x86/kvm: Don't waste memory if kvmclock is disabled

Wanpeng Li · bonzini · commit 3c51d0a6c761 · 2022-02-25T10:09:34.000-05:00
Even if "no-kvmclock" is passed in cmdline parameter, the guest kernel
still allocates hvclock_mem which is scaled by the number of vCPUs,
let's check kvmclock enable in advance to avoid this memory waste.

Signed-off-by: Wanpeng Li &lt;wanpengli@tencent.com&gt;
Message-Id: &lt;1645520523-30814-1-git-send-email-wanpengli@tencent.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
@@ -239,6 +239,9 @@ static void __init kvmclock_init_mem(void)
 
 static int __init kvm_setup_vsyscall_timeinfo(void)
 {
+	if (!kvmclock)
+		return 0;
+
 	kvmclock_init_mem();
 
 #ifdef CONFIG_X86_64

Original file line number	Diff line number	Diff line change
`@@ -239,6 +239,9 @@ static void __init kvmclock_init_mem(void)`
`239`	`239`
`240`	`240`	`static int __init kvm_setup_vsyscall_timeinfo(void)`
`241`	`241`	`{`
	`242`	`+ if (!kvmclock)`
	`243`	`+ return 0;`
	`244`	`+`
`242`	`245`	`kvmclock_init_mem();`
`243`	`246`
`244`	`247`	`#ifdef CONFIG_X86_64`