[PATCH 07/15] KVM: Use dedicated flag to track if KVM is handling an NMI from guest
From: Sean Christopherson <seanjc@google.com>
Date: 2021-08-27 00:57:58
Also in:
kvm, kvmarm, linux-perf-users, linux-riscv, lkml, xen-devel
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Add a dedicated flag to detect the case where KVM's PMC overflow
callback was originally invoked in response to an NMI that arrived while
the guest was running. Using current_vcpu is less precise as IRQs also
set current_vcpu (though presumably KVM's callback should not be reached
in that case), and more importantly, this will allow dropping
current_vcpu as the perf callbacks can switch to kvm_running_vcpu now
that the perf callbacks are precisely registered, i.e. kvm_running_vcpu
doesn't need to be used to detect if a PMI arrived in the guest.
Fixes: dd60d217062f ("KVM: x86: Fix perf timer mode IP reporting")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/kvm_host.h | 3 +--
arch/x86/kvm/pmu.c | 2 +-
arch/x86/kvm/svm/svm.c | 2 +-
arch/x86/kvm/vmx/vmx.c | 2 +-
arch/x86/kvm/x86.c | 4 ++--
arch/x86/kvm/x86.h | 4 +++-
6 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1ea4943a73d7..465b35736d9b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h@@ -763,6 +763,7 @@ struct kvm_vcpu_arch { unsigned nmi_pending; /* NMI queued after currently running handler */ bool nmi_injected; /* Trying to inject an NMI this entry */ bool smi_pending; /* SMI queued after currently running handler */ + bool handling_nmi_from_guest; struct kvm_mtrr mtrr_state; u64 pat;
@@ -1874,8 +1875,6 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu); int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err); void __kvm_request_immediate_exit(struct kvm_vcpu *vcpu); -int kvm_is_in_guest(void); - void __user *__x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size); bool kvm_vcpu_is_reset_bsp(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 0772bad9165c..2b8934b452ea 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c@@ -87,7 +87,7 @@ static void kvm_perf_overflow_intr(struct perf_event *perf_event, * woken up. So we should wake it, but this is impossible from * NMI context. Do it from irq work instead. */ - if (!kvm_is_in_guest()) + if (!pmc->vcpu->arch.handling_nmi_from_guest) irq_work_queue(&pmc_to_pmu(pmc)->irq_work); else kvm_make_request(KVM_REQ_PMI, pmc->vcpu);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 1a70e11f0487..3fc6767e5fd8 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c@@ -3843,7 +3843,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) } if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI)) - kvm_before_interrupt(vcpu); + kvm_before_interrupt(vcpu, true); kvm_load_host_xsave_state(vcpu); stgi();
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f19d72136f77..f08980ef7c44 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c@@ -6344,7 +6344,7 @@ void vmx_do_interrupt_nmi_irqoff(unsigned long entry); static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu, unsigned long entry) { - kvm_before_interrupt(vcpu); + kvm_before_interrupt(vcpu, entry == (unsigned long)asm_exc_nmi_noist); vmx_do_interrupt_nmi_irqoff(entry); kvm_after_interrupt(vcpu); }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bc4ee6ea7752..d4d91944fde7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -8267,7 +8267,7 @@ static void kvm_timer_init(void) DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu); EXPORT_PER_CPU_SYMBOL_GPL(current_vcpu); -int kvm_is_in_guest(void) +static int kvm_is_in_guest(void) { return __this_cpu_read(current_vcpu) != NULL; }
@@ -9678,7 +9678,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) * interrupts on processors that implement an interrupt shadow, the * stat.exits increment will do nicely. */ - kvm_before_interrupt(vcpu); + kvm_before_interrupt(vcpu, false); local_irq_enable(); ++vcpu->stat.exits; local_irq_disable();
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 5cedc0e8a5d5..4c5ba4128b38 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h@@ -395,9 +395,10 @@ static inline void kvm_unregister_perf_callbacks(void) DECLARE_PER_CPU(struct kvm_vcpu *, current_vcpu); -static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu) +static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu, bool is_nmi) { __this_cpu_write(current_vcpu, vcpu); + WRITE_ONCE(vcpu->arch.handling_nmi_from_guest, is_nmi); kvm_register_perf_callbacks(); }
@@ -406,6 +407,7 @@ static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu) { kvm_unregister_perf_callbacks(); + WRITE_ONCE(vcpu->arch.handling_nmi_from_guest, false); __this_cpu_write(current_vcpu, NULL); }
--
2.33.0.259.gc128427fd7-goog
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