Re: [PATCH v5 04/12] xen/arm: add SVE exception class handling

[Julien Grall <julien@xxxxxxx>]

Hi,

On 12/04/2023 10:49, Luca Fancellu wrote:
> SVE has a new exception class with code 0x19, introduce the new code
> and handle the exception.
>
> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
> ---
> Changes from v4:
>   - No changes
> Changes from v3:
>   - No changes
> Changes from v2:
>   - No changes
> Changes from v1:
>   - No changes
> Changes from RFC:
>   - No changes
> ---
>   xen/arch/arm/include/asm/processor.h |  1 +
>   xen/arch/arm/traps.c                 | 12 ++++++++++++
>   2 files changed, 13 insertions(+)
>
> diff --git a/xen/arch/arm/include/asm/processor.h 
> b/xen/arch/arm/include/asm/processor.h
> index bc683334125c..7e42ff8811fc 100644
> --- a/xen/arch/arm/include/asm/processor.h
> +++ b/xen/arch/arm/include/asm/processor.h
> @@ -426,6 +426,7 @@
>   #define HSR_EC_HVC64                0x16
>   #define HSR_EC_SMC64                0x17
>   #define HSR_EC_SYSREG               0x18
> +#define HSR_EC_SVE                  0x19
>   #endif
>   #define HSR_EC_INSTR_ABORT_LOWER_EL 0x20
>   #define HSR_EC_INSTR_ABORT_CURR_EL  0x21
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index a78a99ddadd0..c2e30feafd5a 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -2160,6 +2160,13 @@ void do_trap_guest_sync(struct cpu_user_regs *regs)
>           perfc_incr(trap_sysreg);
>           do_sysreg(regs, hsr);
>           break;
> +    case HSR_EC_SVE:
> +        GUEST_BUG_ON(regs_mode_is_32bit(regs));
> +        gprintk(XENLOG_WARNING,
> +                "Domain id %d tried to use SVE while not allowed\n",
> +                current->domain->domain_id);
gprintk() will already print the domain/vCPU for you. Also, if you want 
to print a domain ID, then you should use ("%pd", d) rather than ("%d", 
d->domain_id).
> +        inject_undef_exception(regs, hsr);
> +        break;
>   #endif
>   
>       case HSR_EC_INSTR_ABORT_LOWER_EL:
> @@ -2189,6 +2196,11 @@ void do_trap_hyp_sync(struct cpu_user_regs *regs)
>       case HSR_EC_BRK:
>           do_trap_brk(regs, hsr);
>           break;
> +    case HSR_EC_SVE:
> +        /* An SVE exception is a bug somewhere in hypervisor code */
> +        printk("SVE trap at EL2.\n");
> +        do_unexpected_trap("Hypervisor", regs);
I think it would be better if you pass "SVE trap at EL2" as a string 
rather than adding your own printk above.
> +        break;
>   #endif
>       case HSR_EC_DATA_ABORT_CURR_EL:
>       case HSR_EC_INSTR_ABORT_CURR_EL:
Cheers,

--
Julien Grall