FAILED: patch "[PATCH] KVM: x86: don't expose MSR_IA32_UMWAIT_CONTROL" failed to apply to 5.6-stable tree

The patch below does not apply to the 5.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f4cfcd2d5aea4e96c5d483c476f3057b6b7baf6a Mon Sep 17 00:00:00 2001
From: Maxim Levitsky <[email protected]>
Date: Sat, 23 May 2020 19:14:55 +0300
Subject: [PATCH] KVM: x86: don't expose MSR_IA32_UMWAIT_CONTROL
unconditionally

This msr is only available when the host supports WAITPKG feature.

This breaks a nested guest, if the L1 hypervisor is set to ignore unknown msrs, because the only other safety check that the kernel does is that it attempts to read the msr and rejects it if it gets an exception.

Message-Id: <[email protected]>

index c17e6eb9ad43..e0083a08da9e 100644
@@ -5242,6 +5242,10 @@ static void kvm_init_msr_list(void)
 			if (!kvm_cpu_cap_has(X86_FEATURE_RDTSCP))
 				continue;
 			break;
+		case MSR_IA32_UMWAIT_CONTROL:
+			if (!kvm_cpu_cap_has(X86_FEATURE_WAITPKG))
+				continue;
+			break;
 		case MSR_IA32_RTIT_CTL:
 		case MSR_IA32_RTIT_STATUS:
 			if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT))