diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2020-07-08 21:51:54 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-07-09 07:08:38 -0400 |
| commit | 87fa7f3e98a1310ef1ac1900e7ee7f9610a038bc (patch) | |
| tree | 379a0801cbf4a7494cbbe2e469ca71b110315193 | |
| parent | 841c2be09fe4f495fe5224952a419bd8c7e5b455 (diff) | |
| download | linux-stable-87fa7f3e98a1310ef1ac1900e7ee7f9610a038bc.tar.gz linux-stable-87fa7f3e98a1310ef1ac1900e7ee7f9610a038bc.tar.bz2 linux-stable-87fa7f3e98a1310ef1ac1900e7ee7f9610a038bc.zip | |
x86/kvm: Move context tracking where it belongs
Context tracking for KVM happens way too early in the vcpu_run()
code. Anything after guest_enter_irqoff() and before guest_exit_irqoff()
cannot use RCU and should also be not instrumented.
The current way of doing this covers way too much code. Move it closer to
the actual vmenter/exit code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200708195321.724574345@linutronix.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/svm/svm.c | 16 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 10 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 2 |
3 files changed, 26 insertions, 2 deletions
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 9b59e63567bb..0227c4cbe642 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3398,6 +3398,14 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) */ x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl); + /* + * Tell context tracking that this CPU is about to enter guest + * mode. This has to be after x86_spec_ctrl_set_guest() because + * that can take locks (lockdep needs RCU) and calls into world and + * some more. + */ + guest_enter_irqoff(); + __svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&svm->vcpu.arch.regs); #ifdef CONFIG_X86_64 @@ -3408,6 +3416,14 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) loadsegment(gs, svm->host.gs); #endif #endif + /* + * Tell context tracking that this CPU is back. + * + * This needs to be done before the below as native_read_msr() + * contains a tracepoint and x86_spec_ctrl_restore_host() calls + * into world and some more. + */ + guest_exit_irqoff(); /* * We do not use IBRS in the kernel. If this vCPU has used the diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 0d526b32f041..4b4796d5123d 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6731,6 +6731,11 @@ reenter_guest: */ x86_spec_ctrl_set_guest(vmx->spec_ctrl, 0); + /* + * Tell context tracking that this CPU is about to enter guest mode. + */ + guest_enter_irqoff(); + /* L1D Flush includes CPU buffer clear to mitigate MDS */ if (static_branch_unlikely(&vmx_l1d_should_flush)) vmx_l1d_flush(vcpu); @@ -6746,6 +6751,11 @@ reenter_guest: vcpu->arch.cr2 = read_cr2(); /* + * Tell context tracking that this CPU is back. + */ + guest_exit_irqoff(); + + /* * We do not use IBRS in the kernel. If this vCPU has used the * SPEC_CTRL MSR it may have left it on; save the value and * turn it off. This is much more efficient than blindly adding diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7f32169e8449..d7d82b3c0e4c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8522,7 +8522,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) } trace_kvm_entry(vcpu->vcpu_id); - guest_enter_irqoff(); fpregs_assert_state_consistent(); if (test_thread_flag(TIF_NEED_FPU_LOAD)) @@ -8585,7 +8584,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) local_irq_disable(); kvm_after_interrupt(vcpu); - guest_exit_irqoff(); if (lapic_in_kernel(vcpu)) { s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta; if (delta != S64_MIN) { |