[PATCH 4/4] KVM: x86: open pv lazy tscdeadline forcily w/o modification in qemu

[Wang Jianchao]

This is not part of the patchset, but just a debug patch to make
the test convenient. It can open the pv lazy tscdeadline w/o
involving the qemu.

echo 1 > /proc/sys/kernel/apic_lazy_tsc_deadline

Since it is just for testing, the serializing is not so exact.
Please use it w/o any running guests ;)

Signed-off-by: Wang Jianchao <jianchwa@xxxxxxxxxxx>
---
 arch/x86/kernel/apic/apic.c |  1 +
 arch/x86/kvm/cpuid.c        | 13 +++++++++++++
 kernel/sysctl.c             | 12 ++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 0fe1215..e60aaa3 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -679,6 +679,7 @@ static void setup_APIC_timer(void)
 		if (kvm_para_available() &&
 		    kvm_para_has_feature(KVM_FEATURE_LAZY_TSCDEADLINE)) {
 			levt->set_next_event = kvm_lapic_next_deadline;
+			pr_info("%s: switch set_next_event to lazy tscdeadline version\n", __func__);
 		} else {
 			levt->set_next_event = lapic_next_deadline;
 		}
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 5a12601..ee5a828 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -380,9 +380,12 @@ u64 kvm_vcpu_reserved_gpa_bits_raw(struct kvm_vcpu *vcpu)
 	return rsvd_bits(cpuid_maxphyaddr(vcpu), 63);
 }
 
+extern int sysctl_apic_lazy_tsc_deadline;
+
 static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
                         int nent)
 {
+	struct kvm_cpuid_entry2 *pve2;
 	int r;
 
 	__kvm_update_cpuid_runtime(vcpu, e2, nent);
@@ -423,6 +426,16 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
 
 	vcpu->arch.kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
 	vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
+
+	if (sysctl_apic_lazy_tsc_deadline) {
+		pve2 = kvm_find_kvm_cpuid_features(vcpu);
+		if (pve2) {
+			pr_info("set lazy tscdeadline forcily\n");
+			pve2->eax |= 1 << KVM_FEATURE_LAZY_TSCDEADLINE;
+		} else {
+			pr_err("cannot open lazy tscdeadline forcily\n");
+		}
+	}
 	kvm_vcpu_after_set_cpuid(vcpu);
 
 	return 0;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index bfe53e8..f5f94dd 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -137,6 +137,9 @@ int sysctl_legacy_va_layout;
 
 #endif /* CONFIG_SYSCTL */
 
+int sysctl_apic_lazy_tsc_deadline;
+EXPORT_SYMBOL_GPL(sysctl_apic_lazy_tsc_deadline);
+
 /*
  * /proc/sys support
  */
@@ -2055,6 +2058,15 @@ static struct ctl_table kern_table[] = {
 		.extra2		= SYSCTL_INT_MAX,
 	},
 #endif
+	{
+		.procname	= "apic_lazy_tsc_deadline",
+		.data		= &sysctl_apic_lazy_tsc_deadline,
+		.maxlen		= sizeof(sysctl_apic_lazy_tsc_deadline),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
 	{ }
 };
 
-- 
2.7.4


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