korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-11 04:18:39 +08:00
Code Issues Packages Projects Releases Wiki Activity

x86/sev: Provide guest VMPL level to userspace

Browse Source 
Requesting an attestation report from userspace involves providing the VMPL
level for the report. Currently any value from 0-3 is valid because Linux
enforces running at VMPL0.

When an SVSM is present, though, Linux will not be running at VMPL0 and only
VMPL values starting at the VMPL level Linux is running at to 3 are valid. In
order to allow userspace to determine the minimum VMPL value that can be
supplied to an attestation report, create a sysfs entry that can be used to
retrieve the current VMPL level of the kernel.

  [ bp: Add CONFIG_SYSFS ifdeffery. ]

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/fff846da0d8d561f9fdaf297dcf8cd907545a25b.1717600736.git.thomas.lendacky@amd.com
This commit is contained in:
Tom Lendacky 2024-06-05 10:18:50 -05:00 committed by Borislav Petkov (AMD)
parent 1beb348d5c
commit 61564d3468
2 changed files with 58 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
Documentation/ABI/testing/sysfs-devices-system-cpu
View File

@ -605,6 +605,18 @@ Description: Umwait control
Note that a value of zero means there is no limit.
Low order two bits must be zero.
What: /sys/devices/system/cpu/sev
/sys/devices/system/cpu/sev/vmpl
Date: May 2024
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Description: Secure Encrypted Virtualization (SEV) information
This directory is only present when running as an SEV-SNP guest.
vmpl: Reports the Virtual Machine Privilege Level (VMPL) at which
the SEV-SNP guest is running.
What: /sys/devices/system/cpu/svm
Date: August 2019
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>

46
arch/x86/kernel/sev.c
View File

@ -2504,3 +2504,49 @@ void __init snp_update_svsm_ca(void)
/* Update the CAA to a proper kernel address */
boot_svsm_caa = &boot_svsm_ca_page;
}
#ifdef CONFIG_SYSFS
static ssize_t vmpl_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sysfs_emit(buf, "%d\n", snp_vmpl);
}
static struct kobj_attribute vmpl_attr = __ATTR_RO(vmpl);
static struct attribute *vmpl_attrs[] = {
&vmpl_attr.attr,
NULL
};
static struct attribute_group sev_attr_group = {
.attrs = vmpl_attrs,
};
static int __init sev_sysfs_init(void)
{
struct kobject *sev_kobj;
struct device *dev_root;
int ret;
if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
return -ENODEV;
dev_root = bus_get_dev_root(&cpu_subsys);
if (!dev_root)
return -ENODEV;
sev_kobj = kobject_create_and_add("sev", &dev_root->kobj);
put_device(dev_root);
if (!sev_kobj)
return -ENOMEM;
ret = sysfs_create_group(sev_kobj, &sev_attr_group);
if (ret)
kobject_put(sev_kobj);
return ret;
}
arch_initcall(sev_sysfs_init);
#endif // CONFIG_SYSFS