1. 22 Jun, 2023 2 commits
  2. 16 Jun, 2023 1 commit
  3. 13 Jun, 2023 1 commit
  4. 07 Jun, 2023 1 commit
  5. 06 Jun, 2023 2 commits
  6. 05 Jun, 2023 1 commit
  7. 01 Jun, 2023 11 commits
  8. 21 May, 2023 3 commits
  9. 19 May, 2023 4 commits
    • Michal Luczaj's avatar
      KVM: Fix vcpu_array[0] races · afb2acb2
      Michal Luczaj authored
      In kvm_vm_ioctl_create_vcpu(), add vcpu to vcpu_array iff it's safe to
      access vcpu via kvm_get_vcpu() and kvm_for_each_vcpu(), i.e. when there's
      no failure path requiring vcpu removal and destruction. Such order is
      important because vcpu_array accessors may end up referencing vcpu at
      vcpu_array[0] even before online_vcpus is set to 1.
      
      When online_vcpus=0, any call to kvm_get_vcpu() goes through
      array_index_nospec() and ends with an attempt to xa_load(vcpu_array, 0):
      
      	int num_vcpus = atomic_read(&kvm->online_vcpus);
      	i = array_index_nospec(i, num_vcpus);
      	return xa_load(&kvm->vcpu_array, i);
      
      Similarly, when online_vcpus=0, a kvm_for_each_vcpu() does not iterate over
      an "empty" range, but actually [0, ULONG_MAX]:
      
      	xa_for_each_range(&kvm->vcpu_array, idx, vcpup, 0, \
      			  (atomic_read(&kvm->online_vcpus) - 1))
      
      In both cases, such online_vcpus=0 edge case, even if leading to
      unnecessary calls to XArray API, should not be an issue; requesting
      unpopulated indexes/ranges is handled by xa_load() and xa_for_each_range().
      
      However, this means that when the first vCPU is created and inserted in
      vcpu_array *and* before online_vcpus is incremented, code calling
      kvm_get_vcpu()/kvm_for_each_vcpu() already has access to that first vCPU.
      
      This should not pose a problem assuming that once a vcpu is stored in
      vcpu_array, it will remain there, but that's not the case:
      kvm_vm_ioctl_create_vcpu() first inserts to vcpu_array, then requests a
      file descriptor. If create_vcpu_fd() fails, newly inserted vcpu is removed
      from the vcpu_array, then destroyed:
      
      	vcpu->vcpu_idx = atomic_read(&kvm->online_vcpus);
      	r = xa_insert(&kvm->vcpu_array, vcpu->vcpu_idx, vcpu, GFP_KERNEL_ACCOUNT);
      	kvm_get_kvm(kvm);
      	r = create_vcpu_fd(vcpu);
      	if (r < 0) {
      		xa_erase(&kvm->vcpu_array, vcpu->vcpu_idx);
      		kvm_put_kvm_no_destroy(kvm);
      		goto unlock_vcpu_destroy;
      	}
      	atomic_inc(&kvm->online_vcpus);
      
      This results in a possible race condition when a reference to a vcpu is
      acquired (via kvm_get_vcpu() or kvm_for_each_vcpu()) moments before said
      vcpu is destroyed.
      Signed-off-by: default avatarMichal Luczaj <mhal@rbox.co>
      Message-Id: <20230510140410.1093987-2-mhal@rbox.co>
      Cc: stable@vger.kernel.org
      Fixes: c5b07754 ("KVM: Convert the kvm->vcpus array to a xarray", 2021-12-08)
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      afb2acb2
    • Jacob Xu's avatar
      KVM: VMX: Fix header file dependency of asm/vmx.h · 3367eeab
      Jacob Xu authored
      Include a definition of WARN_ON_ONCE() before using it.
      
      Fixes: bb1fcc70 ("KVM: nVMX: Allow L1 to use 5-level page walks for nested EPT")
      Cc: Sean Christopherson <seanjc@google.com>
      Signed-off-by: default avatarJacob Xu <jacobhxu@google.com>
      [reworded commit message; changed <asm/bug.h> to <linux/bug.h>]
      Signed-off-by: default avatarJim Mattson <jmattson@google.com>
      Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20220225012959.1554168-1-jmattson@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      3367eeab
    • Sean Christopherson's avatar
      KVM: Don't enable hardware after a restart/shutdown is initiated · e0ceec22
      Sean Christopherson authored
      Reject hardware enabling, i.e. VM creation, if a restart/shutdown has
      been initiated to avoid re-enabling hardware between kvm_reboot() and
      machine_{halt,power_off,restart}().  The restart case is especially
      problematic (for x86) as enabling VMX (or clearing GIF in KVM_RUN on
      SVM) blocks INIT, which results in the restart/reboot hanging as BIOS
      is unable to wake and rendezvous with APs.
      
      Note, this bug, and the original issue that motivated the addition of
      kvm_reboot(), is effectively limited to a forced reboot, e.g. `reboot -f`.
      In a "normal" reboot, userspace will gracefully teardown userspace before
      triggering the kernel reboot (modulo bugs, errors, etc), i.e. any process
      that might do ioctl(KVM_CREATE_VM) is long gone.
      
      Fixes: 8e1c1815 ("KVM: VMX: Disable VMX when system shutdown")
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Acked-by: default avatarMarc Zyngier <maz@kernel.org>
      Message-Id: <20230512233127.804012-3-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e0ceec22
    • Sean Christopherson's avatar
      KVM: Use syscore_ops instead of reboot_notifier to hook restart/shutdown · 6735150b
      Sean Christopherson authored
      Use syscore_ops.shutdown to disable hardware virtualization during a
      reboot instead of using the dedicated reboot_notifier so that KVM disables
      virtualization _after_ system_state has been updated.  This will allow
      fixing a race in KVM's handling of a forced reboot where KVM can end up
      enabling hardware virtualization between kernel_restart_prepare() and
      machine_restart().
      
      Rename KVM's hook to match the syscore op to avoid any possible confusion
      from wiring up a "reboot" helper to a "shutdown" hook (neither "shutdown
      nor "reboot" is completely accurate as the hook handles both).
      
      Opportunistically rewrite kvm_shutdown()'s comment to make it less VMX
      specific, and to explain why kvm_rebooting exists.
      
      Cc: Marc Zyngier <maz@kernel.org>
      Cc: Oliver Upton <oliver.upton@linux.dev>
      Cc: James Morse <james.morse@arm.com>
      Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
      Cc: Zenghui Yu <yuzenghui@huawei.com>
      Cc: kvmarm@lists.linux.dev
      Cc: Huacai Chen <chenhuacai@kernel.org>
      Cc: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
      Cc: Anup Patel <anup@brainfault.org>
      Cc: Atish Patra <atishp@atishpatra.org>
      Cc: kvm-riscv@lists.infradead.org
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Acked-by: default avatarMarc Zyngier <maz@kernel.org>
      Message-Id: <20230512233127.804012-2-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      6735150b
  10. 17 May, 2023 1 commit
    • Paolo Bonzini's avatar
      Merge tag 'kvmarm-fixes-6.4-1' of... · 39428f6e
      Paolo Bonzini authored
      Merge tag 'kvmarm-fixes-6.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
      
      KVM/arm64 fixes for 6.4, take #1
      
      - Plug a race in the stage-2 mapping code where the IPA and the PA
        would end up being out of sync
      
      - Make better use of the bitmap API (bitmap_zero, bitmap_zalloc...)
      
      - FP/SVE/SME documentation update, in the hope that this field
        becomes clearer...
      
      - Add workaround for the usual Apple SEIS brokenness
      
      - Random comment fixes
      39428f6e
  11. 14 May, 2023 13 commits