41 lines
1.4 KiB
Diff
41 lines
1.4 KiB
Diff
From 80718f0b78e1f76c9b8937257215b63ed4355e23 Mon Sep 17 00:00:00 2001
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Message-Id: <80718f0b78e1f76c9b8937257215b63ed4355e23.1596234183.git.zanussi@kernel.org>
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In-Reply-To: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org>
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References: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org>
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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 090/329] 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-4.19.135-rt60.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 5b2440e591fc..9fc847c237da 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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@@ -6850,6 +6850,13 @@ 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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2.17.1
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