Exit to userspace if a fastpath handler triggers such an exit, which can
happen when skipping the instruction, e.g. due to userspace
single-stepping the guest via KVM_GUESTDBG_SINGLESTEP or because of an
emulation failure.
Fixes: 404d5d7bff0d ("KVM: X86: Introduce more exit_fastpath_completion enum values")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/x86.c | 9 +++++++--
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 950a03e0181e..736dda300849 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -211,6 +211,7 @@ enum exit_fastpath_completion {
EXIT_FASTPATH_NONE,
EXIT_FASTPATH_REENTER_GUEST,
EXIT_FASTPATH_EXIT_HANDLED,
+ EXIT_FASTPATH_EXIT_USERSPACE,
};
typedef enum exit_fastpath_completion fastpath_t;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 332584476129..3c54a241696f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2184,8 +2184,10 @@ fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu)
}
if (handled) {
- kvm_skip_emulated_instruction(vcpu);
- ret = EXIT_FASTPATH_REENTER_GUEST;
+ if (!kvm_skip_emulated_instruction(vcpu))
+ ret = EXIT_FASTPATH_EXIT_USERSPACE;
+ else
+ ret = EXIT_FASTPATH_REENTER_GUEST;
trace_kvm_msr_write(msr, data);
} else {
ret = EXIT_FASTPATH_NONE;
@@ -11206,6 +11208,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (vcpu->arch.apic_attention)
kvm_lapic_sync_from_vapic(vcpu);
+ if (unlikely(exit_fastpath == EXIT_FASTPATH_EXIT_USERSPACE))
+ return 0;
+
r = kvm_x86_call(handle_exit)(vcpu, exit_fastpath);
return r;
--
2.46.0.rc2.264.g509ed76dc8-goog
