1. 27 Apr, 2017 9 commits
  2. 26 Apr, 2017 4 commits
  3. 21 Apr, 2017 9 commits
    • Marcelo Tosatti's avatar
      KVM: x86: remove irq disablement around KVM_SET_CLOCK/KVM_GET_CLOCK · e891a32e
      Marcelo Tosatti authored
      The disablement of interrupts at KVM_SET_CLOCK/KVM_GET_CLOCK
      attempts to disable software suspend from causing "non atomic behaviour" of
      the operation:
      
          Add a helper function to compute the kernel time and convert nanoseconds
          back to CPU specific cycles.  Note that these must not be called in preemptible
          context, as that would mean the kernel could enter software suspend state,
          which would cause non-atomic operation.
      
      However, assume the kernel can enter software suspend at the following 2 points:
      
              ktime_get_ts(&ts);
      1.
      						hypothetical_ktime_get_ts(&ts)
              monotonic_to_bootbased(&ts);
      2.
      
      monotonic_to_bootbased() should be correct relative to a ktime_get_ts(&ts)
      performed after point 1 (that is after resuming from software suspend),
      hypothetical_ktime_get_ts()
      
      Therefore it is also correct for the ktime_get_ts(&ts) before point 1,
      which is
      
      	ktime_get_ts(&ts) = hypothetical_ktime_get_ts(&ts) + time-to-execute-suspend-code
      
      Note CLOCK_MONOTONIC does not count during suspension.
      
      So remove the irq disablement, which causes the following warning on
      -RT kernels:
      
       With this reasoning, and the -RT bug that the irq disablement causes
       (because spin_lock is now a sleeping lock), remove the IRQ protection as it
       causes:
      
       [ 1064.668109] in_atomic(): 0, irqs_disabled(): 1, pid: 15296, name:m
       [ 1064.668110] INFO: lockdep is turned off.
       [ 1064.668110] irq event stamp: 0
       [ 1064.668112] hardirqs last  enabled at (0): [<          (null)>]  )
       [ 1064.668116] hardirqs last disabled at (0): [] c0
       [ 1064.668118] softirqs last  enabled at (0): [] c0
       [ 1064.668118] softirqs last disabled at (0): [<          (null)>]  )
       [ 1064.668121] CPU: 13 PID: 15296 Comm: qemu-kvm Not tainted 3.10.0-1
       [ 1064.668121] Hardware name: Dell Inc. PowerEdge R730/0H21J3, BIOS 5
       [ 1064.668123]  ffff8c1796b88000 00000000afe7344c ffff8c179abf3c68 f3
       [ 1064.668125]  ffff8c179abf3c90 ffffffff930ccb3d ffff8c1b992b3610 f0
       [ 1064.668126]  00007ffc1a26fbc0 ffff8c179abf3cb0 ffffffff9375f694 f0
       [ 1064.668126] Call Trace:
       [ 1064.668132]  [] dump_stack+0x19/0x1b
       [ 1064.668135]  [] __might_sleep+0x12d/0x1f0
       [ 1064.668138]  [] rt_spin_lock+0x24/0x60
       [ 1064.668155]  [] __get_kvmclock_ns+0x36/0x110 [k]
       [ 1064.668159]  [] ? futex_wait_queue_me+0x103/0x10
       [ 1064.668171]  [] kvm_arch_vm_ioctl+0xa2/0xd70 [k]
       [ 1064.668173]  [] ? futex_wait+0x1ac/0x2a0
      
      v2: notice get_kvmclock_ns with the same problem (Pankaj).
      v3: remove useless helper function (Pankaj).
      Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e891a32e
    • Michael S. Tsirkin's avatar
      kvm: better MWAIT emulation for guests · 668fffa3
      Michael S. Tsirkin authored
      Guests that are heavy on futexes end up IPI'ing each other a lot. That
      can lead to significant slowdowns and latency increase for those guests
      when running within KVM.
      
      If only a single guest is needed on a host, we have a lot of spare host
      CPU time we can throw at the problem. Modern CPUs implement a feature
      called "MWAIT" which allows guests to wake up sleeping remote CPUs without
      an IPI - thus without an exit - at the expense of never going out of guest
      context.
      
      The decision whether this is something sensible to use should be up to the
      VM admin, so to user space. We can however allow MWAIT execution on systems
      that support it properly hardware wise.
      
      This patch adds a CAP to user space and a KVM cpuid leaf to indicate
      availability of native MWAIT execution. With that enabled, the worst a
      guest can do is waste as many cycles as a "jmp ." would do, so it's not
      a privilege problem.
      
      We consciously do *not* expose the feature in our CPUID bitmap, as most
      people will want to benefit from sleeping vCPUs to allow for over commit.
      Reported-by: default avatar"Gabriel L. Somlo" <gsomlo@gmail.com>
      Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
      [agraf: fix amd, change commit message]
      Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      668fffa3
    • Kyle Huey's avatar
      KVM: x86: virtualize cpuid faulting · db2336a8
      Kyle Huey authored
      Hardware support for faulting on the cpuid instruction is not required to
      emulate it, because cpuid triggers a VM exit anyways. KVM handles the relevant
      MSRs (MSR_PLATFORM_INFO and MSR_MISC_FEATURES_ENABLE) and upon a
      cpuid-induced VM exit checks the cpuid faulting state and the CPL.
      kvm_require_cpl is even kind enough to inject the GP fault for us.
      Signed-off-by: default avatarKyle Huey <khuey@kylehuey.com>
      Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
      [Return "1" from kvm_emulate_cpuid, it's not void. - Paolo]
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      db2336a8
    • Paolo Bonzini's avatar
      Merge tag 'kvm-s390-next-4.12-2' of... · bd17117b
      Paolo Bonzini authored
      Merge tag 'kvm-s390-next-4.12-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD
      
      KVM: s390: Guarded storage fixup and keyless subset mode
      
      - detect and use the keyless subset mode (guests without
        storage keys)
      - fix vSIE support for sdnxc
      - fix machine check data for guarded storage
      bd17117b
    • Paolo Bonzini's avatar
      Merge branch 'kvm-ppc-next' of... · ec594c47
      Paolo Bonzini authored
      Merge branch 'kvm-ppc-next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc into HEAD
      ec594c47
    • Paolo Bonzini's avatar
      Merge branch 'x86/process' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into HEAD · 8afd74c2
      Paolo Bonzini authored
      Required for KVM support of the CPUID faulting feature.
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      8afd74c2
    • David Hildenbrand's avatar
      KVM: VMX: drop vmm_exclusive module parameter · fe0e80be
      David Hildenbrand authored
      vmm_exclusive=0 leads to KVM setting X86_CR4_VMXE always and calling
      VMXON only when the vcpu is loaded. X86_CR4_VMXE is used as an
      indication in cpu_emergency_vmxoff() (called on kdump) if VMXOFF has to be
      called. This is obviously not the case if both are used independtly.
      Calling VMXOFF without a previous VMXON will result in an exception.
      
      In addition, X86_CR4_VMXE is used as a mean to test if VMX is already in
      use by another VMM in hardware_enable(). So there can't really be
      co-existance. If the other VMM is prepared for co-existance and does a
      similar check, only one VMM can exist. If the other VMM is not prepared
      and blindly sets/clears X86_CR4_VMXE, we will get inconsistencies with
      X86_CR4_VMXE.
      
      As we also had bug reports related to clearing of vmcs with vmm_exclusive=0
      this seems to be pretty much untested. So let's better drop it.
      
      While at it, directly move setting/clearing X86_CR4_VMXE into
      kvm_cpu_vmxon/off.
      Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      fe0e80be
    • Farhan Ali's avatar
      KVM: s390: Support keyless subset guest mode · 730cd632
      Farhan Ali authored
      If the KSS facility is available on the machine, we also make it
      available for our KVM guests.
      
      The KSS facility bypasses storage key management as long as the guest
      does not issue a related instruction. When that happens, the control is
      returned to the host, which has to turn off KSS for a guest vcpu
      before retrying the instruction.
      Signed-off-by: default avatarCorey S. McQuay <csmcquay@linux.vnet.ibm.com>
      Signed-off-by: default avatarFarhan Ali <alifm@linux.vnet.ibm.com>
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      730cd632
    • Farhan Ali's avatar
      s390/sclp: Detect KSS facility · 71cb1bf6
      Farhan Ali authored
      Let's detect the keyless subset facility.
      Signed-off-by: default avatarFarhan Ali <alifm@linux.vnet.ibm.com>
      Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
      Reviewed-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Acked-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      71cb1bf6
  4. 20 Apr, 2017 18 commits