Linux Virtualization - Feb 2018 - [PATCH 2/6] pci: Scan all functions when probing while running over Jailhouse

Basic x86 support [1] for running Linux as secondary Jailhouse [2] guest
is currently pending in the tip tree. This builds on top and enhances
the PCI support for x86 and also ARM guests (ARM[64] does not require
platform patches and works already).

Key elements of this series are:
 - detection of Jailhouse via device tree hypervisor node
 - function-level PCI scan if Jailhouse is detected
 - MMCONFIG support for x86 guests

As most changes affect x86, I would suggest to route the series also via
tip after the necessary acks are collected.

Jan

[1] https://lkml.org/lkml/2017/11/27/125
[2] http://jailhouse-project.org

CC: Benedikt Spranger <b.spranger at linutronix.de>
CC: Mark Rutland <mark.rutland at arm.com>
CC: Otavio Pontes <otavio.pontes at intel.com>
CC: Rob Herring <robh+dt at kernel.org>

Jan Kiszka (5):
  jailhouse: Provide detection for non-x86 systems
  pci: Scan all functions when probing while running over Jailhouse
  x86: Consolidate PCI_MMCONFIG configs
  x86/jailhouse: Allow to use PCI_MMCONFIG without ACPI
  MAINTAINERS: Add entry for Jailhouse

Otavio Pontes (1):
  x86/jailhouse: Enable PCI mmconfig access in inmates

 Documentation/devicetree/bindings/jailhouse.txt |  8 ++++++++
 MAINTAINERS                                     |  7 +++++++
 arch/x86/Kconfig                                | 11 ++++++-----
 arch/x86/include/asm/jailhouse_para.h           |  2 +-
 arch/x86/include/asm/pci_x86.h                  |  2 ++
 arch/x86/kernel/Makefile                        |  2 +-
 arch/x86/kernel/cpu/amd.c                       |  2 +-
 arch/x86/kernel/jailhouse.c                     |  7 +++++++
 arch/x86/pci/legacy.c                           |  4 +++-
 arch/x86/pci/mmconfig-shared.c                  |  4 ++--
 drivers/pci/probe.c                             |  4 +++-
 include/linux/hypervisor.h                      | 17 +++++++++++++++--
 12 files changed, 56 insertions(+), 14 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/jailhouse.txt

-- 
2.13.6

From: Jan Kiszka <jan.kiszka at siemens.com>

Implement jailhouse_paravirt() via device tree probing on architectures
!= x86. Will be used by the PCI core.

CC: Rob Herring <robh+dt at kernel.org>
CC: Mark Rutland <mark.rutland at arm.com>
Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
---
 Documentation/devicetree/bindings/jailhouse.txt |  8 ++++++++
 arch/x86/include/asm/jailhouse_para.h           |  2 +-
 include/linux/hypervisor.h                      | 17 +++++++++++++++--
 3 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/jailhouse.txt

diff --git a/Documentation/devicetree/bindings/jailhouse.txt
b/Documentation/devicetree/bindings/jailhouse.txt
new file mode 100644
index 000000000000..2901c25ff340
--- /dev/null
+++ b/Documentation/devicetree/bindings/jailhouse.txt
@@ -0,0 +1,8 @@
+Jailhouse non-root cell device tree bindings
+--------------------------------------------
+
+When running in a non-root Jailhouse cell (partition), the device tree of this
+platform shall have a top-level "hypervisor" node with the following
+properties:
+
+- compatible = "jailhouse,cell"
diff --git a/arch/x86/include/asm/jailhouse_para.h
b/arch/x86/include/asm/jailhouse_para.h
index 875b54376689..b885a961a150 100644
--- a/arch/x86/include/asm/jailhouse_para.h
+++ b/arch/x86/include/asm/jailhouse_para.h
@@ -1,7 +1,7 @@
 /* SPDX-License-Identifier: GPL2.0 */
 
 /*
- * Jailhouse paravirt_ops implementation
+ * Jailhouse paravirt detection
  *
  * Copyright (c) Siemens AG, 2015-2017
  *
diff --git a/include/linux/hypervisor.h b/include/linux/hypervisor.h
index b19563f9a8eb..fc08b433c856 100644
--- a/include/linux/hypervisor.h
+++ b/include/linux/hypervisor.h
@@ -8,15 +8,28 @@
  */
 
 #ifdef CONFIG_X86
+
+#include <asm/jailhouse_para.h>
 #include <asm/x86_init.h>
+
 static inline void hypervisor_pin_vcpu(int cpu)
 {
 	x86_platform.hyper.pin_vcpu(cpu);
 }
-#else
+
+#else /* !CONFIG_X86 */
+
+#include <linux/of.h>
+
 static inline void hypervisor_pin_vcpu(int cpu)
 {
 }
-#endif
+
+static inline bool jailhouse_paravirt(void)
+{
+	return of_find_compatible_node(NULL, NULL, "jailhouse,cell");
+}
+
+#endif /* !CONFIG_X86 */
 
 #endif /* __LINUX_HYPEVISOR_H */
-- 
2.13.6

From: Jan Kiszka <jan.kiszka at siemens.com>

PCI and PCIBIOS probing only scans devices at function number 0/8/16/...
Subdevices (e.g. multiqueue) have function numbers which are not a
multiple of 8.

The simple hypervisor Jailhouse passes subdevices directly w/o providing
a virtual PCI topology like KVM. As a consequence a PCI passthrough from
Jailhouse to a guest will not be detected by Linux.

Based on patch by Benedikt Spranger, adding Jailhouse probing to avoid
changing the behavior in the absence of the hypervisor.

CC: Benedikt Spranger <b.spranger at linutronix.de>
Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
---
 arch/x86/pci/legacy.c | 4 +++-
 drivers/pci/probe.c   | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/pci/legacy.c b/arch/x86/pci/legacy.c
index 1cb01abcb1be..a7b0476b4f44 100644
--- a/arch/x86/pci/legacy.c
+++ b/arch/x86/pci/legacy.c
@@ -5,6 +5,7 @@
 #include <linux/export.h>
 #include <linux/pci.h>
 #include <asm/pci_x86.h>
+#include <asm/jailhouse_para.h>
 
 /*
  * Discover remaining PCI buses in case there are peer host bridges.
@@ -34,13 +35,14 @@ int __init pci_legacy_init(void)
 
 void pcibios_scan_specific_bus(int busn)
 {
+	int stride = jailhouse_paravirt() ? 1 : 8;
 	int devfn;
 	u32 l;
 
 	if (pci_find_bus(0, busn))
 		return;
 
-	for (devfn = 0; devfn < 256; devfn += 8) {
+	for (devfn = 0; devfn < 256; devfn += stride) {
 		if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) &&
 		    l != 0x0000 && l != 0xffff) {
 			DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 14e0ea1ff38b..60ad14c8245f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -17,6 +17,7 @@
 #include <linux/acpi.h>
 #include <linux/irqdomain.h>
 #include <linux/pm_runtime.h>
+#include <linux/hypervisor.h>
 #include "pci.h"
 
 #define CARDBUS_LATENCY_TIMER	176	/* secondary latency timer */
@@ -2454,6 +2455,7 @@ static unsigned int pci_scan_child_bus_extend(struct
pci_bus *bus,
 					      unsigned int available_buses)
 {
 	unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0;
+	unsigned int stride = jailhouse_paravirt() ? 1 : 8;
 	unsigned int start = bus->busn_res.start;
 	unsigned int devfn, cmax, max = start;
 	struct pci_dev *dev;
@@ -2461,7 +2463,7 @@ static unsigned int pci_scan_child_bus_extend(struct
pci_bus *bus,
 	dev_dbg(&bus->dev, "scanning bus\n");
 
 	/* Go find them, Rover! */
-	for (devfn = 0; devfn < 0x100; devfn += 8)
+	for (devfn = 0; devfn < 0x100; devfn += stride)
 		pci_scan_slot(bus, devfn);
 
 	/* Reserve buses for SR-IOV capability. */
-- 
2.13.6

From: Otavio Pontes <otavio.pontes at intel.com>

Use the PCI mmconfig base address exported by jailhouse in boot
parameters in order to access the memory mapped PCI configuration space.

Signed-off-by: Otavio Pontes <otavio.pontes at intel.com>
[Jan: rebased, fixed !CONFIG_PCI_MMCONFIG]
Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
---
 arch/x86/include/asm/pci_x86.h | 2 ++
 arch/x86/kernel/jailhouse.c    | 7 +++++++
 arch/x86/pci/mmconfig-shared.c | 4 ++--
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
index eb66fa9cd0fc..959d618dbb17 100644
--- a/arch/x86/include/asm/pci_x86.h
+++ b/arch/x86/include/asm/pci_x86.h
@@ -151,6 +151,8 @@ extern int pci_mmconfig_insert(struct device *dev, u16 seg,
u8 start, u8 end,
 			       phys_addr_t addr);
 extern int pci_mmconfig_delete(u16 seg, u8 start, u8 end);
 extern struct pci_mmcfg_region *pci_mmconfig_lookup(int segment, int bus);
+extern struct pci_mmcfg_region *__init pci_mmconfig_add(int segment, int start,
+							int end, u64 addr);
 
 extern struct list_head pci_mmcfg_list;
 
diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
index b68fd895235a..7fe2a73da0b3 100644
--- a/arch/x86/kernel/jailhouse.c
+++ b/arch/x86/kernel/jailhouse.c
@@ -124,6 +124,13 @@ static int __init jailhouse_pci_arch_init(void)
 	if (pcibios_last_bus < 0)
 		pcibios_last_bus = 0xff;
 
+#ifdef CONFIG_PCI_MMCONFIG
+	if (setup_data.pci_mmconfig_base) {
+		pci_mmconfig_add(0, 0, 0xff, setup_data.pci_mmconfig_base);
+		pci_mmcfg_arch_init();
+	}
+#endif
+
 	return 0;
 }
 
diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 96684d0adcf9..0e590272366b 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -94,8 +94,8 @@ static struct pci_mmcfg_region *pci_mmconfig_alloc(int
segment, int start,
 	return new;
 }
 
-static struct pci_mmcfg_region *__init pci_mmconfig_add(int segment, int start,
-							int end, u64 addr)
+struct pci_mmcfg_region *__init pci_mmconfig_add(int segment, int start,
+						 int end, u64 addr)
 {
 	struct pci_mmcfg_region *new;
 
-- 
2.13.6

From: Jan Kiszka <jan.kiszka at siemens.com>

Not sure if those two worked by design or just by chance so far. In any
case, it's at least cleaner and clearer to express this in a single
config statement.

Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
---
 arch/x86/Kconfig | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 423e4b64e683..f2038417a590 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2595,8 +2595,9 @@ config PCI_DIRECT
 	depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC
|| PCI_GOMMCONFIG))
 
 config PCI_MMCONFIG
-	def_bool y
-	depends on X86_32 && PCI && (ACPI || SFI) &&
(PCI_GOMMCONFIG || PCI_GOANY)
+	bool "Support mmconfig PCI config space access" if X86_64
+	default y
+	depends on PCI && (ACPI || SFI) && (PCI_GOMMCONFIG ||
PCI_GOANY || X86_64)
 
 config PCI_OLPC
 	def_bool y
@@ -2611,10 +2612,6 @@ config PCI_DOMAINS
 	def_bool y
 	depends on PCI
 
-config PCI_MMCONFIG
-	bool "Support mmconfig PCI config space access"
-	depends on X86_64 && PCI && ACPI
-
 config PCI_CNB20LE_QUIRK
 	bool "Read CNB20LE Host Bridge Windows" if EXPERT
 	depends on PCI
-- 
2.13.6

From: Jan Kiszka <jan.kiszka at siemens.com>

Jailhouse does not use ACPI, but it does support MMCONFIG. Make sure the
latter can be built without having to enable ACPI as well. Primarily, we
need to make the AMD mmconf-fam10h_64 depend upon MMCONFIG and ACPI,
instead of just the former.

Saves some bytes in the Jailhouse non-root kernel.

Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
---
 arch/x86/Kconfig          | 6 +++++-
 arch/x86/kernel/Makefile  | 2 +-
 arch/x86/kernel/cpu/amd.c | 2 +-
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f2038417a590..77ba0eb0a258 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2597,7 +2597,7 @@ config PCI_DIRECT
 config PCI_MMCONFIG
 	bool "Support mmconfig PCI config space access" if X86_64
 	default y
-	depends on PCI && (ACPI || SFI) && (PCI_GOMMCONFIG ||
PCI_GOANY || X86_64)
+	depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST) &&
(PCI_GOMMCONFIG || PCI_GOANY || X86_64)
 
 config PCI_OLPC
 	def_bool y
@@ -2612,6 +2612,10 @@ config PCI_DOMAINS
 	def_bool y
 	depends on PCI
 
+config MMCONF_FAM10H
+	def_bool y
+	depends on PCI_MMCONFIG && ACPI
+
 config PCI_CNB20LE_QUIRK
 	bool "Read CNB20LE Host Bridge Windows" if EXPERT
 	depends on PCI
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index aed9296dccd3..b2c9e230e2fe 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -143,6 +143,6 @@ ifeq ($(CONFIG_X86_64),y)
 	obj-$(CONFIG_GART_IOMMU)	+= amd_gart_64.o aperture_64.o
 	obj-$(CONFIG_CALGARY_IOMMU)	+= pci-calgary_64.o tce_64.o
 
-	obj-$(CONFIG_PCI_MMCONFIG)	+= mmconf-fam10h_64.o
+	obj-$(CONFIG_MMCONF_FAM10H)	+= mmconf-fam10h_64.o
 	obj-y				+= vsmp_64.o
 endif
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index ea831c858195..47edf599f6fd 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -690,7 +690,7 @@ static void init_amd_k8(struct cpuinfo_x86 *c)
 
 static void init_amd_gh(struct cpuinfo_x86 *c)
 {
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_MMCONF_FAM10H
 	/* do this for boot cpu */
 	if (c == &boot_cpu_data)
 		check_enable_amd_mmconf_dmi();
-- 
2.13.6

From: Jan Kiszka <jan.kiszka at siemens.com>

Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 426ba037d943..dd51a2012b36 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7468,6 +7468,13 @@ Q:	http://patchwork.linuxtv.org/project/linux-media/list/
 S:	Maintained
 F:	drivers/media/dvb-frontends/ix2505v*
 
+JAILHOUSE HYPERVISOR INTERFACE
+M:	Jan Kiszka <jan.kiszka at siemens.com>
+L:	jailhouse-dev at googlegroups.com
+S:	Maintained
+F:	arch/x86/kernel/jailhouse.c
+F:	arch/x86/include/asm/jailhouse_para.h
+
 JC42.4 TEMPERATURE SENSOR DRIVER
 M:	Guenter Roeck <linux at roeck-us.net>
 L:	linux-hwmon at vger.kernel.org
-- 
2.13.6

On Mon, Jan 22, 2018 at 8:12 AM, Jan Kiszka <jan.kiszka at siemens.com>
wrote:
> From: Jan Kiszka <jan.kiszka at siemens.com>
>
> Not sure if those two worked by design or just by chance so far. In any
> case, it's at least cleaner and clearer to express this in a single
> config statement.
Congrats! You found by the way a bug in

commit e279b6c1d329e50b766bce96aacc197eae8a053b
Author: Sam Ravnborg <sam at ravnborg.org>
Date:   Tue Nov 6 20:41:05 2007 +0100

   x86: start unification of arch/x86/Kconfig.*

...and proper fix seems to split PCI stuff to common + X86_32 only + X86_64 only

-- 
With Best Regards,
Andy Shevchenko

On Mon, Jan 22, 2018 at 8:12 AM, Jan Kiszka <jan.kiszka at siemens.com>
wrote:
>  #include <linux/export.h>
>  #include <linux/pci.h>
>  #include <asm/pci_x86.h>
> +#include <asm/jailhouse_para.h>
Keep it in order?

>  #include <linux/acpi.h>
>  #include <linux/irqdomain.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/hypervisor.h>
Ditto.

-- 
With Best Regards,
Andy Shevchenko

On 2018-02-22 21:57, Bjorn Helgaas wrote:
> On Mon, Jan 22, 2018 at 07:12:46AM +0100, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka at siemens.com>
>>
>> PCI and PCIBIOS probing only scans devices at function number
0/8/16/...
>> Subdevices (e.g. multiqueue) have function numbers which are not a
>> multiple of 8.
> 
> Suggested text:
> 
>   Per PCIe r4.0, sec 7.5.1.1.9, multi-function devices are required to
>   have a function 0.  Therefore, Linux scans for devices at function 0
>   (devfn 0/8/16/...) and only scans for other functions if function 0
>   has its Multi-Function Device bit set or ARI or SR-IOV indicate
>   there are more functions.
>   
>   The Jailhouse hypervisor may pass individual functions of a
>   multi-function device to a guest without passing function 0, which
>   means a Linux guest won't find them.
> 
>   Change Linux PCI probing so it scans all function numbers when
>   running as a guest over Jailhouse.
>   
>   This is technically prohibited by the spec, so it is possible that
>   PCI devices without the Multi-Function Device bit set may have
>   unexpected behavior in response to this probe.
> 
>> The simple hypervisor Jailhouse passes subdevices directly w/o
providing
>> a virtual PCI topology like KVM. As a consequence a PCI passthrough
from
>> Jailhouse to a guest will not be detected by Linux.
>>
>> Based on patch by Benedikt Spranger, adding Jailhouse probing to avoid
>> changing the behavior in the absence of the hypervisor.
>>
>> CC: Benedikt Spranger <b.spranger at linutronix.de>
>> Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
> 
> With subject change to:
> 
>   PCI: Scan all functions when running over Jailhouse
> 
> Acked-by: Bjorn Helgaas <bhelgaas at google.com>
> 
Thanks, all suggestions picked up for next round.

Jan

-- 
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Corporate Competence Center Embedded Linux