Introduce msi_domain_update_hwsize() helper for updating hwsize.

Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Guanghui Feng <guanghuifeng@linux.alibaba.com>
---
 include/linux/msi.h |  3 +++
 kernel/irq/msi.c    | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/linux/msi.h b/include/linux/msi.h
index fa41eed62868..6de938ba2245 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -647,6 +647,9 @@ bool msi_create_device_irq_domain(struct device *dev, unsigned int domid,
 				  void *chip_data);
 void msi_remove_device_irq_domain(struct device *dev, unsigned int domid);
 
+int msi_domain_update_hwsize(struct device *dev, unsigned int domid,
+			     unsigned int hwsize_new);
+
 bool msi_match_device_irq_domain(struct device *dev, unsigned int domid,
 				 enum irq_domain_bus_token bus_token);
 
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 3cafa40e6ce3..162e7263ef7f 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -1133,6 +1133,28 @@ void msi_remove_device_irq_domain(struct device *dev, unsigned int domid)
 	kfree(container_of(info, struct msi_domain_template, info));
 }
 
+int msi_domain_update_hwsize(struct device *dev, unsigned int domid,
+			     unsigned int hwsize_new)
+{
+	struct msi_domain_info *info;
+	struct irq_domain *domain;
+
+	if (hwsize_new > MSI_XA_DOMAIN_SIZE)
+		return -EINVAL;
+	if (!hwsize_new)
+		hwsize_new = MSI_XA_DOMAIN_SIZE;
+
+	domain = msi_get_device_domain(dev, domid);
+	if (!domain)
+		return -ENODEV;
+
+	info = domain->host_data;
+	if (hwsize_new != info->hwsize)
+		info->hwsize = hwsize_new;
+
+	return 0;
+}
+
 /**
  * msi_match_device_irq_domain - Match a device irq domain against a bus token
  * @dev:	Pointer to the device
-- 
2.32.0.3.g01195cf9f

On Tue, Mar 24 2026 at 09:47, Guixin Liu wrote:
> +int msi_domain_update_hwsize(struct device *dev, unsigned int domid,
> +			     unsigned int hwsize_new)
> +{
> +	struct msi_domain_info *info;
> +	struct irq_domain *domain;
> +
> +	if (hwsize_new > MSI_XA_DOMAIN_SIZE)
> +		return -EINVAL;
> +	if (!hwsize_new)
> +		hwsize_new = MSI_XA_DOMAIN_SIZE;
> +
> +	domain = msi_get_device_domain(dev, domid);
> +	if (!domain)
> +		return -ENODEV;
> +
> +	info = domain->host_data;
> +	if (hwsize_new != info->hwsize)
> +		info->hwsize = hwsize_new;

This is incorrect because the underlying irqdomain has been created with
the original hardware size. So just fiddling with info->hwsize results
in inconsistent state.

在 2026/3/25 16:15, Thomas Gleixner 写道:
> On Tue, Mar 24 2026 at 09:47, Guixin Liu wrote:
>> +int msi_domain_update_hwsize(struct device *dev, unsigned int domid,
>> +			     unsigned int hwsize_new)
>> +{
>> +	struct msi_domain_info *info;
>> +	struct irq_domain *domain;
>> +
>> +	if (hwsize_new > MSI_XA_DOMAIN_SIZE)
>> +		return -EINVAL;
>> +	if (!hwsize_new)
>> +		hwsize_new = MSI_XA_DOMAIN_SIZE;
>> +
>> +	domain = msi_get_device_domain(dev, domid);
>> +	if (!domain)
>> +		return -ENODEV;
>> +
>> +	info = domain->host_data;
>> +	if (hwsize_new != info->hwsize)
>> +		info->hwsize = hwsize_new;
> This is incorrect because the underlying irqdomain has been created with
> the original hardware size. So just fiddling with info->hwsize results
> in inconsistent state.
I found that hwsize only affects the range checking when allocating and
releasing intterrupts after the irq_domain is established,
and the kernel does not allocate related resources based on it.
Cloud you plz tell me specifically where the inconsistency is? thanks.

Best Regards,
Guixin Liu