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KVM: selftests: riscv: Improve unexpected guest trap handling

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Currently, we simply hang using "while (1) ;" upon any unexpected
guest traps because the default guest trap handler is guest_hang().

The above approach is not useful to anyone because KVM selftests
users will only see a hung application upon any unexpected guest
trap.

This patch improves unexpected guest trap handling for KVM RISC-V
selftests by doing the following:
1) Return to host user-space
2) Dump VCPU registers
3) Die using TEST_ASSERT(0, ...)

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Tested-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Anup Patel 2022-04-09 10:02:36 +05:30 committed by Anup Patel
parent 42226c9897
commit ac6c85e962
3 changed files with 30 additions and 16 deletions
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8
tools/testing/selftests/kvm/include/riscv/processor.h
View file

@ -119,10 +119,12 @@ static inline void set_reg(struct kvm_vm *vm, uint32_t vcpuid, uint64_t id,
#define SATP_ASID_SHIFT 44
#define SATP_ASID_MASK _AC(0xFFFF, UL)
#define SBI_EXT_EXPERIMENTAL_START 0x08000000
#define SBI_EXT_EXPERIMENTAL_END 0x08FFFFFF
#define SBI_EXT_EXPERIMENTAL_START 0x08000000
#define SBI_EXT_EXPERIMENTAL_END 0x08FFFFFF
#define KVM_RISCV_SELFTESTS_SBI_EXT SBI_EXT_EXPERIMENTAL_END
#define KVM_RISCV_SELFTESTS_SBI_EXT SBI_EXT_EXPERIMENTAL_END
#define KVM_RISCV_SELFTESTS_SBI_UCALL 0
#define KVM_RISCV_SELFTESTS_SBI_UNEXP 1
struct sbiret {
long error;

9
tools/testing/selftests/kvm/lib/riscv/processor.c
View file

@ -268,10 +268,11 @@ void vcpu_dump(FILE *stream, struct kvm_vm *vm, uint32_t vcpuid, uint8_t indent)
core.regs.t3, core.regs.t4, core.regs.t5, core.regs.t6);
}
static void __aligned(16) guest_hang(void)
static void __aligned(16) guest_unexp_trap(void)
{
while (1)
;
sbi_ecall(KVM_RISCV_SELFTESTS_SBI_EXT,
KVM_RISCV_SELFTESTS_SBI_UNEXP,
0, 0, 0, 0, 0, 0);
}
void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code)
@ -310,7 +311,7 @@ void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code)
/* Setup default exception vector of guest */
set_reg(vm, vcpuid, RISCV_CSR_REG(stvec),
(unsigned long)guest_hang);
(unsigned long)guest_unexp_trap);
}
void vcpu_args_set(struct kvm_vm *vm, uint32_t vcpuid, unsigned int num, ...)

29
tools/testing/selftests/kvm/lib/riscv/ucall.c
View file

@ -60,8 +60,9 @@ void ucall(uint64_t cmd, int nargs, ...)
uc.args[i] = va_arg(va, uint64_t);
va_end(va);
sbi_ecall(KVM_RISCV_SELFTESTS_SBI_EXT, 0, (vm_vaddr_t)&uc,
0, 0, 0, 0, 0);
sbi_ecall(KVM_RISCV_SELFTESTS_SBI_EXT,
KVM_RISCV_SELFTESTS_SBI_UCALL,
(vm_vaddr_t)&uc, 0, 0, 0, 0, 0);
}
uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
@ -73,14 +74,24 @@ uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
memset(uc, 0, sizeof(*uc));
if (run->exit_reason == KVM_EXIT_RISCV_SBI &&
run->riscv_sbi.extension_id == KVM_RISCV_SELFTESTS_SBI_EXT &&
run->riscv_sbi.function_id == 0) {
memcpy(&ucall, addr_gva2hva(vm, run->riscv_sbi.args[0]),
sizeof(ucall));
run->riscv_sbi.extension_id == KVM_RISCV_SELFTESTS_SBI_EXT) {
switch (run->riscv_sbi.function_id) {
case KVM_RISCV_SELFTESTS_SBI_UCALL:
memcpy(&ucall, addr_gva2hva(vm,
run->riscv_sbi.args[0]), sizeof(ucall));
vcpu_run_complete_io(vm, vcpu_id);
if (uc)
memcpy(uc, &ucall, sizeof(ucall));
vcpu_run_complete_io(vm, vcpu_id);
if (uc)
memcpy(uc, &ucall, sizeof(ucall));
break;
case KVM_RISCV_SELFTESTS_SBI_UNEXP:
vcpu_dump(stderr, vm, vcpu_id, 2);
TEST_ASSERT(0, "Unexpected trap taken by guest");
break;
default:
break;
}
}
return ucall.cmd;