1/*
2 * Copyright 2011 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License, version 2, as
6 * published by the Free Software Foundation.
7 */
8
9#include <linux/cpu.h>
10#include <linux/kvm_host.h>
11#include <linux/preempt.h>
12#include <linux/export.h>
13#include <linux/sched.h>
14#include <linux/spinlock.h>
15#include <linux/init.h>
16#include <linux/memblock.h>
17#include <linux/sizes.h>
18#include <linux/cma.h>
19#include <linux/bitops.h>
20
21#include <asm/cputable.h>
22#include <asm/kvm_ppc.h>
23#include <asm/kvm_book3s.h>
24#include <asm/archrandom.h>
25#include <asm/xics.h>
26#include <asm/dbell.h>
27#include <asm/cputhreads.h>
28
29#define KVM_CMA_CHUNK_ORDER	18
30
31/*
32 * Hash page table alignment on newer cpus(CPU_FTR_ARCH_206)
33 * should be power of 2.
34 */
35#define HPT_ALIGN_PAGES		((1 << 18) >> PAGE_SHIFT) /* 256k */
36/*
37 * By default we reserve 5% of memory for hash pagetable allocation.
38 */
39static unsigned long kvm_cma_resv_ratio = 5;
40
41static struct cma *kvm_cma;
42
43static int __init early_parse_kvm_cma_resv(char *p)
44{
45	pr_debug("%s(%s)\n", __func__, p);
46	if (!p)
47		return -EINVAL;
48	return kstrtoul(p, 0, &kvm_cma_resv_ratio);
49}
50early_param("kvm_cma_resv_ratio", early_parse_kvm_cma_resv);
51
52struct page *kvm_alloc_hpt(unsigned long nr_pages)
53{
54	VM_BUG_ON(order_base_2(nr_pages) < KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
55
56	return cma_alloc(kvm_cma, nr_pages, order_base_2(HPT_ALIGN_PAGES));
57}
58EXPORT_SYMBOL_GPL(kvm_alloc_hpt);
59
60void kvm_release_hpt(struct page *page, unsigned long nr_pages)
61{
62	cma_release(kvm_cma, page, nr_pages);
63}
64EXPORT_SYMBOL_GPL(kvm_release_hpt);
65
66/**
67 * kvm_cma_reserve() - reserve area for kvm hash pagetable
68 *
69 * This function reserves memory from early allocator. It should be
70 * called by arch specific code once the memblock allocator
71 * has been activated and all other subsystems have already allocated/reserved
72 * memory.
73 */
74void __init kvm_cma_reserve(void)
75{
76	unsigned long align_size;
77	struct memblock_region *reg;
78	phys_addr_t selected_size = 0;
79
80	/*
81	 * We need CMA reservation only when we are in HV mode
82	 */
83	if (!cpu_has_feature(CPU_FTR_HVMODE))
84		return;
85	/*
86	 * We cannot use memblock_phys_mem_size() here, because
87	 * memblock_analyze() has not been called yet.
88	 */
89	for_each_memblock(memory, reg)
90		selected_size += memblock_region_memory_end_pfn(reg) -
91				 memblock_region_memory_base_pfn(reg);
92
93	selected_size = (selected_size * kvm_cma_resv_ratio / 100) << PAGE_SHIFT;
94	if (selected_size) {
95		pr_debug("%s: reserving %ld MiB for global area\n", __func__,
96			 (unsigned long)selected_size / SZ_1M);
97		align_size = HPT_ALIGN_PAGES << PAGE_SHIFT;
98		cma_declare_contiguous(0, selected_size, 0, align_size,
99			KVM_CMA_CHUNK_ORDER - PAGE_SHIFT, false, &kvm_cma);
100	}
101}
102
103/*
104 * Real-mode H_CONFER implementation.
105 * We check if we are the only vcpu out of this virtual core
106 * still running in the guest and not ceded.  If so, we pop up
107 * to the virtual-mode implementation; if not, just return to
108 * the guest.
109 */
110long int kvmppc_rm_h_confer(struct kvm_vcpu *vcpu, int target,
111			    unsigned int yield_count)
112{
113	struct kvmppc_vcore *vc = vcpu->arch.vcore;
114	int threads_running;
115	int threads_ceded;
116	int threads_conferring;
117	u64 stop = get_tb() + 10 * tb_ticks_per_usec;
118	int rv = H_SUCCESS; /* => don't yield */
119
120	set_bit(vcpu->arch.ptid, &vc->conferring_threads);
121	while ((get_tb() < stop) && !VCORE_IS_EXITING(vc)) {
122		threads_running = VCORE_ENTRY_MAP(vc);
123		threads_ceded = vc->napping_threads;
124		threads_conferring = vc->conferring_threads;
125		if ((threads_ceded | threads_conferring) == threads_running) {
126			rv = H_TOO_HARD; /* => do yield */
127			break;
128		}
129	}
130	clear_bit(vcpu->arch.ptid, &vc->conferring_threads);
131	return rv;
132}
133
134/*
135 * When running HV mode KVM we need to block certain operations while KVM VMs
136 * exist in the system. We use a counter of VMs to track this.
137 *
138 * One of the operations we need to block is onlining of secondaries, so we
139 * protect hv_vm_count with get/put_online_cpus().
140 */
141static atomic_t hv_vm_count;
142
143void kvm_hv_vm_activated(void)
144{
145	get_online_cpus();
146	atomic_inc(&hv_vm_count);
147	put_online_cpus();
148}
149EXPORT_SYMBOL_GPL(kvm_hv_vm_activated);
150
151void kvm_hv_vm_deactivated(void)
152{
153	get_online_cpus();
154	atomic_dec(&hv_vm_count);
155	put_online_cpus();
156}
157EXPORT_SYMBOL_GPL(kvm_hv_vm_deactivated);
158
159bool kvm_hv_mode_active(void)
160{
161	return atomic_read(&hv_vm_count) != 0;
162}
163
164extern int hcall_real_table[], hcall_real_table_end[];
165
166int kvmppc_hcall_impl_hv_realmode(unsigned long cmd)
167{
168	cmd /= 4;
169	if (cmd < hcall_real_table_end - hcall_real_table &&
170	    hcall_real_table[cmd])
171		return 1;
172
173	return 0;
174}
175EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
176
177int kvmppc_hwrng_present(void)
178{
179	return powernv_hwrng_present();
180}
181EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
182
183long kvmppc_h_random(struct kvm_vcpu *vcpu)
184{
185	if (powernv_get_random_real_mode(&vcpu->arch.gpr[4]))
186		return H_SUCCESS;
187
188	return H_HARDWARE;
189}
190
191static inline void rm_writeb(unsigned long paddr, u8 val)
192{
193	__asm__ __volatile__("stbcix %0,0,%1"
194		: : "r" (val), "r" (paddr) : "memory");
195}
196
197/*
198 * Send an interrupt or message to another CPU.
199 * This can only be called in real mode.
200 * The caller needs to include any barrier needed to order writes
201 * to memory vs. the IPI/message.
202 */
203void kvmhv_rm_send_ipi(int cpu)
204{
205	unsigned long xics_phys;
206
207	/* On POWER8 for IPIs to threads in the same core, use msgsnd */
208	if (cpu_has_feature(CPU_FTR_ARCH_207S) &&
209	    cpu_first_thread_sibling(cpu) ==
210	    cpu_first_thread_sibling(raw_smp_processor_id())) {
211		unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
212		msg |= cpu_thread_in_core(cpu);
213		__asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
214		return;
215	}
216
217	/* Else poke the target with an IPI */
218	xics_phys = paca[cpu].kvm_hstate.xics_phys;
219	rm_writeb(xics_phys + XICS_MFRR, IPI_PRIORITY);
220}
221
222/*
223 * The following functions are called from the assembly code
224 * in book3s_hv_rmhandlers.S.
225 */
226static void kvmhv_interrupt_vcore(struct kvmppc_vcore *vc, int active)
227{
228	int cpu = vc->pcpu;
229
230	/* Order setting of exit map vs. msgsnd/IPI */
231	smp_mb();
232	for (; active; active >>= 1, ++cpu)
233		if (active & 1)
234			kvmhv_rm_send_ipi(cpu);
235}
236
237void kvmhv_commence_exit(int trap)
238{
239	struct kvmppc_vcore *vc = local_paca->kvm_hstate.kvm_vcore;
240	int ptid = local_paca->kvm_hstate.ptid;
241	int me, ee;
242
243	/* Set our bit in the threads-exiting-guest map in the 0xff00
244	   bits of vcore->entry_exit_map */
245	me = 0x100 << ptid;
246	do {
247		ee = vc->entry_exit_map;
248	} while (cmpxchg(&vc->entry_exit_map, ee, ee | me) != ee);
249
250	/* Are we the first here? */
251	if ((ee >> 8) != 0)
252		return;
253
254	/*
255	 * Trigger the other threads in this vcore to exit the guest.
256	 * If this is a hypervisor decrementer interrupt then they
257	 * will be already on their way out of the guest.
258	 */
259	if (trap != BOOK3S_INTERRUPT_HV_DECREMENTER)
260		kvmhv_interrupt_vcore(vc, ee & ~(1 << ptid));
261}
262