From: Thomas Gleixner tglx@linutronix.de
commit 8a4b06d391b0a42a373808979b5028f5c84d9c6a upstream.
Add the sysfs reporting file for MDS. It exposes the vulnerability and mitigation state similar to the existing files for the other speculative hardware vulnerabilities.
Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Reviewed-by: Borislav Petkov bp@suse.de Reviewed-by: Jon Masters jcm@redhat.com Tested-by: Jon Masters jcm@redhat.com [bwh: Backported to 4.4: - Test x86_hyper instead of using hypervisor_is_type() - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/ABI/testing/sysfs-devices-system-cpu | 1 arch/x86/kernel/cpu/bugs.c | 27 +++++++++++++++++++++ drivers/base/cpu.c | 8 ++++++ include/linux/cpu.h | 2 + 4 files changed, 38 insertions(+)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -278,6 +278,7 @@ What: /sys/devices/system/cpu/vulnerabi /sys/devices/system/cpu/vulnerabilities/spectre_v2 /sys/devices/system/cpu/vulnerabilities/spec_store_bypass /sys/devices/system/cpu/vulnerabilities/l1tf + /sys/devices/system/cpu/vulnerabilities/mds Date: January 2018 Contact: Linux kernel mailing list linux-kernel@vger.kernel.org Description: Information about CPU vulnerabilities --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -24,6 +24,7 @@ #include <asm/msr.h> #include <asm/paravirt.h> #include <asm/alternative.h> +#include <asm/hypervisor.h> #include <asm/pgtable.h> #include <asm/cacheflush.h> #include <asm/intel-family.h> @@ -1066,6 +1067,24 @@ static void __init l1tf_select_mitigatio
#ifdef CONFIG_SYSFS
+static ssize_t mds_show_state(char *buf) +{ +#ifdef CONFIG_HYPERVISOR_GUEST + if (x86_hyper) { + return sprintf(buf, "%s; SMT Host state unknown\n", + mds_strings[mds_mitigation]); + } +#endif + + if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) { + return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation], + sched_smt_active() ? "mitigated" : "disabled"); + } + + return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation], + sched_smt_active() ? "vulnerable" : "disabled"); +} + static char *stibp_state(void) { if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) @@ -1128,6 +1147,9 @@ static ssize_t cpu_show_common(struct de return sprintf(buf, "Mitigation: Page Table Inversion\n"); break;
+ case X86_BUG_MDS: + return mds_show_state(buf); + default: break; } @@ -1159,4 +1181,9 @@ ssize_t cpu_show_l1tf(struct device *dev { return cpu_show_common(dev, attr, buf, X86_BUG_L1TF); } + +ssize_t cpu_show_mds(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_MDS); +} #endif --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -530,11 +530,18 @@ ssize_t __weak cpu_show_l1tf(struct devi return sprintf(buf, "Not affected\n"); }
+ssize_t __weak cpu_show_mds(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(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); static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL); static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL); +static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);
static struct attribute *cpu_root_vulnerabilities_attrs[] = { &dev_attr_meltdown.attr, @@ -542,6 +549,7 @@ static struct attribute *cpu_root_vulner &dev_attr_spectre_v2.attr, &dev_attr_spec_store_bypass.attr, &dev_attr_l1tf.attr, + &dev_attr_mds.attr, NULL };
--- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -50,6 +50,8 @@ extern ssize_t cpu_show_spec_store_bypas struct device_attribute *attr, char *buf); extern ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf); +extern ssize_t cpu_show_mds(struct device *dev, + struct device_attribute *attr, char *buf);
extern __printf(4, 5) struct device *cpu_device_create(struct device *parent, void *drvdata,