Re: [4.18.0 rc8 BUG] possible irq lock inversion dependency detected

[Thomas Gleixner <tglx@linutronix.de>]

On Sat, 11 Aug 2018, Mikhail Gavrilov wrote:
> >         /*
> >          * If this vCPU has touched SPEC_CTRL, restore the guest's value if
> >          * it's non-zero. Since vmentry is serialising on affected CPUs, there
> > @@ -5590,6 +5588,8 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
> >          */
> >         x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl);
> >
> > +       local_irq_enable();
> > +
> >         asm volatile (
> >                 "push %%" _ASM_BP "; \n\t"
> >                 "mov %c[rbx](%[svm]), %%" _ASM_BX " \n\t"
> >
> 
> 
> I am tested this patch, but it not help solve issue.
> New dmesg output is attached here.

Bah, stupid me. Forgot to fix the other end of that function as
well. Complete fix below.

Thanks,

	tglx

8<---------------
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index f059a73f0fd0..9799f86388e7 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5580,8 +5580,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 
 	clgi();
 
-	local_irq_enable();
-
 	/*
 	 * If this vCPU has touched SPEC_CTRL, restore the guest's value if
 	 * it's non-zero. Since vmentry is serialising on affected CPUs, there
@@ -5590,6 +5588,8 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 	 */
 	x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl);
 
+	local_irq_enable();
+
 	asm volatile (
 		"push %%" _ASM_BP "; \n\t"
 		"mov %c[rbx](%[svm]), %%" _ASM_BX " \n\t"
@@ -5712,12 +5712,12 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 	if (unlikely(!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL)))
 		svm->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL);
 
-	x86_spec_ctrl_restore_host(svm->spec_ctrl, svm->virt_spec_ctrl);
-
 	reload_tss(vcpu);
 
 	local_irq_disable();
 
+	x86_spec_ctrl_restore_host(svm->spec_ctrl, svm->virt_spec_ctrl);
+
 	vcpu->arch.cr2 = svm->vmcb->save.cr2;
 	vcpu->arch.regs[VCPU_REGS_RAX] = svm->vmcb->save.rax;
 	vcpu->arch.regs[VCPU_REGS_RSP] = svm->vmcb->save.rsp;