wilk wrote:
> > > 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.
> > > 
> > > Reported-by: Sander Eikelenboom <linux@eikelenboom.it
> > > Reported-by: Anthony PERARD <anthony.perard@citrix.com>
> > > Reported-by: Fabio Fantoni <fabio.fantoni@m2r.biz>
> > 
> > For input:
> > 
> > Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> 
> Thank you. I need to do some extra changes to the other subsystems but
> for the fb/kbd itshould be still throught the same function as this
> patch has exposed. I will repost it and include your Ack if you are OK
> with that?

Sure.
diff mbox

Patch

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;
+		/* 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;
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 432db1b..9616b81 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -2074,7 +2074,7 @@  static int __init xlblk_init(void)
 	if (!xen_domain())
 		return -ENODEV;
 
-	if (xen_hvm_domain() && !xen_platform_pci_unplug)
+	if (!xen_has_pv_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 c8ff4df..62e7d38 100644
--- a/drivers/char/tpm/xen-tpmfront.c
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -17,6 +17,7 @@ 
 #include <xen/xenbus.h>
 #include <xen/page.h>
 #include "tpm.h"
+#include <xen/platform_pci.h>
 
 struct tpm_private {
 	struct tpm_chip *chip;
@@ -421,6 +422,9 @@  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 e59acb1..d4b52e9 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -2115,7 +2115,7 @@  static int __init netif_init(void)
 	if (!xen_domain())
 		return -ENODEV;
 
-	if (xen_hvm_domain() && !xen_platform_pci_unplug)
+	if (!xen_has_pv_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 129bf84..cb385c1 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..87bc59c 100644
--- a/include/xen/platform_pci.h
+++ b/include/xen/platform_pci.h
@@ -47,5 +47,16 @@  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);
+#else
+static inline bool xen_has_pv_devices(void)
+{
+#if defined(CONFIG_XEN)
+	return true;
+#else
+	return false;
+#endif
+}
+#endif
 #endif /* _XEN_PLATFORM_PCI_H */