From: David Woodhouse <dwmw@amazon.co.uk>
Date: Mon, 2 Oct 2023 10:15:10 +0000 (+0100)
Subject: timer hack to show kvmclock drift
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ccc5926d03f10f017a4bcceec6b4ed4277af3388;p=users%2Fdwmw2%2Flinux.git

timer hack to show kvmclock drift
---

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 856b12875bcbe..6631f9a2a366a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3262,7 +3262,7 @@ uint64_t kvm_get_wall_clock_epoch(struct kvm *kvm)
 		local_tsc_khz = get_cpu_tsc_khz();
 
 		if (local_tsc_khz &&
-		    !kvm_get_walltime_and_clockread(&ts, &host_tsc))
+		    !kvm_get_time_and_clockread(&ts.tv_sec, &host_tsc))
 			local_tsc_khz = 0; /* Fall back to old method */
 
 		hv_clock.tsc_timestamp = ka->master_cycle_now;
@@ -3280,6 +3280,14 @@ uint64_t kvm_get_wall_clock_epoch(struct kvm *kvm)
 		kvm_get_time_scale(NSEC_PER_SEC, local_tsc_khz * 1000LL,
 				   &hv_clock.tsc_shift,
 				   &hv_clock.tsc_to_system_mul);
+
+		uint64_t res = __pvclock_read_cycles(&hv_clock, host_tsc);
+		uint64_t d2 = ts.tv_sec + ka->kvmclock_offset;
+		printk("Calculated %lld (%lld/%lld delta %lld, ns %lld o %lld)\n",
+		       res,
+		       ts.tv_sec, d2, d2-res,
+		       ka->master_kernel_ns, ka->kvmclock_offset);
+		if (0)
 		return ts.tv_nsec + NSEC_PER_SEC * ts.tv_sec -
 			__pvclock_read_cycles(&hv_clock, host_tsc);
 	}
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 6bab715be428d..276a5b602d9bd 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -106,7 +106,7 @@ static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
 	wc->version = wc_version + 1;
 	read_unlock_irq(&gpc->lock);
 
-	kvm_make_all_cpus_request(kvm, KVM_REQ_MASTERCLOCK_UPDATE);
+	//kvm_make_all_cpus_request(kvm, KVM_REQ_MASTERCLOCK_UPDATE);
 
 out:
 	srcu_read_unlock(&kvm->srcu, idx);