user/sven/linux.git/Documentation/admin-guide, branch v4.14.181

ACPI: watchdog: Allow disabling WDAT at boot

2020-03-20T09:54:23Z

[ Upstream commit 3f9e12e0df012c4a9a7fd7eb0d3ae69b459d6b2c ] In case the WDAT interface is broken, give the user an option to ignore it to let a native driver bind to the watchdog device instead. Signed-off-by: Jean Delvare Acked-by: Mika Westerberg Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

Documentation: Document arm64 kpti control

2020-01-29T14:02:37Z

commit de19055564c8f8f9d366f8db3395836da0b2176c upstream. For a while Arm64 has been capable of force enabling or disabling the kpti mitigations. Lets make sure the documentation reflects that. Signed-off-by: Jeremy Linton Reviewed-by: Andre Przywara Signed-off-by: Jonathan Corbet Signed-off-by: Greg Kroah-Hartman

USB: documentation: flags on usb-storage versus UAS

2019-12-17T19:39:03Z

commit 65cc8bf99349f651a0a2cee69333525fe581f306 upstream. Document which flags work storage, UAS or both Signed-off-by: Oliver Neukum Cc: stable Link: https://lore.kernel.org/r/20191114112758.32747-4-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman

x86/speculation: Fix incorrect MDS/TAA mitigation status

2019-12-01T08:14:22Z

commit 64870ed1b12e235cfca3f6c6da75b542c973ff78 upstream. For MDS vulnerable processors with TSX support, enabling either MDS or TAA mitigations will enable the use of VERW to flush internal processor buffers at the right code path. IOW, they are either both mitigated or both not. However, if the command line options are inconsistent, the vulnerabilites sysfs files may not report the mitigation status correctly. For example, with only the "mds=off" option: vulnerabilities/mds:Vulnerable; SMT vulnerable vulnerabilities/tsx_async_abort:Mitigation: Clear CPU buffers; SMT vulnerable The mds vulnerabilities file has wrong status in this case. Similarly, the taa vulnerability file will be wrong with mds mitigation on, but taa off. Change taa_select_mitigation() to sync up the two mitigation status and have them turned off if both "mds=off" and "tsx_async_abort=off" are present. Update documentation to emphasize the fact that both "mds=off" and "tsx_async_abort=off" have to be specified together for processors that are affected by both TAA and MDS to be effective. [ bp: Massage and add kernel-parameters.txt change too. ] Fixes: 1b42f017415b ("x86/speculation/taa: Add mitigation for TSX Async Abort") Signed-off-by: Waiman Long Signed-off-by: Borislav Petkov Cc: Greg Kroah-Hartman Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jiri Kosina Cc: Jonathan Corbet Cc: Josh Poimboeuf Cc: linux-doc@vger.kernel.org Cc: Mark Gross Cc: Cc: Pawan Gupta Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tim Chen Cc: Tony Luck Cc: Tyler Hicks Cc: x86-ml Link: https://lkml.kernel.org/r/20191115161445.30809-2-longman@redhat.com Signed-off-by: Greg Kroah-Hartman

kvm: x86: mmu: Recovery of shattered NX large pages

2019-11-12T18:19:08Z

commit 1aa9b9572b10529c2e64e2b8f44025d86e124308 upstream. The page table pages corresponding to broken down large pages are zapped in FIFO order, so that the large page can potentially be recovered, if it is not longer being used for execution. This removes the performance penalty for walking deeper EPT page tables. By default, one large page will last about one hour once the guest reaches a steady state. Signed-off-by: Junaid Shahid Signed-off-by: Paolo Bonzini Signed-off-by: Thomas Gleixner Signed-off-by: Paolo Bonzini Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

kvm: mmu: ITLB_MULTIHIT mitigation

2019-11-12T18:19:08Z

commit b8e8c8303ff28c61046a4d0f6ea99aea609a7dc0 upstream. With some Intel processors, putting the same virtual address in the TLB as both a 4 KiB and 2 MiB page can confuse the instruction fetch unit and cause the processor to issue a machine check resulting in a CPU lockup. Unfortunately when EPT page tables use huge pages, it is possible for a malicious guest to cause this situation. Add a knob to mark huge pages as non-executable. When the nx_huge_pages parameter is enabled (and we are using EPT), all huge pages are marked as NX. If the guest attempts to execute in one of those pages, the page is broken down into 4K pages, which are then marked executable. This is not an issue for shadow paging (except nested EPT), because then the host is in control of TLB flushes and the problematic situation cannot happen. With nested EPT, again the nested guest can cause problems shadow and direct EPT is treated in the same way. [ tglx: Fixup default to auto and massage wording a bit ] Originally-by: Junaid Shahid Signed-off-by: Paolo Bonzini Signed-off-by: Thomas Gleixner Signed-off-by: Paolo Bonzini Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

Documentation: Add ITLB_MULTIHIT documentation

2019-11-12T18:19:05Z

commit 7f00cc8d4a51074eb0ad4c3f16c15757b1ddfb7d upstream. Add the initial ITLB_MULTIHIT documentation. [ tglx: Add it to the index so it gets actually built. ] Signed-off-by: Antonio Gomez Iglesias Signed-off-by: Nelson D'Souza Signed-off-by: Paolo Bonzini Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

x86/speculation/taa: Add documentation for TSX Async Abort

2019-11-12T18:19:02Z

commit a7a248c593e4fd7a67c50b5f5318fe42a0db335e upstream. Add the documenation for TSX Async Abort. Include the description of the issue, how to check the mitigation state, control the mitigation, guidance for system administrators. [ bp: Add proper SPDX tags, touch ups by Josh and me. ] Co-developed-by: Antonio Gomez Iglesias Signed-off-by: Pawan Gupta Signed-off-by: Antonio Gomez Iglesias Signed-off-by: Borislav Petkov Signed-off-by: Thomas Gleixner Reviewed-by: Mark Gross Reviewed-by: Tony Luck Reviewed-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman

x86/tsx: Add "auto" option to the tsx= cmdline parameter

2019-11-12T18:19:01Z

commit 7531a3596e3272d1f6841e0d601a614555dc6b65 upstream. Platforms which are not affected by X86_BUG_TAA may want the TSX feature enabled. Add "auto" option to the TSX cmdline parameter. When tsx=auto disable TSX when X86_BUG_TAA is present, otherwise enable TSX. More details on X86_BUG_TAA can be found here: https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html [ bp: Extend the arg buffer to accommodate "auto\0". ] Signed-off-by: Pawan Gupta Signed-off-by: Borislav Petkov Signed-off-by: Thomas Gleixner Reviewed-by: Tony Luck Reviewed-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman

x86/cpu: Add a "tsx=" cmdline option with TSX disabled by default

2019-11-12T18:18:59Z

commit 95c5824f75f3ba4c9e8e5a4b1a623c95390ac266 upstream. Add a kernel cmdline parameter "tsx" to control the Transactional Synchronization Extensions (TSX) feature. On CPUs that support TSX control, use "tsx=on|off" to enable or disable TSX. Not specifying this option is equivalent to "tsx=off". This is because on certain processors TSX may be used as a part of a speculative side channel attack. Carve out the TSX controlling functionality into a separate compilation unit because TSX is a CPU feature while the TSX async abort control machinery will go to cpu/bugs.c. [ bp: - Massage, shorten and clear the arg buffer. - Clarifications of the tsx= possible options - Josh. - Expand on TSX_CTRL availability - Pawan. ] Signed-off-by: Pawan Gupta Signed-off-by: Borislav Petkov Signed-off-by: Thomas Gleixner Reviewed-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman