Some Dell systems that use some models of Intel CPUs are susceptible to hangs

and system instability during or after microcode update to revision 0xc6/0xca

(included as part of microcode-20191113/microcode-20191115 update that addressed

CVE-2019-0117, CVE-2019-0123, CVE-2019-11135, and CVE-2019-11139)

and/or revision 0xd6 (included as part of microcode-20200609 update

that addressed CVE-2020-0543, CVE-2020-0548, and CVE-2020-0549)

[1][2][3][4][5][6].  In order to address this, microcode update to the newer

revision has been disabled by default on these systems, and the previously

published microcode revisions 0xae/0xb4/0xb8 are used by default

for the OS-driven microcode update.

[1] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/23

[2] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/24

[3] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/33

[4] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/34

[5] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/35

[6] https://bugzilla.redhat.com/show_bug.cgi?id=1846097

This caveat contains latest microcode revisions publicly released by Intel;

for the revision 0xca of the microcode files, please refer to caveat

06-8e-9e-0x-0xca.

For the reference, microarchitectures of the affected CPU models:

 * Amber Lake-Y

 * Kaby Lake-G/H/S/U/X/Y/Xeon E3

 * Coffee Lake-H/S/U/Xeon E

 * Comet Lake-U 4+2

 * Whiskey Lake-U

Family names of the affected CPU models:

 * 7th Generation Intel® Core™ Processor Family

 * 8th Generation Intel® Core™ Processor Family

 * 9th Generation Intel® Core™ Processor Family

 * 10th Generation Intel® Core™ Processor Family (selected models)

 * Intel® Celeron® Processor G Series

 * Intel® Celeron® Processor 5000 Series

 * Intel® Core™ X-series Processors (i7-7740X, i5-7640X only)

 * Intel® Pentium® Gold Processor Series

 * Intel® Pentium® Processor Series (selected models)

 * Intel® Xeon® Processor E Family

 * Intel® Xeon® Processor E3 v6 Family

SHA1 checksums of the microcode files containing microcode revisions

in question:

 * 06-8e-09, revision 0xb4: e253c95c29c3eef6576db851dfa069d82a91256f

 * 06-8e-0a, revision 0xb4: 45bcba494be07df9eeccff9627578095a97fba4d

 * 06-8e-0b, revision 0xb8: 3e54bf91d642ad81ff07fe274d0cfb5d10d09c43

 * 06-8e-0c, revision 0xb8: bf635c87177d6dc4e067ec11e1caeb19d3c325f0

 * 06-9e-09, revision 0xb4: 42f68eec4ddb79dd6be0c95c4ce60e514e4504b1

 * 06-9e-0a, revision 0xb4: 37c7cb394dd36610b57943578343723da67d50f0

 * 06-9e-0b, revision 0xb4: b5399109d0a5ce8f5fb623ff942da0322b438b95

 * 06-9e-0c, revision 0xae: 131bce89e4d210de8322ffbc6bd787f1af66a7df

 * 06-9e-0d, revision 0xb8: 22511b007d1df55558d115abb13a1c23ea398317

 * 06-8e-09, revision 0xca: 9afa1bae40995207afef13247f114be042d88083

 * 06-8e-0a, revision 0xca: 1d90291cc25e17dc6c36c764cf8c06b41fed4c16

 * 06-8e-0b, revision 0xca: 3fb1246a6594eff5e2c2076c63c600d734f10777

 * 06-8e-0c, revision 0xca: e871540671f59b4fa5d0d454798f09a4d412aace

 * 06-9e-09, revision 0xca: b5eed11108ab7ac1e675fe75d0e7454a400ddd35

 * 06-9e-0a, revision 0xca: e472304aaa2f3815a32822cb111ab3f43bf3dfe4

 * 06-9e-0b, revision 0xca: 78f47c5162da680878ed057dc7c853f9737c524b

 * 06-9e-0c, revision 0xca: f23848a009928796a153cb9e8f44522136969408

 * 06-9e-0d, revision 0xca: c7a3d469469ee828ba9faf91b67af881fceec3b7

 * 06-8e-09, revision 0xd6: 2272c621768437d20e602207752201e0966e5a8c

 * 06-8e-0a, revision 0xd6: 0b145afb88e028e612f04c2a86385e7d7c3fefc4

 * 06-8e-0b, revision 0xd6: c3831b05da83be54f3acc451a1bce90f75e2e9e5

 * 06-8e-0c, revision 0xd6: 4b8938a93e23f4b5a2d9de40b87f6afcfdc27c05

 * 06-9e-09, revision 0xd6: 4bacba8c598508e7dd4e87e179586abe7a1a987f

 * 06-9e-0a, revision 0xd6: 4c236afeef9f80ff3a286698fe7cef72926722f0

 * 06-9e-0b, revision 0xd6: 2f9ab9b2ba29559ce177632281d7290a24fed2ef

 * 06-9e-0c, revision 0xd6: 4b9059e519bcab6085b6c103f5d99e509fe0b2bb

 * 06-9e-0d, revision 0xd6: 3a3b7edfd8126bb34b761b46a32102a622047899

 * 06-8e-09, revision 0xde: 84d7514101eb8904834a3dacdee684b3c574245f

 * 06-8e-0a, revision 0xe0: 080b9e3ebbcf6bb1eca0fb5f640e6bfbfe3a1e6e

 * 06-8e-0b, revision 0xde: 80fed976231bbff4c7103e373498e07eef0bff31

 * 06-8e-0c, revision 0xde: 84f160587fea4acb81451c8ff53dc51afba06343

 * 06-9e-09, revision 0xde: 422026ffb2cca446693c586be98d0d9e7dfeb116

 * 06-9e-0a, revision 0xde: b6c44b9fe26e1d6bafa27f37ffe010284294bf1c

 * 06-9e-0b, revision 0xde: 6452937a0d359066b95f9e679a41a15490770312

 * 06-9e-0c, revision 0xde: a95021a4e497e0bf3691ecf3d020728f25a3f542

 * 06-9e-0d, revision 0xde: 03b20fdc2fa3f9586f93a7e40d3b61be5b7b788c

Please contact your system vendor for a BIOS/firmware update that contains

the latest microcode version.  For the information regarding microcode versions

required for mitigating specific side-channel cache attacks, please refer

to the following knowledge base articles:

 * CVE-2017-5715 ("Spectre"):

   https://access.redhat.com/articles/3436091

 * CVE-2018-3639 ("Speculative Store Bypass"):

   https://access.redhat.com/articles/3540901

 * CVE-2018-3620, CVE-2018-3646 ("L1 Terminal Fault Attack"):

   https://access.redhat.com/articles/3562741

 * CVE-2018-12130, CVE-2018-12126, CVE-2018-12127, and CVE-2019-11091

   ("Microarchitectural Data Sampling"):

   https://access.redhat.com/articles/4138151

 * CVE-2019-0117 (Intel SGX Information Leak),

   CVE-2019-0123 (Intel SGX Privilege Escalation),

   CVE-2019-11135 (TSX Asynchronous Abort),

   CVE-2019-11139 (Voltage Setting Modulation):

   https://access.redhat.com/solutions/2019-microcode-nov

 * CVE-2020-0543 (Special Register Buffer Data Sampling),

   CVE-2020-0548 (Vector Register Data Sampling),

   CVE-2020-0549 (L1D Cache Eviction Sampling):

   https://access.redhat.com/solutions/5142751

The information regarding disabling microcode update is provided below.

To disable usage of the newer microcode revision for a specific kernel

version, please create a file "disallow-intel-06-8e-9e-0x-dell" inside

/lib/firmware/<kernel_version> directory, run

"/usr/libexec/microcode_ctl/update_ucode" to update firmware directory

used for late microcode updates, and run "dracut -f --kver <kernel_version>"

so initramfs for this kernel version is regenerated, for example:

    touch /lib/firmware/3.10.0-862.9.1/disallow-intel-06-8e-9e-0x-dell

    /usr/libexec/microcode_ctl/update_ucode

    dracut -f --kver 3.10.0-862.9.1

To disable usage of the newer microcode revision for all kernels, please create

file "/etc/microcode_ctl/ucode_with_caveats/disallow-intel-06-8e-9e-0x-dell",

run "/usr/libexec/microcode_ctl/update_ucode" to update firmware directories

used for late microcode updates, and run "dracut -f --regenerate-all"

so initramfs images get regenerated, for example:

    mkdir -p /etc/microcode_ctl/ucode_with_caveats

    touch /etc/microcode_ctl/ucode_with_caveats/disallow-intel-06-8e-9e-dell

    /usr/libexec/microcode_ctl/update_ucode

    dracut -f --regenerate-all

Please refer to /usr/share/doc/microcode_ctl/README.caveats for additional

information.