From db4d30fbb71b47e4ecb11c4efa5d8aad4b03dfae Mon Sep 17 00:00:00 2001 From: Vineela Tummalapalli Date: Mon, 4 Nov 2019 12:22:01 +0100 Subject: x86/bugs: Add ITLB_MULTIHIT bug infrastructure Some processors may incur a machine check error possibly resulting in an unrecoverable CPU lockup when an instruction fetch encounters a TLB multi-hit in the instruction TLB. This can occur when the page size is changed along with either the physical address or cache type. The relevant erratum can be found here: https://bugzilla.kernel.org/show_bug.cgi?id=205195 There are other processors affected for which the erratum does not fully disclose the impact. This issue affects both bare-metal x86 page tables and EPT. It can be mitigated by either eliminating the use of large pages or by using careful TLB invalidations when changing the page size in the page tables. Just like Spectre, Meltdown, L1TF and MDS, a new bit has been allocated in MSR_IA32_ARCH_CAPABILITIES (PSCHANGE_MC_NO) and will be set on CPUs which are mitigated against this issue. Signed-off-by: Vineela Tummalapalli Co-developed-by: Pawan Gupta Signed-off-by: Pawan Gupta Signed-off-by: Paolo Bonzini Signed-off-by: Thomas Gleixner --- drivers/base/cpu.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers/base') diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 0fccd8c0312e..6265871a4af2 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -561,6 +561,12 @@ ssize_t __weak cpu_show_tsx_async_abort(struct device *dev, return sprintf(buf, "Not affected\n"); } +ssize_t __weak cpu_show_itlb_multihit(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); @@ -568,6 +574,7 @@ 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 DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL); +static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL); static struct attribute *cpu_root_vulnerabilities_attrs[] = { &dev_attr_meltdown.attr, @@ -577,6 +584,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = { &dev_attr_l1tf.attr, &dev_attr_mds.attr, &dev_attr_tsx_async_abort.attr, + &dev_attr_itlb_multihit.attr, NULL }; -- cgit v1.2.3