Commit 5e17b2ee authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Paolo Bonzini
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kvm: x86: Require const tsc for RT 



Non constant TSC is a nightmare on bare metal already, but with
virtualization it becomes a complete disaster because the workarounds
are horrible latency wise. That's also a preliminary for running RT in
a guest on top of a RT host.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Message-Id: <Yh5eJSG19S2sjZfy@linutronix.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent f144c49e

arch/x86/kvm/x86.c

+6 −0
Original line number Diff line number Diff line
@@ -8865,6 +8865,12 @@ int kvm_arch_init(void *opaque) 
		goto out;

	}



	if (IS_ENABLED(CONFIG_PREEMPT_RT) && !boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {

		pr_err("RT requires X86_FEATURE_CONSTANT_TSC\n");

		r = -EOPNOTSUPP;

		goto out;

	}



	r = -ENOMEM;



	x86_emulator_cache = kvm_alloc_emulator_cache();