drivers/virt/acrn/hsm.c:391 remove_cpu_store() warn: potential spectre issue '__per_cpu_offset' (local cap)

drivers/virt/acrn/hsm.c:391 remove_cpu_store() warn: potential spectre issue '__per_cpu_offset' (local cap)

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
CC: linux-kernel(a)vger.kernel.org
TO: Shuo Liu <shuo.a.liu@intel.com>
CC: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
CC: Zhi Wang <zhi.a.wang@intel.com>
CC: Reinette Chatre <reinette.chatre@intel.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   5695e51619745d4fe3ec2506a2f0cd982c5e27a4
commit: 279dcf693ac76c9d16b91ffc41280babaff26bb2 virt: acrn: Introduce an interface for Service VM to control vCPU
date:   3 weeks ago
:::::: branch date: 3 hours ago
:::::: commit date: 3 weeks ago
config: x86_64-randconfig-m001-20210228 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
drivers/virt/acrn/hsm.c:391 remove_cpu_store() warn: potential spectre issue '__per_cpu_offset' [w] (local cap)

vim +/__per_cpu_offset +391 drivers/virt/acrn/hsm.c

666834c47d3b41 Shuo Liu 2021-02-07  374  
279dcf693ac76c Shuo Liu 2021-02-07  375  static ssize_t remove_cpu_store(struct device *dev,
279dcf693ac76c Shuo Liu 2021-02-07  376  				struct device_attribute *attr,
279dcf693ac76c Shuo Liu 2021-02-07  377  				const char *buf, size_t count)
279dcf693ac76c Shuo Liu 2021-02-07  378  {
279dcf693ac76c Shuo Liu 2021-02-07  379  	u64 cpu, lapicid;
279dcf693ac76c Shuo Liu 2021-02-07  380  	int ret;
279dcf693ac76c Shuo Liu 2021-02-07  381  
279dcf693ac76c Shuo Liu 2021-02-07  382  	if (kstrtoull(buf, 0, &cpu) < 0)
279dcf693ac76c Shuo Liu 2021-02-07  383  		return -EINVAL;
279dcf693ac76c Shuo Liu 2021-02-07  384  
279dcf693ac76c Shuo Liu 2021-02-07  385  	if (cpu >= num_possible_cpus() || cpu == 0 || !cpu_is_hotpluggable(cpu))
279dcf693ac76c Shuo Liu 2021-02-07  386  		return -EINVAL;
279dcf693ac76c Shuo Liu 2021-02-07  387  
279dcf693ac76c Shuo Liu 2021-02-07  388  	if (cpu_online(cpu))
279dcf693ac76c Shuo Liu 2021-02-07  389  		remove_cpu(cpu);
279dcf693ac76c Shuo Liu 2021-02-07  390  
279dcf693ac76c Shuo Liu 2021-02-07 @391  	lapicid = cpu_data(cpu).apicid;
279dcf693ac76c Shuo Liu 2021-02-07  392  	dev_dbg(dev, "Try to remove cpu %lld with lapicid %lld\n", cpu, lapicid);
279dcf693ac76c Shuo Liu 2021-02-07  393  	ret = hcall_sos_remove_cpu(lapicid);
279dcf693ac76c Shuo Liu 2021-02-07  394  	if (ret < 0) {
279dcf693ac76c Shuo Liu 2021-02-07  395  		dev_err(dev, "Failed to remove cpu %lld!\n", cpu);
279dcf693ac76c Shuo Liu 2021-02-07  396  		goto fail_remove;
279dcf693ac76c Shuo Liu 2021-02-07  397  	}
279dcf693ac76c Shuo Liu 2021-02-07  398  
279dcf693ac76c Shuo Liu 2021-02-07  399  	return count;
279dcf693ac76c Shuo Liu 2021-02-07  400  
279dcf693ac76c Shuo Liu 2021-02-07  401  fail_remove:
279dcf693ac76c Shuo Liu 2021-02-07  402  	add_cpu(cpu);
279dcf693ac76c Shuo Liu 2021-02-07  403  	return ret;
279dcf693ac76c Shuo Liu 2021-02-07  404  }
279dcf693ac76c Shuo Liu 2021-02-07  405  static DEVICE_ATTR_WO(remove_cpu);
279dcf693ac76c Shuo Liu 2021-02-07  406  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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