tools/testing/selftests/kvm/lib/ucall_common.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include "linux/types.h"
   3 #include "linux/bitmap.h"
   4 #include "linux/atomic.h"
   5
   6 #include "kvm_util.h"
   7 #include "ucall_common.h"
   8
   9
  10 #define GUEST_UCALL_FAILED -1
  11
  12 struct ucall_header {
  13         DECLARE_BITMAP(in_use, KVM_MAX_VCPUS);
  14         struct ucall ucalls[KVM_MAX_VCPUS];
  15 };
  16
  17 int ucall_nr_pages_required(uint64_t page_size)
  18 {
  19         return align_up(sizeof(struct ucall_header), page_size) / page_size;
  20 }
  21
  22 /*
  23  * ucall_pool holds per-VM values (global data is duplicated by each VM), it
  24  * must not be accessed from host code.
  25  */
  26 static struct ucall_header *ucall_pool;
  27
  28 void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
  29 {
  30         struct ucall_header *hdr;
  31         struct ucall *uc;
  32         vm_vaddr_t vaddr;
  33         int i;
  34
  35         vaddr = vm_vaddr_alloc_shared(vm, sizeof(*hdr), KVM_UTIL_MIN_VADDR,
  36                                       MEM_REGION_DATA);
  37         hdr = (struct ucall_header *)addr_gva2hva(vm, vaddr);
  38         memset(hdr, 0, sizeof(*hdr));
  39
  40         for (i = 0; i < KVM_MAX_VCPUS; ++i) {
  41                 uc = &hdr->ucalls[i];
  42                 uc->hva = uc;
  43         }
  44
  45         write_guest_global(vm, ucall_pool, (struct ucall_header *)vaddr);
  46
  47         ucall_arch_init(vm, mmio_gpa);
  48 }
  49
  50 static struct ucall *ucall_alloc(void)
  51 {
  52         struct ucall *uc;
  53         int i;
  54
  55         if (!ucall_pool)
  56                 goto ucall_failed;
  57
  58         for (i = 0; i < KVM_MAX_VCPUS; ++i) {
  59                 if (!test_and_set_bit(i, ucall_pool->in_use)) {
  60                         uc = &ucall_pool->ucalls[i];
  61                         memset(uc->args, 0, sizeof(uc->args));
  62                         return uc;
  63                 }
  64         }
  65
  66 ucall_failed:
  67         /*
  68          * If the vCPU cannot grab a ucall structure, make a bare ucall with a
  69          * magic value to signal to get_ucall() that things went sideways.
  70          * GUEST_ASSERT() depends on ucall_alloc() and so cannot be used here.
  71          */
  72         ucall_arch_do_ucall(GUEST_UCALL_FAILED);
  73         return NULL;
  74 }
  75
  76 static void ucall_free(struct ucall *uc)
  77 {
  78         /* Beware, here be pointer arithmetic.  */
  79         clear_bit(uc - ucall_pool->ucalls, ucall_pool->in_use);
  80 }
  81
  82 void ucall_assert(uint64_t cmd, const char *exp, const char *file,
  83                   unsigned int line, const char *fmt, ...)
  84 {
  85         struct ucall *uc;
  86         va_list va;
  87
  88         uc = ucall_alloc();
  89         uc->cmd = cmd;
  90
  91         WRITE_ONCE(uc->args[GUEST_ERROR_STRING], (uint64_t)(exp));
  92         WRITE_ONCE(uc->args[GUEST_FILE], (uint64_t)(file));
  93         WRITE_ONCE(uc->args[GUEST_LINE], line);
  94
  95         va_start(va, fmt);
  96         guest_vsnprintf(uc->buffer, UCALL_BUFFER_LEN, fmt, va);
  97         va_end(va);
  98
  99         ucall_arch_do_ucall((vm_vaddr_t)uc->hva);
 100
 101         ucall_free(uc);
 102 }
 103
 104 void ucall_fmt(uint64_t cmd, const char *fmt, ...)
 105 {
 106         struct ucall *uc;
 107         va_list va;
 108
 109         uc = ucall_alloc();
 110         uc->cmd = cmd;
 111
 112         va_start(va, fmt);
 113         guest_vsnprintf(uc->buffer, UCALL_BUFFER_LEN, fmt, va);
 114         va_end(va);
 115
 116         ucall_arch_do_ucall((vm_vaddr_t)uc->hva);
 117
 118         ucall_free(uc);
 119 }
 120
 121 void ucall(uint64_t cmd, int nargs, ...)
 122 {
 123         struct ucall *uc;
 124         va_list va;
 125         int i;
 126
 127         uc = ucall_alloc();
 128
 129         WRITE_ONCE(uc->cmd, cmd);
 130
 131         nargs = min(nargs, UCALL_MAX_ARGS);
 132
 133         va_start(va, nargs);
 134         for (i = 0; i < nargs; ++i)
 135                 WRITE_ONCE(uc->args[i], va_arg(va, uint64_t));
 136         va_end(va);
 137
 138         ucall_arch_do_ucall((vm_vaddr_t)uc->hva);
 139
 140         ucall_free(uc);
 141 }
 142
 143 uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc)
 144 {
 145         struct ucall ucall;
 146         void *addr;
 147
 148         if (!uc)
 149                 uc = &ucall;
 150
 151         addr = ucall_arch_get_ucall(vcpu);
 152         if (addr) {
 153                 TEST_ASSERT(addr != (void *)GUEST_UCALL_FAILED,
 154                             "Guest failed to allocate ucall struct");
 155
 156                 memcpy(uc, addr, sizeof(*uc));
 157                 vcpu_run_complete_io(vcpu);
 158         } else {
 159                 memset(uc, 0, sizeof(*uc));
 160         }
 161
 162         return uc->cmd;
 163 }