linux-kernel - [PATCH RESEND v2 2/2] virt: acrn: Make remove_cpu sysfs invisible with !CONFIG_HOTPLUG

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Date:   Sun, 21 Feb 2021 21:43:39 +0800
From:   shuo.a.liu@...el.com
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-next@...r.kernel.org,
        Shuo Liu <shuo.a.liu@...el.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Qais Yousef <qais.yousef@....com>
Subject: [PATCH RESEND v2 2/2] virt: acrn: Make remove_cpu sysfs invisible with !CONFIG_HOTPLUG_CPU

From: Shuo Liu <shuo.a.liu@...el.com>

Without cpu hotplug support, vCPU cannot be removed from a Service VM.
Don't expose remove_cpu sysfs when CONFIG_HOTPLUG_CPU disabled.

Signed-off-by: Shuo Liu <shuo.a.liu@...el.com>
Acked-by: Randy Dunlap <rdunlap@...radead.org> # build-tested
Cc: Stephen Rothwell <sfr@...b.auug.org.au>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Qais Yousef <qais.yousef@....com>
---
 drivers/virt/acrn/hsm.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/virt/acrn/hsm.c b/drivers/virt/acrn/hsm.c
index 1f6b7c54a1a4..6996ea6219e5 100644
--- a/drivers/virt/acrn/hsm.c
+++ b/drivers/virt/acrn/hsm.c
@@ -404,6 +404,14 @@ static ssize_t remove_cpu_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(remove_cpu);
 
+static umode_t acrn_attr_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+       if (a == &dev_attr_remove_cpu.attr)
+               return IS_ENABLED(CONFIG_HOTPLUG_CPU) ? a->mode : 0;
+
+       return a->mode;
+}
+
 static struct attribute *acrn_attrs[] = {
 	&dev_attr_remove_cpu.attr,
 	NULL
@@ -411,6 +419,7 @@ static struct attribute *acrn_attrs[] = {
 
 static struct attribute_group acrn_attr_group = {
 	.attrs = acrn_attrs,
+	.is_visible = acrn_attr_visible,
 };
 
 static const struct attribute_group *acrn_attr_groups[] = {
-- 
2.28.0