diff options
Diffstat (limited to 'features/rt/x86-kvm-Require-const-tsc-for-RT.patch')
| -rw-r--r-- | features/rt/x86-kvm-Require-const-tsc-for-RT.patch | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/features/rt/x86-kvm-Require-const-tsc-for-RT.patch b/features/rt/x86-kvm-Require-const-tsc-for-RT.patch new file mode 100644 index 00000000..0b9a6b96 --- /dev/null +++ b/features/rt/x86-kvm-Require-const-tsc-for-RT.patch @@ -0,0 +1,37 @@ +From bc5cb37aa8e610d93aada2612abf77e85d034c75 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Sun, 6 Nov 2011 12:26:18 +0100 +Subject: [PATCH 117/191] 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 <tglx@linutronix.de> +--- + 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 47e021bdcc94..891c3239e2b0 100644 +--- a/arch/x86/kvm/x86.c ++++ b/arch/x86/kvm/x86.c +@@ -7979,6 +7979,14 @@ int kvm_arch_init(void *opaque) + goto out; + } + ++#ifdef CONFIG_PREEMPT_RT ++ 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 + |