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Linux/arch/powerpc/kvm/book3s_hv_builtin.c

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  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  */
 39 static unsigned long kvm_cma_resv_ratio = 5;
 40 
 41 static struct cma *kvm_cma;
 42 
 43 static 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 }
 50 early_param("kvm_cma_resv_ratio", early_parse_kvm_cma_resv);
 51 
 52 struct 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 }
 58 EXPORT_SYMBOL_GPL(kvm_alloc_hpt);
 59 
 60 void kvm_release_hpt(struct page *page, unsigned long nr_pages)
 61 {
 62         cma_release(kvm_cma, page, nr_pages);
 63 }
 64 EXPORT_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  */
 74 void __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  */
110 long int kvmppc_rm_h_confer(struct kvm_vcpu *vcpu, int target,
111                             unsigned int yield_count)
112 {
113         struct kvmppc_vcore *vc = local_paca->kvm_hstate.kvm_vcore;
114         int ptid = local_paca->kvm_hstate.ptid;
115         int threads_running;
116         int threads_ceded;
117         int threads_conferring;
118         u64 stop = get_tb() + 10 * tb_ticks_per_usec;
119         int rv = H_SUCCESS; /* => don't yield */
120 
121         set_bit(ptid, &vc->conferring_threads);
122         while ((get_tb() < stop) && !VCORE_IS_EXITING(vc)) {
123                 threads_running = VCORE_ENTRY_MAP(vc);
124                 threads_ceded = vc->napping_threads;
125                 threads_conferring = vc->conferring_threads;
126                 if ((threads_ceded | threads_conferring) == threads_running) {
127                         rv = H_TOO_HARD; /* => do yield */
128                         break;
129                 }
130         }
131         clear_bit(ptid, &vc->conferring_threads);
132         return rv;
133 }
134 
135 /*
136  * When running HV mode KVM we need to block certain operations while KVM VMs
137  * exist in the system. We use a counter of VMs to track this.
138  *
139  * One of the operations we need to block is onlining of secondaries, so we
140  * protect hv_vm_count with get/put_online_cpus().
141  */
142 static atomic_t hv_vm_count;
143 
144 void kvm_hv_vm_activated(void)
145 {
146         get_online_cpus();
147         atomic_inc(&hv_vm_count);
148         put_online_cpus();
149 }
150 EXPORT_SYMBOL_GPL(kvm_hv_vm_activated);
151 
152 void kvm_hv_vm_deactivated(void)
153 {
154         get_online_cpus();
155         atomic_dec(&hv_vm_count);
156         put_online_cpus();
157 }
158 EXPORT_SYMBOL_GPL(kvm_hv_vm_deactivated);
159 
160 bool kvm_hv_mode_active(void)
161 {
162         return atomic_read(&hv_vm_count) != 0;
163 }
164 
165 extern int hcall_real_table[], hcall_real_table_end[];
166 
167 int kvmppc_hcall_impl_hv_realmode(unsigned long cmd)
168 {
169         cmd /= 4;
170         if (cmd < hcall_real_table_end - hcall_real_table &&
171             hcall_real_table[cmd])
172                 return 1;
173 
174         return 0;
175 }
176 EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
177 
178 int kvmppc_hwrng_present(void)
179 {
180         return powernv_hwrng_present();
181 }
182 EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
183 
184 long kvmppc_h_random(struct kvm_vcpu *vcpu)
185 {
186         if (powernv_get_random_real_mode(&vcpu->arch.gpr[4]))
187                 return H_SUCCESS;
188 
189         return H_HARDWARE;
190 }
191 
192 static inline void rm_writeb(unsigned long paddr, u8 val)
193 {
194         __asm__ __volatile__("stbcix %0,0,%1"
195                 : : "r" (val), "r" (paddr) : "memory");
196 }
197 
198 /*
199  * Send an interrupt or message to another CPU.
200  * This can only be called in real mode.
201  * The caller needs to include any barrier needed to order writes
202  * to memory vs. the IPI/message.
203  */
204 void kvmhv_rm_send_ipi(int cpu)
205 {
206         unsigned long xics_phys;
207 
208         /* On POWER8 for IPIs to threads in the same core, use msgsnd */
209         if (cpu_has_feature(CPU_FTR_ARCH_207S) &&
210             cpu_first_thread_sibling(cpu) ==
211             cpu_first_thread_sibling(raw_smp_processor_id())) {
212                 unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
213                 msg |= cpu_thread_in_core(cpu);
214                 __asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
215                 return;
216         }
217 
218         /* Else poke the target with an IPI */
219         xics_phys = paca[cpu].kvm_hstate.xics_phys;
220         rm_writeb(xics_phys + XICS_MFRR, IPI_PRIORITY);
221 }
222 
223 /*
224  * The following functions are called from the assembly code
225  * in book3s_hv_rmhandlers.S.
226  */
227 static void kvmhv_interrupt_vcore(struct kvmppc_vcore *vc, int active)
228 {
229         int cpu = vc->pcpu;
230 
231         /* Order setting of exit map vs. msgsnd/IPI */
232         smp_mb();
233         for (; active; active >>= 1, ++cpu)
234                 if (active & 1)
235                         kvmhv_rm_send_ipi(cpu);
236 }
237 
238 void kvmhv_commence_exit(int trap)
239 {
240         struct kvmppc_vcore *vc = local_paca->kvm_hstate.kvm_vcore;
241         int ptid = local_paca->kvm_hstate.ptid;
242         struct kvm_split_mode *sip = local_paca->kvm_hstate.kvm_split_mode;
243         int me, ee, i;
244 
245         /* Set our bit in the threads-exiting-guest map in the 0xff00
246            bits of vcore->entry_exit_map */
247         me = 0x100 << ptid;
248         do {
249                 ee = vc->entry_exit_map;
250         } while (cmpxchg(&vc->entry_exit_map, ee, ee | me) != ee);
251 
252         /* Are we the first here? */
253         if ((ee >> 8) != 0)
254                 return;
255 
256         /*
257          * Trigger the other threads in this vcore to exit the guest.
258          * If this is a hypervisor decrementer interrupt then they
259          * will be already on their way out of the guest.
260          */
261         if (trap != BOOK3S_INTERRUPT_HV_DECREMENTER)
262                 kvmhv_interrupt_vcore(vc, ee & ~(1 << ptid));
263 
264         /*
265          * If we are doing dynamic micro-threading, interrupt the other
266          * subcores to pull them out of their guests too.
267          */
268         if (!sip)
269                 return;
270 
271         for (i = 0; i < MAX_SUBCORES; ++i) {
272                 vc = sip->master_vcs[i];
273                 if (!vc)
274                         break;
275                 do {
276                         ee = vc->entry_exit_map;
277                         /* Already asked to exit? */
278                         if ((ee >> 8) != 0)
279                                 break;
280                 } while (cmpxchg(&vc->entry_exit_map, ee,
281                                  ee | VCORE_EXIT_REQ) != ee);
282                 if ((ee >> 8) == 0)
283                         kvmhv_interrupt_vcore(vc, ee);
284         }
285 }
286 
287 struct kvmppc_host_rm_ops *kvmppc_host_rm_ops_hv;
288 EXPORT_SYMBOL_GPL(kvmppc_host_rm_ops_hv);
289 

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