/*
   * 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;
  }
  
  
  int hv_synic_alloc(void)
  {
  	size_t size = sizeof(struct tasklet_struct);
  	int cpu;
  
  	for_each_online_cpu(cpu) {
  		hv_context.event_dpc[cpu] = kmalloc(size, GFP_ATOMIC);
  		if (hv_context.event_dpc[cpu] == NULL) {
  			pr_err("Unable to allocate event dpc
  ");
  			goto err;
  		}
  		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 err;
  		}
  
  		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 err;
  		}
  	}
  
  	return 0;
  err:
  	return -ENOMEM;
  }
  
  static void hv_synic_free_cpu(int cpu)
  {
  	kfree(hv_context.event_dpc[cpu]);
  	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]);
  }
  
  void hv_synic_free(void)
  {
  	int cpu;
  
  	for_each_online_cpu(cpu)
  		hv_synic_free_cpu(cpu);
  }
  
  /*
   * 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);
  
  	/* 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;
  }
  
  /*
   * 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]);
  }