1. 24 Feb, 2018 23 commits
    • Wanpeng Li's avatar
      KVM: X86: Avoid traversing all the cpus for pv tlb flush when steal time is disabled · 4f2f61fc
      Wanpeng Li authored
      Avoid traversing all the cpus for pv tlb flush when steal time
      is disabled since pv tlb flush depends on the field in steal time
      for shared data.
      
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Radim KrÄmáŠ<rkrcmar@redhat.com>
      Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      4f2f61fc
    • Dou Liyang's avatar
      x86/kvm: Make parse_no_xxx __init for kvm · afdc3f58
      Dou Liyang authored
      The early_param() is only called during kernel initialization, So Linux
      marks the functions of it with __init macro to save memory.
      
      But it forgot to mark the parse_no_kvmapf/stealacc/kvmclock_vsyscall,
      So, Make them __init as well.
      
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: rkrcmar@redhat.com
      Cc: kvm@vger.kernel.org
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: x86@kernel.org
      Signed-off-by: default avatarDou Liyang <douly.fnst@cn.fujitsu.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      afdc3f58
    • Radim Krčmář's avatar
      KVM: x86: fix backward migration with async_PF · fe2a3027
      Radim Krčmář authored
      Guests on new hypersiors might set KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT
      bit when enabling async_PF, but this bit is reserved on old hypervisors,
      which results in a failure upon migration.
      
      To avoid breaking different cases, we are checking for CPUID feature bit
      before enabling the feature and nothing else.
      
      Fixes: 52a5c155 ("KVM: async_pf: Let guest support delivery of async_pf from guest mode")
      Cc: <stable@vger.kernel.org>
      Reviewed-by: default avatarWanpeng Li <wanpengli@tencent.com>
      Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
      Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      fe2a3027
    • Sebastian Ott's avatar
      kvm: fix warning for non-x86 builds · f75e4924
      Sebastian Ott authored
      Fix the following sparse warning by moving the prototype
      of kvm_arch_mmu_notifier_invalidate_range() to linux/kvm_host.h .
      
        CHECK   arch/s390/kvm/../../../virt/kvm/kvm_main.c
      arch/s390/kvm/../../../virt/kvm/kvm_main.c:138:13: warning: symbol 'kvm_arch_mmu_notifier_invalidate_range' was not declared. Should it be static?
      Signed-off-by: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f75e4924
    • Sebastian Ott's avatar
      kvm: fix warning for CONFIG_HAVE_KVM_EVENTFD builds · 07646749
      Sebastian Ott authored
      Move the kvm_arch_irq_routing_update() prototype outside of
      ifdef CONFIG_HAVE_KVM_EVENTFD guards to fix the following sparse warning:
      
      arch/s390/kvm/../../../virt/kvm/irqchip.c:171:28: warning: symbol 'kvm_arch_irq_routing_update' was not declared. Should it be static?
      Signed-off-by: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
      Acked-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      07646749
    • Stefan Raspl's avatar
      tools/kvm_stat: print 'Total' line for multiple events only · 6789af03
      Stefan Raspl authored
      The 'Total' line looks a bit weird when we have a single event only. This
      can happen e.g. due to filters. Therefore suppress when there's only a
      single event in the output.
      Signed-off-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      6789af03
    • Stefan Raspl's avatar
      tools/kvm_stat: group child events indented after parent · df72ecfc
      Stefan Raspl authored
      We keep the current logic that sorts all events (parent and child), but
      re-shuffle the events afterwards, grouping the children after the
      respective parent. Note that the percentage column for child events
      gives the percentage of the parent's total.
      Since we rework the logic anyway, we modify the total average
      calculation to use the raw numbers instead of the (rounded) averages.
      Note that this can result in differing numbers (between total average
      and the sum of the individual averages) due to rounding errors.
      Signed-off-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      df72ecfc
    • Stefan Raspl's avatar
      tools/kvm_stat: separate drilldown and fields filtering · 18e8f410
      Stefan Raspl authored
      Drilldown (i.e. toggle display of child trace events) was implemented by
      overriding the fields filter. This resulted in inconsistencies: E.g. when
      drilldown was not active, adding a filter that also matches child trace
      events would not only filter fields according to the filter, but also add
      in the child trace events matching the filter. E.g. on x86, setting
      'kvm_userspace_exit' as the fields filter after startup would result in
      display of kvm_userspace_exit(DCR), although that wasn't previously
      present - not exactly what one would expect from a filter.
      This patch addresses the issue by keeping drilldown and fields filter
      separate. While at it, we also fix a PEP8 issue by adding a blank line
      at one place (since we're in the area...).
      We implement this by adding a framework that also allows to define a
      taxonomy among the debugfs events to identify child trace events. I.e.
      drilldown using 'x' can now also work with debugfs. A respective parent-
      child relationship is only known for S390 at the moment, but could be
      added adjusting other platforms' ARCH.dbg_is_child() methods
      accordingly.
      Signed-off-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      18e8f410
    • Stefan Raspl's avatar
      tools/kvm_stat: eliminate extra guest/pid selection dialog · 516f1190
      Stefan Raspl authored
      We can do with a single dialog that takes both, pids and guest names.
      Note that we keep both interactive commands, 'p' and 'g' for now, to
      avoid confusion among users used to a specific key.
      
      While at it, we improve on some minor glitches regarding curses usage,
      e.g. cursor still visible when not supposed to be.
      Signed-off-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      516f1190
    • Stefan Raspl's avatar
      tools/kvm_stat: mark private methods as such · c0e8c21e
      Stefan Raspl authored
      Helps quite a bit reading the code when it's obvious when a method is
      intended for internal use only.
      Signed-off-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      c0e8c21e
    • Stefan Raspl's avatar
      tools/kvm_stat: fix debugfs handling · 1fd6a708
      Stefan Raspl authored
      Te checks for debugfs assumed that debugfs is always mounted at
      /sys/kernel/debug - which is likely, but not guaranteed. This is addressed
      by checking /proc/mounts for the actual location.
      Furthermore, when debugfs was mounted, but the kvm module not loaded, a
      misleading error pointing towards debugfs not present was given.
      To reproduce,
      (a) run kvm_stat with debugfs mounted at a place different from
          /sys/kernel/debug
      (b) run kvm_stat with debugfs mounted but kvm module not loaded
      Signed-off-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      1fd6a708
    • Stefan Raspl's avatar
      tools/kvm_stat: print error on invalid regex · 1cd8bfb1
      Stefan Raspl authored
      Entering an invalid regular expression did not produce any indication of an
      error so far.
      To reproduce, press 'f' and enter 'foo(' (with an unescaped bracket).
      Signed-off-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      1cd8bfb1
    • Stefan Raspl's avatar
      tools/kvm_stat: fix crash when filtering out all non-child trace events · 3df33a0f
      Stefan Raspl authored
      When we apply a filter that will only leave child trace events, we
      receive a ZeroDivisionError when calculating the percentages.
      In that case, provide percentages based on child events only.
      To reproduce, run 'kvm_stat -f .*[\(].*'.
      Signed-off-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      3df33a0f
    • Marc Hartmayer's avatar
      tools/kvm_stat: avoid 'is' for equality checks · 369d5a85
      Marc Hartmayer authored
      Use '==' for equality checks and 'is' when comparing identities.
      
      An example where '==' and 'is' behave differently:
      >>> a = 4242
      >>> a == 4242
      True
      >>> a is 4242
      False
      Signed-off-by: default avatarMarc Hartmayer <mhartmay@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      369d5a85
    • Marc Hartmayer's avatar
      tools/kvm_stat: use a more pythonic way to iterate over dictionaries · 0eb57800
      Marc Hartmayer authored
      If it's clear that the values of a dictionary will be used then use
      the '.items()' method.
      Signed-off-by: default avatarMarc Hartmayer <mhartmay@linux.vnet.ibm.com>
      Tested-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      [Include fix for logging mode by Stefan Raspl]
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      0eb57800
    • Marc Hartmayer's avatar
      tools/kvm_stat: use a namedtuple for storing the values · 006f1548
      Marc Hartmayer authored
      Use a namedtuple for storing the values as it allows to access the
      fields of a tuple via names. This makes the overall code much easier
      to read and to understand. Access by index is still possible as
      before.
      Signed-off-by: default avatarMarc Hartmayer <mhartmay@linux.vnet.ibm.com>
      Tested-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      006f1548
    • Marc Hartmayer's avatar
      tools/kvm_stat: simplify the sortkey function · faa312a5
      Marc Hartmayer authored
      The 'sortkey' function references a value in its enclosing
      scope (closure). This is not common practice for a sort key function
      so let's replace it. Additionally, the function 'sorted' has already a
      parameter for reversing the result therefore the inversion of the
      values is unneeded. The check for stats[x][1] is also superfluous as
      it's ensured that this value is initialized with 0.
      Signed-off-by: default avatarMarc Hartmayer <mhartmay@linux.vnet.ibm.com>
      Tested-by: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      faa312a5
    • Wanpeng Li's avatar
      KVM: X86: Fix SMRAM accessing even if VM is shutdown · 95e057e2
      Wanpeng Li authored
      Reported by syzkaller:
      
         WARNING: CPU: 6 PID: 2434 at arch/x86/kvm/vmx.c:6660 handle_ept_misconfig+0x54/0x1e0 [kvm_intel]
         CPU: 6 PID: 2434 Comm: repro_test Not tainted 4.15.0+ #4
         RIP: 0010:handle_ept_misconfig+0x54/0x1e0 [kvm_intel]
         Call Trace:
          vmx_handle_exit+0xbd/0xe20 [kvm_intel]
          kvm_arch_vcpu_ioctl_run+0xdaf/0x1d50 [kvm]
          kvm_vcpu_ioctl+0x3e9/0x720 [kvm]
          do_vfs_ioctl+0xa4/0x6a0
          SyS_ioctl+0x79/0x90
          entry_SYSCALL_64_fastpath+0x25/0x9c
      
      The testcase creates a first thread to issue KVM_SMI ioctl, and then creates
      a second thread to mmap and operate on the same vCPU.  This triggers a race
      condition when running the testcase with multiple threads. Sometimes one thread
      exits with a triple fault while another thread mmaps and operates on the same
      vCPU.  Because CS=0x3000/IP=0x8000 is not mapped, accessing the SMI handler
      results in an EPT misconfig. This patch fixes it by returning RET_PF_EMULATE
      in kvm_handle_bad_page(), which will go on to cause an emulation failure and an
      exit with KVM_EXIT_INTERNAL_ERROR.
      
      Reported-by: syzbot+c1d9517cab094dae65e446c0c5b4de6c40f4dc58@syzkaller.appspotmail.com
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      95e057e2
    • Chao Gao's avatar
      KVM: nVMX: Don't halt vcpu when L1 is injecting events to L2 · 135a06c3
      Chao Gao authored
      Although L2 is in halt state, it will be in the active state after
      VM entry if the VM entry is vectoring according to SDM 26.6.2 Activity
      State. Halting the vcpu here means the event won't be injected to L2
      and this decision isn't reported to L1. Thus L0 drops an event that
      should be injected to L2.
      
      Cc: Liran Alon <liran.alon@oracle.com>
      Reviewed-by: default avatarLiran Alon <liran.alon@oracle.com>
      Signed-off-by: default avatarChao Gao <chao.gao@intel.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      135a06c3
    • Wanpeng Li's avatar
      KVM: mmu: Fix overlap between public and private memslots · b28676bb
      Wanpeng Li authored
      Reported by syzkaller:
      
          pte_list_remove: ffff9714eb1f8078 0->BUG
          ------------[ cut here ]------------
          kernel BUG at arch/x86/kvm/mmu.c:1157!
          invalid opcode: 0000 [#1] SMP
          RIP: 0010:pte_list_remove+0x11b/0x120 [kvm]
          Call Trace:
           drop_spte+0x83/0xb0 [kvm]
           mmu_page_zap_pte+0xcc/0xe0 [kvm]
           kvm_mmu_prepare_zap_page+0x81/0x4a0 [kvm]
           kvm_mmu_invalidate_zap_all_pages+0x159/0x220 [kvm]
           kvm_arch_flush_shadow_all+0xe/0x10 [kvm]
           kvm_mmu_notifier_release+0x6c/0xa0 [kvm]
           ? kvm_mmu_notifier_release+0x5/0xa0 [kvm]
           __mmu_notifier_release+0x79/0x110
           ? __mmu_notifier_release+0x5/0x110
           exit_mmap+0x15a/0x170
           ? do_exit+0x281/0xcb0
           mmput+0x66/0x160
           do_exit+0x2c9/0xcb0
           ? __context_tracking_exit.part.5+0x4a/0x150
           do_group_exit+0x50/0xd0
           SyS_exit_group+0x14/0x20
           do_syscall_64+0x73/0x1f0
           entry_SYSCALL64_slow_path+0x25/0x25
      
      The reason is that when creates new memslot, there is no guarantee for new
      memslot not overlap with private memslots. This can be triggered by the
      following program:
      
         #include <fcntl.h>
         #include <pthread.h>
         #include <setjmp.h>
         #include <signal.h>
         #include <stddef.h>
         #include <stdint.h>
         #include <stdio.h>
         #include <stdlib.h>
         #include <string.h>
         #include <sys/ioctl.h>
         #include <sys/stat.h>
         #include <sys/syscall.h>
         #include <sys/types.h>
         #include <unistd.h>
         #include <linux/kvm.h>
      
         long r[16];
      
         int main()
         {
      	void *p = valloc(0x4000);
      
      	r[2] = open("/dev/kvm", 0);
      	r[3] = ioctl(r[2], KVM_CREATE_VM, 0x0ul);
      
      	uint64_t addr = 0xf000;
      	ioctl(r[3], KVM_SET_IDENTITY_MAP_ADDR, &addr);
      	r[6] = ioctl(r[3], KVM_CREATE_VCPU, 0x0ul);
      	ioctl(r[3], KVM_SET_TSS_ADDR, 0x0ul);
      	ioctl(r[6], KVM_RUN, 0);
      	ioctl(r[6], KVM_RUN, 0);
      
      	struct kvm_userspace_memory_region mr = {
      		.slot = 0,
      		.flags = KVM_MEM_LOG_DIRTY_PAGES,
      		.guest_phys_addr = 0xf000,
      		.memory_size = 0x4000,
      		.userspace_addr = (uintptr_t) p
      	};
      	ioctl(r[3], KVM_SET_USER_MEMORY_REGION, &mr);
      	return 0;
         }
      
      This patch fixes the bug by not adding a new memslot even if it
      overlaps with private memslots.
      Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Eric Biggers <ebiggers3@gmail.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
      ---
       virt/kvm/kvm_main.c | 3 +--
       1 file changed, 1 insertion(+), 2 deletions(-)
      b28676bb
    • Eric Biggers's avatar
      KVM/x86: remove WARN_ON() for when vm_munmap() fails · 103c763c
      Eric Biggers authored
      On x86, special KVM memslots such as the TSS region have anonymous
      memory mappings created on behalf of userspace, and these mappings are
      removed when the VM is destroyed.
      
      It is however possible for removing these mappings via vm_munmap() to
      fail.  This can most easily happen if the thread receives SIGKILL while
      it's waiting to acquire ->mmap_sem.   This triggers the 'WARN_ON(r < 0)'
      in __x86_set_memory_region().  syzkaller was able to hit this, using
      'exit()' to send the SIGKILL.  Note that while the vm_munmap() failure
      results in the mapping not being removed immediately, it is not leaked
      forever but rather will be freed when the process exits.
      
      It's not really possible to handle this failure properly, so almost
      every other caller of vm_munmap() doesn't check the return value.  It's
      a limitation of having the kernel manage these mappings rather than
      userspace.
      
      So just remove the WARN_ON() so that users can't spam the kernel log
      with this warning.
      
      Fixes: f0d648bd ("KVM: x86: map/unmap private slots in __x86_set_memory_region")
      Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
      Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
      Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
      103c763c
    • Radim Krčmář's avatar
      KVM: nVMX: preserve SECONDARY_EXEC_DESC without UMIP · 99158246
      Radim Krčmář authored
      L1 might want to use SECONDARY_EXEC_DESC, so we must not clear the VMCS
      bit if UMIP is not being emulated.
      
      We must still set the bit when emulating UMIP as the feature can be
      passed to L2 where L0 will do the emulation and because L2 can change
      CR4 without a VM exit, we should clear the bit if UMIP is disabled.
      
      Fixes: 0367f205 ("KVM: vmx: add support for emulating UMIP")
      Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
      99158246
    • Paolo Bonzini's avatar
      KVM: x86: move LAPIC initialization after VMCS creation · 0b2e9904
      Paolo Bonzini authored
      The initial reset of the local APIC is performed before the VMCS has been
      created, but it tries to do a vmwrite:
      
       vmwrite error: reg 810 value 4a00 (err 18944)
       CPU: 54 PID: 38652 Comm: qemu-kvm Tainted: G        W I      4.16.0-0.rc2.git0.1.fc28.x86_64 #1
       Hardware name: Intel Corporation S2600CW/S2600CW, BIOS SE5C610.86B.01.01.0003.090520141303 09/05/2014
       Call Trace:
        vmx_set_rvi [kvm_intel]
        vmx_hwapic_irr_update [kvm_intel]
        kvm_lapic_reset [kvm]
        kvm_create_lapic [kvm]
        kvm_arch_vcpu_init [kvm]
        kvm_vcpu_init [kvm]
        vmx_create_vcpu [kvm_intel]
        kvm_vm_ioctl [kvm]
      
      Move it later, after the VMCS has been created.
      
      Fixes: 4191db26 ("KVM: x86: Update APICv on APIC reset")
      Cc: stable@vger.kernel.org
      Cc: Liran Alon <liran.alon@oracle.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      0b2e9904
  2. 23 Feb, 2018 2 commits
  3. 20 Feb, 2018 4 commits
  4. 15 Feb, 2018 2 commits
    • Arnd Bergmann's avatar
      ARM: kvm: fix building with gcc-8 · 67870eb1
      Arnd Bergmann authored
      In banked-sr.c, we use a top-level '__asm__(".arch_extension virt")'
      statement to allow compilation of a multi-CPU kernel for ARMv6
      and older ARMv7-A that don't normally support access to the banked
      registers.
      
      This is considered to be a programming error by the gcc developers
      and will no longer work in gcc-8, where we now get a build error:
      
      /tmp/cc4Qy7GR.s:34: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_usr'
      /tmp/cc4Qy7GR.s:41: Error: Banked registers are not available with this architecture. -- `mrs r3,ELR_hyp'
      /tmp/cc4Qy7GR.s:55: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_svc'
      /tmp/cc4Qy7GR.s:62: Error: Banked registers are not available with this architecture. -- `mrs r3,LR_svc'
      /tmp/cc4Qy7GR.s:69: Error: Banked registers are not available with this architecture. -- `mrs r3,SPSR_svc'
      /tmp/cc4Qy7GR.s:76: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_abt'
      
      Passign the '-march-armv7ve' flag to gcc works, and is ok here, because
      we know the functions won't ever be called on pre-ARMv7VE machines.
      Unfortunately, older compiler versions (4.8 and earlier) do not understand
      that flag, so we still need to keep the asm around.
      
      Backporting to stable kernels (4.6+) is needed to allow those to be built
      with future compilers as well.
      
      Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84129
      Fixes: 33280b4c ("ARM: KVM: Add banked registers save/restore")
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
      67870eb1
    • Christoffer Dall's avatar
      KVM: arm/arm64: Fix arch timers with userspace irqchips · d60d8b64
      Christoffer Dall authored
      When introducing support for irqchip in userspace we needed a way to
      mask the timer signal to prevent the guest continuously exiting due to a
      screaming timer.
      
      We did this by disabling the corresponding percpu interrupt on the
      host interrupt controller, because we cannot rely on the host system
      having a GIC, and therefore cannot make any assumptions about having an
      active state to hide the timer signal.
      
      Unfortunately, when introducing this feature, it became entirely
      possible that a VCPU which belongs to a VM that has a userspace irqchip
      can disable the vtimer irq on the host on some physical CPU, and then go
      away without ever enabling the vtimer irq on that physical CPU again.
      
      This means that using irqchips in userspace on a system that also
      supports running VMs with an in-kernel GIC can prevent forward progress
      from in-kernel GIC VMs.
      
      Later on, when we started taking virtual timer interrupts in the arch
      timer code, we would also leave this timer state active for userspace
      irqchip VMs, because we leave it up to a VGIC-enabled guest to
      deactivate the hardware IRQ using the HW bit in the LR.
      
      Both issues are solved by only using the enable/disable trick on systems
      that do not have a host GIC which supports the active state, because all
      VMs on such systems must use irqchips in userspace.  Systems that have a
      working GIC with support for an active state use the active state to
      mask the timer signal for both userspace and in-kernel irqchips.
      
      Cc: Alexander Graf <agraf@suse.de>
      Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
      Cc: <stable@vger.kernel.org> # v4.12+
      Fixes: d9e13977 ("KVM: arm/arm64: Support arch timers with a userspace gic")
      Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
      d60d8b64
  5. 14 Feb, 2018 7 commits
  6. 11 Feb, 2018 2 commits
    • Linus Torvalds's avatar
      Linux 4.16-rc1 · 7928b2cb
      Linus Torvalds authored
      7928b2cb
    • Al Viro's avatar
      unify {de,}mangle_poll(), get rid of kernel-side POLL... · 7a163b21
      Al Viro authored
      except, again, POLLFREE and POLL_BUSY_LOOP.
      
      With this, we finally get to the promised end result:
      
       - POLL{IN,OUT,...} are plain integers and *not* in __poll_t, so any
         stray instances of ->poll() still using those will be caught by
         sparse.
      
       - eventpoll.c and select.c warning-free wrt __poll_t
      
       - no more kernel-side definitions of POLL... - userland ones are
         visible through the entire kernel (and used pretty much only for
         mangle/demangle)
      
       - same behavior as after the first series (i.e. sparc et.al. epoll(2)
         working correctly).
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7a163b21