1. 29 8月, 2019 1 次提交
    • T
      x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h · e063b03b
      Tom Lendacky 提交于
      commit c49a0a80137c7ca7d6ced4c812c9e07a949f6f24 upstream.
      
      There have been reports of RDRAND issues after resuming from suspend on
      some AMD family 15h and family 16h systems. This issue stems from a BIOS
      not performing the proper steps during resume to ensure RDRAND continues
      to function properly.
      
      RDRAND support is indicated by CPUID Fn00000001_ECX[30]. This bit can be
      reset by clearing MSR C001_1004[62]. Any software that checks for RDRAND
      support using CPUID, including the kernel, will believe that RDRAND is
      not supported.
      
      Update the CPU initialization to clear the RDRAND CPUID bit for any family
      15h and 16h processor that supports RDRAND. If it is known that the family
      15h or family 16h system does not have an RDRAND resume issue or that the
      system will not be placed in suspend, the "rdrand=force" kernel parameter
      can be used to stop the clearing of the RDRAND CPUID bit.
      
      Additionally, update the suspend and resume path to save and restore the
      MSR C001_1004 value to ensure that the RDRAND CPUID setting remains in
      place after resuming from suspend.
      
      Note, that clearing the RDRAND CPUID bit does not prevent a processor
      that normally supports the RDRAND instruction from executing it. So any
      code that determined the support based on family and model won't #UD.
      Signed-off-by: NTom Lendacky <thomas.lendacky@amd.com>
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Cc: Andrew Cooper <andrew.cooper3@citrix.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Chen Yu <yu.c.chen@intel.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>
      Cc: "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>
      Cc: Nathan Chancellor <natechancellor@gmail.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Pavel Machek <pavel@ucw.cz>
      Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
      Cc: <stable@vger.kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "x86@kernel.org" <x86@kernel.org>
      Link: https://lkml.kernel.org/r/7543af91666f491547bd86cebb1e17c66824ab9f.1566229943.git.thomas.lendacky@amd.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e063b03b
  2. 22 6月, 2019 1 次提交
    • F
      x86/CPU/AMD: Don't force the CPB cap when running under a hypervisor · a35e7822
      Frank van der Linden 提交于
      [ Upstream commit 2ac44ab608705948564791ce1d15d43ba81a1e38 ]
      
      For F17h AMD CPUs, the CPB capability ('Core Performance Boost') is forcibly set,
      because some versions of that chip incorrectly report that they do not have it.
      
      However, a hypervisor may filter out the CPB capability, for good
      reasons. For example, KVM currently does not emulate setting the CPB
      bit in MSR_K7_HWCR, and unchecked MSR access errors will be thrown
      when trying to set it as a guest:
      
      	unchecked MSR access error: WRMSR to 0xc0010015 (tried to write 0x0000000001000011) at rIP: 0xffffffff890638f4 (native_write_msr+0x4/0x20)
      
      	Call Trace:
      	boost_set_msr+0x50/0x80 [acpi_cpufreq]
      	cpuhp_invoke_callback+0x86/0x560
      	sort_range+0x20/0x20
      	cpuhp_thread_fun+0xb0/0x110
      	smpboot_thread_fn+0xef/0x160
      	kthread+0x113/0x130
      	kthread_create_worker_on_cpu+0x70/0x70
      	ret_from_fork+0x35/0x40
      
      To avoid this issue, don't forcibly set the CPB capability for a CPU
      when running under a hypervisor.
      Signed-off-by: NFrank van der Linden <fllinden@amazon.com>
      Acked-by: NBorislav Petkov <bp@suse.de>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: bp@alien8.de
      Cc: jiaxun.yang@flygoat.com
      Fixes: 0237199186e7 ("x86/CPU/AMD: Set the CPB bit unconditionally on F17h")
      Link: http://lkml.kernel.org/r/20190522221745.GA15789@dev-dsk-fllinden-2c-c1893d73.us-west-2.amazon.com
      [ Minor edits to the changelog. ]
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      Signed-off-by: NSasha Levin <sashal@kernel.org>
      a35e7822
  3. 10 3月, 2019 1 次提交
  4. 03 10月, 2018 1 次提交
  5. 20 7月, 2018 1 次提交
    • P
      x86/jump_label: Initialize static branching early · 8990cac6
      Pavel Tatashin 提交于
      Static branching is useful to runtime patch branches that are used in hot
      path, but are infrequently changed.
      
      The x86 clock framework is one example that uses static branches to setup
      the best clock during boot and never changes it again.
      
      It is desired to enable the TSC based sched clock early to allow fine
      grained boot time analysis early on. That requires the static branching
      functionality to be functional early as well.
      
      Static branching requires patching nop instructions, thus,
      arch_init_ideal_nops() must be called prior to jump_label_init().
      
      Do all the necessary steps to call arch_init_ideal_nops() right after
      early_cpu_init(), which also allows to insert a call to jump_label_init()
      right after that. jump_label_init() will be called again from the generic
      init code, but the code is protected against reinitialization already.
      
      [ tglx: Massaged changelog ]
      Suggested-by: NPeter Zijlstra <peterz@infradead.org>
      Signed-off-by: NPavel Tatashin <pasha.tatashin@oracle.com>
      Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: NBorislav Petkov <bp@suse.de>
      Cc: steven.sistare@oracle.com
      Cc: daniel.m.jordan@oracle.com
      Cc: linux@armlinux.org.uk
      Cc: schwidefsky@de.ibm.com
      Cc: heiko.carstens@de.ibm.com
      Cc: john.stultz@linaro.org
      Cc: sboyd@codeaurora.org
      Cc: hpa@zytor.com
      Cc: douly.fnst@cn.fujitsu.com
      Cc: prarit@redhat.com
      Cc: feng.tang@intel.com
      Cc: pmladek@suse.com
      Cc: gnomes@lxorguk.ukuu.org.uk
      Cc: linux-s390@vger.kernel.org
      Cc: boris.ostrovsky@oracle.com
      Cc: jgross@suse.com
      Cc: pbonzini@redhat.com
      Link: https://lkml.kernel.org/r/20180719205545.16512-10-pasha.tatashin@oracle.com
      8990cac6
  6. 03 7月, 2018 1 次提交
  7. 22 6月, 2018 1 次提交
  8. 21 6月, 2018 3 次提交
  9. 17 5月, 2018 2 次提交
  10. 10 5月, 2018 1 次提交
    • K
      x86/bugs: Rename _RDS to _SSBD · 9f65fb29
      Konrad Rzeszutek Wilk 提交于
      Intel collateral will reference the SSB mitigation bit in IA32_SPEC_CTL[2]
      as SSBD (Speculative Store Bypass Disable).
      
      Hence changing it.
      
      It is unclear yet what the MSR_IA32_ARCH_CAPABILITIES (0x10a) Bit(4) name
      is going to be. Following the rename it would be SSBD_NO but that rolls out
      to Speculative Store Bypass Disable No.
      
      Also fixed the missing space in X86_FEATURE_AMD_SSBD.
      
      [ tglx: Fixup x86_amd_rds_enable() and rds_tif_to_amd_ls_cfg() as well ]
      Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      9f65fb29
  11. 06 5月, 2018 3 次提交
  12. 03 5月, 2018 2 次提交
  13. 08 3月, 2018 1 次提交
  14. 15 2月, 2018 1 次提交
  15. 09 1月, 2018 2 次提交
  16. 17 12月, 2017 1 次提交
  17. 06 12月, 2017 1 次提交
  18. 05 12月, 2017 1 次提交
    • T
      x86/CPU/AMD: Add the Secure Encrypted Virtualization CPU feature · 18c71ce9
      Tom Lendacky 提交于
      Update the CPU features to include identifying and reporting on the
      Secure Encrypted Virtualization (SEV) feature.  SEV is identified by
      CPUID 0x8000001f, but requires BIOS support to enable it (set bit 23 of
      MSR_K8_SYSCFG and set bit 0 of MSR_K7_HWCR).  Only show the SEV feature
      as available if reported by CPUID and enabled by BIOS.
      
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: "Radim Krčmář" <rkrcmar@redhat.com>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: kvm@vger.kernel.org
      Cc: x86@kernel.org
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NTom Lendacky <thomas.lendacky@amd.com>
      Signed-off-by: NBrijesh Singh <brijesh.singh@amd.com>
      Reviewed-by: NBorislav Petkov <bp@suse.de>
      18c71ce9
  19. 15 9月, 2017 1 次提交
  20. 11 8月, 2017 1 次提交
  21. 10 8月, 2017 1 次提交
    • S
      x86/cpu/amd: Limit cpu_core_id fixup to families older than F17h · b89b41d0
      Suravee Suthikulpanit 提交于
      Current cpu_core_id fixup causes downcored F17h configurations to be
      incorrect:
      
        NODE: 0
        processor  0 core id : 0
        processor  1 core id : 1
        processor  2 core id : 2
        processor  3 core id : 4
        processor  4 core id : 5
        processor  5 core id : 0
      
        NODE: 1
        processor  6 core id : 2
        processor  7 core id : 3
        processor  8 core id : 4
        processor  9 core id : 0
        processor 10 core id : 1
        processor 11 core id : 2
      
      Code that relies on the cpu_core_id, like match_smt(), for example,
      which builds the thread siblings masks used by the scheduler, is
      mislead.
      
      So, limit the fixup to pre-F17h machines. The new value for cpu_core_id
      for F17h and later will represent the CPUID_Fn8000001E_EBX[CoreId],
      which is guaranteed to be unique for each core within a socket.
      
      This way we have:
      
        NODE: 0
        processor  0 core id : 0
        processor  1 core id : 1
        processor  2 core id : 2
        processor  3 core id : 4
        processor  4 core id : 5
        processor  5 core id : 6
      
        NODE: 1
        processor  6 core id : 8
        processor  7 core id : 9
        processor  8 core id : 10
        processor  9 core id : 12
        processor 10 core id : 13
        processor 11 core id : 14
      Signed-off-by: NSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>
      [ Heavily massaged. ]
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Yazen Ghannam <Yazen.Ghannam@amd.com>
      Link: http://lkml.kernel.org/r/20170731085159.9455-2-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      b89b41d0
  22. 18 7月, 2017 3 次提交
    • T
      x86/cpu/AMD: Make the microcode level available earlier in the boot · f655e6e6
      Tom Lendacky 提交于
      Move the setting of the cpuinfo_x86.microcode field from amd_init() to
      early_amd_init() so that it is available earlier in the boot process. This
      avoids having to read MSR_AMD64_PATCH_LEVEL directly during early boot.
      Signed-off-by: NTom Lendacky <thomas.lendacky@amd.com>
      Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: NBorislav Petkov <bp@suse.de>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brijesh Singh <brijesh.singh@amd.com>
      Cc: Dave Young <dyoung@redhat.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Cc: Larry Woodman <lwoodman@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Matt Fleming <matt@codeblueprint.co.uk>
      Cc: Michael S. Tsirkin <mst@redhat.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Toshimitsu Kani <toshi.kani@hpe.com>
      Cc: kasan-dev@googlegroups.com
      Cc: kvm@vger.kernel.org
      Cc: linux-arch@vger.kernel.org
      Cc: linux-doc@vger.kernel.org
      Cc: linux-efi@vger.kernel.org
      Cc: linux-mm@kvack.org
      Link: http://lkml.kernel.org/r/7b7525fa12593dac5f4b01fcc25c95f97e93862f.1500319216.git.thomas.lendacky@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f655e6e6
    • T
      x86/cpu/AMD: Handle SME reduction in physical address size · 9af9b940
      Tom Lendacky 提交于
      When System Memory Encryption (SME) is enabled, the physical address
      space is reduced. Adjust the x86_phys_bits value to reflect this
      reduction.
      Signed-off-by: NTom Lendacky <thomas.lendacky@amd.com>
      Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: NBorislav Petkov <bp@suse.de>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brijesh Singh <brijesh.singh@amd.com>
      Cc: Dave Young <dyoung@redhat.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Cc: Larry Woodman <lwoodman@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Matt Fleming <matt@codeblueprint.co.uk>
      Cc: Michael S. Tsirkin <mst@redhat.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Toshimitsu Kani <toshi.kani@hpe.com>
      Cc: kasan-dev@googlegroups.com
      Cc: kvm@vger.kernel.org
      Cc: linux-arch@vger.kernel.org
      Cc: linux-doc@vger.kernel.org
      Cc: linux-efi@vger.kernel.org
      Cc: linux-mm@kvack.org
      Link: http://lkml.kernel.org/r/593c037a3cad85ba92f3d061ffa7462e9ce3531d.1500319216.git.thomas.lendacky@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      9af9b940
    • T
      x86/cpu/AMD: Add the Secure Memory Encryption CPU feature · 872cbefd
      Tom Lendacky 提交于
      Update the CPU features to include identifying and reporting on the
      Secure Memory Encryption (SME) feature.  SME is identified by CPUID
      0x8000001f, but requires BIOS support to enable it (set bit 23 of
      MSR_K8_SYSCFG).  Only show the SME feature as available if reported by
      CPUID, enabled by BIOS and not configured as CONFIG_X86_32=y.
      Signed-off-by: NTom Lendacky <thomas.lendacky@amd.com>
      Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brijesh Singh <brijesh.singh@amd.com>
      Cc: Dave Young <dyoung@redhat.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Cc: Larry Woodman <lwoodman@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Matt Fleming <matt@codeblueprint.co.uk>
      Cc: Michael S. Tsirkin <mst@redhat.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Toshimitsu Kani <toshi.kani@hpe.com>
      Cc: kasan-dev@googlegroups.com
      Cc: kvm@vger.kernel.org
      Cc: linux-arch@vger.kernel.org
      Cc: linux-doc@vger.kernel.org
      Cc: linux-efi@vger.kernel.org
      Cc: linux-mm@kvack.org
      Link: http://lkml.kernel.org/r/85c17ff450721abccddc95e611ae8df3f4d9718b.1500319216.git.thomas.lendacky@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      872cbefd
  23. 16 7月, 2017 1 次提交
  24. 11 5月, 2017 1 次提交
  25. 09 5月, 2017 1 次提交
  26. 02 3月, 2017 2 次提交
    • P
      sched/clock, x86/tsc: Rework the x86 'unstable' sched_clock() interface · f94c8d11
      Peter Zijlstra 提交于
      Wanpeng Li reported that since the following commit:
      
        acb04058 ("sched/clock: Fix hotplug crash")
      
      ... KVM always runs with unstable sched-clock even though KVM's
      kvm_clock _is_ stable.
      
      The problem is that we've tied clear_sched_clock_stable() to the TSC
      state, and overlooked that sched_clock() is a paravirt function.
      
      Solve this by doing two things:
      
       - tie the sched_clock() stable state more clearly to the TSC stable
         state for the normal (!paravirt) case.
      
       - only call clear_sched_clock_stable() when we mark TSC unstable
         when we use native_sched_clock().
      
      The first means we can actually run with stable sched_clock in more
      situations then before, which is good. And since commit:
      
        12907fbb ("sched/clock, clocksource: Add optional cs::mark_unstable() method")
      
      ... this should be reliable. Since any detection of TSC fail now results
      in marking the TSC unstable.
      Reported-by: NWanpeng Li <kernellwp@gmail.com>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mike Galbraith <efault@gmx.de>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Fixes: acb04058 ("sched/clock: Fix hotplug crash")
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      f94c8d11
    • I
      sched/headers: Prepare for new header dependencies before moving code to <linux/sched/clock.h> · e6017571
      Ingo Molnar 提交于
      We are going to split <linux/sched/clock.h> out of <linux/sched.h>, which
      will have to be picked up from other headers and .c files.
      
      Create a trivial placeholder <linux/sched/clock.h> file that just
      maps to <linux/sched.h> to make this patch obviously correct and
      bisectable.
      
      Include the new header in the files that are going to need it.
      Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
      Cc: Mike Galbraith <efault@gmx.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      e6017571
  27. 05 2月, 2017 2 次提交
    • Y
      x86/CPU/AMD: Fix Zen SMT topology · 08b25963
      Yazen Ghannam 提交于
      After:
      
        a33d3317 ("x86/CPU/AMD: Fix Bulldozer topology")
      
      our  SMT scheduling topology for Fam17h systems is broken, because
      the ThreadId is included in the ApicId when SMT is enabled.
      
      So, without further decoding cpu_core_id is unique for each thread
      rather than the same for threads on the same core. This didn't affect
      systems with SMT disabled. Make cpu_core_id be what it is defined to be.
      Signed-off-by: NYazen Ghannam <Yazen.Ghannam@amd.com>
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Cc: <stable@vger.kernel.org> # 4.9
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/20170205105022.8705-2-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      08b25963
    • B
      x86/CPU/AMD: Bring back Compute Unit ID · 79a8b9aa
      Borislav Petkov 提交于
      Commit:
      
        a33d3317 ("x86/CPU/AMD: Fix Bulldozer topology")
      
      restored the initial approach we had with the Fam15h topology of
      enumerating CU (Compute Unit) threads as cores. And this is still
      correct - they're beefier than HT threads but still have some
      shared functionality.
      
      Our current approach has a problem with the Mad Max Steam game, for
      example. Yves Dionne reported a certain "choppiness" while playing on
      v4.9.5.
      
      That problem stems most likely from the fact that the CU threads share
      resources within one CU and when we schedule to a thread of a different
      compute unit, this incurs latency due to migrating the working set to a
      different CU through the caches.
      
      When the thread siblings mask mirrors that aspect of the CUs and
      threads, the scheduler pays attention to it and tries to schedule within
      one CU first. Which takes care of the latency, of course.
      Reported-by: NYves Dionne <yves.dionne@gmail.com>
      Signed-off-by: NBorislav Petkov <bp@suse.de>
      Cc: <stable@vger.kernel.org> # 4.9
      Cc: Brice Goglin <Brice.Goglin@inria.fr>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Yazen Ghannam <yazen.ghannam@amd.com>
      Link: http://lkml.kernel.org/r/20170205105022.8705-1-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      79a8b9aa
  28. 20 1月, 2017 1 次提交
    • P
      sched/clock: Fix hotplug crash · acb04058
      Peter Zijlstra 提交于
      Mike reported that he could trigger the WARN_ON_ONCE() in
      set_sched_clock_stable() using hotplug.
      
      This exposed a fundamental problem with the interface, we should never
      mark the TSC stable if we ever find it to be unstable. Therefore
      set_sched_clock_stable() is a broken interface.
      
      The reason it existed is that not having it is a pain, it means all
      relevant architecture code needs to call clear_sched_clock_stable()
      where appropriate.
      
      Of the three architectures that select HAVE_UNSTABLE_SCHED_CLOCK ia64
      and parisc are trivial in that they never called
      set_sched_clock_stable(), so add an unconditional call to
      clear_sched_clock_stable() to them.
      
      For x86 the story is a lot more involved, and what this patch tries to
      do is ensure we preserve the status quo. So even is Cyrix or Transmeta
      have usable TSC they never called set_sched_clock_stable() so they now
      get an explicit mark unstable.
      Reported-by: NMike Galbraith <efault@gmx.de>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Fixes: 9881b024 ("sched/clock: Delay switching sched_clock to stable")
      Link: http://lkml.kernel.org/r/20170119133633.GB6536@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
      acb04058
  29. 06 1月, 2017 1 次提交