/*
   * Copyright 2011 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License, version 2, as
   * published by the Free Software Foundation.
   */
  
  #include <linux/cpu.h>
  #include <linux/kvm_host.h>
  #include <linux/preempt.h>
  #include <linux/export.h>
  #include <linux/sched.h>
  #include <linux/spinlock.h>
  #include <linux/init.h>
  #include <linux/memblock.h>
  #include <linux/sizes.h>
  #include <linux/cma.h>
  #include <linux/bitops.h>
  
  #include <asm/cputable.h>
  #include <asm/kvm_ppc.h>
  #include <asm/kvm_book3s.h>
  #include <asm/archrandom.h>
  #include <asm/xics.h>
  #include <asm/dbell.h>
  #include <asm/cputhreads.h>
  
  #define KVM_CMA_CHUNK_ORDER	18
  
  /*
   * Hash page table alignment on newer cpus(CPU_FTR_ARCH_206)
   * should be power of 2.
   */
  #define HPT_ALIGN_PAGES		((1 << 18) >> PAGE_SHIFT) /* 256k */
  /*
   * By default we reserve 5% of memory for hash pagetable allocation.
   */
  static unsigned long kvm_cma_resv_ratio = 5;
  
  static struct cma *kvm_cma;
  
  static int __init early_parse_kvm_cma_resv(char *p)
  {
  	pr_debug("%s(%s)
  ", __func__, p);
  	if (!p)
  		return -EINVAL;
  	return kstrtoul(p, 0, &kvm_cma_resv_ratio);
  }
  early_param("kvm_cma_resv_ratio", early_parse_kvm_cma_resv);
  
  struct page *kvm_alloc_hpt(unsigned long nr_pages)
  {
  	VM_BUG_ON(order_base_2(nr_pages) < KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
  
  	return cma_alloc(kvm_cma, nr_pages, order_base_2(HPT_ALIGN_PAGES));
  }
  EXPORT_SYMBOL_GPL(kvm_alloc_hpt);
  
  void kvm_release_hpt(struct page *page, unsigned long nr_pages)
  {
  	cma_release(kvm_cma, page, nr_pages);
  }
  EXPORT_SYMBOL_GPL(kvm_release_hpt);
  
  /**
   * kvm_cma_reserve() - reserve area for kvm hash pagetable
   *
   * This function reserves memory from early allocator. It should be
   * called by arch specific code once the memblock allocator
   * has been activated and all other subsystems have already allocated/reserved
   * memory.
   */
  void __init kvm_cma_reserve(void)
  {
  	unsigned long align_size;
  	struct memblock_region *reg;
  	phys_addr_t selected_size = 0;
  
  	/*
  	 * We need CMA reservation only when we are in HV mode
  	 */
  	if (!cpu_has_feature(CPU_FTR_HVMODE))
  		return;
  	/*
  	 * We cannot use memblock_phys_mem_size() here, because
  	 * memblock_analyze() has not been called yet.
  	 */
  	for_each_memblock(memory, reg)
  		selected_size += memblock_region_memory_end_pfn(reg) -
  				 memblock_region_memory_base_pfn(reg);
  
  	selected_size = (selected_size * kvm_cma_resv_ratio / 100) << PAGE_SHIFT;
  	if (selected_size) {
  		pr_debug("%s: reserving %ld MiB for global area
  ", __func__,
  			 (unsigned long)selected_size / SZ_1M);
  		align_size = HPT_ALIGN_PAGES << PAGE_SHIFT;
  		cma_declare_contiguous(0, selected_size, 0, align_size,
  			KVM_CMA_CHUNK_ORDER - PAGE_SHIFT, false, &kvm_cma);
  	}
  }
  
  /*
   * Real-mode H_CONFER implementation.
   * We check if we are the only vcpu out of this virtual core
   * still running in the guest and not ceded.  If so, we pop up
   * to the virtual-mode implementation; if not, just return to
   * the guest.
   */
  long int kvmppc_rm_h_confer(struct kvm_vcpu *vcpu, int target,
  			    unsigned int yield_count)
  {
  	struct kvmppc_vcore *vc = local_paca->kvm_hstate.kvm_vcore;
  	int ptid = local_paca->kvm_hstate.ptid;
  	int threads_running;
  	int threads_ceded;
  	int threads_conferring;
  	u64 stop = get_tb() + 10 * tb_ticks_per_usec;
  	int rv = H_SUCCESS; /* => don't yield */
  
  	set_bit(ptid, &vc->conferring_threads);
  	while ((get_tb() < stop) && !VCORE_IS_EXITING(vc)) {
  		threads_running = VCORE_ENTRY_MAP(vc);
  		threads_ceded = vc->napping_threads;
  		threads_conferring = vc->conferring_threads;
  		if ((threads_ceded | threads_conferring) == threads_running) {
  			rv = H_TOO_HARD; /* => do yield */
  			break;
  		}
  	}
  	clear_bit(ptid, &vc->conferring_threads);
  	return rv;
  }
  
  /*
   * When running HV mode KVM we need to block certain operations while KVM VMs
   * exist in the system. We use a counter of VMs to track this.
   *
   * One of the operations we need to block is onlining of secondaries, so we
   * protect hv_vm_count with get/put_online_cpus().
   */
  static atomic_t hv_vm_count;
  
  void kvm_hv_vm_activated(void)
  {
  	get_online_cpus();
  	atomic_inc(&hv_vm_count);
  	put_online_cpus();
  }
  EXPORT_SYMBOL_GPL(kvm_hv_vm_activated);
  
  void kvm_hv_vm_deactivated(void)
  {
  	get_online_cpus();
  	atomic_dec(&hv_vm_count);
  	put_online_cpus();
  }
  EXPORT_SYMBOL_GPL(kvm_hv_vm_deactivated);
  
  bool kvm_hv_mode_active(void)
  {
  	return atomic_read(&hv_vm_count) != 0;
  }
  
  extern int hcall_real_table[], hcall_real_table_end[];
  
  int kvmppc_hcall_impl_hv_realmode(unsigned long cmd)
  {
  	cmd /= 4;
  	if (cmd < hcall_real_table_end - hcall_real_table &&
  	    hcall_real_table[cmd])
  		return 1;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
  
  int kvmppc_hwrng_present(void)
  {
  	return powernv_hwrng_present();
  }
  EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
  
  long kvmppc_h_random(struct kvm_vcpu *vcpu)
  {
  	if (powernv_get_random_real_mode(&vcpu->arch.gpr[4]))
  		return H_SUCCESS;
  
  	return H_HARDWARE;
  }
  
  static inline void rm_writeb(unsigned long paddr, u8 val)
  {
  	__asm__ __volatile__("stbcix %0,0,%1"
  		: : "r" (val), "r" (paddr) : "memory");
  }
  
  /*
   * Send an interrupt or message to another CPU.
   * This can only be called in real mode.
   * The caller needs to include any barrier needed to order writes
   * to memory vs. the IPI/message.
   */
  void kvmhv_rm_send_ipi(int cpu)
  {
  	unsigned long xics_phys;
  
  	/* On POWER8 for IPIs to threads in the same core, use msgsnd */
  	if (cpu_has_feature(CPU_FTR_ARCH_207S) &&
  	    cpu_first_thread_sibling(cpu) ==
  	    cpu_first_thread_sibling(raw_smp_processor_id())) {
  		unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
  		msg |= cpu_thread_in_core(cpu);
  		__asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
  		return;
  	}
  
  	/* Else poke the target with an IPI */
  	xics_phys = paca[cpu].kvm_hstate.xics_phys;
  	rm_writeb(xics_phys + XICS_MFRR, IPI_PRIORITY);
  }
  
  /*
   * The following functions are called from the assembly code
   * in book3s_hv_rmhandlers.S.
   */
  static void kvmhv_interrupt_vcore(struct kvmppc_vcore *vc, int active)
  {
  	int cpu = vc->pcpu;
  
  	/* Order setting of exit map vs. msgsnd/IPI */
  	smp_mb();
  	for (; active; active >>= 1, ++cpu)
  		if (active & 1)
  			kvmhv_rm_send_ipi(cpu);
  }
  
  void kvmhv_commence_exit(int trap)
  {
  	struct kvmppc_vcore *vc = local_paca->kvm_hstate.kvm_vcore;
  	int ptid = local_paca->kvm_hstate.ptid;
  	struct kvm_split_mode *sip = local_paca->kvm_hstate.kvm_split_mode;
  	int me, ee, i;
  
  	/* Set our bit in the threads-exiting-guest map in the 0xff00
  	   bits of vcore->entry_exit_map */
  	me = 0x100 << ptid;
  	do {
  		ee = vc->entry_exit_map;
  	} while (cmpxchg(&vc->entry_exit_map, ee, ee | me) != ee);
  
  	/* Are we the first here? */
  	if ((ee >> 8) != 0)
  		return;
  
  	/*
  	 * Trigger the other threads in this vcore to exit the guest.
  	 * If this is a hypervisor decrementer interrupt then they
  	 * will be already on their way out of the guest.
  	 */
  	if (trap != BOOK3S_INTERRUPT_HV_DECREMENTER)
  		kvmhv_interrupt_vcore(vc, ee & ~(1 << ptid));
  
  	/*
  	 * If we are doing dynamic micro-threading, interrupt the other
  	 * subcores to pull them out of their guests too.
  	 */
  	if (!sip)
  		return;
  
  	for (i = 0; i < MAX_SUBCORES; ++i) {
  		vc = sip->master_vcs[i];
  		if (!vc)
  			break;
  		do {
  			ee = vc->entry_exit_map;
  			/* Already asked to exit? */
  			if ((ee >> 8) != 0)
  				break;
  		} while (cmpxchg(&vc->entry_exit_map, ee,
  				 ee | VCORE_EXIT_REQ) != ee);
  		if ((ee >> 8) == 0)
  			kvmhv_interrupt_vcore(vc, ee);
  	}
  }