kernel.git/arch/x86/kernel, branch linux-5.13.y

x86/hyperv: fix for unwanted manipulation of sched_clock when TSC marked unstable

2021-09-18T11:41:59Z

[ Upstream commit c445535c3efbfb8cb42d098e624d46ab149664b7 ] Marking TSC as unstable has a side effect of marking sched_clock as unstable when TSC is still being used as the sched_clock. This is not desirable. Hyper-V ultimately uses a paravirtualized clock source that provides a stable scheduler clock even on systems without TscInvariant CPU capability. Hence, mark_tsc_unstable() call should be called _after_ scheduler clock has been changed to the paravirtualized clocksource. This will prevent any unwanted manipulation of the sched_clock. Only TSC will be correctly marked as unstable. Signed-off-by: Ani Sinha Reviewed-by: Michael Kelley Tested-by: Michael Kelley Link: https://lore.kernel.org/r/20210713030522.1714803-1-ani@anisinha.ca Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

x86/resctrl: Fix a maybe-uninitialized build warning treated as error

2021-09-15T08:00:57Z

commit 527f721478bce3f49b513a733bacd19d6f34b08c upstream. The recent commit 064855a69003 ("x86/resctrl: Fix default monitoring groups reporting") caused a RHEL build failure with an uninitialized variable warning treated as an error because it removed the default case snippet. The RHEL Makefile uses '-Werror=maybe-uninitialized' to force possibly uninitialized variable warnings to be treated as errors. This is also reported by smatch via the 0day robot. The error from the RHEL build is: arch/x86/kernel/cpu/resctrl/monitor.c: In function ‘__mon_event_count’: arch/x86/kernel/cpu/resctrl/monitor.c:261:12: error: ‘m’ may be used uninitialized in this function [-Werror=maybe-uninitialized] m->chunks += chunks; ^~ The upstream Makefile does not build using '-Werror=maybe-uninitialized'. So, the problem is not seen there. Fix the problem by putting back the default case snippet. [ bp: note that there's nothing wrong with the code and other compilers do not trigger this warning - this is being done just so the RHEL compiler is happy. ] Fixes: 064855a69003 ("x86/resctrl: Fix default monitoring groups reporting") Reported-by: Terry Bowman Reported-by: kernel test robot Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov Reviewed-by: Reinette Chatre Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/162949631908.23903.17090272726012848523.stgit@bmoger-ubuntu Signed-off-by: Greg Kroah-Hartman

x86/mce: Defer processing of early errors

2021-09-15T08:00:34Z

[ Upstream commit 3bff147b187d5dfccfca1ee231b0761a89f1eff5 ] When a fatal machine check results in a system reset, Linux does not clear the error(s) from machine check bank(s) - hardware preserves the machine check banks across a warm reset. During initialization of the kernel after the reboot, Linux reads, logs, and clears all machine check banks. But there is a problem. In: 5de97c9f6d85 ("x86/mce: Factor out and deprecate the /dev/mcelog driver") the call to mce_register_decode_chain() moved later in the boot sequence. This means that /dev/mcelog doesn't see those early error logs. This was partially fixed by: cd9c57cad3fe ("x86/MCE: Dump MCE to dmesg if no consumers") which made sure that the logs were not lost completely by printing to the console. But parsing console logs is error prone. Users of /dev/mcelog should expect to find any early errors logged to standard places. Add a new flag MCP_QUEUE_LOG to machine_check_poll() to be used in early machine check initialization to indicate that any errors found should just be queued to genpool. When mcheck_late_init() is called it will call mce_schedule_work() to actually log and flush any errors queued in the genpool. [ Based on an original patch, commit message by and completely productized by Tony Luck. ] Fixes: 5de97c9f6d85 ("x86/mce: Factor out and deprecate the /dev/mcelog driver") Reported-by: Sumanth Kamatala Signed-off-by: Borislav Petkov Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210824003129.GA1642753@agluck-desk2.amr.corp.intel.com Signed-off-by: Sasha Levin

x86/reboot: Limit Dell Optiplex 990 quirk to early BIOS versions

2021-09-12T07:00:00Z

commit a729691b541f6e63043beae72e635635abe5dc09 upstream. When this platform was relatively new in November 2011, with early BIOS revisions, a reboot quirk was added in commit 6be30bb7d750 ("x86/reboot: Blacklist Dell OptiPlex 990 known to require PCI reboot") However, this quirk (and several others) are open-ended to all BIOS versions and left no automatic expiry if/when the system BIOS fixed the issue, meaning that nobody is likely to come along and re-test. What is really problematic with using PCI reboot as this quirk does, is that it causes this platform to do a full power down, wait one second, and then power back on. This is less than ideal if one is using it for boot testing and/or bisecting kernels when legacy rotating hard disks are installed. It was only by chance that the quirk was noticed in dmesg - and when disabled it turned out that it wasn't required anymore (BIOS A24), and a default reboot would work fine without the "harshness" of power cycling the machine (and disks) down and up like the PCI reboot does. Doing a bit more research, it seems that the "newest" BIOS for which the issue was reported[1] was version A06, however Dell[2] seemed to suggest only up to and including version A05, with the A06 having a large number of fixes[3] listed. As is typical with a new platform, the initial BIOS updates come frequently and then taper off (and in this case, with a revival for CPU CVEs); a search for O990-A.exe reveals the following dates: A02 16 Mar 2011 A03 11 May 2011 A06 14 Sep 2011 A07 24 Oct 2011 A10 08 Dec 2011 A14 06 Sep 2012 A16 15 Oct 2012 A18 30 Sep 2013 A19 23 Sep 2015 A20 02 Jun 2017 A23 07 Mar 2018 A24 21 Aug 2018 While it's overkill to flash and test each of the above, it would seem likely that the issue was contained within A0x BIOS versions, given the dates above and the dates of issue reports[4] from distros. So rather than just throw out the quirk entirely, limit the scope to just those early BIOS versions, in case people are still running systems from 2011 with the original as-shipped early A0x BIOS versions. [1] https://lore.kernel.org/lkml/1320373471-3942-1-git-send-email-trenn@suse.de/ [2] https://www.dell.com/support/kbdoc/en-ca/000131908/linux-based-operating-systems-stall-upon-reboot-on-optiplex-390-790-990-systems [3] https://www.dell.com/support/home/en-ca/drivers/driversdetails?driverid=85j10 [4] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/768039 Fixes: 6be30bb7d750 ("x86/reboot: Blacklist Dell OptiPlex 990 known to require PCI reboot") Signed-off-by: Paul Gortmaker Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210530162447.996461-4-paul.gortmaker@windriver.com Signed-off-by: Greg Kroah-Hartman

x86/resctrl: Fix default monitoring groups reporting

2021-08-18T07:07:04Z

commit 064855a69003c24bd6b473b367d364e418c57625 upstream. Creating a new sub monitoring group in the root /sys/fs/resctrl leads to getting the "Unavailable" value for mbm_total_bytes and mbm_local_bytes on the entire filesystem. Steps to reproduce: 1. mount -t resctrl resctrl /sys/fs/resctrl/ 2. cd /sys/fs/resctrl/ 3. cat mon_data/mon_L3_00/mbm_total_bytes 23189832 4. Create sub monitor group: mkdir mon_groups/test1 5. cat mon_data/mon_L3_00/mbm_total_bytes Unavailable When a new monitoring group is created, a new RMID is assigned to the new group. But the RMID is not active yet. When the events are read on the new RMID, it is expected to report the status as "Unavailable". When the user reads the events on the default monitoring group with multiple subgroups, the events on all subgroups are consolidated together. Currently, if any of the RMID reads report as "Unavailable", then everything will be reported as "Unavailable". Fix the issue by discarding the "Unavailable" reads and reporting all the successful RMID reads. This is not a problem on Intel systems as Intel reports 0 on Inactive RMIDs. Fixes: d89b7379015f ("x86/intel_rdt/cqm: Add mon_data") Reported-by: Paweł Szulik Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov Acked-by: Reinette Chatre Cc: stable@vger.kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=213311 Link: https://lkml.kernel.org/r/162793309296.9224.15871659871696482080.stgit@bmoger-ubuntu Signed-off-by: Greg Kroah-Hartman

x86/ioapic: Force affinity setup before startup

2021-08-18T07:07:04Z

commit 0c0e37dc11671384e53ba6ede53a4d91162a2cc5 upstream. The IO/APIC cannot handle interrupt affinity changes safely after startup other than from an interrupt handler. The startup sequence in the generic interrupt code violates that assumption. Mark the irq chip with the new IRQCHIP_AFFINITY_PRE_STARTUP flag so that the default interrupt setting happens before the interrupt is started up for the first time. Fixes: 18404756765c ("genirq: Expose default irq affinity mask (take 3)") Signed-off-by: Thomas Gleixner Tested-by: Marc Zyngier Reviewed-by: Marc Zyngier Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210729222542.832143400@linutronix.de Signed-off-by: Greg Kroah-Hartman

x86/msi: Force affinity setup before startup

2021-08-18T07:07:04Z

commit ff363f480e5997051dd1de949121ffda3b753741 upstream. The X86 MSI mechanism cannot handle interrupt affinity changes safely after startup other than from an interrupt handler, unless interrupt remapping is enabled. The startup sequence in the generic interrupt code violates that assumption. Mark the irq chips with the new IRQCHIP_AFFINITY_PRE_STARTUP flag so that the default interrupt setting happens before the interrupt is started up for the first time. While the interrupt remapping MSI chip does not require this, there is no point in treating it differently as this might spare an interrupt to a CPU which is not in the default affinity mask. For the non-remapping case go to the direct write path when the interrupt is not yet started similar to the not yet activated case. Fixes: 18404756765c ("genirq: Expose default irq affinity mask (take 3)") Signed-off-by: Thomas Gleixner Tested-by: Marc Zyngier Reviewed-by: Marc Zyngier Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210729222542.886722080@linutronix.de Signed-off-by: Greg Kroah-Hartman

x86/fpu: Limit xstate copy size in xstateregs_set()

2021-07-20T14:00:31Z

[ Upstream commit 07d6688b22e09be465652cf2da0da6bf86154df6 ] If the count argument is larger than the xstate size, this will happily copy beyond the end of xstate. Fixes: 91c3dba7dbc1 ("x86/fpu/xstate: Fix PTRACE frames for XSAVES") Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Andy Lutomirski Reviewed-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210623121452.120741557@linutronix.de Signed-off-by: Sasha Levin

x86/fpu: Fix copy_xstate_to_kernel() gap handling

2021-07-20T14:00:31Z

[ Upstream commit 9625895011d130033d1bc7aac0d77a9bf68ff8a6 ] The gap handling in copy_xstate_to_kernel() is wrong when XSAVES is in use. Using init_fpstate for copying the init state of features which are not set in the xstate header is only correct for the legacy area, but not for the extended features area because when XSAVES is in use then init_fpstate is in compacted form which means the xstate offsets which are used to copy from init_fpstate are not valid. Fortunately, this is not a real problem today because all extended features in use have an all-zeros init state, but it is wrong nevertheless and with a potentially dynamically sized init_fpstate this would result in an access outside of the init_fpstate. Fix this by keeping track of the last copied state in the target buffer and explicitly zero it when there is a feature or alignment gap. Use the compacted offset when accessing the extended feature space in init_fpstate. As this is not a functional issue on older kernels this is intentionally not tagged for stable. Fixes: b8be15d58806 ("x86/fpu/xstate: Re-enable XSAVES") Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210623121451.294282032@linutronix.de Signed-off-by: Sasha Levin

x86/signal: Detect and prevent an alternate signal stack overflow

2021-07-20T14:00:27Z

[ Upstream commit 2beb4a53fc3f1081cedc1c1a198c7f56cc4fc60c ] The kernel pushes context on to the userspace stack to prepare for the user's signal handler. When the user has supplied an alternate signal stack, via sigaltstack(2), it is easy for the kernel to verify that the stack size is sufficient for the current hardware context. Check if writing the hardware context to the alternate stack will exceed it's size. If yes, then instead of corrupting user-data and proceeding with the original signal handler, an immediate SIGSEGV signal is delivered. Refactor the stack pointer check code from on_sig_stack() and use the new helper. While the kernel allows new source code to discover and use a sufficient alternate signal stack size, this check is still necessary to protect binaries with insufficient alternate signal stack size from data corruption. Fixes: c2bc11f10a39 ("x86, AVX-512: Enable AVX-512 States Context Switch") Reported-by: Florian Weimer Suggested-by: Jann Horn Suggested-by: Andy Lutomirski Signed-off-by: Chang S. Bae Signed-off-by: Borislav Petkov Reviewed-by: Len Brown Acked-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20210518200320.17239-6-chang.seok.bae@intel.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=153531 Signed-off-by: Sasha Levin