clocksource/drivers: Make Hyper-V clocksource ISA agnostic

Hyper-V clock/timer code and data structures are currently mixed
in with other code in the ISA independent drivers/hv directory as
well as the ISA dependent Hyper-V code under arch/x86.

Consolidate this code and data structures into a Hyper-V clocksource driver
to better follow the Linux model. In doing so, separate out the ISA
dependent portions so the new clocksource driver works for x86 and for the
in-process Hyper-V on ARM64 code.

To start, move the existing clockevents code to create the new clocksource
driver. Update the VMbus driver to call initialization and cleanup routines
since the Hyper-V synthetic timers are not independently enumerated in
ACPI.

No behavior is changed and no new functionality is added.

Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "bp@alien8.de" <bp@alien8.de>
Cc: "will.deacon@arm.com" <will.deacon@arm.com>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>
Cc: "apw@canonical.com" <apw@canonical.com>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>
Cc: Sunil Muthuswamy <sunilmut@microsoft.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: "sashal@kernel.org" <sashal@kernel.org>
Cc: "vincenzo.frascino@arm.com" <vincenzo.frascino@arm.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Cc: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Cc: "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>
Cc: "arnd@arndb.de" <arnd@arndb.de>
Cc: "linux@armlinux.org.uk" <linux@armlinux.org.uk>
Cc: "ralf@linux-mips.org" <ralf@linux-mips.org>
Cc: "paul.burton@mips.com" <paul.burton@mips.com>
Cc: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Cc: "salyzyn@android.com" <salyzyn@android.com>
Cc: "pcc@google.com" <pcc@google.com>
Cc: "shuah@kernel.org" <shuah@kernel.org>
Cc: "0x7f454c46@gmail.com" <0x7f454c46@gmail.com>
Cc: "linux@rasmusvillemoes.dk" <linux@rasmusvillemoes.dk>
Cc: "huw@codeweavers.com" <huw@codeweavers.com>
Cc: "sfr@canb.auug.org.au" <sfr@canb.auug.org.au>
Cc: "pbonzini@redhat.com" <pbonzini@redhat.com>
Cc: "rkrcmar@redhat.com" <rkrcmar@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Link: https://lkml.kernel.org/r/1561955054-1838-2-git-send-email-mikelley@microsoft.com

drivers/hv/vmbus_drv.c

@@ -30,6 +30,7 @@
 #include <linux/kdebug.h>
 #include <linux/efi.h>
 #include <linux/random.h>
+#include <clocksource/hyperv_timer.h>
 #include "hyperv_vmbus.h"
 
 struct vmbus_dynid {
@@ -955,17 +956,6 @@ static void vmbus_onmessage_work(struct work_struct *work)
 	kfree(ctx);
 }
 
-static void hv_process_timer_expiration(struct hv_message *msg,
-					struct hv_per_cpu_context *hv_cpu)
-{
-	struct clock_event_device *dev = hv_cpu->clk_evt;
-
-	if (dev->event_handler)
-		dev->event_handler(dev);
-
-	vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
-}
-
 void vmbus_on_msg_dpc(unsigned long data)
 {
 	struct hv_per_cpu_context *hv_cpu = (void *)data;
@@ -1159,9 +1149,10 @@ static void vmbus_isr(void)
 
 	/* Check if there are actual msgs to be processed */
 	if (msg->header.message_type != HVMSG_NONE) {
-		if (msg->header.message_type == HVMSG_TIMER_EXPIRED)
-			hv_process_timer_expiration(msg, hv_cpu);
-		else
+		if (msg->header.message_type == HVMSG_TIMER_EXPIRED) {
+			hv_stimer0_isr();
+			vmbus_signal_eom(msg, HVMSG_TIMER_EXPIRED);
+		} else
 			tasklet_schedule(&hv_cpu->msg_dpc);
 	}
 
@@ -1263,14 +1254,19 @@ static int vmbus_bus_init(void)
 	ret = hv_synic_alloc();
 	if (ret)
 		goto err_alloc;
+
+	ret = hv_stimer_alloc(VMBUS_MESSAGE_SINT);
+	if (ret < 0)
+		goto err_alloc;
+
 	/*
-	 * Initialize the per-cpu interrupt state and
-	 * connect to the host.
+	 * Initialize the per-cpu interrupt state and stimer state.
+	 * Then connect to the host.
 	 */
 	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus:online",
 				hv_synic_init, hv_synic_cleanup);
 	if (ret < 0)
-		goto err_alloc;
+		goto err_cpuhp;
 	hyperv_cpuhp_online = ret;
 
 	ret = vmbus_connect();
@@ -1318,6 +1314,8 @@ static int vmbus_bus_init(void)
 
 err_connect:
 	cpuhp_remove_state(hyperv_cpuhp_online);
+err_cpuhp:
+	hv_stimer_free();
 err_alloc:
 	hv_synic_free();
 	hv_remove_vmbus_irq();
@@ -2064,7 +2062,7 @@ static struct acpi_driver vmbus_acpi_driver = {
 
 static void hv_kexec_handler(void)
 {
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_initiate_unload(false);
 	vmbus_connection.conn_state = DISCONNECTED;
 	/* Make sure conn_state is set as hv_synic_cleanup checks for it */
@@ -2075,6 +2073,8 @@ static void hv_kexec_handler(void)
 
 static void hv_crash_handler(struct pt_regs *regs)
 {
+	int cpu;
+
 	vmbus_initiate_unload(true);
 	/*
 	 * In crash handler we can't schedule synic cleanup for all CPUs,
@@ -2082,7 +2082,9 @@ static void hv_crash_handler(struct pt_regs *regs)
 	 * for kdump.
 	 */
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_cleanup(smp_processor_id());
+	cpu = smp_processor_id();
+	hv_stimer_cleanup(cpu);
+	hv_synic_cleanup(cpu);
 	hyperv_cleanup();
 };
 
@@ -2131,7 +2133,7 @@ static void __exit vmbus_exit(void)
 	hv_remove_kexec_handler();
 	hv_remove_crash_handler();
 	vmbus_connection.conn_state = DISCONNECTED;
-	hv_synic_clockevents_cleanup();
+	hv_stimer_global_cleanup();
 	vmbus_disconnect();
 	hv_remove_vmbus_irq();
 	for_each_online_cpu(cpu) {