38 lines
1.1 KiB
Diff
38 lines
1.1 KiB
Diff
From 9d89b02f01f1b2e5a9eacb0f65b3794aae03a28c Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Sun, 6 Nov 2011 12:26:18 +0100
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Subject: [PATCH 090/325] x86: kvm Require const tsc for RT
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.115-rt48.tar.xz
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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 | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
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index 2cb379e261c0..a94c1a01b894 100644
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--- a/arch/x86/kvm/x86.c
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+++ b/arch/x86/kvm/x86.c
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@@ -6873,6 +6873,13 @@ int kvm_arch_init(void *opaque)
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goto out;
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}
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+ if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
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+ printk(KERN_ERR "RT requires X86_FEATURE_CONSTANT_TSC\n");
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+ return -EOPNOTSUPP;
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+ }
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+#endif
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+
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r = kvm_mmu_module_init();
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if (r)
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goto out_free_percpu;
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--
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2.25.1
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