[PATCH v2 10/25] KVM: arm64: nv: Turn encoding ranges into discrete XArray stores

[Joey Gouly]

On Tue, Jan 30, 2024 at 08:45:17PM +0000, Marc Zyngier wrote:
> In order to be able to store different values for member of an
> encoding range, replace xa_store_range() calls with discrete
> xa_store() calls and an encoding iterator.
> 
> We end-up using a bit more memory, but we gain some flexibility
> that we will make use of shortly.
> 
> Take this opportunity to tidy up the error handling path.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/kvm/emulate-nested.c | 49 ++++++++++++++++++++++++---------
>  1 file changed, 36 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
> index ef46c2e45307..42f5b4483c80 100644
> --- a/arch/arm64/kvm/emulate-nested.c
> +++ b/arch/arm64/kvm/emulate-nested.c
> @@ -1757,6 +1757,28 @@ static __init void print_nv_trap_error(const struct encoding_to_trap_config *tc,
>  		err);
>  }
>  
> +static u32 encoding_next(u32 encoding)
> +{
> +	u8 op0, op1, crn, crm, op2;
> +
> +	op0 = sys_reg_Op0(encoding);
> +	op1 = sys_reg_Op1(encoding);
> +	crn = sys_reg_CRn(encoding);
> +	crm = sys_reg_CRm(encoding);
> +	op2 = sys_reg_Op2(encoding);
> +
> +	if (op2 < Op2_mask)
> +		return sys_reg(op0, op1, crn, crm, op2 + 1);
> +	if (crm < CRm_mask)
> +		return sys_reg(op0, op1, crn, crm + 1, 0);
> +	if (crn < CRn_mask)
> +		return sys_reg(op0, op1, crn + 1, 0, 0);
> +	if (op1 < Op1_mask)
> +		return sys_reg(op0, op1 + 1, 0, 0, 0);
> +
> +	return sys_reg(op0 + 1, 0, 0, 0, 0);
> +}
> +
>  int __init populate_nv_trap_config(void)
>  {
>  	int ret = 0;
> @@ -1775,23 +1797,18 @@ int __init populate_nv_trap_config(void)
>  			ret = -EINVAL;
>  		}
>  
> -		if (cgt->encoding != cgt->end) {
> -			prev = xa_store_range(&sr_forward_xa,
> -					      cgt->encoding, cgt->end,
> -					      xa_mk_value(cgt->tc.val),
> -					      GFP_KERNEL);
> -		} else {
> -			prev = xa_store(&sr_forward_xa, cgt->encoding,
> +		for (u32 enc = cgt->encoding; enc <= cgt->end; enc = encoding_next(enc)) {
> +			prev = xa_store(&sr_forward_xa, enc,
>  					xa_mk_value(cgt->tc.val), GFP_KERNEL);
>  			if (prev && !xa_is_err(prev)) {
>  				ret = -EINVAL;
>  				print_nv_trap_error(cgt, "Duplicate CGT", ret);
>  			}
> -		}
>  
> -		if (xa_is_err(prev)) {
> -			ret = xa_err(prev);
> -			print_nv_trap_error(cgt, "Failed CGT insertion", ret);
> +			if (xa_is_err(prev)) {
> +				ret = xa_err(prev);
> +				print_nv_trap_error(cgt, "Failed CGT insertion", ret);
> +			}
>  		}
>  	}
>  
> @@ -1804,6 +1821,7 @@ int __init populate_nv_trap_config(void)
>  	for (int i = 0; i < ARRAY_SIZE(encoding_to_fgt); i++) {
>  		const struct encoding_to_trap_config *fgt = &encoding_to_fgt[i];
>  		union trap_config tc;
> +		void *prev;
>  
>  		if (fgt->tc.fgt >= __NR_FGT_GROUP_IDS__) {
>  			ret = -EINVAL;
> @@ -1818,8 +1836,13 @@ int __init populate_nv_trap_config(void)
>  		}
>  
>  		tc.val |= fgt->tc.val;
> -		xa_store(&sr_forward_xa, fgt->encoding,
> -			 xa_mk_value(tc.val), GFP_KERNEL);
> +		prev = xa_store(&sr_forward_xa, fgt->encoding,
> +				xa_mk_value(tc.val), GFP_KERNEL);
> +
> +		if (xa_is_err(prev)) {
> +			ret = xa_err(prev);
> +			print_nv_trap_error(fgt, "Failed FGT insertion", ret);
> +		}
>  	}
>  
>  	kvm_info("nv: %ld fine grained trap handlers\n",

Tidied up error handling from v1.

Reviewed-by: Joey Gouly <joey.gouly at arm.com>

Thanks,
Joey