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x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

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commit 8d50cdf8b8 upstream

Add the sysfs reporting file for Processor MMIO Stale Data
vulnerability. It exposes the vulnerability and mitigation state similar
to the existing files for the other hardware vulnerabilities.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pawan Gupta 2022-05-19 20:32:13 -07:00 committed by Greg Kroah-Hartman
parent e0fccc13eb
commit ae62092804
4 changed files with 34 additions and 0 deletions
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1
Documentation/ABI/testing/sysfs-devices-system-cpu
View File

@ -384,6 +384,7 @@ What: /sys/devices/system/cpu/vulnerabilities
/sys/devices/system/cpu/vulnerabilities/srbds
/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
/sys/devices/system/cpu/vulnerabilities/itlb_multihit
/sys/devices/system/cpu/vulnerabilities/mmio_stale_data
Date: January 2018
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Description: Information about CPU vulnerabilities

22
arch/x86/kernel/cpu/bugs.c
View File

@ -1808,6 +1808,20 @@ static ssize_t tsx_async_abort_show_state(char *buf)
sched_smt_active() ? "vulnerable" : "disabled");
}
static ssize_t mmio_stale_data_show_state(char *buf)
{
if (mmio_mitigation == MMIO_MITIGATION_OFF)
return sysfs_emit(buf, "%s\n", mmio_strings[mmio_mitigation]);
if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
return sysfs_emit(buf, "%s; SMT Host state unknown\n",
mmio_strings[mmio_mitigation]);
}
return sysfs_emit(buf, "%s; SMT %s\n", mmio_strings[mmio_mitigation],
sched_smt_active() ? "vulnerable" : "disabled");
}
static char *stibp_state(void)
{
if (spectre_v2_in_eibrs_mode(spectre_v2_enabled))
@ -1905,6 +1919,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
case X86_BUG_SRBDS:
return srbds_show_state(buf);
case X86_BUG_MMIO_STALE_DATA:
return mmio_stale_data_show_state(buf);
default:
break;
}
@ -1956,4 +1973,9 @@ ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *
{
return cpu_show_common(dev, attr, buf, X86_BUG_SRBDS);
}
ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *attr, char *buf)
{
return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA);
}
#endif

8
drivers/base/cpu.c
View File

@ -558,6 +558,12 @@ ssize_t __weak cpu_show_srbds(struct device *dev,
return sprintf(buf, "Not affected\n");
}
ssize_t __weak cpu_show_mmio_stale_data(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sysfs_emit(buf, "Not affected\n");
}
static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
@ -567,6 +573,7 @@ static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);
static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);
static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);
static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);
static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL);
static struct attribute *cpu_root_vulnerabilities_attrs[] = {
&dev_attr_meltdown.attr,
@ -578,6 +585,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = {
&dev_attr_tsx_async_abort.attr,
&dev_attr_itlb_multihit.attr,
&dev_attr_srbds.attr,
&dev_attr_mmio_stale_data.attr,
NULL
};

3
include/linux/cpu.h
View File

@ -65,6 +65,9 @@ extern ssize_t cpu_show_tsx_async_abort(struct device *dev,
extern ssize_t cpu_show_itlb_multihit(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_mmio_stale_data(struct device *dev,
struct device_attribute *attr,
char *buf);
extern __printf(4, 5)
struct device *cpu_device_create(struct device *parent, void *drvdata,