[PATCH v6 0/5] Device tree support for Hyper-V VMBus driver

[PATCH v6 0/5] Device tree support for Hyper-V VMBus driver

[Saurabh Sengar]

This set of patches expands the VMBus driver to include device tree
support. This feature allows for a kernel boot without the use of ACPI
tables, resulting in a smaller memory footprint and potentially faster
boot times. This is tested by enabling CONFIG_FLAT and OF_EARLY_FLATTREE
for x86.

The first two patches enable compilation of Hyper-V APIs in a non-ACPI
build.

The third patch converts the VMBus driver from acpi to more generic
platform driver.

Further to add device tree documentation for VMBus, it needs to club with
other virtualization driver's documentation. For this rename the virtio
folder to more generic hypervisor, so that all the hypervisor based
devices can co-exist in a single place in device tree documentation. The
fourth patch does this renaming.

The fifth patch introduces the device tree documentation for VMBus.

The sixth patch adds device tree support to the VMBus driver. Currently
this is tested only for x86 and it may not work for other archs.

[V6]
- define acpi_sleep_state_supported in acpi header for !ACPI,
  dropped the changes done in hv_common.c under #ifdef CONFIG_ACPI
- "Devicetree" instead of "device tree"
- Remove initialize of ret
- set "np = pdev->dev.of_node;" on declarartion
- remove one error print
- use bus_addr instead of pci_addr


[V5]
- Removed #else for device tree parsing code. This should help better
  test coverage.
- Fix macro '__maybe_unused' warning
- Added below options in Kconfig to enable device tree options for HYPERV
	select OF if !ACPI
	select OF_EARLY_FLATTREE if !ACPI
- moved dt documantation to bus folder
- update the dt node to have 'bus' as parent node instead of 'soc'. Also
  added compatible and ranges property for parent node.
- Made sure dt_binding_check have no error/varnings for microsoft,vmbus.yaml file
- Fix commit messages and add Reviwed-by from Michael for first 3 patches

[V4]
- rebased which fixed return type of 'vmbus_mmio_remove' from int to void
- used __maybe_unused for 'vmbus_of_match' and safeguard vmbus_acpi_device_ids
  under #ifdef

[V3]
- Changed the logic to use generic api (for_each_of_range) for parsing "ranges".
- Remove dependency of ACPI for HYPERV in case of x86.
- Removed "device tree bindings" from title and patch subject.
- Removed duplicate vendor prefix, used microsoft instead of msft.
- Use 'soc' in example of device tree documantation for parent node.
- Fixed compatible schemas error generated in other modules referring to

Saurabh Sengar (5):
  drivers/clocksource/hyper-v: non ACPI support in hyperv clock
  ACPI: bus: Add stub acpi_sleep_state_supported() in non-ACPI cases
  Drivers: hv: vmbus: Convert acpi_device to more generic
    platform_device
  dt-bindings: hypervisor: VMBus
  Driver: VMBus: Add Devicetree support

 .../bindings/bus/microsoft,vmbus.yaml         |  50 ++++++++
 MAINTAINERS                                   |   1 +
 drivers/clocksource/hyperv_timer.c            |  15 ++-
 drivers/hv/Kconfig                            |   6 +-
 drivers/hv/vmbus_drv.c                        | 115 ++++++++++++++----
 include/linux/acpi.h                          |   5 +
 6 files changed, 163 insertions(+), 29 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml

-- 
2.34.1

[PATCH v6 1/5] drivers/clocksource/hyper-v: non ACPI support in hyperv clock

[Saurabh Sengar]

Add a placeholder function for the hv_setup_stimer0_irq API to accommodate
systems without ACPI support. Since this function is not utilized on
x86/x64 systems and non-ACPI support is only intended for x86/x64 systems,
a placeholder function is sufficient for now and can be improved upon if
necessary in the future.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
---
 drivers/clocksource/hyperv_timer.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index c0cef92b12b8..f32948c8a96f 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -49,7 +49,7 @@ static bool direct_mode_enabled;
 
 static int stimer0_irq = -1;
 static int stimer0_message_sint;
-static DEFINE_PER_CPU(long, stimer0_evt);
+static __maybe_unused DEFINE_PER_CPU(long, stimer0_evt);
 
 /*
  * Common code for stimer0 interrupts coming via Direct Mode or
@@ -68,7 +68,7 @@ EXPORT_SYMBOL_GPL(hv_stimer0_isr);
  * stimer0 interrupt handler for architectures that support
  * per-cpu interrupts, which also implies Direct Mode.
  */
-static irqreturn_t hv_stimer0_percpu_isr(int irq, void *dev_id)
+static irqreturn_t __maybe_unused hv_stimer0_percpu_isr(int irq, void *dev_id)
 {
 	hv_stimer0_isr();
 	return IRQ_HANDLED;
@@ -196,6 +196,7 @@ void __weak hv_remove_stimer0_handler(void)
 {
 };
 
+#ifdef CONFIG_ACPI
 /* Called only on architectures with per-cpu IRQs (i.e., not x86/x64) */
 static int hv_setup_stimer0_irq(void)
 {
@@ -230,6 +231,16 @@ static void hv_remove_stimer0_irq(void)
 		stimer0_irq = -1;
 	}
 }
+#else
+static int hv_setup_stimer0_irq(void)
+{
+	return 0;
+}
+
+static void hv_remove_stimer0_irq(void)
+{
+}
+#endif
 
 /* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */
 int hv_stimer_alloc(bool have_percpu_irqs)
-- 
2.34.1

[PATCH v6 2/5] ACPI: bus: Add stub acpi_sleep_state_supported() in non-ACPI cases

[Saurabh Sengar]

acpi_sleep_state_supported() is defined only when CONFIG_ACPI=y. The
function is in acpi_bus.h, and acpi_bus.h can only be used in
CONFIG_ACPI=y cases. Add the stub function to linux/acpi.h to make
compilation successful for !CONFIG_ACPI cases.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
---
 include/linux/acpi.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index efff750f326d..d331f76b0c19 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1075,6 +1075,11 @@ static inline u32 acpi_osc_ctx_get_cxl_control(struct acpi_osc_context *context)
 	return 0;
 }
 
+static inline bool acpi_sleep_state_supported(u8 sleep_state)
+{
+	return false;
+}
+
 #endif	/* !CONFIG_ACPI */
 
 #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
-- 
2.34.1

[PATCH v6 3/5] Drivers: hv: vmbus: Convert acpi_device to more generic platform_device

[Saurabh Sengar]

VMBus driver code currently has direct dependency on ACPI and struct
acpi_device.  As a staging step toward optionally configuring based on
Devicetree instead of ACPI, use a more generic platform device to reduce
the dependency on ACPI where possible, though the dependency on ACPI
is not completely removed.  Also rename the function vmbus_acpi_remove()
to the more generic vmbus_mmio_remove().

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
---
[V6]
- "Devicetree" instead of "device tree"

 drivers/hv/vmbus_drv.c | 58 +++++++++++++++++++++++++-----------------
 1 file changed, 35 insertions(+), 23 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index d24dd65b33d4..73497157a23a 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -12,6 +12,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/device.h>
+#include <linux/platform_device.h>
 #include <linux/interrupt.h>
 #include <linux/sysctl.h>
 #include <linux/slab.h>
@@ -44,7 +45,7 @@ struct vmbus_dynid {
 	struct hv_vmbus_device_id id;
 };
 
-static struct acpi_device  *hv_acpi_dev;
+static struct device  *hv_dev;
 
 static int hyperv_cpuhp_online;
 
@@ -143,7 +144,7 @@ static DEFINE_MUTEX(hyperv_mmio_lock);
 
 static int vmbus_exists(void)
 {
-	if (hv_acpi_dev == NULL)
+	if (hv_dev == NULL)
 		return -ENODEV;
 
 	return 0;
@@ -932,7 +933,7 @@ static int vmbus_dma_configure(struct device *child_device)
 	 * On x86/x64 coherence is assumed and these calls have no effect.
 	 */
 	hv_setup_dma_ops(child_device,
-		device_get_dma_attr(&hv_acpi_dev->dev) == DEV_DMA_COHERENT);
+		device_get_dma_attr(hv_dev) == DEV_DMA_COHERENT);
 	return 0;
 }
 
@@ -2090,7 +2091,7 @@ int vmbus_device_register(struct hv_device *child_device_obj)
 		     &child_device_obj->channel->offermsg.offer.if_instance);
 
 	child_device_obj->device.bus = &hv_bus;
-	child_device_obj->device.parent = &hv_acpi_dev->dev;
+	child_device_obj->device.parent = hv_dev;
 	child_device_obj->device.release = vmbus_device_release;
 
 	child_device_obj->device.dma_parms = &child_device_obj->dma_parms;
@@ -2262,7 +2263,7 @@ static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
 	return AE_OK;
 }
 
-static void vmbus_acpi_remove(struct acpi_device *device)
+static void vmbus_mmio_remove(void)
 {
 	struct resource *cur_res;
 	struct resource *next_res;
@@ -2441,13 +2442,14 @@ void vmbus_free_mmio(resource_size_t start, resource_size_t size)
 }
 EXPORT_SYMBOL_GPL(vmbus_free_mmio);
 
-static int vmbus_acpi_add(struct acpi_device *device)
+static int vmbus_acpi_add(struct platform_device *pdev)
 {
 	acpi_status result;
 	int ret_val = -ENODEV;
 	struct acpi_device *ancestor;
+	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
 
-	hv_acpi_dev = device;
+	hv_dev = &device->dev;
 
 	/*
 	 * Older versions of Hyper-V for ARM64 fail to include the _CCA
@@ -2489,10 +2491,21 @@ static int vmbus_acpi_add(struct acpi_device *device)
 
 acpi_walk_err:
 	if (ret_val)
-		vmbus_acpi_remove(device);
+		vmbus_mmio_remove();
 	return ret_val;
 }
 
+static int vmbus_platform_driver_probe(struct platform_device *pdev)
+{
+	return vmbus_acpi_add(pdev);
+}
+
+static int vmbus_platform_driver_remove(struct platform_device *pdev)
+{
+	vmbus_mmio_remove();
+	return 0;
+}
+
 #ifdef CONFIG_PM_SLEEP
 static int vmbus_bus_suspend(struct device *dev)
 {
@@ -2658,15 +2671,15 @@ static const struct dev_pm_ops vmbus_bus_pm = {
 	.restore_noirq	= vmbus_bus_resume
 };
 
-static struct acpi_driver vmbus_acpi_driver = {
-	.name = "vmbus",
-	.ids = vmbus_acpi_device_ids,
-	.ops = {
-		.add = vmbus_acpi_add,
-		.remove = vmbus_acpi_remove,
-	},
-	.drv.pm = &vmbus_bus_pm,
-	.drv.probe_type = PROBE_FORCE_SYNCHRONOUS,
+static struct platform_driver vmbus_platform_driver = {
+	.probe = vmbus_platform_driver_probe,
+	.remove = vmbus_platform_driver_remove,
+	.driver = {
+		.name = "vmbus",
+		.acpi_match_table = ACPI_PTR(vmbus_acpi_device_ids),
+		.pm = &vmbus_bus_pm,
+		.probe_type = PROBE_FORCE_SYNCHRONOUS,
+	}
 };
 
 static void hv_kexec_handler(void)
@@ -2750,12 +2763,11 @@ static int __init hv_acpi_init(void)
 	/*
 	 * Get ACPI resources first.
 	 */
-	ret = acpi_bus_register_driver(&vmbus_acpi_driver);
-
+	ret = platform_driver_register(&vmbus_platform_driver);
 	if (ret)
 		return ret;
 
-	if (!hv_acpi_dev) {
+	if (!hv_dev) {
 		ret = -ENODEV;
 		goto cleanup;
 	}
@@ -2785,8 +2797,8 @@ static int __init hv_acpi_init(void)
 	return 0;
 
 cleanup:
-	acpi_bus_unregister_driver(&vmbus_acpi_driver);
-	hv_acpi_dev = NULL;
+	platform_driver_unregister(&vmbus_platform_driver);
+	hv_dev = NULL;
 	return ret;
 }
 
@@ -2839,7 +2851,7 @@ static void __exit vmbus_exit(void)
 
 	cpuhp_remove_state(hyperv_cpuhp_online);
 	hv_synic_free();
-	acpi_bus_unregister_driver(&vmbus_acpi_driver);
+	platform_driver_unregister(&vmbus_platform_driver);
 }
 
 
-- 
2.34.1

[PATCH v6 4/5] dt-bindings: hypervisor: VMBus

[Saurabh Sengar]

Add dt-bindings for Hyper-V VMBus.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
---
 .../bindings/bus/microsoft,vmbus.yaml         | 50 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml

diff --git a/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml b/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
new file mode 100644
index 000000000000..40daefc37615
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/microsoft,vmbus.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microsoft Hyper-V VMBus
+
+maintainers:
+  - Saurabh Sengar <ssengar@linux.microsoft.com>
+
+description:
+  VMBus is a software bus that implement the protocols for communication
+  between the root or host OS and guest OSs (virtual machines).
+
+properties:
+  compatible:
+    const: microsoft,vmbus
+
+  ranges: true
+
+  '#address-cells':
+    const: 2
+
+  '#size-cells':
+    const: 1
+
+required:
+  - compatible
+  - ranges
+  - '#address-cells'
+  - '#size-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    bus@ff0000000 {
+        compatible = "simple-bus";
+        #address-cells = <2>;
+        #size-cells = <1>;
+        ranges = <0x0 0xf 0xf0000000 0x10000000>;
+
+        vmbus@ff0000000 {
+            compatible = "microsoft,vmbus";
+            #address-cells = <2>;
+            #size-cells = <1>;
+            ranges = <0x0f 0xf0000000 0x0f 0xf0000000 0x10000000>;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index df202a1e4b96..67ddecd1a383 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9490,6 +9490,7 @@ S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git
 F:	Documentation/ABI/stable/sysfs-bus-vmbus
 F:	Documentation/ABI/testing/debugfs-hyperv
+F:	Documentation/devicetree/bindings/bus/microsoft,vmbus.yaml
 F:	Documentation/virt/hyperv
 F:	Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst
 F:	arch/arm64/hyperv
-- 
2.34.1

[PATCH v6 5/5] Driver: VMBus: Add Devicetree support

[Saurabh Sengar]

Update the driver to support Devicetree boot as well along with ACPI.
At present the Devicetree parsing only provides the mmio region info
and is not the exact copy of ACPI parsing. This is sufficient to cater
all the current Devicetree usecases for VMBus.

Currently Devicetree is supported only for x86 systems.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
---
[V6]
- "Devicetree" instead of "device tree"
- Remove initialize of ret
- set "np = pdev->dev.of_node;" on declarartion
- remove one error print
- use bus_addr instead of pci_addr

 drivers/hv/Kconfig     |  6 +++--
 drivers/hv/vmbus_drv.c | 57 ++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 0747a8f1fcee..1a55bf32d195 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -4,11 +4,13 @@ menu "Microsoft Hyper-V guest support"
 
 config HYPERV
 	tristate "Microsoft Hyper-V client drivers"
-	depends on ACPI && ((X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
-		|| (ARM64 && !CPU_BIG_ENDIAN))
+	depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
+		|| (ACPI && ARM64 && !CPU_BIG_ENDIAN)
 	select PARAVIRT
 	select X86_HV_CALLBACK_VECTOR if X86
 	select VMAP_PFN
+	select OF if !ACPI
+	select OF_EARLY_FLATTREE if !ACPI
 	help
 	  Select this option to run Linux as a Hyper-V client operating
 	  system.
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 73497157a23a..0a4f0060a184 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -20,6 +20,7 @@
 #include <linux/completion.h>
 #include <linux/hyperv.h>
 #include <linux/kernel_stat.h>
+#include <linux/of_address.h>
 #include <linux/clockchips.h>
 #include <linux/cpu.h>
 #include <linux/sched/isolation.h>
@@ -2152,7 +2153,7 @@ void vmbus_device_unregister(struct hv_device *device_obj)
 	device_unregister(&device_obj->device);
 }
 
-
+#ifdef CONFIG_ACPI
 /*
  * VMBUS is an acpi enumerated device. Get the information we
  * need from DSDT.
@@ -2262,6 +2263,7 @@ static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
 
 	return AE_OK;
 }
+#endif
 
 static void vmbus_mmio_remove(void)
 {
@@ -2282,7 +2284,7 @@ static void vmbus_mmio_remove(void)
 	}
 }
 
-static void vmbus_reserve_fb(void)
+static void __maybe_unused vmbus_reserve_fb(void)
 {
 	resource_size_t start = 0, size;
 	struct pci_dev *pdev;
@@ -2442,6 +2444,7 @@ void vmbus_free_mmio(resource_size_t start, resource_size_t size)
 }
 EXPORT_SYMBOL_GPL(vmbus_free_mmio);
 
+#ifdef CONFIG_ACPI
 static int vmbus_acpi_add(struct platform_device *pdev)
 {
 	acpi_status result;
@@ -2494,10 +2497,47 @@ static int vmbus_acpi_add(struct platform_device *pdev)
 		vmbus_mmio_remove();
 	return ret_val;
 }
+#endif
+
+static int vmbus_device_add(struct platform_device *pdev)
+{
+	struct resource **cur_res = &hyperv_mmio;
+	struct of_range range;
+	struct of_range_parser parser;
+	struct device_node *np = pdev->dev.of_node;
+	int ret;
+
+	hv_dev = &pdev->dev;
+
+	ret = of_range_parser_init(&parser, np);
+	if (ret)
+		return ret;
+
+	for_each_of_range(&parser, &range) {
+		struct resource *res;
+
+		res = kzalloc(sizeof(*res), GFP_ATOMIC);
+		if (!res)
+			return -ENOMEM;
+
+		res->name = "hyperv mmio";
+		res->flags = IORESOURCE_MEM | IORESOURCE_MEM_64;
+		res->start = range.bus_addr;
+		res->end = range.bus_addr + range.size;
+
+		*cur_res = res;
+		cur_res = &res->sibling;
+	}
+
+	return ret;
+}
 
 static int vmbus_platform_driver_probe(struct platform_device *pdev)
 {
+#ifdef CONFIG_ACPI
 	return vmbus_acpi_add(pdev);
+#endif
+	return vmbus_device_add(pdev);
 }
 
 static int vmbus_platform_driver_remove(struct platform_device *pdev)
@@ -2643,12 +2683,24 @@ static int vmbus_bus_resume(struct device *dev)
 #define vmbus_bus_resume NULL
 #endif /* CONFIG_PM_SLEEP */
 
+static const __maybe_unused struct of_device_id vmbus_of_match[] = {
+	{
+		.compatible = "microsoft,vmbus",
+	},
+	{
+		/* sentinel */
+	},
+};
+MODULE_DEVICE_TABLE(of, vmbus_of_match);
+
+#ifdef CONFIG_ACPI
 static const struct acpi_device_id vmbus_acpi_device_ids[] = {
 	{"VMBUS", 0},
 	{"VMBus", 0},
 	{"", 0},
 };
 MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);
+#endif
 
 /*
  * Note: we must use the "no_irq" ops, otherwise hibernation can not work with
@@ -2677,6 +2729,7 @@ static struct platform_driver vmbus_platform_driver = {
 	.driver = {
 		.name = "vmbus",
 		.acpi_match_table = ACPI_PTR(vmbus_acpi_device_ids),
+		.of_match_table = of_match_ptr(vmbus_of_match),
 		.pm = &vmbus_bus_pm,
 		.probe_type = PROBE_FORCE_SYNCHRONOUS,
 	}
-- 
2.34.1

Re: [PATCH v6 2/5] ACPI: bus: Add stub acpi_sleep_state_supported() in non-ACPI cases

[Rafael J. Wysocki]

On Fri, Feb 10, 2023 at 10:34 AM Saurabh Sengar
<ssengar@linux.microsoft.com> wrote:
>
> acpi_sleep_state_supported() is defined only when CONFIG_ACPI=y. The
> function is in acpi_bus.h, and acpi_bus.h can only be used in
> CONFIG_ACPI=y cases. Add the stub function to linux/acpi.h to make
> compilation successful for !CONFIG_ACPI cases.
>
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

and please feel free to toute this patch whichever way is convenient.

Thanks!

> ---
>  include/linux/acpi.h | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index efff750f326d..d331f76b0c19 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -1075,6 +1075,11 @@ static inline u32 acpi_osc_ctx_get_cxl_control(struct acpi_osc_context *context)
>         return 0;
>  }
>
> +static inline bool acpi_sleep_state_supported(u8 sleep_state)
> +{
> +       return false;
> +}
> +
>  #endif /* !CONFIG_ACPI */
>
>  #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
> --
> 2.34.1
>