Processor vulnerability
CVE-2018-12207
If software changes a code page to a large page before invalidating the TLB, an instruction fetch can hit two TLB entries and raise a machine check.
- Name
- Machine Check Error Avoidance on Page Size Change
- Also known as
- iTLB multihit
- Kind
- Other
- CVE published
- 2019-11-14 CVE record
- Advisories
- INTEL-SA-00210
- Linux reports it in
itlb_multihit
When software remaps a linear address from 4 KB pages to a large
page (2 MB, 4 MB or 1 GB) with a different physical address or
memory type, an affected processor can find both the old and the new
translation in its instruction TLB on the next code fetch, before
software invalidates the old one, and raise a machine check that
hangs or resets the machine. An operating system does not do this,
but a guest controls its own page tables, so on a host that maps
guest memory with large pages it can take down the host. It is a
denial of service, not a leak.What the sources say of each microarchitecture. Intel’s list gives each CPUID family, model and stepping it covers, with Intel’s mitigation for it (Software, MCU for a microcode update, or Hardware).
Affected processors
16 of the 57 microarchitectures listed are affected in all or some of their models.
| Microarchitecture | Status | Detail | Source |
|---|---|---|---|
| NetBurst (Prescott, Nocona) | Affected | Linux 7.3 sets the bug on INTEL_P4_CEDARMILL, INTEL_P4_PRESCOTT, INTEL_P4_PRESCOTT_2M: cpu_vuln_whitelist does not list them with NO_ITLB_MULTIHIT; and a processor released before 2018 does not report PSCHANGE_MC_NO | Linux 7.3 |
| Core (Merom, Conroe) | Affected | Linux 7.3 sets the bug on INTEL_CORE2_MEROM, INTEL_CORE2_MEROM_L: cpu_vuln_whitelist does not list them with NO_ITLB_MULTIHIT; and a processor released before 2018 does not report PSCHANGE_MC_NO | Linux 7.3 |
| Penryn | Affected | Linux 7.3 sets the bug on INTEL_CORE2_DUNNINGTON, INTEL_CORE2_PENRYN: cpu_vuln_whitelist does not list them with NO_ITLB_MULTIHIT; and a processor released before 2018 does not report PSCHANGE_MC_NO | Linux 7.3 |
| Nehalem | Affected | Linux 7.3 sets the bug on INTEL_NEHALEM, INTEL_NEHALEM_EP, INTEL_NEHALEM_EX, INTEL_NEHALEM_G: cpu_vuln_whitelist does not list them with NO_ITLB_MULTIHIT; and a processor released before 2018 does not report PSCHANGE_MC_NO | Linux 7.3 |
| Westmere | Affected | Linux 7.3 sets the bug on INTEL_WESTMERE, INTEL_WESTMERE_EP, INTEL_WESTMERE_EX: cpu_vuln_whitelist does not list them with NO_ITLB_MULTIHIT; and a processor released before 2018 does not report PSCHANGE_MC_NO | Linux 7.3 |
| Sandy Bridge | Affected | Linux 7.3 sets the bug on INTEL_SANDYBRIDGE, INTEL_SANDYBRIDGE_X: cpu_vuln_whitelist does not list them with NO_ITLB_MULTIHIT; and a processor released before 2018 does not report PSCHANGE_MC_NO | Linux 7.3 |
| Ivy Bridge | Affected | Linux 7.3 sets the bug on INTEL_IVYBRIDGE, INTEL_IVYBRIDGE_X: cpu_vuln_whitelist does not list them with NO_ITLB_MULTIHIT; and a processor released before 2018 does not report PSCHANGE_MC_NO | Linux 7.3 |
| Haswell | Affected | 06_3FH stepping 2 (Haswell Server EP/EP4S): Software 06_3FH stepping 4 (Haswell Server EX): Software | Intel’s list |
| Broadwell | Affected | 06_4FH stepping 1 (1. Broadwell Server E/EP/EP4S - 2. Broadwell Server EX): Software 06_56H stepping 3 (Broadwell DE V2 - V3): Software 06_56H stepping 4 (Broadwell DE Y0): Software 06_56H stepping 5 (Hewitt Lake (Broadwell DE)): Software | Intel’s list |
| Skylake | Affected | 06_5EH stepping 3 (1. Skylake Xeon E3 - 2. Skylake H - 3. Skylake S): Software | Intel’s list |
| Kaby Lake | Affected | 06_8EH stepping 9 (1. Amber Lake-Y - 2. Kaby Lake U - 3. Kaby Lake U23e - 4. Kaby Lake Y): Software 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): Software 06_9EH stepping 9 (1. Kaby Lake S - 2. Kaby Lake Xeon E3): Software | Intel’s list |
| Coffee Lake | Affected | 06_8EH stepping A (1. Coffee Lake U43e - 2. Whiskey Lake): Software 06_8EH stepping B (Whiskey Lake U): Software 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): Software 06_9EH stepping A (Coffee Lake H): Software 06_9EH stepping C (Coffee Lake S): Software 06_9EH stepping D (1. Coffee Lake H - 2. Coffee Lake Xeon E - 3. Coffee Lake S): Software | Intel’s list |
| Comet Lake | Affected | 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): Software 06_A5H stepping 2 (Comet Lake H): Software 06_A5H stepping 3 (Comet Lake-S): Software 06_A5H stepping 5 (Comet Lake-S): Software 06_A6H stepping 0 (Comet Lake U62): Software 06_A6H stepping 1 (Comet Lake U62): Software | Intel’s list |
| Ice Lake (client) | Affected | 06_7EH stepping 5 (Ice Lake U - Ice Lake Y): Software | Intel’s list |
| Skylake-SP | Affected | 06_55H stepping 3 (Skylake Server): Software 06_55H stepping 4 (1. Skylake Server - 2. Skylake D/Bakerville): Software | Intel’s list |
| Cooper Lake | Affected | 06_55H stepping B (Cooper Lake): Software | Intel’s list |
| Tiger Lake | Not affected | 06_8CH stepping 1 (Tiger Lake U): Not Affected 06_8CH stepping 1 (Tiger Lake U): Not Affected 06_8CH stepping 2 (1. Tiger Lake U Refresh - 2. Tiger Lake H35): Not Affected 06_8DH stepping 1 (Tiger Lake H): Not Affected 06_8DH stepping 1 (Tiger Lake H): Not Affected | Intel’s list |
| Alder Lake | Not affected | 06_97H stepping 2 (Alder Lake S (Golden Cove - Gracemont)): Not Affected 06_97H stepping 5 (Alder Lake S (Golden Cove - Gracemont)): Not Affected 06_97H stepping 5 (Catlow (Golden Cove)): Not Affected 06_9AH stepping 3 (1. Alder Lake H (Golden Cove - Gracemont) - 2. Alder Lake P (Golden Cove - Gracemont)): Not Affected 06_9AH stepping 4 (Alder Lake U (Golden Cove - Gracemont)): Not Affected | Intel’s list |
| Rocket Lake | Not affected | 06_A7H stepping 1 (Rocket Lake): Not Affected | Intel’s list |
| Raptor Lake | Not affected | 06_B7H stepping 1 (1. Raptor Lake S - 2. Raptor Lake HX (Raptor Cove/Gracemont)): Not Affected 06_B7H stepping 1 (Catlow (Raptor Cove)): Not Affected 06_BAH stepping 2 - 3 - 8 (1. Raptor Lake P - 2. Raptor Lake H + refresh - 3. Raptor Lake U + refresh (Raptor Cove/Gracemont)): Not Affected 06_BFH stepping 2 - 5 (Raptor Lake S (Raptor Cove/Gracemont)): Not Affected | Intel’s list |
| Meteor Lake | Not affected | 06_AAH stepping 4 (Meteor Lake U/H/PS (Redwood Cove - Crestmont)): Not Affected | Intel’s list |
| Arrow Lake | Not affected | 06_B5H stepping 0 (Arrow Lake U (Redwood Cove - Crestmont)): Not Affected 06_C5H stepping 2 (Arrow Lake H (Lion Cove - Skymont)): Not Affected 06_C6H stepping 2 (Arrow Lake H/HX/S/S Plus (Lion Cove - Skymont)): Not Affected | Intel’s list |
| Lunar Lake | Not affected | 06_BDH stepping 1 (Lunar Lake (Lion Cove - Skymont)): Not Affected | Intel’s list |
| Panther Lake | Not affected | 06_CCH stepping 2 - 3 (Panther Lake (Cougar Cove - Darkmont)): Not Affected | Intel’s list |
| Ice Lake (server) | Not affected | 06_6AH stepping 6 (Ice Lake Xeon-SP): Not Affected 06_6CH stepping All (Ice Lake Xeon D (Idaville)): Not Affected | Intel’s list |
| Emerald Rapids | Not affected | 06_CFH stepping 2 (Emerald Rapids (Raptor Cove)): Not Affected | Intel’s list |
| Sapphire Rapids | Not affected | 06_8FH stepping 5 - 6 - 7 - 8 (1. Sapphire Rapids - 2. Sapphire Rapids Edge Enhanced (Golden Cove)): Not Affected 06_8FH stepping 5 - 6 - 8 (Sapphire Rapids (Golden Cove) - Sapphire Rapids HBM): Not Affected | Intel’s list |
| Granite Rapids | Not affected | 06_ADH stepping 1 (Granite Rapids (Redwood Cove)): Not Affected 06_ADH stepping 1 (Granite Rapids (Redwood Cove)): Not Affected 06_ADH stepping 1 (Granite Rapids R1S (Redwood Cove)): Not Affected 06_AEH stepping 1 (Granite Rapids D (Redwood Cove)/Kaseyville): Not Affected | Intel’s list |
| Sierra Forest | Not affected | 06_AFH stepping 3 (Sierra Forest (Crestmont)): Not Affected | Intel’s list |
| Clearwater Forest | Not affected | 06_DDH stepping 1 (Clearwater Forest (Darkmont)): Not Affected | Intel’s list |
| Bonnell | Not affected | Linux 7.3 lists INTEL_ATOM_BONNELL, INTEL_ATOM_BONNELL_MID in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Saltwell | Not affected | Linux 7.3 lists INTEL_ATOM_SALTWELL, INTEL_ATOM_SALTWELL_MID, INTEL_ATOM_SALTWELL_TABLET in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Silvermont | Not affected | Linux 7.3 lists INTEL_ATOM_SILVERMONT, INTEL_ATOM_SILVERMONT_D, INTEL_ATOM_SILVERMONT_MID, INTEL_ATOM_SILVERMONT_MID2 in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Airmont | Not affected | Linux 7.3 lists INTEL_ATOM_AIRMONT, INTEL_ATOM_AIRMONT_NP in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Goldmont | Not affected | 06_5CH stepping A (Apollo Lake): Not Affected 06_5FH stepping All (Denverton (Goldmont)): Not Affected | Intel’s list |
| Goldmont Plus | Not affected | 06_7AH stepping 8 (Gemini Lake): Not Affected | Intel’s list |
| Tremont | Not affected | 06_86H stepping 5 (Snow Ridge BTS (Tremont)): Not Affected 06_86H stepping 7 (Parker Ridge / Snow Ridge NS/NX/BTS): Not Affected 06_96H stepping All (Elkhart Lake (Tremont)): Not Affected 06_9CH stepping All (Jasper Lake (Tremont)): Not Affected | Intel’s list |
| Gracemont | Not affected | 06_9AH stepping 4 (Arizona Beach (Gracemont)): Not Affected 06_BEH stepping 0 (Alder Lake N (Gracemont)/Twin Lake): Not Affected | Intel’s list |
| Knights Landing | Not affected | Linux 7.3 lists INTEL_XEON_PHI_KNL in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Knights Mill | Not affected | Linux 7.3 lists INTEL_XEON_PHI_KNM in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| K8 (Hammer) | Not affected | Linux 7.3 lists AMD family Fh in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| K10 (Family 10h) | Not affected | Linux 7.3 lists AMD family 10h, AMD family 12h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Bulldozer | Not affected | Linux 7.3 lists AMD family 15h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Piledriver | Not affected | Linux 7.3 lists AMD family 15h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Steamroller | Not affected | Linux 7.3 lists AMD family 15h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Excavator | Not affected | Linux 7.3 lists AMD family 15h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Zen | Not affected | Linux 7.3 lists AMD family 17h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Zen+ | Not affected | Linux 7.3 lists AMD family 17h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Zen 2 | Not affected | Linux 7.3 lists AMD family 17h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Zen 3 | Not affected | Linux 7.3 lists AMD family 19h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Zen 4 | Not affected | Linux 7.3 lists AMD family 19h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Zen 5 | Not affected | Linux 7.3 lists AMD family 1Ah in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Zen 6 | Not affected | Linux 7.3 lists AMD family 1Ah in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Bobcat | Not affected | Linux 7.3 lists AMD family 14h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Jaguar | Not affected | Linux 7.3 lists AMD family 16h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Puma | Not affected | Linux 7.3 lists AMD family 16h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
| Dhyana | Not affected | Linux 7.3 lists Hygon family 18h in cpu_vuln_whitelist with NO_ITLB_MULTIHIT | Linux 7.3 |
Mitigations
- Hypervisor: KVM maps guest memory in large pages only as not executable; when the guest runs code there, KVM splits that page into 4 KB pages. The kvm.nx_huge_pages option controls it. Source.
How to check a machine
On Linux, /sys/devices/system/cpu/vulnerabilities/itlb_multihit holds one of these lines:
Not affectedKVM: Mitigation: VMX disabledKVM: Mitigation: Split huge pagesKVM: Vulnerable