From 5dfa26a76cefd4220962ac1dfbf9028081c0ac5a Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Wed, 13 Feb 2008 18:09:27 +0000 Subject: [PATCH] vmx realmode: Only check for pending interrupts every 16th instruction, since it is a moderately expensive operation. Signed-off-by: Keir Fraser --- xen/arch/x86/hvm/vmx/realmode.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/xen/arch/x86/hvm/vmx/realmode.c b/xen/arch/x86/hvm/vmx/realmode.c index dc9f76e645..8d7572e0d5 100644 --- a/xen/arch/x86/hvm/vmx/realmode.c +++ b/xen/arch/x86/hvm/vmx/realmode.c @@ -781,7 +781,7 @@ void vmx_realmode(struct cpu_user_regs *regs) struct vcpu *curr = current; struct realmode_emulate_ctxt rm_ctxt; unsigned long intr_info = __vmread(VM_ENTRY_INTR_INFO); - int i; + unsigned int i, emulations = 0; rm_ctxt.ctxt.regs = regs; @@ -804,11 +804,19 @@ void vmx_realmode(struct cpu_user_regs *regs) while ( curr->arch.hvm_vmx.vmxemul && !softirq_pending(smp_processor_id()) && - !curr->arch.hvm_vmx.real_mode_io_in_progress && - /* Check for pending interrupts only in proper real mode. */ - ((curr->arch.hvm_vcpu.guest_cr[0] & X86_CR0_PE) || - !hvm_local_events_need_delivery(curr)) ) + !curr->arch.hvm_vmx.real_mode_io_in_progress ) + { + /* + * Check for pending interrupts only every 16 instructions, because + * hvm_local_events_need_delivery() is moderately expensive, and only + * in real mode, because we don't emulate protected-mode IDT vectoring. + */ + if ( unlikely(!(++emulations & 15)) && + !(curr->arch.hvm_vcpu.guest_cr[0] & X86_CR0_PE) && + hvm_local_events_need_delivery(curr) ) + break; realmode_emulate_one(&rm_ctxt); + } if ( !curr->arch.hvm_vmx.vmxemul ) { -- 2.30.2