[PATCH] kvm tools: Emulate RTC to fix system time in guests

[Pekka Enberg <penberg@kernel.org>]

This patch fixes system time in guests by implementing proper CMOS RTC clock
support.

  # Before:

  sh-2.05b# date
  Fri Aug  7 04:02:01 UTC 2009

  # After:

  sh-2.05b# date
  Thu Apr 28 19:12:21 UTC 2011

Cc: Asias He <asias.hejun@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Prasad Joshi <prasadjoshi124@gmail.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
---
 tools/kvm/Makefile          |    3 +-
 tools/kvm/include/kvm/rtc.h |    6 +++
 tools/kvm/ioport.c          |   26 -------------
 tools/kvm/kvm-run.c         |    3 +
 tools/kvm/rtc.c             |   87 +++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 98 insertions(+), 27 deletions(-)
 create mode 100644 tools/kvm/include/kvm/rtc.h
 create mode 100644 tools/kvm/rtc.c

diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile
index fbce14d..659bc35 100644
--- a/tools/kvm/Makefile
+++ b/tools/kvm/Makefile
@@ -26,8 +26,9 @@ OBJS	+= kvm-cpu.o
 OBJS	+= main.o
 OBJS	+= mmio.o
 OBJS	+= pci.o
-OBJS	+= util.o
+OBJS	+= rtc.o
 OBJS	+= term.o
+OBJS	+= util.o
 OBJS	+= virtio.o
 OBJS    += util/parse-options.o
 OBJS    += util/strbuf.o
diff --git a/tools/kvm/include/kvm/rtc.h b/tools/kvm/include/kvm/rtc.h
new file mode 100644
index 0000000..0b8d9f9
--- /dev/null
+++ b/tools/kvm/include/kvm/rtc.h
@@ -0,0 +1,6 @@
+#ifndef KVM__RTC_H
+#define KVM__RTC_H
+
+void rtc__init(void);
+
+#endif /* KVM__RTC_H */
diff --git a/tools/kvm/ioport.c b/tools/kvm/ioport.c
index e3f67fc..a38d2d1 100644
--- a/tools/kvm/ioport.c
+++ b/tools/kvm/ioport.c
@@ -12,28 +12,6 @@
 
 bool ioport_debug;
 
-static uint8_t ioport_to_uint8(void *data)
-{
-	uint8_t *p = data;
-
-	return *p;
-}
-
-static bool cmos_ram_rtc_io_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
-{
-	uint8_t value;
-
-	value	= ioport_to_uint8(data);
-
-	self->nmi_disabled	= value & (1UL << 7);
-
-	return true;
-}
-
-static struct ioport_operations cmos_ram_rtc_ops = {
-	.io_out		= cmos_ram_rtc_io_out,
-};
-
 static bool debug_io_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
 {
 	exit(EXIT_SUCCESS);
@@ -128,10 +106,6 @@ void ioport__setup_legacy(void)
 	ioport__register(0x0060, &dummy_read_write_ioport_ops, 2);
 	ioport__register(0x0064, &dummy_read_write_ioport_ops, 1);
 
-	/* PORT 0070-007F - CMOS RAM/RTC (REAL TIME CLOCK) */
-	ioport__register(0x0070, &cmos_ram_rtc_ops, 1);
-	ioport__register(0x0071, &dummy_read_write_ioport_ops, 1);
-
 	/* 0x00A0 - 0x00AF - 8259A PIC 2 */
 	ioport__register(0x00A0, &dummy_read_write_ioport_ops, 2);
 
diff --git a/tools/kvm/kvm-run.c b/tools/kvm/kvm-run.c
index b21b4a2..64f3409 100644
--- a/tools/kvm/kvm-run.c
+++ b/tools/kvm/kvm-run.c
@@ -22,6 +22,7 @@
 #include <kvm/disk-image.h>
 #include <kvm/util.h>
 #include <kvm/pci.h>
+#include <kvm/rtc.h>
 #include <kvm/term.h>
 #include <kvm/ioport.h>
 #include <kvm/threadpool.h>
@@ -416,6 +417,8 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
 
 	ioport__setup_legacy();
 
+	rtc__init();
+
 	kvm__setup_bios(kvm);
 
 	serial8250__init(kvm);
diff --git a/tools/kvm/rtc.c b/tools/kvm/rtc.c
new file mode 100644
index 0000000..b9c09b9
--- /dev/null
+++ b/tools/kvm/rtc.c
@@ -0,0 +1,87 @@
+#include "kvm/rtc.h"
+
+#include "kvm/ioport.h"
+#include "kvm/kvm.h"
+
+#include <time.h>
+
+static uint8_t cmos_index;
+
+#define CMOS_RTC_SECONDS		0x00
+#define CMOS_RTC_MINUTES		0x02
+#define CMOS_RTC_HOURS			0x04
+#define CMOS_RTC_DATE_OF_MONTH		0x07
+#define CMOS_RTC_MONTH			0x08
+#define CMOS_RTC_YEAR			0x09
+
+static inline unsigned char bin2bcd(unsigned val)
+{
+	return ((val / 10) << 4) + val % 10;
+}
+
+static bool cmos_ram_data_in(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
+{
+	struct tm *tm;
+	time_t ti;
+
+	time(&ti);
+
+	tm = gmtime(&ti);
+
+	switch (cmos_index) {
+	case CMOS_RTC_SECONDS:
+		ioport__write8(data, bin2bcd(tm->tm_sec));
+		break;
+	case CMOS_RTC_MINUTES:
+		ioport__write8(data, bin2bcd(tm->tm_min));
+		break;
+	case CMOS_RTC_HOURS:
+		ioport__write8(data, bin2bcd(tm->tm_hour));
+		break;
+	case CMOS_RTC_DATE_OF_MONTH:
+		ioport__write8(data, bin2bcd(tm->tm_mday));
+		break;
+	case CMOS_RTC_MONTH:
+		ioport__write8(data, bin2bcd(tm->tm_mon + 1));
+		break;
+	case CMOS_RTC_YEAR:
+		ioport__write8(data, bin2bcd(tm->tm_year));
+		break;
+	}
+
+	return true;
+}
+
+static bool cmos_ram_data_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
+{
+	return true;
+}
+
+static struct ioport_operations cmos_ram_data_ioport_ops = {
+	.io_out		= cmos_ram_data_out,
+	.io_in		= cmos_ram_data_in,
+};
+
+static bool cmos_ram_index_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
+{
+	uint8_t value;
+
+	value	= ioport__read8(data);
+
+	self->nmi_disabled	= value & (1UL << 7);
+
+	cmos_index		= value & ~(1UL << 7);
+
+	return true;
+}
+
+static struct ioport_operations cmos_ram_index_ioport_ops = {
+	.io_out		= cmos_ram_index_out,
+};
+
+void rtc__init(void)
+{
+	/* PORT 0070-007F - CMOS RAM/RTC (REAL TIME CLOCK) */
+	ioport__register(0x0070, &cmos_ram_index_ioport_ops, 1);
+	ioport__register(0x0071, &cmos_ram_data_ioport_ops, 1);
+}
-- 
1.7.0.4