diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0013-KVM-X86-Fix-preempt-the-preemption-timer-cancel.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0013-KVM-X86-Fix-preempt-the-preemption-timer-cancel.patch | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0013-KVM-X86-Fix-preempt-the-preemption-timer-cancel.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0013-KVM-X86-Fix-preempt-the-preemption-timer-cancel.patch new file mode 100644 index 00000000..4331a9f4 --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0013-KVM-X86-Fix-preempt-the-preemption-timer-cancel.patch @@ -0,0 +1,93 @@ +From b541de5f53d608796a946a42f5c3251e4dd07522 Mon Sep 17 00:00:00 2001 +From: Wanpeng Li <wanpeng.li@hotmail.com> +Date: Sat, 20 May 2017 20:32:32 -0700 +Subject: [PATCH 13/93] KVM: X86: Fix preempt the preemption timer cancel +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +[ Upstream commit 5acc1ca4fb15f00bfa3d4046e35ca381bc25d580 ] + +Preemption can occur during cancel preemption timer, and there will be +inconsistent status in lapic, vmx and vmcs field. + + CPU0 CPU1 + + preemption timer vmexit + handle_preemption_timer(vCPU0) + kvm_lapic_expired_hv_timer + vmx_cancel_hv_timer + vmx->hv_deadline_tsc = -1 + vmcs_clear_bits + /* hv_timer_in_use still true */ + sched_out + sched_in + kvm_arch_vcpu_load + vmx_set_hv_timer + write vmx->hv_deadline_tsc + vmcs_set_bits + /* back in kvm_lapic_expired_hv_timer */ + hv_timer_in_use = false + ... + vmx_vcpu_run + vmx_arm_hv_run + write preemption timer deadline + spurious preemption timer vmexit + handle_preemption_timer(vCPU0) + kvm_lapic_expired_hv_timer + WARN_ON(!apic->lapic_timer.hv_timer_in_use); + +This can be reproduced sporadically during boot of L2 on a +preemptible L1, causing a splat on L1. + + WARNING: CPU: 3 PID: 1952 at arch/x86/kvm/lapic.c:1529 kvm_lapic_expired_hv_timer+0xb5/0xd0 [kvm] + CPU: 3 PID: 1952 Comm: qemu-system-x86 Not tainted 4.12.0-rc1+ #24 RIP: 0010:kvm_lapic_expired_hv_timer+0xb5/0xd0 [kvm] + Call Trace: + handle_preemption_timer+0xe/0x20 [kvm_intel] + vmx_handle_exit+0xc9/0x15f0 [kvm_intel] + ? lock_acquire+0xdb/0x250 + ? lock_acquire+0xdb/0x250 + ? kvm_arch_vcpu_ioctl_run+0xdf3/0x1ce0 [kvm] + kvm_arch_vcpu_ioctl_run+0xe55/0x1ce0 [kvm] + kvm_vcpu_ioctl+0x384/0x7b0 [kvm] + ? kvm_vcpu_ioctl+0x384/0x7b0 [kvm] + ? __fget+0xf3/0x210 + do_vfs_ioctl+0xa4/0x700 + ? __fget+0x114/0x210 + SyS_ioctl+0x79/0x90 + do_syscall_64+0x8f/0x750 + ? trace_hardirqs_on_thunk+0x1a/0x1c + entry_SYSCALL64_slow_path+0x25/0x25 + +This patch fixes it by disabling preemption while cancelling +preemption timer. This way cancel_hv_timer is atomic with +respect to kvm_arch_vcpu_load. + +Cc: Paolo Bonzini <pbonzini@redhat.com> +Cc: Radim Krčmář <rkrcmar@redhat.com> +Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> +Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> +Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + arch/x86/kvm/lapic.c | 2 ++ + 1 file changed, 2 insertions(+) + +diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c +index 3f05c04..650ff4a 100644 +--- a/arch/x86/kvm/lapic.c ++++ b/arch/x86/kvm/lapic.c +@@ -1358,8 +1358,10 @@ EXPORT_SYMBOL_GPL(kvm_lapic_hv_timer_in_use); + + static void cancel_hv_tscdeadline(struct kvm_lapic *apic) + { ++ preempt_disable(); + kvm_x86_ops->cancel_hv_timer(apic->vcpu); + apic->lapic_timer.hv_timer_in_use = false; ++ preempt_enable(); + } + + void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu) +-- +2.7.4 + |