Commit 87fa7f3e authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Paolo Bonzini

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: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200708195321.724574345@linutronix.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 841c2be0
...@@ -3398,6 +3398,14 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) ...@@ -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); 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); __svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&svm->vcpu.arch.regs);
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
...@@ -3408,6 +3416,14 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) ...@@ -3408,6 +3416,14 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
loadsegment(gs, svm->host.gs); loadsegment(gs, svm->host.gs);
#endif #endif
#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 * We do not use IBRS in the kernel. If this vCPU has used the
......
...@@ -6731,6 +6731,11 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu) ...@@ -6731,6 +6731,11 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
*/ */
x86_spec_ctrl_set_guest(vmx->spec_ctrl, 0); 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 */ /* L1D Flush includes CPU buffer clear to mitigate MDS */
if (static_branch_unlikely(&vmx_l1d_should_flush)) if (static_branch_unlikely(&vmx_l1d_should_flush))
vmx_l1d_flush(vcpu); vmx_l1d_flush(vcpu);
...@@ -6745,6 +6750,11 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu) ...@@ -6745,6 +6750,11 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
vcpu->arch.cr2 = read_cr2(); 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 * 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 * SPEC_CTRL MSR it may have left it on; save the value and
......
...@@ -8522,7 +8522,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) ...@@ -8522,7 +8522,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
} }
trace_kvm_entry(vcpu->vcpu_id); trace_kvm_entry(vcpu->vcpu_id);
guest_enter_irqoff();
fpregs_assert_state_consistent(); fpregs_assert_state_consistent();
if (test_thread_flag(TIF_NEED_FPU_LOAD)) if (test_thread_flag(TIF_NEED_FPU_LOAD))
...@@ -8585,7 +8584,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) ...@@ -8585,7 +8584,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
local_irq_disable(); local_irq_disable();
kvm_after_interrupt(vcpu); kvm_after_interrupt(vcpu);
guest_exit_irqoff();
if (lapic_in_kernel(vcpu)) { if (lapic_in_kernel(vcpu)) {
s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta; s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta;
if (delta != S64_MIN) { if (delta != S64_MIN) {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment