Re: [PATCH v3 07/16] KVM: SVM: Move core EFER.SVME enablement to kernel

[Chao Gao]

>-static inline void kvm_cpu_svm_disable(void)
>-{
>-	uint64_t efer;
>-
>-	wrmsrq(MSR_VM_HSAVE_PA, 0);
>-	rdmsrq(MSR_EFER, efer);
>-	if (efer & EFER_SVME) {
>-		/*
>-		 * Force GIF=1 prior to disabling SVM, e.g. to ensure INIT and
>-		 * NMI aren't blocked.
>-		 */
>-		stgi();
>-		wrmsrq(MSR_EFER, efer & ~EFER_SVME);
>-	}
>-}
>-
> static void svm_emergency_disable_virtualization_cpu(void)
> {
>-	virt_rebooting = true;
>-
>-	kvm_cpu_svm_disable();
>+	wrmsrq(MSR_VM_HSAVE_PA, 0);
> }
> 
> static void svm_disable_virtualization_cpu(void)
>@@ -507,7 +489,7 @@ static void svm_disable_virtualization_cpu(void)
> 	if (tsc_scaling)
> 		__svm_write_tsc_multiplier(SVM_TSC_RATIO_DEFAULT);
> 
>-	kvm_cpu_svm_disable();
>+	x86_svm_disable_virtualization_cpu();

There's a functional change here. The new x86_svm_disable_virtualization_cpu()
doesn't reset MSR_VM_HSAVE_PA, but the old kvm_cpu_svm_disable() does.


>+int x86_svm_disable_virtualization_cpu(void)
>+{
>+	int r = -EIO;
>+	u64 efer;
>+
>+	/*
>+	 * Force GIF=1 prior to disabling SVM, e.g. to ensure INIT and
>+	 * NMI aren't blocked.
>+	 */
>+	asm goto("1: stgi\n\t"
>+		 _ASM_EXTABLE(1b, %l[fault])
>+		 ::: "memory" : fault);
>+	r = 0;
>+
>+fault:
>+	rdmsrq(MSR_EFER, efer);
>+	wrmsrq(MSR_EFER, efer & ~EFER_SVME);
>+	return r;
>+}
>+EXPORT_SYMBOL_FOR_KVM(x86_svm_disable_virtualization_cpu);