Re: [PATCH v2 1/3] KVM: riscv: selftests: Align the trap information wiht pt_regs

Andrew Jones
2025-04-30T07:05:32Z

On Tue, Apr 29, 2025 at 05:18:45PM -0700, Atish Patra wrote:
> The current exeception register structure in selftests are missing
> few registers (e.g stval). Instead of adding it manually, change
> the ex_regs to align with pt_regs to make it future proof.
>
> Suggested-by: Andrew Jones <ajones@ventanamicro.com>
> Signed-off-by: Atish Patra <atishp@rivosinc.com>
> ---
> .../selftests/kvm/include/riscv/processor.h | 10 +-
> tools/testing/selftests/kvm/lib/riscv/handlers.S | 164 ++++++++++++---------
> tools/testing/selftests/kvm/lib/riscv/processor.c | 2 +-
> tools/testing/selftests/kvm/riscv/arch_timer.c | 2 +-
> tools/testing/selftests/kvm/riscv/ebreak_test.c | 2 +-
> tools/testing/selftests/kvm/riscv/sbi_pmu_test.c | 4 +-
> 6 files changed, 104 insertions(+), 80 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/riscv/processor.h b/tools/testing/selftests/kvm/include/riscv/processor.h
> index 5f389166338c..1b5aef87de0f 100644
> --- a/tools/testing/selftests/kvm/include/riscv/processor.h
> +++ b/tools/testing/selftests/kvm/include/riscv/processor.h
> @@ -60,7 +60,8 @@ static inline bool __vcpu_has_sbi_ext(struct kvm_vcpu *vcpu, uint64_t sbi_ext)
> return __vcpu_has_ext(vcpu, RISCV_SBI_EXT_REG(sbi_ext));
> }
>
> -struct ex_regs {
> +struct pt_regs {
> + unsigned long epc;
> unsigned long ra;
> unsigned long sp;
> unsigned long gp;
> @@ -92,16 +93,19 @@ struct ex_regs {
> unsigned long t4;
> unsigned long t5;
> unsigned long t6;
> - unsigned long epc;
> + /* Supervisor/Machine CSRs */
> unsigned long status;
> + unsigned long badaddr;
> unsigned long cause;
> + /* a0 value before the syscall */
> + unsigned long orig_a0;
> };
>
> #define NR_VECTORS 2
> #define NR_EXCEPTIONS 32
> #define EC_MASK (NR_EXCEPTIONS - 1)
>
> -typedef void(*exception_handler_fn)(struct ex_regs *);
> +typedef void(*exception_handler_fn)(struct pt_regs *);
>
> void vm_init_vector_tables(struct kvm_vm *vm);
> void vcpu_init_vector_tables(struct kvm_vcpu *vcpu);
> diff --git a/tools/testing/selftests/kvm/lib/riscv/handlers.S b/tools/testing/selftests/kvm/lib/riscv/handlers.S
> index aa0abd3f35bb..9c99b258cae7 100644
> --- a/tools/testing/selftests/kvm/lib/riscv/handlers.S
> +++ b/tools/testing/selftests/kvm/lib/riscv/handlers.S
> @@ -9,86 +9,106 @@
>
> #include <asm/csr.h>
>
> +#ifdef __ASSEMBLY__
> +#define __ASM_STR(x) x
> +#else
> +#define __ASM_STR(x) #x
> +#endif

We should always have __ASSEMBLY__ (or actually __ASSMEBLER__) defined
when compiling this .S file.

> +
> +#if __riscv_xlen == 64
> +#define __REG_SEL(a, b) __ASM_STR(a)
> +#elif __riscv_xlen == 32
> +#define __REG_SEL(a, b) __ASM_STR(b)
> +#else
> +#error "Unexpected __riscv_xlen"
> +#endif
> +
> +#define REG_L __REG_SEL(ld, lw)
> +#define REG_S __REG_SEL(sd, sw)

We don't need these macros since we only support 64-bit. We always
have -DCONFIG_64BIT appended to CFLAGS. But it doesn't hurt to
have them either...

> +
> .macro save_context
> - addi sp, sp, (-8*34)
> - sd x1, 0(sp)
> - sd x2, 8(sp)
> - sd x3, 16(sp)
> - sd x4, 24(sp)
> - sd x5, 32(sp)
> - sd x6, 40(sp)
> - sd x7, 48(sp)
> - sd x8, 56(sp)
> - sd x9, 64(sp)
> - sd x10, 72(sp)
> - sd x11, 80(sp)
> - sd x12, 88(sp)
> - sd x13, 96(sp)
> - sd x14, 104(sp)
> - sd x15, 112(sp)
> - sd x16, 120(sp)
> - sd x17, 128(sp)
> - sd x18, 136(sp)
> - sd x19, 144(sp)
> - sd x20, 152(sp)
> - sd x21, 160(sp)
> - sd x22, 168(sp)
> - sd x23, 176(sp)
> - sd x24, 184(sp)
> - sd x25, 192(sp)
> - sd x26, 200(sp)
> - sd x27, 208(sp)
> - sd x28, 216(sp)
> - sd x29, 224(sp)
> - sd x30, 232(sp)
> - sd x31, 240(sp)
> + addi sp, sp, (-8*36)
> + REG_S x1, 8(sp)
> + REG_S x2, 16(sp)
> + REG_S x3, 24(sp)
> + REG_S x4, 32(sp)
> + REG_S x5, 40(sp)
> + REG_S x6, 48(sp)
> + REG_S x7, 56(sp)
> + REG_S x8, 64(sp)
> + REG_S x9, 72(sp)
> + REG_S x10, 80(sp)
> + REG_S x11, 88(sp)
> + REG_S x12, 96(sp)
> + REG_S x13, 104(sp)
> + REG_S x14, 112(sp)
> + REG_S x15, 120(sp)
> + REG_S x16, 128(sp)
> + REG_S x17, 136(sp)
> + REG_S x18, 144(sp)
> + REG_S x19, 152(sp)
> + REG_S x20, 160(sp)
> + REG_S x21, 168(sp)
> + REG_S x22, 176(sp)
> + REG_S x23, 184(sp)
> + REG_S x24, 192(sp)
> + REG_S x25, 200(sp)
> + REG_S x26, 208(sp)
> + REG_S x27, 216(sp)
> + REG_S x28, 224(sp)
> + REG_S x29, 232(sp)
> + REG_S x30, 240(sp)
> + REG_S x31, 248(sp)
> csrr s0, CSR_SEPC
> csrr s1, CSR_SSTATUS
> - csrr s2, CSR_SCAUSE
> - sd s0, 248(sp)
> - sd s1, 256(sp)
> - sd s2, 264(sp)
> + csrr s2, CSR_STVAL
> + csrr s3, CSR_SCAUSE
> + REG_S s0, 0(sp)
> + REG_S s1, 256(sp)
> + REG_S s2, 264(sp)
> + REG_S s3, 272(sp)
> .endm
>
> .macro restore_context
> - ld s2, 264(sp)
> - ld s1, 256(sp)
> - ld s0, 248(sp)
> - csrw CSR_SCAUSE, s2
> + REG_L s3, 272(sp)
> + REG_L s2, 264(sp)
> + REG_L s1, 256(sp)
> + REG_L s0, 0(sp)
> + csrw CSR_SCAUSE, s3
> csrw CSR_SSTATUS, s1
> csrw CSR_SEPC, s0
> - ld x31, 240(sp)
> - ld x30, 232(sp)
> - ld x29, 224(sp)
> - ld x28, 216(sp)
> - ld x27, 208(sp)
> - ld x26, 200(sp)
> - ld x25, 192(sp)
> - ld x24, 184(sp)
> - ld x23, 176(sp)
> - ld x22, 168(sp)
> - ld x21, 160(sp)
> - ld x20, 152(sp)
> - ld x19, 144(sp)
> - ld x18, 136(sp)
> - ld x17, 128(sp)
> - ld x16, 120(sp)
> - ld x15, 112(sp)
> - ld x14, 104(sp)
> - ld x13, 96(sp)
> - ld x12, 88(sp)
> - ld x11, 80(sp)
> - ld x10, 72(sp)
> - ld x9, 64(sp)
> - ld x8, 56(sp)
> - ld x7, 48(sp)
> - ld x6, 40(sp)
> - ld x5, 32(sp)
> - ld x4, 24(sp)
> - ld x3, 16(sp)
> - ld x2, 8(sp)
> - ld x1, 0(sp)
> - addi sp, sp, (8*34)
> + REG_L x31, 248(sp)
> + REG_L x30, 240(sp)
> + REG_L x29, 232(sp)
> + REG_L x28, 224(sp)
> + REG_L x27, 216(sp)
> + REG_L x26, 208(sp)
> + REG_L x25, 200(sp)
> + REG_L x24, 192(sp)
> + REG_L x23, 184(sp)
> + REG_L x22, 176(sp)
> + REG_L x21, 168(sp)
> + REG_L x20, 160(sp)
> + REG_L x19, 152(sp)
> + REG_L x18, 144(sp)
> + REG_L x17, 136(sp)
> + REG_L x16, 128(sp)
> + REG_L x15, 120(sp)
> + REG_L x14, 112(sp)
> + REG_L x13, 104(sp)
> + REG_L x12, 96(sp)
> + REG_L x11, 88(sp)
> + REG_L x10, 80(sp)
> + REG_L x9, 72(sp)
> + REG_L x8, 64(sp)
> + REG_L x7, 56(sp)
> + REG_L x6, 48(sp)
> + REG_L x5, 40(sp)
> + REG_L x4, 32(sp)
> + REG_L x3, 24(sp)
> + REG_L x2, 16(sp)
> + REG_L x1, 8(sp)
> + addi sp, sp, (8*36)
> .endm
>
> .balign 4
> diff --git a/tools/testing/selftests/kvm/lib/riscv/processor.c b/tools/testing/selftests/kvm/lib/riscv/processor.c
> index dd663bcf0cc0..2eac7d4b59e9 100644
> --- a/tools/testing/selftests/kvm/lib/riscv/processor.c
> +++ b/tools/testing/selftests/kvm/lib/riscv/processor.c
> @@ -402,7 +402,7 @@ struct handlers {
> exception_handler_fn exception_handlers[NR_VECTORS][NR_EXCEPTIONS];
> };
>
> -void route_exception(struct ex_regs *regs)
> +void route_exception(struct pt_regs *regs)
> {
> struct handlers *handlers = (struct handlers *)exception_handlers;
> int vector = 0, ec;
> diff --git a/tools/testing/selftests/kvm/riscv/arch_timer.c b/tools/testing/selftests/kvm/riscv/arch_timer.c
> index 9e370800a6a2..f962fefc48fa 100644
> --- a/tools/testing/selftests/kvm/riscv/arch_timer.c
> +++ b/tools/testing/selftests/kvm/riscv/arch_timer.c
> @@ -15,7 +15,7 @@
>
> static int timer_irq = IRQ_S_TIMER;
>
> -static void guest_irq_handler(struct ex_regs *regs)
> +static void guest_irq_handler(struct pt_regs *regs)
> {
> uint64_t xcnt, xcnt_diff_us, cmp;
> unsigned int intid = regs->cause & ~CAUSE_IRQ_FLAG;
> diff --git a/tools/testing/selftests/kvm/riscv/ebreak_test.c b/tools/testing/selftests/kvm/riscv/ebreak_test.c
> index cfed6c727bfc..739d17befb5a 100644
> --- a/tools/testing/selftests/kvm/riscv/ebreak_test.c
> +++ b/tools/testing/selftests/kvm/riscv/ebreak_test.c
> @@ -27,7 +27,7 @@ static void guest_code(void)
> GUEST_DONE();
> }
>
> -static void guest_breakpoint_handler(struct ex_regs *regs)
> +static void guest_breakpoint_handler(struct pt_regs *regs)
> {
> WRITE_ONCE(sw_bp_addr, regs->epc);
> regs->epc += 4;
> diff --git a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> index 03406de4989d..6e66833e5941 100644
> --- a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> +++ b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
> @@ -128,7 +128,7 @@ static void stop_counter(unsigned long counter, unsigned long stop_flags)
> "Unable to stop counter %ld error %ld\n", counter, ret.error);
> }
>
> -static void guest_illegal_exception_handler(struct ex_regs *regs)
> +static void guest_illegal_exception_handler(struct pt_regs *regs)
> {
> __GUEST_ASSERT(regs->cause == EXC_INST_ILLEGAL,
> "Unexpected exception handler %lx\n", regs->cause);
> @@ -138,7 +138,7 @@ static void guest_illegal_exception_handler(struct ex_regs *regs)
> regs->epc += 4;
> }
>
> -static void guest_irq_handler(struct ex_regs *regs)
> +static void guest_irq_handler(struct pt_regs *regs)
> {
> unsigned int irq_num = regs->cause & ~CAUSE_IRQ_FLAG;
> struct riscv_pmu_snapshot_data *snapshot_data = snapshot_gva;
>
> --
> 2.43.0
>

Other than the macro comments,

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Thanks,
drew