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 = 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  */
 141 static atomic_t hv_vm_count;
 142
 143 void kvm_hv_vm_activated(void)
 144 {
 145         get_online_cpus();
 146         atomic_inc(&hv_vm_count);
 147         put_online_cpus();
 148 }
 149 EXPORT_SYMBOL_GPL(kvm_hv_vm_activated);
 150
 151 void kvm_hv_vm_deactivated(void)
 152 {
 153         get_online_cpus();
 154         atomic_dec(&hv_vm_count);
 155         put_online_cpus();
 156 }
 157 EXPORT_SYMBOL_GPL(kvm_hv_vm_deactivated);
 158
 159 bool kvm_hv_mode_active(void)
 160 {
 161         return atomic_read(&hv_vm_count) != 0;
 162 }
 163
 164 extern int hcall_real_table[], hcall_real_table_end[];
 165
 166 int 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 }
 175 EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
 176
 177 int kvmppc_hwrng_present(void)
 178 {
 179         return powernv_hwrng_present();
 180 }
 181 EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
 182
 183 long 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
 191 static 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  */
 203 void 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  */
 226 static 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
 237 void 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 }