Quelle  hypercalls.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only

/* hypercalls: Check the ARM64's psuedo-firmware bitmap register interface.
 *
 * The test validates the basic hypercall functionalities that are exposed
 * via the psuedo-firmware bitmap register. This includes the registers'
 * read/write behavior before and after the VM has started, and if the
 * hypercalls are properly masked or unmasked to the guest when disabled or
 * enabled from the KVM userspace, respectively.
 */
#include <errno.h>
#include <linux/arm-smccc.h>
#include <asm/kvm.h>
#include <kvm_util.h>

#include "processor.h"

#define FW_REG_ULIMIT_VAL(max_feat_bit) (GENMASK(max_feat_bit, 0))

/* Last valid bits of the bitmapped firmware registers */
#define KVM_REG_ARM_STD_BMAP_BIT_MAX  0
#define KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX 0
#define KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_MAX 1
#define KVM_REG_ARM_VENDOR_HYP_BMAP_2_BIT_MAX   1

#define KVM_REG_ARM_STD_BMAP_RESET_VAL  FW_REG_ULIMIT_VAL(KVM_REG_ARM_STD_BMAP_BIT_MAX)
#define KVM_REG_ARM_STD_HYP_BMAP_RESET_VAL FW_REG_ULIMIT_VAL(KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX)
#define KVM_REG_ARM_VENDOR_HYP_BMAP_RESET_VAL FW_REG_ULIMIT_VAL(KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_MAX)
#define KVM_REG_ARM_VENDOR_HYP_BMAP_2_RESET_VAL 0

struct kvm_fw_reg_info {
 uint64_t reg;  /* Register definition */
 uint64_t max_feat_bit; /* Bit that represents the upper limit of the feature-map */
 uint64_t reset_val; /* Reset value for the register */
};

#define FW_REG_INFO(r)   \
 {     \
  .reg = r,   \
  .max_feat_bit = r##_BIT_MAX, \
  .reset_val = r##_RESET_VAL \
 }

static const struct kvm_fw_reg_info fw_reg_info[] = {
 FW_REG_INFO(KVM_REG_ARM_STD_BMAP),
 FW_REG_INFO(KVM_REG_ARM_STD_HYP_BMAP),
 FW_REG_INFO(KVM_REG_ARM_VENDOR_HYP_BMAP),
 FW_REG_INFO(KVM_REG_ARM_VENDOR_HYP_BMAP_2),
};

enum test_stage {
 TEST_STAGE_REG_IFACE,
 TEST_STAGE_HVC_IFACE_FEAT_DISABLED,
 TEST_STAGE_HVC_IFACE_FEAT_ENABLED,
 TEST_STAGE_HVC_IFACE_FALSE_INFO,
 TEST_STAGE_END,
};

static int stage = TEST_STAGE_REG_IFACE;

struct test_hvc_info {
 uint32_t func_id;
 uint64_t arg1;
};

#define TEST_HVC_INFO(f, a1) \
 {   \
  .func_id = f, \
  .arg1 = a1, \
 }

static const struct test_hvc_info hvc_info[] = {
 /* KVM_REG_ARM_STD_BMAP */
 TEST_HVC_INFO(ARM_SMCCC_TRNG_VERSION, 0),
 TEST_HVC_INFO(ARM_SMCCC_TRNG_FEATURES, ARM_SMCCC_TRNG_RND64),
 TEST_HVC_INFO(ARM_SMCCC_TRNG_GET_UUID, 0),
 TEST_HVC_INFO(ARM_SMCCC_TRNG_RND32, 0),
 TEST_HVC_INFO(ARM_SMCCC_TRNG_RND64, 0),

 /* KVM_REG_ARM_STD_HYP_BMAP */
 TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_HV_PV_TIME_FEATURES),
 TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_FEATURES, ARM_SMCCC_HV_PV_TIME_ST),
 TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_ST, 0),

 /* KVM_REG_ARM_VENDOR_HYP_BMAP */
 TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID,
   ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID),
 TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, 0),
 TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, KVM_PTP_VIRT_COUNTER),
};

/* Feed false hypercall info to test the KVM behavior */
static const struct test_hvc_info false_hvc_info[] = {
 /* Feature support check against a different family of hypercalls */
 TEST_HVC_INFO(ARM_SMCCC_TRNG_FEATURES, ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID),
 TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_TRNG_RND64),
 TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_FEATURES, ARM_SMCCC_TRNG_RND64),
};

static void guest_test_hvc(const struct test_hvc_info *hc_info)
{
 unsigned int i;
 struct arm_smccc_res res;
 unsigned int hvc_info_arr_sz;

 hvc_info_arr_sz =
 hc_info == hvc_info ? ARRAY_SIZE(hvc_info) : ARRAY_SIZE(false_hvc_info);

 for (i = 0; i < hvc_info_arr_sz; i++, hc_info++) {
  memset(&res, 0, sizeof(res));
  smccc_hvc(hc_info->func_id, hc_info->arg1, 0, 0, 0, 0, 0, 0, &res);

  switch (stage) {
  case TEST_STAGE_HVC_IFACE_FEAT_DISABLED:
  case TEST_STAGE_HVC_IFACE_FALSE_INFO:
   __GUEST_ASSERT(res.a0 == SMCCC_RET_NOT_SUPPORTED,
           "a0 = 0x%lx, func_id = 0x%x, arg1 = 0x%lx, stage = %u",
     res.a0, hc_info->func_id, hc_info->arg1, stage);
   break;
  case TEST_STAGE_HVC_IFACE_FEAT_ENABLED:
   __GUEST_ASSERT(res.a0 != SMCCC_RET_NOT_SUPPORTED,
           "a0 = 0x%lx, func_id = 0x%x, arg1 = 0x%lx, stage = %u",
     res.a0, hc_info->func_id, hc_info->arg1, stage);
   break;
  default:
   GUEST_FAIL("Unexpected stage = %u", stage);
  }
 }
}

static void guest_code(void)
{
 while (stage != TEST_STAGE_END) {
  switch (stage) {
  case TEST_STAGE_REG_IFACE:
   break;
  case TEST_STAGE_HVC_IFACE_FEAT_DISABLED:
  case TEST_STAGE_HVC_IFACE_FEAT_ENABLED:
   guest_test_hvc(hvc_info);
   break;
  case TEST_STAGE_HVC_IFACE_FALSE_INFO:
   guest_test_hvc(false_hvc_info);
   break;
  default:
   GUEST_FAIL("Unexpected stage = %u", stage);
  }

  GUEST_SYNC(stage);
 }

 GUEST_DONE();
}

struct st_time {
 uint32_t rev;
 uint32_t attr;
 uint64_t st_time;
};

#define STEAL_TIME_SIZE  ((sizeof(struct st_time) + 63) & ~63)
#define ST_GPA_BASE  (1 << 30)

static void steal_time_init(struct kvm_vcpu *vcpu)
{
 uint64_t st_ipa = (ulong)ST_GPA_BASE;
 unsigned int gpages;

 gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE);
 vm_userspace_mem_region_add(vcpu->vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0);

 vcpu_device_attr_set(vcpu, KVM_ARM_VCPU_PVTIME_CTRL,
        KVM_ARM_VCPU_PVTIME_IPA, &st_ipa);
}

static void test_fw_regs_before_vm_start(struct kvm_vcpu *vcpu)
{
 uint64_t val;
 unsigned int i;
 int ret;

 for (i = 0; i < ARRAY_SIZE(fw_reg_info); i++) {
  const struct kvm_fw_reg_info *reg_info = &fw_reg_info[i];
  uint64_t set_val;

  /* First 'read' should be the reset value for the reg  */
  val = vcpu_get_reg(vcpu, reg_info->reg);
  TEST_ASSERT(val == reg_info->reset_val,
   "Unexpected reset value for reg: 0x%lx; expected: 0x%lx; read: 0x%lx",
   reg_info->reg, reg_info->reset_val, val);

  if (reg_info->reset_val)
   set_val = 0;
  else
   set_val = FW_REG_ULIMIT_VAL(reg_info->max_feat_bit);

  ret = __vcpu_set_reg(vcpu, reg_info->reg, set_val);
  TEST_ASSERT(ret == 0,
   "Failed to %s all the features of reg: 0x%lx; ret: %d",
   (set_val ? "set" : "clear"), reg_info->reg, errno);

  val = vcpu_get_reg(vcpu, reg_info->reg);
  TEST_ASSERT(val == set_val,
   "Expected all the features to be %s for reg: 0x%lx",
   (set_val ? "set" : "cleared"), reg_info->reg);

  /*
 * If the reg has been set, clear it as test_fw_regs_after_vm_start()
 * expects it to be cleared.
 */
  if (set_val) {
   ret = __vcpu_set_reg(vcpu, reg_info->reg, 0);
   TEST_ASSERT(ret == 0,
   "Failed to clear all the features of reg: 0x%lx; ret: %d",
   reg_info->reg, errno);
  }

  /*
 * Test enabling a feature that's not supported.
 * Avoid this check if all the bits are occupied.
 */
  if (reg_info->max_feat_bit < 63) {
   ret = __vcpu_set_reg(vcpu, reg_info->reg, BIT(reg_info->max_feat_bit + 1));
   TEST_ASSERT(ret != 0 && errno == EINVAL,
   "Unexpected behavior or return value (%d) while setting an unsupported feature for reg: 0x%lx",
   errno, reg_info->reg);
  }
 }
}

static void test_fw_regs_after_vm_start(struct kvm_vcpu *vcpu)
{
 uint64_t val;
 unsigned int i;
 int ret;

 for (i = 0; i < ARRAY_SIZE(fw_reg_info); i++) {
  const struct kvm_fw_reg_info *reg_info = &fw_reg_info[i];

  /*
 * Before starting the VM, the test clears all the bits.
 * Check if that's still the case.
 */
  val = vcpu_get_reg(vcpu, reg_info->reg);
  TEST_ASSERT(val == 0,
   "Expected all the features to be cleared for reg: 0x%lx",
   reg_info->reg);

  /*
 * Since the VM has run at least once, KVM shouldn't allow modification of
 * the registers and should return EBUSY. Set the registers and check for
 * the expected errno.
 */
  ret = __vcpu_set_reg(vcpu, reg_info->reg, FW_REG_ULIMIT_VAL(reg_info->max_feat_bit));
  TEST_ASSERT(ret != 0 && errno == EBUSY,
  "Unexpected behavior or return value (%d) while setting a feature while VM is running for reg: 0x%lx",
  errno, reg_info->reg);
 }
}

static struct kvm_vm *test_vm_create(struct kvm_vcpu **vcpu)
{
 struct kvm_vm *vm;

 vm = vm_create_with_one_vcpu(vcpu, guest_code);

 steal_time_init(*vcpu);

 return vm;
}

static void test_guest_stage(struct kvm_vm **vm, struct kvm_vcpu **vcpu)
{
 int prev_stage = stage;

 pr_debug("Stage: %d\n", prev_stage);

 /* Sync the stage early, the VM might be freed below. */
 stage++;
 sync_global_to_guest(*vm, stage);

 switch (prev_stage) {
 case TEST_STAGE_REG_IFACE:
  test_fw_regs_after_vm_start(*vcpu);
  break;
 case TEST_STAGE_HVC_IFACE_FEAT_DISABLED:
  /* Start a new VM so that all the features are now enabled by default */
  kvm_vm_free(*vm);
  *vm = test_vm_create(vcpu);
  break;
 case TEST_STAGE_HVC_IFACE_FEAT_ENABLED:
 case TEST_STAGE_HVC_IFACE_FALSE_INFO:
  break;
 default:
  TEST_FAIL("Unknown test stage: %d", prev_stage);
 }
}

static void test_run(void)
{
 struct kvm_vcpu *vcpu;
 struct kvm_vm *vm;
 struct ucall uc;
 bool guest_done = false;

 vm = test_vm_create(&vcpu);

 test_fw_regs_before_vm_start(vcpu);

 while (!guest_done) {
  vcpu_run(vcpu);

  switch (get_ucall(vcpu, &uc)) {
  case UCALL_SYNC:
   test_guest_stage(&vm, &vcpu);
   break;
  case UCALL_DONE:
   guest_done = true;
   break;
  case UCALL_ABORT:
   REPORT_GUEST_ASSERT(uc);
   break;
  default:
   TEST_FAIL("Unexpected guest exit");
  }
 }

 kvm_vm_free(vm);
}

int main(void)
{
 test_run();
 return 0;
}