kvm: x86: disable shattered huge page recovery for PREEMPT_RT. (13fb5927) · Commits · 戴 / test

If a huge page is recovered (and becomes no executable) while another thread is executing it, the resulting contention on mmu_lock can cause latency spikes. Disabling recovery for PREEMPT_RT kernels fixes this issue. Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -51,7 +51,12 @@
		extern bool itlb_multihit_kvm_mitigation;

		static int __read_mostly nx_huge_pages = -1;
		#ifdef CONFIG_PREEMPT_RT
		/* Recovery can cause latency spikes, disable it for PREEMPT_RT. */
		static uint __read_mostly nx_huge_pages_recovery_ratio = 0;
		#else
		static uint __read_mostly nx_huge_pages_recovery_ratio = 60;
		#endif

		static int set_nx_huge_pages(const char val, const struct kernel_param kp);
		static int set_nx_huge_pages_recovery_ratio(const char val, const struct kernel_param kp);

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