tools/testing/selftests/kvm/lib/s390x/diag318_test_handler.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Test handler for the s390x DIAGNOSE 0x0318 instruction.
   4  *
   5  * Copyright (C) 2020, IBM
   6  */
   7
   8 #include "test_util.h"
   9 #include "kvm_util.h"
  10
  11 #define VCPU_ID 6
  12
  13 #define ICPT_INSTRUCTION        0x04
  14 #define IPA0_DIAG               0x8300
  15
  16 static void guest_code(void)
  17 {
  18         uint64_t diag318_info = 0x12345678;
  19
  20         asm volatile ("diag %0,0,0x318\n" : : "d" (diag318_info));
  21 }
  22
  23 /*
  24  * The DIAGNOSE 0x0318 instruction call must be handled via userspace. As such,
  25  * we create an ad-hoc VM here to handle the instruction then extract the
  26  * necessary data. It is up to the caller to decide what to do with that data.
  27  */
  28 static uint64_t diag318_handler(void)
  29 {
  30         struct kvm_vm *vm;
  31         struct kvm_run *run;
  32         uint64_t reg;
  33         uint64_t diag318_info;
  34
  35         vm = vm_create_default(VCPU_ID, 0, guest_code);
  36         vcpu_run(vm, VCPU_ID);
  37         run = vcpu_state(vm, VCPU_ID);
  38
  39         TEST_ASSERT(run->exit_reason == KVM_EXIT_S390_SIEIC,
  40                     "DIAGNOSE 0x0318 instruction was not intercepted");
  41         TEST_ASSERT(run->s390_sieic.icptcode == ICPT_INSTRUCTION,
  42                     "Unexpected intercept code: 0x%x", run->s390_sieic.icptcode);
  43         TEST_ASSERT((run->s390_sieic.ipa & 0xff00) == IPA0_DIAG,
  44                     "Unexpected IPA0 code: 0x%x", (run->s390_sieic.ipa & 0xff00));
  45
  46         reg = (run->s390_sieic.ipa & 0x00f0) >> 4;
  47         diag318_info = run->s.regs.gprs[reg];
  48
  49         TEST_ASSERT(diag318_info != 0, "DIAGNOSE 0x0318 info not set");
  50
  51         kvm_vm_free(vm);
  52
  53         return diag318_info;
  54 }
  55
  56 uint64_t get_diag318_info(void)
  57 {
  58         static uint64_t diag318_info;
  59         static bool printed_skip;
  60
  61         /*
  62          * If KVM does not support diag318, then return 0 to
  63          * ensure tests do not break.
  64          */
  65         if (!kvm_check_cap(KVM_CAP_S390_DIAG318)) {
  66                 if (!printed_skip) {
  67                         fprintf(stdout, "KVM_CAP_S390_DIAG318 not supported. "
  68                                 "Skipping diag318 test.\n");
  69                         printed_skip = true;
  70                 }
  71                 return 0;
  72         }
  73
  74         /*
  75          * If a test has previously requested the diag318 info,
  76          * then don't bother spinning up a temporary VM again.
  77          */
  78         if (!diag318_info)
  79                 diag318_info = diag318_handler();
  80
  81         return diag318_info;
  82 }