linux-uek5-v4.14.35-2047.515.0-kvm.patch

From 134307954a497c361ecdb2a0b9ff41a2f2ad637e Mon Sep 17 00:00:00 2001
From: Dongli Zhang <dongli.zhang0129@gmail.com>
Date: Sun, 10 Jul 2022 17:40:35 -0700
Subject: [PATCH 1/1] linux-uek5-v4.14.35-2047.515.0-kvm

Signed-off-by: Dongli Zhang <dongli.zhang0129@gmail.com>
---
 arch/x86/kvm/x86.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0b443b9bf562..95744c5df70a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1428,12 +1428,22 @@ struct pvclock_gtod_data {
 	} clock;
 
 	u64		boot_ns;
+	/*
+	 * 在以下使用pvclock_gtod_data->nsec_base:
+	 *   - arch/x86/kvm/x86.c|1454| <<update_pvclock_gtod>> vdata->nsec_base = tk->tkr_mono.xtime_nsec;
+	 *   - arch/x86/kvm/x86.c|1937| <<do_monotonic_boot>> ns = gtod->nsec_base;
+	 *   - arch/x86/kvm/x86.c|1957| <<do_realtime>> ns = gtod->nsec_base;
+	 */
 	u64		nsec_base;
 	u64		wall_time_sec;
 };
 
 static struct pvclock_gtod_data pvclock_gtod_data;
 
+/*
+ * called by:
+ *   - arch/x86/kvm/x86.c|6948| <<pvclock_gtod_notify>> update_pvclock_gtod(tk);
+ */
 static void update_pvclock_gtod(struct timekeeper *tk)
 {
 	struct pvclock_gtod_data *vdata = &pvclock_gtod_data;
@@ -1444,6 +1454,11 @@ static void update_pvclock_gtod(struct timekeeper *tk)
 	write_seqcount_begin(&vdata->seq);
 
 	/* copy pvclock gtod data */
+	/*
+	 * struct timekeeper *tk:
+	 * -> struct tk_read_base     tkr_mono; --> CLOCK_MONOTONIC
+	 * -> struct tk_read_base     tkr_raw;  --> CLOCK_MONOTONIC_RAW
+	 */
 	vdata->clock.vclock_mode	= tk->tkr_mono.clock->archdata.vclock_mode;
 	vdata->clock.cycle_last		= tk->tkr_mono.cycle_last;
 	vdata->clock.mask		= tk->tkr_mono.mask;
@@ -1743,6 +1758,11 @@ static inline bool kvm_check_tsc_unstable(void)
 	return check_tsc_unstable();
 }
 
+/*
+ * called by:
+ *   - arch/x86/kvm/x86.c|2571| <<kvm_set_msr_common(MSR_IA32_TSC)>> kvm_write_tsc(vcpu, msr_info);
+ *   - arch/x86/kvm/x86.c|8852| <<kvm_arch_vcpu_postcreate>> kvm_write_tsc(vcpu, &msr);
+ */
 void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -1925,6 +1945,10 @@ static inline u64 vgettsc(u64 *tsc_timestamp, int *mode)
 	return v * gtod->clock.mult;
 }
 
+/*
+ * called by:
+ *   - arch/x86/kvm/x86.c|1975| <<kvm_get_time_and_clockread>> return gtod_is_based_on_tsc(do_monotonic_boot(kernel_ns,
+ */
 static int do_monotonic_boot(s64 *t, u64 *tsc_timestamp)
 {
 	struct pvclock_gtod_data *gtod = &pvclock_gtod_data;
@@ -1934,6 +1958,12 @@ static int do_monotonic_boot(s64 *t, u64 *tsc_timestamp)
 
 	do {
 		seq = read_seqcount_begin(&gtod->seq);
+		/*
+		 * 在以下使用pvclock_gtod_data->nsec_base:
+		 *   - arch/x86/kvm/x86.c|1454| <<update_pvclock_gtod>> vdata->nsec_base = tk->tkr_mono.xtime_nsec;
+		 *   - arch/x86/kvm/x86.c|1937| <<do_monotonic_boot>> ns = gtod->nsec_base;
+		 *   - arch/x86/kvm/x86.c|1957| <<do_realtime>> ns = gtod->nsec_base;
+		 */
 		ns = gtod->nsec_base;
 		ns += vgettsc(tsc_timestamp, &mode);
 		ns >>= gtod->clock.shift;
@@ -1966,6 +1996,10 @@ static int do_realtime(struct timespec64 *ts, u64 *tsc_timestamp)
 }
 
 /* returns true if host is using TSC based clocksource */
+/*
+ * called by:
+ *   - arch/x86/kvm/x86.c|2046| <<pvclock_update_vm_gtod_copy>> host_tsc_clocksource = kvm_get_time_and_clockread(
+ */
 static bool kvm_get_time_and_clockread(s64 *kernel_ns, u64 *tsc_timestamp)
 {
 	/* checked again under seqlock below */
@@ -2029,6 +2063,12 @@ static bool kvm_get_walltime_and_clockread(struct timespec64 *ts,
  *
  */
 
+/*
+ * called by:
+ *   - arch/x86/kvm/x86.c|2078| <<kvm_gen_update_masterclock>> pvclock_update_vm_gtod_copy(kvm);
+ *   - arch/x86/kvm/x86.c|6754| <<kvm_hyperv_tsc_notifier>> pvclock_update_vm_gtod_copy(kvm);
+ *   - arch/x86/kvm/x86.c|9229| <<kvm_arch_init_vm>> pvclock_update_vm_gtod_copy(kvm);
+ */
 static void pvclock_update_vm_gtod_copy(struct kvm *kvm)
 {
 #ifdef CONFIG_X86_64
@@ -2065,6 +2105,11 @@ void kvm_make_mclock_inprogress_request(struct kvm *kvm)
 	kvm_make_all_cpus_request(kvm, KVM_REQ_MCLOCK_INPROGRESS);
 }
 
+/*
+ * called by:
+ *   - arch/x86/kvm/x86.c|4913| <<kvm_arch_vm_ioctl(KVM_SET_CLOCK)>> kvm_gen_update_masterclock(kvm);
+ *   - arch/x86/kvm/x86.c|7747| <<vcpu_enter_guest(KVM_REQ_MASTERCLOCK_UPDATE)>> kvm_gen_update_masterclock(vcpu->kvm);
+ */
 static void kvm_gen_update_masterclock(struct kvm *kvm)
 {
 #ifdef CONFIG_X86_64
-- 
2.17.1