paravirt: Add interface to calculate the TSC frequency from pvclock

[bryanv]

Summary

We can later use this to determine the TSC frequency like we do with VMware, instead of the DELAY loop that is not always accurate in an VM.

sys/x86/include/pvclock.h

+/*-
+ * Copyright (c) 2014 Bryan Venteicher <[e-mail]>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+
+#include <machine/cpufunc.h>
+
+#include <x86/hypervisor.h>
+#include <x86/kvm.h>
+
+static int              kvm_cpuid_identify(void);
+
+static uint32_t kvm_cpuid_base = -1;
+static uint32_t kvm_cpuid_high = -1;
+
+static int
+kvm_cpuid_identify(void)
+{
+
+        if (kvm_cpuid_base == -1) {
+                hypervisor_cpuid_base("KVMKVMKVM\0\0", 0, &kvm_cpuid_base,
+                    &kvm_cpuid_high);
+        }
+
+        return (kvm_cpuid_base > 0);
+}
+
+int
+kvm_paravirt_supported(void)
+{
+
+        return (kvm_cpuid_base > 0);
+}
+
+uint32_t
+kvm_get_features(void)
+{
+        u_int regs[4];
+
+        if (kvm_paravirt_supported())
+                do_cpuid(kvm_cpuid_base | KVM_CPUID_FEATURES_LEAF, regs);
+        else
+                regs[0] = 0;
+
+        return (regs[0]);
+}
+
+static void
+kvm_init(void)
+{
+
+        if (kvm_cpuid_identify() != 0)
+                hypervisor_register("KVM", VM_GUEST_KVM, NULL);
+}
+
+HYPERVISOR_SYSINIT(kvm, kvm_init);

sys/x86/x86/pvclock.c

+/*-
+ * Copyright (c) 2014 Bryan Venteicher <[e-mail]>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+
+#include <machine/cpufunc.h>
+
+#include <x86/hypervisor.h>
+#include <x86/kvm.h>
+
+static int              kvm_cpuid_identify(void);
+
+static uint32_t kvm_cpuid_base = -1;
+static uint32_t kvm_cpuid_high = -1;
+
+static int
+kvm_cpuid_identify(void)
+{
+
+        if (kvm_cpuid_base == -1) {
+                hypervisor_cpuid_base("KVMKVMKVM\0\0", 0, &kvm_cpuid_base,
+                    &kvm_cpuid_high);
+        }
+
+        return (kvm_cpuid_base > 0);
+}
+
+int
+kvm_paravirt_supported(void)
+{
+
+        return (kvm_cpuid_base > 0);
+}
+
+uint32_t
+kvm_get_features(void)
+{
+        u_int regs[4];
+
+        if (kvm_paravirt_supported())
+                do_cpuid(kvm_cpuid_base | KVM_CPUID_FEATURES_LEAF, regs);
+        else
+                regs[0] = 0;
+
+        return (regs[0]);
+}
+
+static void
+kvm_init(void)
+{
+
+        if (kvm_cpuid_identify() != 0)
+                hypervisor_register("KVM", VM_GUEST_KVM, NULL);
+}
+
+HYPERVISOR_SYSINIT(kvm, kvm_init);