linux-kernel - [PATCH v2] [next] KVM: lapic: allow set apic debug dynamically

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Date:   Thu, 9 May 2019 18:47:57 +0800
From:   Yi Wang <wang.yi59@....com.cn>
To:     pbonzini@...hat.com
Cc:     rkrcmar@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, x86@...nel.org,
        sean.j.christopherson@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, wang.yi59@....com.cn
Subject: [PATCH v2] [next] KVM: lapic: allow set apic debug dynamically

There are many functions invoke apic_debug(), which is defined
a null function by default, and that's incovenient for debuging
lapic.

This patch allows setting apic debug according to add a apic_dbg
parameter of kvm.

Signed-off-by: Yi Wang <wang.yi59@....com.cn>
---
v2: change apic_dbg to bool and tag __read_mostly. Thanks to Sean.

 arch/x86/kvm/lapic.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 9bf70cf..0827e7c 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -54,8 +54,13 @@
 #define PRIu64 "u"
 #define PRIo64 "o"
 
+static bool apic_dbg __read_mostly;
+module_param(apic_dbg, bool, 0644);
+
 /* #define apic_debug(fmt,arg...) printk(KERN_WARNING fmt,##arg) */
-#define apic_debug(fmt, arg...) do {} while (0)
+#define apic_debug(fmt, arg...) do {  if (apic_dbg)   \
+	printk(KERN_DEBUG fmt, ##arg);    \
+} while (0)
 
 /* 14 is the version for Xeon and Pentium 8.4.8*/
 #define APIC_VERSION			(0x14UL | ((KVM_APIC_LVT_NUM - 1) << 16))
-- 
1.8.3.1