linux-kernel - [PATCH v4 1/7] KVM: VMX: Introduce generic fastpath handler

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Date:   Tue, 28 Apr 2020 14:23:23 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Haiwei Li <lihaiwei@...cent.com>
Subject: [PATCH v4 1/7] KVM: VMX: Introduce generic fastpath handler

From: Wanpeng Li <wanpengli@...cent.com>

Introduce generic fastpath handler to handle MSR fastpath, VMX-preemption
timer fastpath etc, move it after vmx_complete_interrupts() in order that
later patch can catch the case vmexit occurred while another event was
being delivered to guest. There is no obversed performance difference for
IPI fastpath testing after this move.

Tested-by: Haiwei Li <lihaiwei@...cent.com>
Cc: Haiwei Li <lihaiwei@...cent.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 arch/x86/kvm/vmx/vmx.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 3ab6ca6..9b5adb4 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6583,6 +6583,20 @@ void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp)
 	}
 }
 
+static enum exit_fastpath_completion vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
+{
+	if (!is_guest_mode(vcpu)) {
+		switch (to_vmx(vcpu)->exit_reason) {
+		case EXIT_REASON_MSR_WRITE:
+			return handle_fastpath_set_msr_irqoff(vcpu);
+		default:
+			return EXIT_FASTPATH_NONE;
+		}
+	}
+
+	return EXIT_FASTPATH_NONE;
+}
+
 bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
 
 static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
@@ -6757,17 +6771,14 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	if (unlikely(vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
 		return EXIT_FASTPATH_NONE;
 
-	if (!is_guest_mode(vcpu) && vmx->exit_reason == EXIT_REASON_MSR_WRITE)
-		exit_fastpath = handle_fastpath_set_msr_irqoff(vcpu);
-	else
-		exit_fastpath = EXIT_FASTPATH_NONE;
-
 	vmx->loaded_vmcs->launched = 1;
 	vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
 
 	vmx_recover_nmi_blocking(vmx);
 	vmx_complete_interrupts(vmx);
 
+	exit_fastpath = vmx_exit_handlers_fastpath(vcpu);
+
 	return exit_fastpath;
 }
 
-- 
2.7.4