From 0f3d5ea6c0318d8b9c890012f800884d24309a3f Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 6 Nov 2011 12:26:18 +0100 Subject: [PATCH 142/298] x86: kvm 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: Thomas Gleixner --- arch/x86/kvm/x86.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8361e6960afb..a3cd44ca9a7d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6907,6 +6907,14 @@ int kvm_arch_init(void *opaque) goto out; } +#ifdef CONFIG_PREEMPT_RT_FULL + if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) { + pr_err("RT requires X86_FEATURE_CONSTANT_TSC\n"); + r = -EOPNOTSUPP; + goto out; + } +#endif + r = -ENOMEM; x86_fpu_cache = kmem_cache_create("x86_fpu", sizeof(struct fpu), __alignof__(struct fpu), SLAB_ACCOUNT, -- 2.19.1