Re: [kvm-unit-tests PATCH 2/4] riscv: Update exception cause list

[Andrew Jones <andrew.jones@linux.dev>]

On Wed, Jun 19, 2024 at 01:30:51AM GMT, James Raphael Tiovalen wrote:
> Update the list of exception and interrupt causes to follow the latest
> RISC-V privileged ISA specification (version 20240411).
> 
> Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
> ---
>  lib/riscv/asm/csr.h       | 15 +++++++++------
>  lib/riscv/asm/processor.h |  2 +-
>  2 files changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/lib/riscv/asm/csr.h b/lib/riscv/asm/csr.h
> index d5879d2a..c1777744 100644
> --- a/lib/riscv/asm/csr.h
> +++ b/lib/riscv/asm/csr.h
> @@ -26,15 +26,18 @@
>  #define EXC_STORE_MISALIGNED	6
>  #define EXC_STORE_ACCESS	7
>  #define EXC_SYSCALL		8
> -#define EXC_HYPERVISOR_SYSCALL	9
> -#define EXC_SUPERVISOR_SYSCALL	10
> +#define EXC_SUPERVISOR_SYSCALL	9
>  #define EXC_INST_PAGE_FAULT	12
>  #define EXC_LOAD_PAGE_FAULT	13
>  #define EXC_STORE_PAGE_FAULT	15
> -#define EXC_INST_GUEST_PAGE_FAULT	20
> -#define EXC_LOAD_GUEST_PAGE_FAULT	21
> -#define EXC_VIRTUAL_INST_FAULT		22
> -#define EXC_STORE_GUEST_PAGE_FAULT	23
> +#define EXC_SOFTWARE_CHECK	18
> +#define EXC_HARDWARE_ERROR	19

The above changes don't update the exception cause list to the latest
spec, they drop the defines supporting the hypervisor extension's
augmentations (see Section 18.6.1 of the 20240411 priv spec).

> +
> +/* Interrupt causes */
> +#define IRQ_SUPERVISOR_SOFTWARE	1
> +#define IRQ_SUPERVISOR_TIMER	5
> +#define IRQ_SUPERVISOR_EXTERNAL	9
> +#define IRQ_COUNTER_OVERFLOW	13

These are fine, but we could also add the defines for the hypervisor
extension's augmentations. I also usually just copy+paste the defines
from Linux since I prefer name consistency.

>  
>  #ifndef __ASSEMBLY__
>  
> diff --git a/lib/riscv/asm/processor.h b/lib/riscv/asm/processor.h
> index 767b1caa..5942ed2e 100644
> --- a/lib/riscv/asm/processor.h
> +++ b/lib/riscv/asm/processor.h
> @@ -4,7 +4,7 @@
>  #include <asm/csr.h>
>  #include <asm/ptrace.h>
>  
> -#define EXCEPTION_CAUSE_MAX	16
> +#define EXCEPTION_CAUSE_MAX	64

If we want to test the H extension, then we'll want 20-23, but everything
else is custom or reserved, so we don't need to allocate handler pointer
space all the way up to 64 as they'll never be used.

Thanks,
drew

>  #define INTERRUPT_CAUSE_MAX	16
>  
>  typedef void (*exception_fn)(struct pt_regs *);
> -- 
> 2.43.0
> 
> 
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