arch/powerpc/kvm/book3s_hv_builtin.c

   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 }