/*

   * Copyright (c) 2009, Microsoft Corporation.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
   * Place - Suite 330, Boston, MA 02111-1307 USA.
   *
   * Authors:
   *   Haiyang Zhang <haiyangz@microsoft.com>
   *   Hank Janssen  <hjanssen@microsoft.com>
   *
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/kernel.h>
  #include <linux/mm.h>

  #include <linux/slab.h>

  #include <linux/vmalloc.h>

  #include <linux/hyperv.h>

  #include <linux/version.h>

  #include <linux/interrupt.h>

  #include <asm/hyperv.h>

  #include "hyperv_vmbus.h"

  /* The one and only */

  struct hv_context hv_context = {
  	.synic_initialized	= false,
  	.hypercall_page		= NULL,

  };

  /*

   * query_hypervisor_info - Get version info of the windows hypervisor

   */

  unsigned int host_info_eax;
  unsigned int host_info_ebx;
  unsigned int host_info_ecx;
  unsigned int host_info_edx;

  static int query_hypervisor_info(void)

  {
  	unsigned int eax;
  	unsigned int ebx;
  	unsigned int ecx;
  	unsigned int edx;

  	unsigned int max_leaf;

  	unsigned int op;

  	/*
  	* Its assumed that this is called after confirming that Viridian
  	* is present. Query id and revision.
  	*/
  	eax = 0;
  	ebx = 0;
  	ecx = 0;
  	edx = 0;

  	op = HVCPUID_VENDOR_MAXFUNCTION;

  	cpuid(op, &eax, &ebx, &ecx, &edx);

  	max_leaf = eax;

  	if (max_leaf >= HVCPUID_VERSION) {

  		eax = 0;
  		ebx = 0;
  		ecx = 0;
  		edx = 0;

  		op = HVCPUID_VERSION;

  		cpuid(op, &eax, &ebx, &ecx, &edx);

  		host_info_eax = eax;
  		host_info_ebx = ebx;
  		host_info_ecx = ecx;
  		host_info_edx = edx;

  	}

  	return max_leaf;

  }

  /*

   * do_hypercall- Invoke the specified hypercall

   */

  static u64 do_hypercall(u64 control, void *input, void *output)

  {

  #ifdef CONFIG_X86_64

  	u64 hv_status = 0;
  	u64 input_address = (input) ? virt_to_phys(input) : 0;
  	u64 output_address = (output) ? virt_to_phys(output) : 0;

  	void *hypercall_page = hv_context.hypercall_page;

  	__asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");
  	__asm__ __volatile__("call *%3" : "=a" (hv_status) :
  			     "c" (control), "d" (input_address),
  			     "m" (hypercall_page));

  	return hv_status;

  
  #else

  	u32 control_hi = control >> 32;
  	u32 control_lo = control & 0xFFFFFFFF;
  	u32 hv_status_hi = 1;
  	u32 hv_status_lo = 1;
  	u64 input_address = (input) ? virt_to_phys(input) : 0;
  	u32 input_address_hi = input_address >> 32;
  	u32 input_address_lo = input_address & 0xFFFFFFFF;
  	u64 output_address = (output) ? virt_to_phys(output) : 0;
  	u32 output_address_hi = output_address >> 32;
  	u32 output_address_lo = output_address & 0xFFFFFFFF;

  	void *hypercall_page = hv_context.hypercall_page;

  	__asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi),
  			      "=a"(hv_status_lo) : "d" (control_hi),
  			      "a" (control_lo), "b" (input_address_hi),
  			      "c" (input_address_lo), "D"(output_address_hi),
  			      "S"(output_address_lo), "m" (hypercall_page));

  	return hv_status_lo | ((u64)hv_status_hi << 32);

  #endif /* !x86_64 */

  }

  /*

   * hv_init - Main initialization routine.

   *
   * This routine must be called before any other routines in here are called
   */

  int hv_init(void)

  {

  	int max_leaf;
  	union hv_x64_msr_hypercall_contents hypercall_msr;
  	void *virtaddr = NULL;

  	memset(hv_context.synic_event_page, 0, sizeof(void *) * NR_CPUS);

  	memset(hv_context.synic_message_page, 0,

  	       sizeof(void *) * NR_CPUS);

  	memset(hv_context.vp_index, 0,
  	       sizeof(int) * NR_CPUS);

  	memset(hv_context.event_dpc, 0,
  	       sizeof(void *) * NR_CPUS);

  	max_leaf = query_hypervisor_info();

  	/*
  	 * Write our OS ID.
  	 */
  	hv_context.guestid = generate_guest_id(0, LINUX_VERSION_CODE, 0);
  	wrmsrl(HV_X64_MSR_GUEST_OS_ID, hv_context.guestid);

  	/* See if the hypercall page is already set */

  	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

  	virtaddr = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_EXEC);

  	if (!virtaddr)

  		goto cleanup;

  	hypercall_msr.enable = 1;

  	hypercall_msr.guest_physical_address = vmalloc_to_pfn(virtaddr);
  	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

  
  	/* Confirm that hypercall page did get setup. */

  	hypercall_msr.as_uint64 = 0;
  	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

  	if (!hypercall_msr.enable)

  		goto cleanup;

  	hv_context.hypercall_page = virtaddr;

  	return 0;

  cleanup:

  	if (virtaddr) {
  		if (hypercall_msr.enable) {
  			hypercall_msr.as_uint64 = 0;
  			wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

  		}

  		vfree(virtaddr);

  	}

  
  	return -ENOTSUPP;

  }

  /*

   * hv_cleanup - Cleanup routine.

   *
   * This routine is called normally during driver unloading or exiting.
   */

  void hv_cleanup(void)

  {

  	union hv_x64_msr_hypercall_contents hypercall_msr;

  	/* Reset our OS id */
  	wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);

  	if (hv_context.hypercall_page) {

  		hypercall_msr.as_uint64 = 0;
  		wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

  		vfree(hv_context.hypercall_page);
  		hv_context.hypercall_page = NULL;

  	}

  }

  /*

   * hv_post_message - Post a message using the hypervisor message IPC.

   *
   * This involves a hypercall.
   */

  int hv_post_message(union hv_connection_id connection_id,

  		  enum hv_message_type message_type,
  		  void *payload, size_t payload_size)

  {

  	struct aligned_input {

  		u64 alignment8;

  		struct hv_input_post_message msg;

  	};

  	struct hv_input_post_message *aligned_msg;

  	u16 status;

  	unsigned long addr;

  	if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)

  		return -EMSGSIZE;

  	addr = (unsigned long)kmalloc(sizeof(struct aligned_input), GFP_ATOMIC);

  	if (!addr)

  		return -ENOMEM;

  	aligned_msg = (struct hv_input_post_message *)

  			(ALIGN(addr, HV_HYPERCALL_PARAM_ALIGN));

  	aligned_msg->connectionid = connection_id;
  	aligned_msg->message_type = message_type;
  	aligned_msg->payload_size = payload_size;
  	memcpy((void *)aligned_msg->payload, payload, payload_size);

  	status = do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL)
  		& 0xFFFF;

  	kfree((void *)addr);

  
  	return status;
  }

  /*

   * hv_signal_event -
   * Signal an event on the specified connection using the hypervisor event IPC.

   *
   * This involves a hypercall.
   */

  u16 hv_signal_event(void *con_id)

  {

  	u16 status;

  	status = (do_hypercall(HVCALL_SIGNAL_EVENT, con_id, NULL) & 0xFFFF);

  	return status;
  }

  /*

   * hv_synic_init - Initialize the Synthethic Interrupt Controller.

   *
   * If it is already initialized by another entity (ie x2v shim), we need to
   * retrieve the initialized message and event pages.  Otherwise, we create and
   * initialize the message and event pages.
   */

  void hv_synic_init(void *arg)

  {

  	u64 version;

  	union hv_synic_simp simp;
  	union hv_synic_siefp siefp;

  	union hv_synic_sint shared_sint;

  	union hv_synic_scontrol sctrl;

  	u64 vp_index;

  	int cpu = smp_processor_id();

  	if (!hv_context.hypercall_page)

  		return;

  	/* Check the version */

  	rdmsrl(HV_X64_MSR_SVERSION, version);

  	hv_context.event_dpc[cpu] = kmalloc(sizeof(struct tasklet_struct),
  					    GFP_ATOMIC);

  	if (hv_context.event_dpc[cpu] == NULL) {
  		pr_err("Unable to allocate event dpc
  ");
  		goto cleanup;
  	}
  	tasklet_init(hv_context.event_dpc[cpu], vmbus_on_event, cpu);

  	hv_context.synic_message_page[cpu] =
  		(void *)get_zeroed_page(GFP_ATOMIC);

  	if (hv_context.synic_message_page[cpu] == NULL) {

  		pr_err("Unable to allocate SYNIC message page
  ");

  		goto cleanup;

  	}

  	hv_context.synic_event_page[cpu] =
  		(void *)get_zeroed_page(GFP_ATOMIC);

  	if (hv_context.synic_event_page[cpu] == NULL) {

  		pr_err("Unable to allocate SYNIC event page
  ");

  		goto cleanup;

  	}

  	/* Setup the Synic's message page */

  	rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
  	simp.simp_enabled = 1;

  	simp.base_simp_gpa = virt_to_phys(hv_context.synic_message_page[cpu])

  		>> PAGE_SHIFT;

  	wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);

  	/* Setup the Synic's event page */

  	rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
  	siefp.siefp_enabled = 1;

  	siefp.base_siefp_gpa = virt_to_phys(hv_context.synic_event_page[cpu])

  		>> PAGE_SHIFT;

  	wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);

  	/* Setup the shared SINT. */

  	rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

  	shared_sint.as_uint64 = 0;

  	shared_sint.vector = HYPERVISOR_CALLBACK_VECTOR;

  	shared_sint.masked = false;

  	shared_sint.auto_eoi = true;

  	wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

  	/* Enable the global synic bit */

  	rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
  	sctrl.enable = 1;

  	wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);

  	hv_context.synic_initialized = true;

  
  	/*
  	 * Setup the mapping between Hyper-V's notion
  	 * of cpuid and Linux' notion of cpuid.
  	 * This array will be indexed using Linux cpuid.
  	 */
  	rdmsrl(HV_X64_MSR_VP_INDEX, vp_index);
  	hv_context.vp_index[cpu] = (u32)vp_index;

  	return;

  cleanup:

  	if (hv_context.synic_event_page[cpu])

  		free_page((unsigned long)hv_context.synic_event_page[cpu]);

  	if (hv_context.synic_message_page[cpu])

  		free_page((unsigned long)hv_context.synic_message_page[cpu]);

  	return;

  }

  /*

   * hv_synic_cleanup - Cleanup routine for hv_synic_init().

   */

  void hv_synic_cleanup(void *arg)

  {

  	union hv_synic_sint shared_sint;

  	union hv_synic_simp simp;
  	union hv_synic_siefp siefp;

  	int cpu = smp_processor_id();

  	if (!hv_context.synic_initialized)

  		return;

  	rdmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

  	shared_sint.masked = 1;

  	/* Need to correctly cleanup in the case of SMP!!! */

  	/* Disable the interrupt */

  	wrmsrl(HV_X64_MSR_SINT0 + VMBUS_MESSAGE_SINT, shared_sint.as_uint64);

  	rdmsrl(HV_X64_MSR_SIMP, simp.as_uint64);
  	simp.simp_enabled = 0;
  	simp.base_simp_gpa = 0;

  	wrmsrl(HV_X64_MSR_SIMP, simp.as_uint64);

  	rdmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
  	siefp.siefp_enabled = 0;
  	siefp.base_siefp_gpa = 0;

  	wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);

  	free_page((unsigned long)hv_context.synic_message_page[cpu]);
  	free_page((unsigned long)hv_context.synic_event_page[cpu]);

  }