From 8578f59657c505982e1d05232272c6bf304cf8aa Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 13 Dec 2022 06:09:07 +0000 Subject: [PATCH] KVM: VMX: Allow VM-Fail path of VMREAD helper to be instrumented Allow instrumentation in the VM-Fail path of __vmcs_readl() so that the helper can be used in noinstr functions, e.g. to get the exit reason in vmx_vcpu_enter_exit() in order to handle NMI VM-Exits in the noinstr section. While allowing instrumentation isn't technically safe, KVM has much bigger problems if VMREAD fails in a noinstr section. Note, all other VMX instructions also allow instrumentation in their VM-Fail paths for similar reasons, VMREAD was simply omitted by commit 3ebccdf373c2 ("x86/kvm/vmx: Move guest enter/exit into .noinstr.text") because VMREAD wasn't used in a noinstr section at the time. Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20221213060912.654668-3-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/vmx_ops.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h index a5282014616c3..db95bde52998f 100644 --- a/arch/x86/kvm/vmx/vmx_ops.h +++ b/arch/x86/kvm/vmx/vmx_ops.h @@ -100,8 +100,10 @@ static __always_inline unsigned long __vmcs_readl(unsigned long field) return value; do_fail: + instrumentation_begin(); WARN_ONCE(1, KBUILD_MODNAME ": vmread failed: field=%lx\n", field); pr_warn_ratelimited(KBUILD_MODNAME ": vmread failed: field=%lx\n", field); + instrumentation_end(); return 0; do_exception: -- 2.30.2