1. 17 May, 2015 16 commits
    • Andre Przywara's avatar
      KVM: arm/arm64: check IRQ number on userland injection · e580744e
      Andre Przywara authored
      [ Upstream commit fd1d0ddf ]
      
      When userland injects a SPI via the KVM_IRQ_LINE ioctl we currently
      only check it against a fixed limit, which historically is set
      to 127. With the new dynamic IRQ allocation the effective limit may
      actually be smaller (64).
      So when now a malicious or buggy userland injects a SPI in that
      range, we spill over on our VGIC bitmaps and bytemaps memory.
      I could trigger a host kernel NULL pointer dereference with current
      mainline by injecting some bogus IRQ number from a hacked kvmtool:
      -----------------
      ....
      DEBUG: kvm_vgic_inject_irq(kvm, cpu=0, irq=114, level=1)
      DEBUG: vgic_update_irq_pending(kvm, cpu=0, irq=114, level=1)
      DEBUG: IRQ #114 still in the game, writing to bytemap now...
      Unable to handle kernel NULL pointer dereference at virtual address 00000000
      pgd = ffffffc07652e000
      [00000000] *pgd=00000000f658b003, *pud=00000000f658b003, *pmd=0000000000000000
      Internal error: Oops: 96000006 [#1] PREEMPT SMP
      Modules linked in:
      CPU: 1 PID: 1053 Comm: lkvm-msi-irqinj Not tainted 4.0.0-rc7+ #3027
      Hardware name: FVP Base (DT)
      task: ffffffc0774e9680 ti: ffffffc0765a8000 task.ti: ffffffc0765a8000
      PC is at kvm_vgic_inject_irq+0x234/0x310
      LR is at kvm_vgic_inject_irq+0x30c/0x310
      pc : [<ffffffc0000ae0a8>] lr : [<ffffffc0000ae180>] pstate: 80000145
      .....
      
      So this patch fixes this by checking the SPI number against the
      actual limit. Also we remove the former legacy hard limit of
      127 in the ioctl code.
      Signed-off-by: default avatarAndre Przywara <andre.przywara@arm.com>
      Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
      CC: <stable@vger.kernel.org> # 4.0, 3.19, 3.18
      [maz: wrap KVM_ARM_IRQ_GIC_MAX with #ifndef __KERNEL__,
      as suggested by Christopher Covington]
      Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      e580744e
    • Radim Krčmář's avatar
      KVM: use slowpath for cross page cached accesses · 35e13292
      Radim Krčmář authored
      [ Upstream commit ca3f0874 ]
      
      kvm_write_guest_cached() does not mark all written pages as dirty and
      code comments in kvm_gfn_to_hva_cache_init() talk about NULL memslot
      with cross page accesses.  Fix all the easy way.
      
      The check is '<= 1' to have the same result for 'len = 0' cache anywhere
      in the page.  (nr_pages_needed is 0 on page boundary.)
      
      Fixes: 8f964525 ("KVM: Allow cross page reads and writes from cached translations.")
      Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
      Message-Id: <20150408121648.GA3519@potion.brq.redhat.com>
      Reviewed-by: default avatarWanpeng Li <wanpeng.li@linux.intel.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      35e13292
    • Heiko Carstens's avatar
      s390/hibernate: fix save and restore of kernel text section · 23786453
      Heiko Carstens authored
      [ Upstream commit d7441949 ]
      
      Sebastian reported a crash caused by a jump label mismatch after resume.
      This happens because we do not save the kernel text section during suspend
      and therefore also do not restore it during resume, but use the kernel image
      that restores the old system.
      
      This means that after a suspend/resume cycle we lost all modifications done
      to the kernel text section.
      The reason for this is the pfn_is_nosave() function, which incorrectly
      returns that read-only pages don't need to be saved. This is incorrect since
      we mark the kernel text section read-only.
      We still need to make sure to not save and restore pages contained within
      NSS and DCSS segment.
      To fix this add an extra case for the kernel text section and only save
      those pages if they are not contained within an NSS segment.
      
      Fixes the following crash (and the above bugs as well):
      
      Jump label code mismatch at netif_receive_skb_internal+0x28/0xd0
      Found:    c0 04 00 00 00 00
      Expected: c0 f4 00 00 00 11
      New:      c0 04 00 00 00 00
      Kernel panic - not syncing: Corrupted kernel text
      CPU: 0 PID: 9 Comm: migration/0 Not tainted 3.19.0-01975-gb1b096e70f23 #4
      Call Trace:
        [<0000000000113972>] show_stack+0x72/0xf0
        [<000000000081f15e>] dump_stack+0x6e/0x90
        [<000000000081c4e8>] panic+0x108/0x2b0
        [<000000000081be64>] jump_label_bug.isra.2+0x104/0x108
        [<0000000000112176>] __jump_label_transform+0x9e/0xd0
        [<00000000001121e6>] __sm_arch_jump_label_transform+0x3e/0x50
        [<00000000001d1136>] multi_cpu_stop+0x12e/0x170
        [<00000000001d1472>] cpu_stopper_thread+0xb2/0x168
        [<000000000015d2ac>] smpboot_thread_fn+0x134/0x1b0
        [<0000000000158baa>] kthread+0x10a/0x110
        [<0000000000824a86>] kernel_thread_starter+0x6/0xc
      Reported-and-tested-by: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      23786453
    • Jens Freimann's avatar
      KVM: s390: fix get_all_floating_irqs · 00d83726
      Jens Freimann authored
      [ Upstream commit 94aa033e ]
      
      This fixes a bug introduced with commit c05c4186 ("KVM: s390:
      add floating irq controller").
      
      get_all_floating_irqs() does copy_to_user() while holding
      a spin lock. Let's fix this by filling a temporary buffer
      first and copy it to userspace after giving up the lock.
      
      Cc: <stable@vger.kernel.org> # 3.18+: 69a8d456 KVM: s390: no need to hold...
      Reviewed-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
      Signed-off-by: default avatarJens Freimann <jfrei@linux.vnet.ibm.com>
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Acked-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      00d83726
    • Christian Borntraeger's avatar
      KVM: s390: no need to hold the kvm->mutex for floating interrupts · 7e15bc0e
      Christian Borntraeger authored
      [ Upstream commit 69a8d456 ]
      
      The kvm mutex was (probably) used to protect against cpu hotplug.
      The current code no longer needs to protect against that, as we only
      rely on CPU data structures that are guaranteed to be available
      if we can access the CPU. (e.g. vcpu_create will put the cpu
      in the array AFTER the cpu is ready).
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Acked-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
      Reviewed-by: default avatarJens Freimann <jfrei@linux.vnet.ibm.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      7e15bc0e
    • Ekaterina Tumanova's avatar
      KVM: s390: Zero out current VMDB of STSI before including level3 data. · abd80ecb
      Ekaterina Tumanova authored
      [ Upstream commit b75f4c9a ]
      
      s390 documentation requires words 0 and 10-15 to be reserved and stored as
      zeros. As we fill out all other fields, we can memset the full structure.
      Signed-off-by: default avatarEkaterina Tumanova <tumanova@linux.vnet.ibm.com>
      Cc: stable@vger.kernel.org
      Reviewed-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      abd80ecb
    • David Hildenbrand's avatar
      KVM: s390: reinjection of irqs can fail in the tpi handler · b7c23d30
      David Hildenbrand authored
      [ Upstream commit 15462e37 ]
      
      The reinjection of an I/O interrupt can fail if the list is at the limit
      and between the dequeue and the reinjection, another I/O interrupt is
      injected (e.g. if user space floods kvm with I/O interrupts).
      
      This patch avoids this memory leak and returns -EFAULT in this special
      case. This error is not recoverable, so let's fail hard. This can later
      be avoided by not dequeuing the interrupt but working directly on the
      locked list.
      Signed-off-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
      Cc: stable@vger.kernel.org # 3.16+
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      b7c23d30
    • David Hildenbrand's avatar
      KVM: s390: fix handling of write errors in the tpi handler · 19881aff
      David Hildenbrand authored
      [ Upstream commit 261520dc ]
      
      If the I/O interrupt could not be written to the guest provided
      area (e.g. access exception), a program exception was injected into the
      guest but "inti" wasn't freed, therefore resulting in a memory leak.
      
      In addition, the I/O interrupt wasn't reinjected. Therefore the dequeued
      interrupt is lost.
      
      This patch fixes the problem while cleaning up the function and making the
      cc and rc logic easier to handle.
      Signed-off-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
      Cc: stable@vger.kernel.org # 3.16+
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      19881aff
    • Andrzej Pietrasiewicz's avatar
      usb: gadget: printer: enqueue printer's response for setup request · 67c5b95c
      Andrzej Pietrasiewicz authored
      [ Upstream commit eb132ccb ]
      
      Function-specific setup requests should be handled in such a way, that
      apart from filling in the data buffer, the requests are also actually
      enqueued: if function-specific setup is called from composte_setup(),
      the "usb_ep_queue()" block of code in composite_setup() is skipped.
      
      The printer function lacks this part and it results in e.g. get device id
      requests failing: the host expects some response, the device prepares it
      but does not equeue it for sending to the host, so the host finally asserts
      timeout.
      
      This patch adds enqueueing the prepared responses.
      
      Cc: <stable@vger.kernel.org> # v3.4+
      Fixes: 2e87edf4: "usb: gadget: make g_printer use composite"
      Signed-off-by: default avatarAndrzej Pietrasiewicz <andrzej.p@samsung.com>
      Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      67c5b95c
    • Filipe Manana's avatar
      Btrfs: fix inode eviction infinite loop after extent_same ioctl · 43e8149d
      Filipe Manana authored
      [ Upstream commit HEAD ]
      
      commit 113e8283 upstream.
      
      If we pass a length of 0 to the extent_same ioctl, we end up locking an
      extent range with a start offset greater then its end offset (if the
      destination file's offset is greater than zero). This results in a warning
      from extent_io.c:insert_state through the following call chain:
      
        btrfs_extent_same()
          btrfs_double_lock()
            lock_extent_range()
              lock_extent(inode->io_tree, offset, offset + len - 1)
                lock_extent_bits()
                  __set_extent_bit()
                    insert_state()
                      --> WARN_ON(end < start)
      
      This leads to an infinite loop when evicting the inode. This is the same
      problem that my previous patch titled
      "Btrfs: fix inode eviction infinite loop after cloning into it" addressed
      but for the extent_same ioctl instead of the clone ioctl.
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      Reviewed-by: default avatarOmar Sandoval <osandov@osandov.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      
      (cherry picked from commit 9dc10661)
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      43e8149d
    • Filipe Manana's avatar
      Btrfs: fix inode eviction infinite loop after cloning into it · d5454242
      Filipe Manana authored
      [ Upstream commit HEAD ]
      
      commit ccccf3d6 upstream.
      
      If we attempt to clone a 0 length region into a file we can end up
      inserting a range in the inode's extent_io tree with a start offset
      that is greater then the end offset, which triggers immediately the
      following warning:
      
      [ 3914.619057] WARNING: CPU: 17 PID: 4199 at fs/btrfs/extent_io.c:435 insert_state+0x4b/0x10b [btrfs]()
      [ 3914.620886] BTRFS: end < start 4095 4096
      (...)
      [ 3914.638093] Call Trace:
      [ 3914.638636]  [<ffffffff81425fd9>] dump_stack+0x4c/0x65
      [ 3914.639620]  [<ffffffff81045390>] warn_slowpath_common+0xa1/0xbb
      [ 3914.640789]  [<ffffffffa03ca44f>] ? insert_state+0x4b/0x10b [btrfs]
      [ 3914.642041]  [<ffffffff810453f0>] warn_slowpath_fmt+0x46/0x48
      [ 3914.643236]  [<ffffffffa03ca44f>] insert_state+0x4b/0x10b [btrfs]
      [ 3914.644441]  [<ffffffffa03ca729>] __set_extent_bit+0x107/0x3f4 [btrfs]
      [ 3914.645711]  [<ffffffffa03cb256>] lock_extent_bits+0x65/0x1bf [btrfs]
      [ 3914.646914]  [<ffffffff8142b2fb>] ? _raw_spin_unlock+0x28/0x33
      [ 3914.648058]  [<ffffffffa03cbac4>] ? test_range_bit+0xcc/0xde [btrfs]
      [ 3914.650105]  [<ffffffffa03cb3c3>] lock_extent+0x13/0x15 [btrfs]
      [ 3914.651361]  [<ffffffffa03db39e>] lock_extent_range+0x3d/0xcd [btrfs]
      [ 3914.652761]  [<ffffffffa03de1fe>] btrfs_ioctl_clone+0x278/0x388 [btrfs]
      [ 3914.654128]  [<ffffffff811226dd>] ? might_fault+0x58/0xb5
      [ 3914.655320]  [<ffffffffa03e0909>] btrfs_ioctl+0xb51/0x2195 [btrfs]
      (...)
      [ 3914.669271] ---[ end trace 14843d3e2e622fc1 ]---
      
      This later makes the inode eviction handler enter an infinite loop that
      keeps dumping the following warning over and over:
      
      [ 3915.117629] WARNING: CPU: 22 PID: 4228 at fs/btrfs/extent_io.c:435 insert_state+0x4b/0x10b [btrfs]()
      [ 3915.119913] BTRFS: end < start 4095 4096
      (...)
      [ 3915.137394] Call Trace:
      [ 3915.137913]  [<ffffffff81425fd9>] dump_stack+0x4c/0x65
      [ 3915.139154]  [<ffffffff81045390>] warn_slowpath_common+0xa1/0xbb
      [ 3915.140316]  [<ffffffffa03ca44f>] ? insert_state+0x4b/0x10b [btrfs]
      [ 3915.141505]  [<ffffffff810453f0>] warn_slowpath_fmt+0x46/0x48
      [ 3915.142709]  [<ffffffffa03ca44f>] insert_state+0x4b/0x10b [btrfs]
      [ 3915.143849]  [<ffffffffa03ca729>] __set_extent_bit+0x107/0x3f4 [btrfs]
      [ 3915.145120]  [<ffffffffa038c1e3>] ? btrfs_kill_super+0x17/0x23 [btrfs]
      [ 3915.146352]  [<ffffffff811548f6>] ? deactivate_locked_super+0x3b/0x50
      [ 3915.147565]  [<ffffffffa03cb256>] lock_extent_bits+0x65/0x1bf [btrfs]
      [ 3915.148785]  [<ffffffff8142b7e2>] ? _raw_write_unlock+0x28/0x33
      [ 3915.149931]  [<ffffffffa03bc325>] btrfs_evict_inode+0x196/0x482 [btrfs]
      [ 3915.151154]  [<ffffffff81168904>] evict+0xa0/0x148
      [ 3915.152094]  [<ffffffff811689e5>] dispose_list+0x39/0x43
      [ 3915.153081]  [<ffffffff81169564>] evict_inodes+0xdc/0xeb
      [ 3915.154062]  [<ffffffff81154418>] generic_shutdown_super+0x49/0xef
      [ 3915.155193]  [<ffffffff811546d1>] kill_anon_super+0x13/0x1e
      [ 3915.156274]  [<ffffffffa038c1e3>] btrfs_kill_super+0x17/0x23 [btrfs]
      (...)
      [ 3915.167404] ---[ end trace 14843d3e2e622fc2 ]---
      
      So just bail out of the clone ioctl if the length of the region to clone
      is zero, without locking any extent range, in order to prevent this issue
      (same behaviour as a pwrite with a 0 length for example).
      
      This is trivial to reproduce. For example, the steps for the test I just
      made for fstests:
      
        mkfs.btrfs -f SCRATCH_DEV
        mount SCRATCH_DEV $SCRATCH_MNT
      
        touch $SCRATCH_MNT/foo
        touch $SCRATCH_MNT/bar
      
        $CLONER_PROG -s 0 -d 4096 -l 0 $SCRATCH_MNT/foo $SCRATCH_MNT/bar
        umount $SCRATCH_MNT
      
      A test case for fstests follows soon.
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      Reviewed-by: default avatarOmar Sandoval <osandov@osandov.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      
      (cherry picked from commit 449b4627)
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      d5454242
    • David Sterba's avatar
      btrfs: don't accept bare namespace as a valid xattr · 5728a924
      David Sterba authored
      [ Upstream commit HEAD ]
      
      commit 3c3b04d1 upstream.
      
      Due to insufficient check in btrfs_is_valid_xattr, this unexpectedly
      works:
      
       $ touch file
       $ setfattr -n user. -v 1 file
       $ getfattr -d file
      user.="1"
      
      ie. the missing attribute name after the namespace.
      
      Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=94291Reported-by: default avatarWilliam Douglas <william.douglas@intel.com>
      Signed-off-by: default avatarDavid Sterba <dsterba@suse.cz>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      
      (cherry picked from commit 1bb2835e)
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      5728a924
    • Filipe Manana's avatar
      Btrfs: fix log tree corruption when fs mounted with -o discard · 372b2ac5
      Filipe Manana authored
      [ Upstream commit HEAD ]
      
      commit dcc82f47 upstream.
      
      While committing a transaction we free the log roots before we write the
      new super block. Freeing the log roots implies marking the disk location
      of every node/leaf (metadata extent) as pinned before the new super block
      is written. This is to prevent the disk location of log metadata extents
      from being reused before the new super block is written, otherwise we
      would have a corrupted log tree if before the new super block is written
      a crash/reboot happens and the location of any log tree metadata extent
      ended up being reused and rewritten.
      
      Even though we pinned the log tree's metadata extents, we were issuing a
      discard against them if the fs was mounted with the -o discard option,
      resulting in corruption of the log tree if a crash/reboot happened before
      writing the new super block - the next time the fs was mounted, during
      the log replay process we would find nodes/leafs of the log btree with
      a content full of zeroes, causing the process to fail and require the
      use of the tool btrfs-zero-log to wipeout the log tree (and all data
      previously fsynced becoming lost forever).
      
      Fix this by not doing a discard when pinning an extent. The discard will
      be done later when it's safe (after the new super block is committed) at
      extent-tree.c:btrfs_finish_extent_commit().
      
      Fixes: e688b725 (Btrfs: fix extent pinning bugs in the tree log)
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      
      (cherry picked from commit 3909e5a9)
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      372b2ac5
    • Nadav Amit's avatar
      KVM: x86: Fix MSR_IA32_BNDCFGS in msrs_to_save · 753fd54a
      Nadav Amit authored
      [ Upstream commit HEAD ]
      
      commit 9e9c3fe4 upstream.
      
      kvm_init_msr_list is currently called before hardware_setup. As a result,
      vmx_mpx_supported always returns false when kvm_init_msr_list checks whether to
      save MSR_IA32_BNDCFGS.
      
      Move kvm_init_msr_list after vmx_hardware_setup is called to fix this issue.
      Signed-off-by: default avatarNadav Amit <namit@cs.technion.ac.il>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      
      Message-Id: <1428864435-4732-1-git-send-email-namit@cs.technion.ac.il>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      
      (cherry picked from commit 702a71cf)
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      753fd54a
    • Mike Galbraith's avatar
      sched/idle/x86: Optimize unnecessary mwait_idle() resched IPIs · 6cbb41b1
      Mike Galbraith authored
      [ Upstream commit f8e617f4 ]
      
      To fully take advantage of MWAIT, apparently the CLFLUSH instruction needs
      another quirk on certain CPUs: proper barriers around it on certain machines.
      
      On a Q6600 SMP system, pipe-test scheduling performance, cross core,
      improves significantly:
      
        3.8.13                   487.2 KHz    1.000
        3.13.0-master            415.5 KHz     .852
        3.13.0-master+           415.2 KHz     .852     + restore mwait_idle
        3.13.0-master++          488.5 KHz    1.002     + restore mwait_idle + IPI fix
      
      Since X86_BUG_CLFLUSH_MONITOR is already a quirk, don't create a separate
      quirk for the extra smp_mb()s.
      Signed-off-by: default avatarMike Galbraith <bitbucket@online.de>
      Cc: <stable@vger.kernel.org> # 3.10+
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Ian Malone <ibmalone@gmail.com>
      Cc: Josh Boyer <jwboyer@redhat.com>
      Cc: Len Brown <len.brown@intel.com>
      Cc: Len Brown <lenb@kernel.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mike Galbraith <efault@gmx.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/1390061684.5566.4.camel@marge.simpson.net
      [ Ported to recent kernel, added comments about the quirk. ]
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      6cbb41b1
    • Len Brown's avatar
      sched/idle/x86: Restore mwait_idle() to fix boot hangs, to improve power... · 560e6448
      Len Brown authored
      sched/idle/x86: Restore mwait_idle() to fix boot hangs, to improve power savings and to improve performance
      
      [ Upstream commit b253149b ]
      
      In Linux-3.9 we removed the mwait_idle() loop:
      
        69fb3676 ("x86 idle: remove mwait_idle() and "idle=mwait" cmdline param")
      
      The reasoning was that modern machines should be sufficiently
      happy during the boot process using the default_idle() HALT
      loop, until cpuidle loads and either acpi_idle or intel_idle
      invoke the newer MWAIT-with-hints idle loop.
      
      But two machines reported problems:
      
       1. Certain Core2-era machines support MWAIT-C1 and HALT only.
          MWAIT-C1 is preferred for optimal power and performance.
          But if they support just C1, cpuidle never loads and
          so they use the boot-time default idle loop forever.
      
       2. Some laptops will boot-hang if HALT is used,
          but will boot successfully if MWAIT is used.
          This appears to be a hidden assumption in BIOS SMI,
          that is presumably valid on the proprietary OS
          where the BIOS was validated.
      
             https://bugzilla.kernel.org/show_bug.cgi?id=60770
      
      So here we effectively revert the patch above, restoring
      the mwait_idle() loop.  However, we don't bother restoring
      the idle=mwait cmdline parameter, since it appears to add
      no value.
      
      Maintainer notes:
      
        For 3.9, simply revert 69fb3676
        for 3.10, patch -F3 applies, fuzz needed due to __cpuinit use in
        context For 3.11, 3.12, 3.13, this patch applies cleanly
      Tested-by: default avatarMike Galbraith <bitbucket@online.de>
      Signed-off-by: default avatarLen Brown <len.brown@intel.com>
      Acked-by: default avatarMike Galbraith <bitbucket@online.de>
      Cc: <stable@vger.kernel.org> # 3.9+
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Ian Malone <ibmalone@gmail.com>
      Cc: Josh Boyer <jwboyer@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mike Galbraith <efault@gmx.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/345254a551eb5a6a866e048d7ab570fd2193aca4.1389763084.git.len.brown@intel.com
      [ Ported to recent kernels. ]
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      560e6448
  2. 11 May, 2015 24 commits