On 16/4/24 12:49, Alexander Graf wrote:
On 09.04.24 20:11, Sudan Landge wrote:
Extend the vmgenid platform driver to support devicetree bindings.
With this support, hypervisors can send vmgenid notifications to
the virtual machine without the need to enable ACPI.
The bindings are located at:
Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml
Signed-off-by: Sudan Landge <sudanl@xxxxxxxxxx>
---
drivers/virt/vmgenid.c | 53 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 51 insertions(+), 2 deletions(-)
diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index 3d93e3fb94c4..e1ad74116c0c 100644
--- a/drivers/virt/vmgenid.c
+++ b/drivers/virt/vmgenid.c
@@ -2,12 +2,13 @@
/*
* Copyright (C) 2022 Jason A. Donenfeld <Jason@xxxxxxxxx>. All
Rights Reserved.
*
- * The "Virtual Machine Generation ID" is exposed via ACPI and
changes when a
+ * The "Virtual Machine Generation ID" is exposed via ACPI or DT and
changes when a
* virtual machine forks or is cloned. This driver exists for
shepherding that
* information to random.c.
*/
#include <linux/acpi.h>
+#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
@@ -20,6 +21,7 @@ enum { VMGENID_SIZE = 16 };
struct vmgenid_state {
u8 *next_id;
u8 this_id[VMGENID_SIZE];
+ int irq;
};
static void vmgenid_notify(struct device *device)
@@ -43,6 +45,14 @@ vmgenid_acpi_handler(acpi_handle __always_unused
handle,
vmgenid_notify(dev);
}
+static __maybe_unused irqreturn_t
Why is this maybe_unused? It seems to be always referenced by
vmgenid_add_of(), no?
You are right, Alex. I removed the attribute and build the kernel
without `CONFIG_OF`
without any warnings. I will remove it in the next version.
+vmgenid_of_irq_handler(int __always_unused irq, void *dev)
+{
+ vmgenid_notify(dev);
+
+ return IRQ_HANDLED;
+}
+
static int __maybe_unused
setup_vmgenid_state(struct vmgenid_state *state, u8 *next_id)
{
@@ -106,6 +116,35 @@ static int vmgenid_add_acpi(struct device
__maybe_unused *dev,
#endif
}
+static int vmgenid_add_of(struct platform_device *pdev,
+ struct vmgenid_state *state)
+{
+ u8 *virt_addr;
+ int ret = 0;
+
+ virt_addr = (u8 *)devm_platform_get_and_ioremap_resource(pdev,
0, NULL);
+ if (IS_ERR(virt_addr))
+ return PTR_ERR(virt_addr);
+
+ ret = setup_vmgenid_state(state, virt_addr);
+ if (ret)
+ return ret;
+
+ ret = platform_get_irq(pdev, 0);
+ if (ret < 0)
+ return ret;
Doesn't this error path need to do something about the ioremap'ed
resource? Or does devm do that automatically for you?
devm should be doing this automatically according to this:
https://docs.kernel.org/driver-api/driver-model/devres.html#devres
Also, I took a quick look in other drivers and it looks like the virtio-mmio
probe callback follows the same pattern:
https://elixir.bootlin.com/linux/latest/source/drivers/virtio/virtio_mmio.c#L636
Cheers,
Babis
Alex
+
+ state->irq = ret;
+ pdev->dev.driver_data = state;
+
+ ret = devm_request_irq(&pdev->dev, state->irq,
vmgenid_of_irq_handler,
+ IRQF_SHARED, "vmgenid", &pdev->dev);
+ if (ret)
+ pdev->dev.driver_data = NULL;
+
+ return ret;
+}
+
static int vmgenid_add(struct platform_device *pdev)
{
struct vmgenid_state *state;
@@ -116,7 +155,10 @@ static int vmgenid_add(struct platform_device
*pdev)
if (!state)
return -ENOMEM;
- ret = vmgenid_add_acpi(dev, state);
+ if (dev->of_node)
+ ret = vmgenid_add_of(pdev, state);
+ else
+ ret = vmgenid_add_acpi(dev, state);
if (ret)
devm_kfree(dev, state);
@@ -124,6 +166,12 @@ static int vmgenid_add(struct platform_device
*pdev)
return ret;
}
+static const struct of_device_id vmgenid_of_ids[] = {
+ { .compatible = "microsoft,vmgenid", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, vmgenid_of_ids);
+
static const struct acpi_device_id vmgenid_acpi_ids[] = {
{ "VMGENCTR", 0 },
{ "VM_GEN_COUNTER", 0 },
@@ -136,6 +184,7 @@ static struct platform_driver
vmgenid_plaform_driver = {
.driver = {
.name = "vmgenid",
.acpi_match_table = vmgenid_acpi_ids,
+ .of_match_table = vmgenid_of_ids,
},
};
