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32 lines
914 B
Diff
32 lines
914 B
Diff
Subject: x86: kvm Require const tsc for RT
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Sun, 06 Nov 2011 12:26:18 +0100
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Non constant TSC is a nightmare on bare metal already, but with
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virtualization it becomes a complete disaster because the workarounds
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are horrible latency wise. That's also a preliminary for running RT in
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a guest on top of a RT host.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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arch/x86/kvm/x86.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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--- a/arch/x86/kvm/x86.c
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+++ b/arch/x86/kvm/x86.c
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@@ -7908,6 +7908,14 @@ int kvm_arch_init(void *opaque)
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goto out;
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}
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+#ifdef CONFIG_PREEMPT_RT
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+ if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
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+ pr_err("RT requires X86_FEATURE_CONSTANT_TSC\n");
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+ r = -EOPNOTSUPP;
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+ goto out;
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+ }
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+#endif
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+
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r = -ENOMEM;
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x86_fpu_cache = kmem_cache_create("x86_fpu", sizeof(struct fpu),
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__alignof__(struct fpu), SLAB_ACCOUNT,
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