KVM: paravirtualized clocksource: host part

This is the host part of kvm clocksource implementation. As it does
not include clockevents, it is a fairly simple implementation. We
only have to register a per-vcpu area, and start writing to it periodically.

The area is binary compatible with xen, as we use the same shadow_info
structure.

[marcelo: fix bad_page on MSR_KVM_SYSTEM_TIME]
[avi: save full value of the msr, even if enable bit is clear]
[avi: clear previous value of time_page]

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/include/asm-x86/kvm_para.h b/include/asm-x86/kvm_para.h
index c6f3fd8d8c53..5ab7d3dbd357 100644
--- a/include/asm-x86/kvm_para.h
+++ b/include/asm-x86/kvm_para.h
@@ -10,10 +10,35 @@
  * paravirtualization, the appropriate feature bit should be checked.
  */
 #define KVM_CPUID_FEATURES      0x40000001
+#define KVM_FEATURE_CLOCKSOURCE 0
+
+#define MSR_KVM_WALL_CLOCK  0x11
+#define MSR_KVM_SYSTEM_TIME 0x12
 
 #ifdef __KERNEL__
 #include <asm/processor.h>
 
+/* xen binary-compatible interface. See xen headers for details */
+struct kvm_vcpu_time_info {
+        uint32_t version;
+        uint32_t pad0;
+        uint64_t tsc_timestamp;
+        uint64_t system_time;
+        uint32_t tsc_to_system_mul;
+        int8_t   tsc_shift;
+        int8_t   pad[3];
+} __attribute__((__packed__)); /* 32 bytes */
+
+struct kvm_wall_clock {
+        uint32_t wc_version;
+        uint32_t wc_sec;
+        uint32_t wc_nsec;
+} __attribute__((__packed__));
+
+
+extern void kvmclock_init(void);
+
+
 /* This instruction is vmcall.  On non-VT architectures, it will generate a
  * trap that we will then rewrite to the appropriate instruction.
  */