Thanks Andrew for all the good suggestions.
Will take them in next revision.
Regards,
Chao
On 2024-03-27 17:00, Andrew Jones <ajones@xxxxxxxxxxxxxxxx> wrote:
>
> On Wed, Mar 27, 2024 at 07:55:26AM +0000, Chao Du wrote:
> > Initial support for RISC-V KVM ebreak test. Check the exit reason and
> > the PC when guest debug is enabled. Also to make sure the guest could
> > handle the ebreak exception without exiting to the VMM when guest debug
> > is not enabled.
> >
> > Signed-off-by: Chao Du <duchao@xxxxxxxxxxxxxxxxxx>
> > ---
> > tools/testing/selftests/kvm/Makefile | 1 +
> > .../testing/selftests/kvm/riscv/ebreak_test.c | 84 +++++++++++++++++++
> > 2 files changed, 85 insertions(+)
> > create mode 100644 tools/testing/selftests/kvm/riscv/ebreak_test.c
> >
> > diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> > index 741c7dc16afc..7f4430242c9e 100644
> > --- a/tools/testing/selftests/kvm/Makefile
> > +++ b/tools/testing/selftests/kvm/Makefile
> > @@ -189,6 +189,7 @@ TEST_GEN_PROGS_s390x += rseq_test
> > TEST_GEN_PROGS_s390x += set_memory_region_test
> > TEST_GEN_PROGS_s390x += kvm_binary_stats_test
> >
> > +TEST_GEN_PROGS_riscv += riscv/ebreak_test
> > TEST_GEN_PROGS_riscv += arch_timer
> > TEST_GEN_PROGS_riscv += demand_paging_test
> > TEST_GEN_PROGS_riscv += dirty_log_test
> > diff --git a/tools/testing/selftests/kvm/riscv/ebreak_test.c b/tools/testing/selftests/kvm/riscv/ebreak_test.c
> > new file mode 100644
> > index 000000000000..4c79c778e026
> > --- /dev/null
> > +++ b/tools/testing/selftests/kvm/riscv/ebreak_test.c
> > @@ -0,0 +1,84 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * RISC-V KVM ebreak test.
> > + *
> > + * Copyright 2024 Beijing ESWIN Computing Technology Co., Ltd.
> > + *
> > + */
> > +#include "kvm_util.h"
> > +
> > +#define PC(v) ((uint64_t)&(v))
>
> PC() isn't a good name for the function this is doing. It's getting
> the address of a label. LABEL_ADDRESS() would be more appropriate.
>
> > +
> > +extern unsigned char sw_bp_1, sw_bp_2;
> > +static volatile uint64_t sw_bp_addr;
>
> Drop volatile here and use READ/WRITE_ONCE on sw_bp_addr when reading and
> writing it.
>
> > +
> > +static void guest_code(void)
> > +{
> > + /*
> > + * nops are inserted to make sure that the "pc += 4" operation is
> > + * compatible with the compressed instructions.
> > + */
> > + asm volatile("sw_bp_1: ebreak\n"
> > + "nop\n"
> > + "sw_bp_2: ebreak\n"
> > + "nop\n");
>
> The nops are fine, but options should work too, something like
>
> asm volatile(
> ".option push\n"
> ".option norvc\n"
> "sw_bp_1: ebreak\n"
> "sw_bp_2: ebreak\n"
> ".option pop\n"
> );
>
> > + GUEST_ASSERT_EQ(sw_bp_addr, PC(sw_bp_2));
> > +
> > + GUEST_DONE();
> > +}
> > +
> > +static void guest_breakpoint_handler(struct ex_regs *regs)
> > +{
> > + sw_bp_addr = regs->epc;
> > + regs->epc += 4;
> > +}
> > +
> > +int main(void)
> > +{
> > + struct kvm_vm *vm;
> > + struct kvm_vcpu *vcpu;
> > + uint64_t pc;
> > + struct kvm_guest_debug debug = {
> > + .control = KVM_GUESTDBG_ENABLE,
> > + };
> > + struct ucall uc;
>
> You don't use 'uc', so you can drop it and...
>
> > +
> > + TEST_REQUIRE(kvm_has_cap(KVM_CAP_SET_GUEST_DEBUG));
> > +
> > + vm = vm_create_with_one_vcpu(&vcpu, guest_code);
> > +
> > + vm_init_vector_tables(vm);
> > + vcpu_init_vector_tables(vcpu);
> > + vm_install_exception_handler(vm, EXC_BREAKPOINT,
> > + guest_breakpoint_handler);
> > +
> > + /*
> > + * Enable the guest debug.
> > + * ebreak should exit to the VMM with KVM_EXIT_DEBUG reason.
> > + */
> > + vcpu_guest_debug_set(vcpu, &debug);
> > + vcpu_run(vcpu);
> > +
> > + TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_DEBUG);
> > +
> > + vcpu_get_reg(vcpu, RISCV_CORE_REG(regs.pc), &pc);
> > + TEST_ASSERT_EQ(pc, PC(sw_bp_1));
> > +
> > + /* skip sw_bp_1 */
> > + vcpu_set_reg(vcpu, RISCV_CORE_REG(regs.pc), pc + 4);
> > +
> > + /*
> > + * Disable all debug controls.
> > + * Guest should handle the ebreak without exiting to the VMM.
> > + */
> > + memset(&debug, 0, sizeof(debug));
> > + vcpu_guest_debug_set(vcpu, &debug);
> > +
> > + vcpu_run(vcpu);
> > +
> > + TEST_ASSERT_EQ(get_ucall(vcpu, &uc), UCALL_DONE);
>
> ...call get_ucall() with NULL for the second parameter.
>
> > +
> > + kvm_vm_free(vm);
> > +
> > + return 0;
> > +}
> > --
> > 2.17.1
> >
>
> Thanks,
> drew
