From 84b6a3491567a540f955e18d8e615493afa36df0 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 29 May 2020 23:27:36 +0200 Subject: x86/entry: Optimize local_db_save() for virt Because DRn access is 'difficult' with virt; but the DR7 read is cheaper than a cacheline miss on native, add a virt specific fast path to local_db_save(), such that when breakpoints are not in use to avoid touching DRn entirely. Suggested-by: Andy Lutomirski Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200529213321.187833200@infradead.org --- arch/x86/kvm/vmx/nested.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kvm/vmx') diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 9c74a732b08d..2e7238a57fc1 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -3087,9 +3087,9 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) /* * VMExit clears RFLAGS.IF and DR7, even on a consistency check. */ - local_irq_enable(); if (hw_breakpoint_active()) set_debugreg(__this_cpu_read(cpu_dr7), 7); + local_irq_enable(); preempt_enable(); /* -- cgit v1.2.3