From: Oleksandr Andrushchenko <[email protected]>
Xen-pciback driver was designed to be built for x86 only. But it
can also be used by other architectures, e.g. Arm.
Currently PCI backend implements multiple functionalities at a time,
such as:
1. It is used as a database for assignable PCI devices, e.g. xl
pci-assignable-{add|remove|list} manipulates that list. So, whenever
the toolstack needs to know which PCI devices can be passed through
it reads that from the relevant sysfs entries of the pciback.
2. It is used to hold the unbound PCI devices list, e.g. when passing
through a PCI device it needs to be unbound from the relevant device
driver and bound to pciback (strictly speaking it is not required
that the device is bound to pciback, but pciback is again used as a
database of the passed through PCI devices, so we can re-bind the
devices back to their original drivers when guest domain shuts down)
3. Device reset for the devices being passed through
4. Para-virtualised use-cases support
The para-virtualised part of the driver is not always needed as some
architectures, e.g. Arm or x86 PVH Dom0, are not using backend-frontend
model for PCI device passthrough.
For such use-cases make the very first step in splitting the
xen-pciback driver into two parts: Xen PCI stub and PCI PV backend
drivers.
For that add new configuration options CONFIG_XEN_PCI_STUB and
CONFIG_XEN_PCIDEV_STUB, so the driver can be limited in its
functionality, e.g. no support for para-virtualised scenario.
x86 platform will continue using CONFIG_XEN_PCIDEV_BACKEND for the
fully featured backend driver.
Signed-off-by: Oleksandr Andrushchenko <[email protected]>
Signed-off-by: Anastasiia Lukianenko <[email protected]>
Reviewed-by: Stefano Stabellini <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
---
Changes since v5:
- rebased
Changes since v4:
- squashed two patches
- simplified Makefile
Changes since v3:
- Fix >>32 shift for 32-bit architectures
Changes since v2:
- swap the patch order
Since v1:
- Do not move pci_xen_initial_domain as it is x86 specific
---
arch/x86/include/asm/xen/pci.h | 19 ------
arch/x86/pci/xen.c | 76 +--------------------
drivers/xen/Kconfig | 24 +++++++
drivers/xen/Makefile | 2 +-
drivers/xen/pci.c | 75 ++++++++++++++++++++
drivers/xen/xen-pciback/Makefile | 7 ++
drivers/xen/xen-pciback/conf_space_header.c | 8 ++-
drivers/xen/xen-pciback/pci_stub.c | 3 +-
drivers/xen/xen-pciback/pciback.h | 5 ++
drivers/xen/xen-pciback/xenbus.c | 8 ++-
include/xen/pci.h | 28 ++++++++
11 files changed, 155 insertions(+), 100 deletions(-)
create mode 100644 include/xen/pci.h
diff --git a/arch/x86/include/asm/xen/pci.h b/arch/x86/include/asm/xen/pci.h
index 4557f7cb0fa6..9015b888edd6 100644
--- a/arch/x86/include/asm/xen/pci.h
+++ b/arch/x86/include/asm/xen/pci.h
@@ -22,25 +22,6 @@ static inline int __init pci_xen_initial_domain(void)
return -1;
}
#endif
-#ifdef CONFIG_XEN_DOM0
-int xen_find_device_domain_owner(struct pci_dev *dev);
-int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
-int xen_unregister_device_domain_owner(struct pci_dev *dev);
-#else
-static inline int xen_find_device_domain_owner(struct pci_dev *dev)
-{
- return -1;
-}
-static inline int xen_register_device_domain_owner(struct pci_dev *dev,
- uint16_t domain)
-{
- return -1;
-}
-static inline int xen_unregister_device_domain_owner(struct pci_dev *dev)
-{
- return -1;
-}
-#endif
#if defined(CONFIG_PCI_MSI)
#if defined(CONFIG_PCI_XEN)
diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 5debe4ac6f81..12da00558631 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -23,6 +23,7 @@
#include <xen/features.h>
#include <xen/events.h>
+#include <xen/pci.h>
#include <asm/xen/pci.h>
#include <asm/xen/cpuid.h>
#include <asm/apic.h>
@@ -585,78 +586,3 @@ int __init pci_xen_initial_domain(void)
}
#endif
-#ifdef CONFIG_XEN_DOM0
-
-struct xen_device_domain_owner {
- domid_t domain;
- struct pci_dev *dev;
- struct list_head list;
-};
-
-static DEFINE_SPINLOCK(dev_domain_list_spinlock);
-static struct list_head dev_domain_list = LIST_HEAD_INIT(dev_domain_list);
-
-static struct xen_device_domain_owner *find_device(struct pci_dev *dev)
-{
- struct xen_device_domain_owner *owner;
-
- list_for_each_entry(owner, &dev_domain_list, list) {
- if (owner->dev == dev)
- return owner;
- }
- return NULL;
-}
-
-int xen_find_device_domain_owner(struct pci_dev *dev)
-{
- struct xen_device_domain_owner *owner;
- int domain = -ENODEV;
-
- spin_lock(&dev_domain_list_spinlock);
- owner = find_device(dev);
- if (owner)
- domain = owner->domain;
- spin_unlock(&dev_domain_list_spinlock);
- return domain;
-}
-EXPORT_SYMBOL_GPL(xen_find_device_domain_owner);
-
-int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
-{
- struct xen_device_domain_owner *owner;
-
- owner = kzalloc(sizeof(struct xen_device_domain_owner), GFP_KERNEL);
- if (!owner)
- return -ENODEV;
-
- spin_lock(&dev_domain_list_spinlock);
- if (find_device(dev)) {
- spin_unlock(&dev_domain_list_spinlock);
- kfree(owner);
- return -EEXIST;
- }
- owner->domain = domain;
- owner->dev = dev;
- list_add_tail(&owner->list, &dev_domain_list);
- spin_unlock(&dev_domain_list_spinlock);
- return 0;
-}
-EXPORT_SYMBOL_GPL(xen_register_device_domain_owner);
-
-int xen_unregister_device_domain_owner(struct pci_dev *dev)
-{
- struct xen_device_domain_owner *owner;
-
- spin_lock(&dev_domain_list_spinlock);
- owner = find_device(dev);
- if (!owner) {
- spin_unlock(&dev_domain_list_spinlock);
- return -ENODEV;
- }
- list_del(&owner->list);
- spin_unlock(&dev_domain_list_spinlock);
- kfree(owner);
- return 0;
-}
-EXPORT_SYMBOL_GPL(xen_unregister_device_domain_owner);
-#endif /* CONFIG_XEN_DOM0 */
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 1b2c3aca6887..a1b11c62da9e 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -181,10 +181,34 @@ config SWIOTLB_XEN
select DMA_OPS
select SWIOTLB
+config XEN_PCI_STUB
+ bool
+
+config XEN_PCIDEV_STUB
+ tristate "Xen PCI-device stub driver"
+ depends on PCI && !X86 && XEN
+ depends on XEN_BACKEND
+ select XEN_PCI_STUB
+ default m
+ help
+ The PCI device stub driver provides limited version of the PCI
+ device backend driver without para-virtualized support for guests.
+ If you select this to be a module, you will need to make sure no
+ other driver has bound to the device(s) you want to make visible to
+ other guests.
+
+ The "hide" parameter (only applicable if backend driver is compiled
+ into the kernel) allows you to bind the PCI devices to this module
+ from the default device drivers. The argument is the list of PCI BDFs:
+ xen-pciback.hide=(03:00.0)(04:00.0)
+
+ If in doubt, say m.
+
config XEN_PCIDEV_BACKEND
tristate "Xen PCI-device backend driver"
depends on PCI && X86 && XEN
depends on XEN_BACKEND
+ select XEN_PCI_STUB
default m
help
The PCI device backend driver allows the kernel to export arbitrary
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 3434593455b2..5aae66e638a7 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -24,7 +24,7 @@ obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
obj-$(CONFIG_XEN_PVHVM_GUEST) += platform-pci.o
obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o
obj-$(CONFIG_XEN_MCE_LOG) += mcelog.o
-obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/
+obj-$(CONFIG_XEN_PCI_STUB) += xen-pciback/
obj-$(CONFIG_XEN_PRIVCMD) += xen-privcmd.o
obj-$(CONFIG_XEN_ACPI_PROCESSOR) += xen-acpi-processor.o
obj-$(CONFIG_XEN_EFI) += efi.o
diff --git a/drivers/xen/pci.c b/drivers/xen/pci.c
index 224df03ce42e..fc8c1249d49f 100644
--- a/drivers/xen/pci.c
+++ b/drivers/xen/pci.c
@@ -254,3 +254,78 @@ static int xen_mcfg_late(void)
return 0;
}
#endif
+
+#ifdef CONFIG_XEN_DOM0
+struct xen_device_domain_owner {
+ domid_t domain;
+ struct pci_dev *dev;
+ struct list_head list;
+};
+
+static DEFINE_SPINLOCK(dev_domain_list_spinlock);
+static struct list_head dev_domain_list = LIST_HEAD_INIT(dev_domain_list);
+
+static struct xen_device_domain_owner *find_device(struct pci_dev *dev)
+{
+ struct xen_device_domain_owner *owner;
+
+ list_for_each_entry(owner, &dev_domain_list, list) {
+ if (owner->dev == dev)
+ return owner;
+ }
+ return NULL;
+}
+
+int xen_find_device_domain_owner(struct pci_dev *dev)
+{
+ struct xen_device_domain_owner *owner;
+ int domain = -ENODEV;
+
+ spin_lock(&dev_domain_list_spinlock);
+ owner = find_device(dev);
+ if (owner)
+ domain = owner->domain;
+ spin_unlock(&dev_domain_list_spinlock);
+ return domain;
+}
+EXPORT_SYMBOL_GPL(xen_find_device_domain_owner);
+
+int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
+{
+ struct xen_device_domain_owner *owner;
+
+ owner = kzalloc(sizeof(struct xen_device_domain_owner), GFP_KERNEL);
+ if (!owner)
+ return -ENODEV;
+
+ spin_lock(&dev_domain_list_spinlock);
+ if (find_device(dev)) {
+ spin_unlock(&dev_domain_list_spinlock);
+ kfree(owner);
+ return -EEXIST;
+ }
+ owner->domain = domain;
+ owner->dev = dev;
+ list_add_tail(&owner->list, &dev_domain_list);
+ spin_unlock(&dev_domain_list_spinlock);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xen_register_device_domain_owner);
+
+int xen_unregister_device_domain_owner(struct pci_dev *dev)
+{
+ struct xen_device_domain_owner *owner;
+
+ spin_lock(&dev_domain_list_spinlock);
+ owner = find_device(dev);
+ if (!owner) {
+ spin_unlock(&dev_domain_list_spinlock);
+ return -ENODEV;
+ }
+ list_del(&owner->list);
+ spin_unlock(&dev_domain_list_spinlock);
+ kfree(owner);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xen_unregister_device_domain_owner);
+#endif
diff --git a/drivers/xen/xen-pciback/Makefile b/drivers/xen/xen-pciback/Makefile
index e8d981d43235..d63df09de81c 100644
--- a/drivers/xen/xen-pciback/Makefile
+++ b/drivers/xen/xen-pciback/Makefile
@@ -1,5 +1,12 @@
# SPDX-License-Identifier: GPL-2.0
+
+# N.B. The below cannot be expressed with a single line using
+# CONFIG_XEN_PCI_STUB as it always remains in "y" state,
+# thus preventing the driver to be built as a module.
+# Please note, that CONFIG_XEN_PCIDEV_BACKEND and
+# CONFIG_XEN_PCIDEV_STUB are mutually exclusive.
obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback.o
+obj-$(CONFIG_XEN_PCIDEV_STUB) += xen-pciback.o
xen-pciback-y := pci_stub.o pciback_ops.o xenbus.o
xen-pciback-y += conf_space.o conf_space_header.o \
diff --git a/drivers/xen/xen-pciback/conf_space_header.c b/drivers/xen/xen-pciback/conf_space_header.c
index ac45cdc38e85..981435103af1 100644
--- a/drivers/xen/xen-pciback/conf_space_header.c
+++ b/drivers/xen/xen-pciback/conf_space_header.c
@@ -236,8 +236,12 @@ static void *bar_init(struct pci_dev *dev, int offset)
else {
pos = (offset - PCI_BASE_ADDRESS_0) / 4;
if (pos && (res[pos - 1].flags & IORESOURCE_MEM_64)) {
- bar->val = res[pos - 1].start >> 32;
- bar->len_val = -resource_size(&res[pos - 1]) >> 32;
+ /*
+ * Use ">> 16 >> 16" instead of direct ">> 32" shift
+ * to avoid warnings on 32-bit architectures.
+ */
+ bar->val = res[pos - 1].start >> 16 >> 16;
+ bar->len_val = -resource_size(&res[pos - 1]) >> 16 >> 16;
return bar;
}
}
diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index f8e4faa96ad6..bba527620507 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -19,7 +19,8 @@
#include <linux/sched.h>
#include <linux/atomic.h>
#include <xen/events.h>
-#include <asm/xen/pci.h>
+#include <xen/pci.h>
+#include <xen/xen.h>
#include <asm/xen/hypervisor.h>
#include <xen/interface/physdev.h>
#include "pciback.h"
diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
index 95e28ee48d52..9a64196e831d 100644
--- a/drivers/xen/xen-pciback/pciback.h
+++ b/drivers/xen/xen-pciback/pciback.h
@@ -71,6 +71,11 @@ struct pci_dev *pcistub_get_pci_dev(struct xen_pcibk_device *pdev,
struct pci_dev *dev);
void pcistub_put_pci_dev(struct pci_dev *dev);
+static inline bool xen_pcibk_pv_support(void)
+{
+ return IS_ENABLED(CONFIG_XEN_PCIDEV_BACKEND);
+}
+
/* Ensure a device is turned off or reset */
void xen_pcibk_reset_device(struct pci_dev *pdev);
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index c09c7ebd6968..bde63ef677b8 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -14,7 +14,7 @@
#include <linux/workqueue.h>
#include <xen/xenbus.h>
#include <xen/events.h>
-#include <asm/xen/pci.h>
+#include <xen/pci.h>
#include "pciback.h"
#define INVALID_EVTCHN_IRQ (-1)
@@ -743,6 +743,9 @@ const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
int __init xen_pcibk_xenbus_register(void)
{
+ if (!xen_pcibk_pv_support())
+ return 0;
+
xen_pcibk_backend = &xen_pcibk_vpci_backend;
if (passthrough)
xen_pcibk_backend = &xen_pcibk_passthrough_backend;
@@ -752,5 +755,6 @@ int __init xen_pcibk_xenbus_register(void)
void __exit xen_pcibk_xenbus_unregister(void)
{
- xenbus_unregister_driver(&xen_pcibk_driver);
+ if (xen_pcibk_pv_support())
+ xenbus_unregister_driver(&xen_pcibk_driver);
}
diff --git a/include/xen/pci.h b/include/xen/pci.h
new file mode 100644
index 000000000000..b8337cf85fd1
--- /dev/null
+++ b/include/xen/pci.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __XEN_PCI_H__
+#define __XEN_PCI_H__
+
+#if defined(CONFIG_XEN_DOM0)
+int xen_find_device_domain_owner(struct pci_dev *dev);
+int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
+int xen_unregister_device_domain_owner(struct pci_dev *dev);
+#else
+static inline int xen_find_device_domain_owner(struct pci_dev *dev)
+{
+ return -1;
+}
+
+static inline int xen_register_device_domain_owner(struct pci_dev *dev,
+ uint16_t domain)
+{
+ return -1;
+}
+
+static inline int xen_unregister_device_domain_owner(struct pci_dev *dev)
+{
+ return -1;
+}
+#endif
+
+#endif
--
2.25.1
Please ignore this patch in favor of "RESEND PATCH v6" due to
a warning reported by kernel test robot <[email protected]>:
I love your patch! Perhaps something to improve:
[auto build test WARNING on xen-tip/linux-next]
[also build test WARNING on linux/master linus/master v5.15-rc7 next-20211028]
[cannot apply to helgaas-pci/next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url:https://github.com/0day-ci/linux/commits/Oleksandr-Andrushchenko/xen-pciback-allow-compiling-on-other-archs-than-x86/20211028-141523
base:https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git linux-next
config: arm64-defconfig (attached as .config)
compiler: aarch64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wgethttps://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
#https://github.com/0day-ci/linux/commit/085a7279d0d85497688bc5be9a1f00ab2cce02ae
git remote add linux-reviewhttps://github.com/0day-ci/linux
git fetch --no-tags linux-review Oleksandr-Andrushchenko/xen-pciback-allow-compiling-on-other-archs-than-x86/20211028-141523
git checkout 085a7279d0d85497688bc5be9a1f00ab2cce02ae
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=arm64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot<[email protected]>
All warnings (new ones prefixed by >>):
>> drivers/xen/pci.c:279:5: warning: no previous prototype for 'xen_find_device_domain_owner' [-Wmissing-prototypes]
279 | int xen_find_device_domain_owner(struct pci_dev *dev)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> drivers/xen/pci.c:293:5: warning: no previous prototype for 'xen_register_device_domain_owner' [-Wmissing-prototypes]
293 | int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> drivers/xen/pci.c:315:5: warning: no previous prototype for 'xen_unregister_device_domain_owner' [-Wmissing-prototypes]
315 | int xen_unregister_device_domain_owner(struct pci_dev *dev)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
vim +/xen_find_device_domain_owner +279 drivers/xen/pci.c
278
> 279 int xen_find_device_domain_owner(struct pci_dev *dev)
280 {
281 struct xen_device_domain_owner *owner;
282 int domain = -ENODEV;
283
284 spin_lock(&dev_domain_list_spinlock);
285 owner = find_device(dev);
286 if (owner)
287 domain = owner->domain;
288 spin_unlock(&dev_domain_list_spinlock);
289 return domain;
290 }
291 EXPORT_SYMBOL_GPL(xen_find_device_domain_owner);
292
> 293 int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
294 {
295 struct xen_device_domain_owner *owner;
296
297 owner = kzalloc(sizeof(struct xen_device_domain_owner), GFP_KERNEL);
298 if (!owner)
299 return -ENODEV;
300
301 spin_lock(&dev_domain_list_spinlock);
302 if (find_device(dev)) {
303 spin_unlock(&dev_domain_list_spinlock);
304 kfree(owner);
305 return -EEXIST;
306 }
307 owner->domain = domain;
308 owner->dev = dev;
309 list_add_tail(&owner->list, &dev_domain_list);
310 spin_unlock(&dev_domain_list_spinlock);
311 return 0;
312 }
313 EXPORT_SYMBOL_GPL(xen_register_device_domain_owner);
314
> 315 int xen_unregister_device_domain_owner(struct pci_dev *dev)
On 28.10.21 09:13, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <[email protected]>
>
> Xen-pciback driver was designed to be built for x86 only. But it
> can also be used by other architectures, e.g. Arm.
>
> Currently PCI backend implements multiple functionalities at a time,
> such as:
> 1. It is used as a database for assignable PCI devices, e.g. xl
> pci-assignable-{add|remove|list} manipulates that list. So, whenever
> the toolstack needs to know which PCI devices can be passed through
> it reads that from the relevant sysfs entries of the pciback.
> 2. It is used to hold the unbound PCI devices list, e.g. when passing
> through a PCI device it needs to be unbound from the relevant device
> driver and bound to pciback (strictly speaking it is not required
> that the device is bound to pciback, but pciback is again used as a
> database of the passed through PCI devices, so we can re-bind the
> devices back to their original drivers when guest domain shuts down)
> 3. Device reset for the devices being passed through
> 4. Para-virtualised use-cases support
>
> The para-virtualised part of the driver is not always needed as some
> architectures, e.g. Arm or x86 PVH Dom0, are not using backend-frontend
> model for PCI device passthrough.
>
> For such use-cases make the very first step in splitting the
> xen-pciback driver into two parts: Xen PCI stub and PCI PV backend
> drivers.
>
> For that add new configuration options CONFIG_XEN_PCI_STUB and
> CONFIG_XEN_PCIDEV_STUB, so the driver can be limited in its
> functionality, e.g. no support for para-virtualised scenario.
> x86 platform will continue using CONFIG_XEN_PCIDEV_BACKEND for the
> fully featured backend driver.
>
> Signed-off-by: Oleksandr Andrushchenko <[email protected]>
> Signed-off-by: Anastasiia Lukianenko <[email protected]>
> Reviewed-by: Stefano Stabellini <[email protected]>
> Reviewed-by: Juergen Gross <[email protected]>
> ---
> Changes since v5:
> - rebased
> Changes since v4:
> - squashed two patches
> - simplified Makefile
> Changes since v3:
> - Fix >>32 shift for 32-bit architectures
> Changes since v2:
> - swap the patch order
> Since v1:
> - Do not move pci_xen_initial_domain as it is x86 specific
> ---
> arch/x86/include/asm/xen/pci.h | 19 ------
> arch/x86/pci/xen.c | 76 +--------------------
> drivers/xen/Kconfig | 24 +++++++
> drivers/xen/Makefile | 2 +-
> drivers/xen/pci.c | 75 ++++++++++++++++++++
> drivers/xen/xen-pciback/Makefile | 7 ++
> drivers/xen/xen-pciback/conf_space_header.c | 8 ++-
> drivers/xen/xen-pciback/pci_stub.c | 3 +-
> drivers/xen/xen-pciback/pciback.h | 5 ++
> drivers/xen/xen-pciback/xenbus.c | 8 ++-
> include/xen/pci.h | 28 ++++++++
> 11 files changed, 155 insertions(+), 100 deletions(-)
> create mode 100644 include/xen/pci.h
>
> diff --git a/arch/x86/include/asm/xen/pci.h b/arch/x86/include/asm/xen/pci.h
> index 4557f7cb0fa6..9015b888edd6 100644
> --- a/arch/x86/include/asm/xen/pci.h
> +++ b/arch/x86/include/asm/xen/pci.h
> @@ -22,25 +22,6 @@ static inline int __init pci_xen_initial_domain(void)
> return -1;
> }
> #endif
> -#ifdef CONFIG_XEN_DOM0
> -int xen_find_device_domain_owner(struct pci_dev *dev);
> -int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
> -int xen_unregister_device_domain_owner(struct pci_dev *dev);
> -#else
> -static inline int xen_find_device_domain_owner(struct pci_dev *dev)
> -{
> - return -1;
> -}
> -static inline int xen_register_device_domain_owner(struct pci_dev *dev,
> - uint16_t domain)
> -{
> - return -1;
> -}
> -static inline int xen_unregister_device_domain_owner(struct pci_dev *dev)
> -{
> - return -1;
> -}
> -#endif
>
> #if defined(CONFIG_PCI_MSI)
> #if defined(CONFIG_PCI_XEN)
> diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
> index 5debe4ac6f81..12da00558631 100644
> --- a/arch/x86/pci/xen.c
> +++ b/arch/x86/pci/xen.c
> @@ -23,6 +23,7 @@
>
> #include <xen/features.h>
> #include <xen/events.h>
> +#include <xen/pci.h>
> #include <asm/xen/pci.h>
> #include <asm/xen/cpuid.h>
> #include <asm/apic.h>
> @@ -585,78 +586,3 @@ int __init pci_xen_initial_domain(void)
> }
> #endif
>
> -#ifdef CONFIG_XEN_DOM0
> -
> -struct xen_device_domain_owner {
> - domid_t domain;
> - struct pci_dev *dev;
> - struct list_head list;
> -};
> -
> -static DEFINE_SPINLOCK(dev_domain_list_spinlock);
> -static struct list_head dev_domain_list = LIST_HEAD_INIT(dev_domain_list);
> -
> -static struct xen_device_domain_owner *find_device(struct pci_dev *dev)
> -{
> - struct xen_device_domain_owner *owner;
> -
> - list_for_each_entry(owner, &dev_domain_list, list) {
> - if (owner->dev == dev)
> - return owner;
> - }
> - return NULL;
> -}
> -
> -int xen_find_device_domain_owner(struct pci_dev *dev)
> -{
> - struct xen_device_domain_owner *owner;
> - int domain = -ENODEV;
> -
> - spin_lock(&dev_domain_list_spinlock);
> - owner = find_device(dev);
> - if (owner)
> - domain = owner->domain;
> - spin_unlock(&dev_domain_list_spinlock);
> - return domain;
> -}
> -EXPORT_SYMBOL_GPL(xen_find_device_domain_owner);
> -
> -int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
> -{
> - struct xen_device_domain_owner *owner;
> -
> - owner = kzalloc(sizeof(struct xen_device_domain_owner), GFP_KERNEL);
> - if (!owner)
> - return -ENODEV;
> -
> - spin_lock(&dev_domain_list_spinlock);
> - if (find_device(dev)) {
> - spin_unlock(&dev_domain_list_spinlock);
> - kfree(owner);
> - return -EEXIST;
> - }
> - owner->domain = domain;
> - owner->dev = dev;
> - list_add_tail(&owner->list, &dev_domain_list);
> - spin_unlock(&dev_domain_list_spinlock);
> - return 0;
> -}
> -EXPORT_SYMBOL_GPL(xen_register_device_domain_owner);
> -
> -int xen_unregister_device_domain_owner(struct pci_dev *dev)
> -{
> - struct xen_device_domain_owner *owner;
> -
> - spin_lock(&dev_domain_list_spinlock);
> - owner = find_device(dev);
> - if (!owner) {
> - spin_unlock(&dev_domain_list_spinlock);
> - return -ENODEV;
> - }
> - list_del(&owner->list);
> - spin_unlock(&dev_domain_list_spinlock);
> - kfree(owner);
> - return 0;
> -}
> -EXPORT_SYMBOL_GPL(xen_unregister_device_domain_owner);
> -#endif /* CONFIG_XEN_DOM0 */
> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> index 1b2c3aca6887..a1b11c62da9e 100644
> --- a/drivers/xen/Kconfig
> +++ b/drivers/xen/Kconfig
> @@ -181,10 +181,34 @@ config SWIOTLB_XEN
> select DMA_OPS
> select SWIOTLB
>
> +config XEN_PCI_STUB
> + bool
> +
> +config XEN_PCIDEV_STUB
> + tristate "Xen PCI-device stub driver"
> + depends on PCI && !X86 && XEN
> + depends on XEN_BACKEND
> + select XEN_PCI_STUB
> + default m
> + help
> + The PCI device stub driver provides limited version of the PCI
> + device backend driver without para-virtualized support for guests.
> + If you select this to be a module, you will need to make sure no
> + other driver has bound to the device(s) you want to make visible to
> + other guests.
> +
> + The "hide" parameter (only applicable if backend driver is compiled
> + into the kernel) allows you to bind the PCI devices to this module
> + from the default device drivers. The argument is the list of PCI BDFs:
> + xen-pciback.hide=(03:00.0)(04:00.0)
> +
> + If in doubt, say m.
> +
> config XEN_PCIDEV_BACKEND
> tristate "Xen PCI-device backend driver"
> depends on PCI && X86 && XEN
> depends on XEN_BACKEND
> + select XEN_PCI_STUB
> default m
> help
> The PCI device backend driver allows the kernel to export arbitrary
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index 3434593455b2..5aae66e638a7 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -24,7 +24,7 @@ obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
> obj-$(CONFIG_XEN_PVHVM_GUEST) += platform-pci.o
> obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o
> obj-$(CONFIG_XEN_MCE_LOG) += mcelog.o
> -obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/
> +obj-$(CONFIG_XEN_PCI_STUB) += xen-pciback/
> obj-$(CONFIG_XEN_PRIVCMD) += xen-privcmd.o
> obj-$(CONFIG_XEN_ACPI_PROCESSOR) += xen-acpi-processor.o
> obj-$(CONFIG_XEN_EFI) += efi.o
> diff --git a/drivers/xen/pci.c b/drivers/xen/pci.c
> index 224df03ce42e..fc8c1249d49f 100644
> --- a/drivers/xen/pci.c
> +++ b/drivers/xen/pci.c
> @@ -254,3 +254,78 @@ static int xen_mcfg_late(void)
> return 0;
> }
> #endif
> +
> +#ifdef CONFIG_XEN_DOM0
> +struct xen_device_domain_owner {
> + domid_t domain;
> + struct pci_dev *dev;
> + struct list_head list;
> +};
> +
> +static DEFINE_SPINLOCK(dev_domain_list_spinlock);
> +static struct list_head dev_domain_list = LIST_HEAD_INIT(dev_domain_list);
> +
> +static struct xen_device_domain_owner *find_device(struct pci_dev *dev)
> +{
> + struct xen_device_domain_owner *owner;
> +
> + list_for_each_entry(owner, &dev_domain_list, list) {
> + if (owner->dev == dev)
> + return owner;
> + }
> + return NULL;
> +}
> +
> +int xen_find_device_domain_owner(struct pci_dev *dev)
> +{
> + struct xen_device_domain_owner *owner;
> + int domain = -ENODEV;
> +
> + spin_lock(&dev_domain_list_spinlock);
> + owner = find_device(dev);
> + if (owner)
> + domain = owner->domain;
> + spin_unlock(&dev_domain_list_spinlock);
> + return domain;
> +}
> +EXPORT_SYMBOL_GPL(xen_find_device_domain_owner);
> +
> +int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
> +{
> + struct xen_device_domain_owner *owner;
> +
> + owner = kzalloc(sizeof(struct xen_device_domain_owner), GFP_KERNEL);
> + if (!owner)
> + return -ENODEV;
> +
> + spin_lock(&dev_domain_list_spinlock);
> + if (find_device(dev)) {
> + spin_unlock(&dev_domain_list_spinlock);
> + kfree(owner);
> + return -EEXIST;
> + }
> + owner->domain = domain;
> + owner->dev = dev;
> + list_add_tail(&owner->list, &dev_domain_list);
> + spin_unlock(&dev_domain_list_spinlock);
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(xen_register_device_domain_owner);
> +
> +int xen_unregister_device_domain_owner(struct pci_dev *dev)
> +{
> + struct xen_device_domain_owner *owner;
> +
> + spin_lock(&dev_domain_list_spinlock);
> + owner = find_device(dev);
> + if (!owner) {
> + spin_unlock(&dev_domain_list_spinlock);
> + return -ENODEV;
> + }
> + list_del(&owner->list);
> + spin_unlock(&dev_domain_list_spinlock);
> + kfree(owner);
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(xen_unregister_device_domain_owner);
> +#endif
> diff --git a/drivers/xen/xen-pciback/Makefile b/drivers/xen/xen-pciback/Makefile
> index e8d981d43235..d63df09de81c 100644
> --- a/drivers/xen/xen-pciback/Makefile
> +++ b/drivers/xen/xen-pciback/Makefile
> @@ -1,5 +1,12 @@
> # SPDX-License-Identifier: GPL-2.0
> +
> +# N.B. The below cannot be expressed with a single line using
> +# CONFIG_XEN_PCI_STUB as it always remains in "y" state,
> +# thus preventing the driver to be built as a module.
> +# Please note, that CONFIG_XEN_PCIDEV_BACKEND and
> +# CONFIG_XEN_PCIDEV_STUB are mutually exclusive.
> obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback.o
> +obj-$(CONFIG_XEN_PCIDEV_STUB) += xen-pciback.o
>
> xen-pciback-y := pci_stub.o pciback_ops.o xenbus.o
> xen-pciback-y += conf_space.o conf_space_header.o \
> diff --git a/drivers/xen/xen-pciback/conf_space_header.c b/drivers/xen/xen-pciback/conf_space_header.c
> index ac45cdc38e85..981435103af1 100644
> --- a/drivers/xen/xen-pciback/conf_space_header.c
> +++ b/drivers/xen/xen-pciback/conf_space_header.c
> @@ -236,8 +236,12 @@ static void *bar_init(struct pci_dev *dev, int offset)
> else {
> pos = (offset - PCI_BASE_ADDRESS_0) / 4;
> if (pos && (res[pos - 1].flags & IORESOURCE_MEM_64)) {
> - bar->val = res[pos - 1].start >> 32;
> - bar->len_val = -resource_size(&res[pos - 1]) >> 32;
> + /*
> + * Use ">> 16 >> 16" instead of direct ">> 32" shift
> + * to avoid warnings on 32-bit architectures.
> + */
> + bar->val = res[pos - 1].start >> 16 >> 16;
> + bar->len_val = -resource_size(&res[pos - 1]) >> 16 >> 16;
> return bar;
> }
> }
> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
> index f8e4faa96ad6..bba527620507 100644
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -19,7 +19,8 @@
> #include <linux/sched.h>
> #include <linux/atomic.h>
> #include <xen/events.h>
> -#include <asm/xen/pci.h>
> +#include <xen/pci.h>
> +#include <xen/xen.h>
> #include <asm/xen/hypervisor.h>
> #include <xen/interface/physdev.h>
> #include "pciback.h"
> diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
> index 95e28ee48d52..9a64196e831d 100644
> --- a/drivers/xen/xen-pciback/pciback.h
> +++ b/drivers/xen/xen-pciback/pciback.h
> @@ -71,6 +71,11 @@ struct pci_dev *pcistub_get_pci_dev(struct xen_pcibk_device *pdev,
> struct pci_dev *dev);
> void pcistub_put_pci_dev(struct pci_dev *dev);
>
> +static inline bool xen_pcibk_pv_support(void)
> +{
> + return IS_ENABLED(CONFIG_XEN_PCIDEV_BACKEND);
> +}
> +
> /* Ensure a device is turned off or reset */
> void xen_pcibk_reset_device(struct pci_dev *pdev);
>
> diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
> index c09c7ebd6968..bde63ef677b8 100644
> --- a/drivers/xen/xen-pciback/xenbus.c
> +++ b/drivers/xen/xen-pciback/xenbus.c
> @@ -14,7 +14,7 @@
> #include <linux/workqueue.h>
> #include <xen/xenbus.h>
> #include <xen/events.h>
> -#include <asm/xen/pci.h>
> +#include <xen/pci.h>
> #include "pciback.h"
>
> #define INVALID_EVTCHN_IRQ (-1)
> @@ -743,6 +743,9 @@ const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
>
> int __init xen_pcibk_xenbus_register(void)
> {
> + if (!xen_pcibk_pv_support())
> + return 0;
> +
> xen_pcibk_backend = &xen_pcibk_vpci_backend;
> if (passthrough)
> xen_pcibk_backend = &xen_pcibk_passthrough_backend;
> @@ -752,5 +755,6 @@ int __init xen_pcibk_xenbus_register(void)
>
> void __exit xen_pcibk_xenbus_unregister(void)
> {
> - xenbus_unregister_driver(&xen_pcibk_driver);
> + if (xen_pcibk_pv_support())
> + xenbus_unregister_driver(&xen_pcibk_driver);
> }
> diff --git a/include/xen/pci.h b/include/xen/pci.h
> new file mode 100644
> index 000000000000..b8337cf85fd1
> --- /dev/null
> +++ b/include/xen/pci.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __XEN_PCI_H__
> +#define __XEN_PCI_H__
> +
> +#if defined(CONFIG_XEN_DOM0)
> +int xen_find_device_domain_owner(struct pci_dev *dev);
> +int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain);
> +int xen_unregister_device_domain_owner(struct pci_dev *dev);
> +#else
> +static inline int xen_find_device_domain_owner(struct pci_dev *dev)
> +{
> + return -1;
> +}
> +
> +static inline int xen_register_device_domain_owner(struct pci_dev *dev,
> + uint16_t domain)
> +{
> + return -1;
> +}
> +
> +static inline int xen_unregister_device_domain_owner(struct pci_dev *dev)
> +{
> + return -1;
> +}
> +#endif
> +
> +#endif
Hi Oleksandr,
On Thu, Oct 28, 2021 at 8:15 AM Oleksandr Andrushchenko
<[email protected]> wrote:
> From: Oleksandr Andrushchenko <[email protected]>
>
> Xen-pciback driver was designed to be built for x86 only. But it
> can also be used by other architectures, e.g. Arm.
>
> Currently PCI backend implements multiple functionalities at a time,
> such as:
> 1. It is used as a database for assignable PCI devices, e.g. xl
> pci-assignable-{add|remove|list} manipulates that list. So, whenever
> the toolstack needs to know which PCI devices can be passed through
> it reads that from the relevant sysfs entries of the pciback.
> 2. It is used to hold the unbound PCI devices list, e.g. when passing
> through a PCI device it needs to be unbound from the relevant device
> driver and bound to pciback (strictly speaking it is not required
> that the device is bound to pciback, but pciback is again used as a
> database of the passed through PCI devices, so we can re-bind the
> devices back to their original drivers when guest domain shuts down)
> 3. Device reset for the devices being passed through
> 4. Para-virtualised use-cases support
>
> The para-virtualised part of the driver is not always needed as some
> architectures, e.g. Arm or x86 PVH Dom0, are not using backend-frontend
> model for PCI device passthrough.
>
> For such use-cases make the very first step in splitting the
> xen-pciback driver into two parts: Xen PCI stub and PCI PV backend
> drivers.
>
> For that add new configuration options CONFIG_XEN_PCI_STUB and
> CONFIG_XEN_PCIDEV_STUB, so the driver can be limited in its
> functionality, e.g. no support for para-virtualised scenario.
> x86 platform will continue using CONFIG_XEN_PCIDEV_BACKEND for the
> fully featured backend driver.
>
> Signed-off-by: Oleksandr Andrushchenko <[email protected]>
> Signed-off-by: Anastasiia Lukianenko <[email protected]>
> Reviewed-by: Stefano Stabellini <[email protected]>
> Reviewed-by: Juergen Gross <[email protected]>
Thanks for your patch, which is now commit a67efff28832a597
("xen-pciback: allow compiling on other archs than x86")
in v5.16-rc1.
> --- a/drivers/xen/Kconfig
> +++ b/drivers/xen/Kconfig
> @@ -181,10 +181,34 @@ config SWIOTLB_XEN
> select DMA_OPS
> select SWIOTLB
>
> +config XEN_PCI_STUB
> + bool
> +
> +config XEN_PCIDEV_STUB
> + tristate "Xen PCI-device stub driver"
> + depends on PCI && !X86 && XEN
> + depends on XEN_BACKEND
> + select XEN_PCI_STUB
> + default m
Please note that this means "default y" if CONFIG_MODULES=n.
Perhaps this should be "default m if MODULES" instead?
> + help
> + The PCI device stub driver provides limited version of the PCI
> + device backend driver without para-virtualized support for guests.
> + If you select this to be a module, you will need to make sure no
> + other driver has bound to the device(s) you want to make visible to
> + other guests.
> +
> + The "hide" parameter (only applicable if backend driver is compiled
> + into the kernel) allows you to bind the PCI devices to this module
> + from the default device drivers. The argument is the list of PCI BDFs:
> + xen-pciback.hide=(03:00.0)(04:00.0)
> +
> + If in doubt, say m.
> +
> config XEN_PCIDEV_BACKEND
> tristate "Xen PCI-device backend driver"
> depends on PCI && X86 && XEN
> depends on XEN_BACKEND
> + select XEN_PCI_STUB
> default m
> help
> The PCI device backend driver allows the kernel to export arbitrary
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
Hi, Geert!
On 16.11.21 11:36, Geert Uytterhoeven wrote:
> Hi Oleksandr,
>
> On Thu, Oct 28, 2021 at 8:15 AM Oleksandr Andrushchenko
> <[email protected]> wrote:
>> From: Oleksandr Andrushchenko <[email protected]>
>>
>> Xen-pciback driver was designed to be built for x86 only. But it
>> can also be used by other architectures, e.g. Arm.
>>
>> Currently PCI backend implements multiple functionalities at a time,
>> such as:
>> 1. It is used as a database for assignable PCI devices, e.g. xl
>> pci-assignable-{add|remove|list} manipulates that list. So, whenever
>> the toolstack needs to know which PCI devices can be passed through
>> it reads that from the relevant sysfs entries of the pciback.
>> 2. It is used to hold the unbound PCI devices list, e.g. when passing
>> through a PCI device it needs to be unbound from the relevant device
>> driver and bound to pciback (strictly speaking it is not required
>> that the device is bound to pciback, but pciback is again used as a
>> database of the passed through PCI devices, so we can re-bind the
>> devices back to their original drivers when guest domain shuts down)
>> 3. Device reset for the devices being passed through
>> 4. Para-virtualised use-cases support
>>
>> The para-virtualised part of the driver is not always needed as some
>> architectures, e.g. Arm or x86 PVH Dom0, are not using backend-frontend
>> model for PCI device passthrough.
>>
>> For such use-cases make the very first step in splitting the
>> xen-pciback driver into two parts: Xen PCI stub and PCI PV backend
>> drivers.
>>
>> For that add new configuration options CONFIG_XEN_PCI_STUB and
>> CONFIG_XEN_PCIDEV_STUB, so the driver can be limited in its
>> functionality, e.g. no support for para-virtualised scenario.
>> x86 platform will continue using CONFIG_XEN_PCIDEV_BACKEND for the
>> fully featured backend driver.
>>
>> Signed-off-by: Oleksandr Andrushchenko <[email protected]>
>> Signed-off-by: Anastasiia Lukianenko <[email protected]>
>> Reviewed-by: Stefano Stabellini <[email protected]>
>> Reviewed-by: Juergen Gross <[email protected]>
> Thanks for your patch, which is now commit a67efff28832a597
> ("xen-pciback: allow compiling on other archs than x86")
> in v5.16-rc1.
>
>> --- a/drivers/xen/Kconfig
>> +++ b/drivers/xen/Kconfig
>> @@ -181,10 +181,34 @@ config SWIOTLB_XEN
>> select DMA_OPS
>> select SWIOTLB
>>
>> +config XEN_PCI_STUB
>> + bool
>> +
>> +config XEN_PCIDEV_STUB
>> + tristate "Xen PCI-device stub driver"
>> + depends on PCI && !X86 && XEN
>> + depends on XEN_BACKEND
>> + select XEN_PCI_STUB
>> + default m
> Please note that this means "default y" if CONFIG_MODULES=n.
> Perhaps this should be "default m if MODULES" instead?
I don't really have strong opinion on this and will let Xen maintainers
speak: @Boris, @Juergen what's your preference here?
>
>> + help
>> + The PCI device stub driver provides limited version of the PCI
>> + device backend driver without para-virtualized support for guests.
>> + If you select this to be a module, you will need to make sure no
>> + other driver has bound to the device(s) you want to make visible to
>> + other guests.
>> +
>> + The "hide" parameter (only applicable if backend driver is compiled
>> + into the kernel) allows you to bind the PCI devices to this module
>> + from the default device drivers. The argument is the list of PCI BDFs:
>> + xen-pciback.hide=(03:00.0)(04:00.0)
>> +
>> + If in doubt, say m.
>> +
>> config XEN_PCIDEV_BACKEND
>> tristate "Xen PCI-device backend driver"
>> depends on PCI && X86 && XEN
>> depends on XEN_BACKEND
>> + select XEN_PCI_STUB
>> default m
>> help
>> The PCI device backend driver allows the kernel to export arbitrary
> Gr{oetje,eeting}s,
>
> Geert
Thank you,
Oleksandr
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
On 16.11.21 11:45, Oleksandr Andrushchenko wrote:
> Hi, Geert!
>
> On 16.11.21 11:36, Geert Uytterhoeven wrote:
>> Hi Oleksandr,
>>
>> On Thu, Oct 28, 2021 at 8:15 AM Oleksandr Andrushchenko
>> <[email protected]> wrote:
>>> From: Oleksandr Andrushchenko <[email protected]>
>>>
>>> Xen-pciback driver was designed to be built for x86 only. But it
>>> can also be used by other architectures, e.g. Arm.
>>>
>>> Currently PCI backend implements multiple functionalities at a time,
>>> such as:
>>> 1. It is used as a database for assignable PCI devices, e.g. xl
>>> pci-assignable-{add|remove|list} manipulates that list. So, whenever
>>> the toolstack needs to know which PCI devices can be passed through
>>> it reads that from the relevant sysfs entries of the pciback.
>>> 2. It is used to hold the unbound PCI devices list, e.g. when passing
>>> through a PCI device it needs to be unbound from the relevant device
>>> driver and bound to pciback (strictly speaking it is not required
>>> that the device is bound to pciback, but pciback is again used as a
>>> database of the passed through PCI devices, so we can re-bind the
>>> devices back to their original drivers when guest domain shuts down)
>>> 3. Device reset for the devices being passed through
>>> 4. Para-virtualised use-cases support
>>>
>>> The para-virtualised part of the driver is not always needed as some
>>> architectures, e.g. Arm or x86 PVH Dom0, are not using backend-frontend
>>> model for PCI device passthrough.
>>>
>>> For such use-cases make the very first step in splitting the
>>> xen-pciback driver into two parts: Xen PCI stub and PCI PV backend
>>> drivers.
>>>
>>> For that add new configuration options CONFIG_XEN_PCI_STUB and
>>> CONFIG_XEN_PCIDEV_STUB, so the driver can be limited in its
>>> functionality, e.g. no support for para-virtualised scenario.
>>> x86 platform will continue using CONFIG_XEN_PCIDEV_BACKEND for the
>>> fully featured backend driver.
>>>
>>> Signed-off-by: Oleksandr Andrushchenko <[email protected]>
>>> Signed-off-by: Anastasiia Lukianenko <[email protected]>
>>> Reviewed-by: Stefano Stabellini <[email protected]>
>>> Reviewed-by: Juergen Gross <[email protected]>
>> Thanks for your patch, which is now commit a67efff28832a597
>> ("xen-pciback: allow compiling on other archs than x86")
>> in v5.16-rc1.
>>
>>> --- a/drivers/xen/Kconfig
>>> +++ b/drivers/xen/Kconfig
>>> @@ -181,10 +181,34 @@ config SWIOTLB_XEN
>>> select DMA_OPS
>>> select SWIOTLB
>>>
>>> +config XEN_PCI_STUB
>>> + bool
>>> +
>>> +config XEN_PCIDEV_STUB
>>> + tristate "Xen PCI-device stub driver"
>>> + depends on PCI && !X86 && XEN
>>> + depends on XEN_BACKEND
>>> + select XEN_PCI_STUB
>>> + default m
>> Please note that this means "default y" if CONFIG_MODULES=n.
>> Perhaps this should be "default m if MODULES" instead?
> I don't really have strong opinion on this and will let Xen maintainers
> speak: @Boris, @Juergen what's your preference here?
TBH, I don't have any.
All other backends have no "default" line, so maybe the cleanest
solution would be to remove the "default" lines for XEN_PCIDEV_STUB
and XEN_PCIDEV_BACKEND, too?
>>
>>> + help
>>> + The PCI device stub driver provides limited version of the PCI
>>> + device backend driver without para-virtualized support for guests.
>>> + If you select this to be a module, you will need to make sure no
>>> + other driver has bound to the device(s) you want to make visible to
>>> + other guests.
>>> +
>>> + The "hide" parameter (only applicable if backend driver is compiled
>>> + into the kernel) allows you to bind the PCI devices to this module
>>> + from the default device drivers. The argument is the list of PCI BDFs:
>>> + xen-pciback.hide=(03:00.0)(04:00.0)
>>> +
>>> + If in doubt, say m.
>>> +
>>> config XEN_PCIDEV_BACKEND
>>> tristate "Xen PCI-device backend driver"
>>> depends on PCI && X86 && XEN
>>> depends on XEN_BACKEND
>>> + select XEN_PCI_STUB
>>> default m
>>> help
>>> The PCI device backend driver allows the kernel to export arbitrary
Juergen