Re: [PATCH v19 1/7] firmware: arm_rmm: Add SMC definitions for calling the RMM

[Ackerley Tng <ackerleytng@google.com>]

Suzuki K Poulose <suzuki.poulose@arm.com> writes:

>
> [...snip...]
>
> +
> +/*
> + * Note many of these fields are smaller than u64 but all fields have u64
> + * alignment, so use u64 to ensure correct alignment.
> + */
> +struct rmm_config {
> +	union { /* 0x0 */
> +		struct {
> +			u64 tracking_region_size;
> +			u64 rmi_granule_size;
> +		};
> +		u8 sizer[SZ_4K];
> +	};
> +};
> +
> +static_assert(sizeof(struct rmm_config) == SZ_4K);
> +
> +#define RMI_REALM_PARAM_FLAG_MEC_POLICY_MASK	GENMASK(8, 7)
> +#define RMI_REALM_PARAM_FLAG_LFA_POLICY_MASK	GENMASK(6, 5)
> +#define RMI_REALM_PARAM_FLAG_DA			BIT(3)
> +#define RMI_REALM_PARAM_FLAG_PMU		BIT(2)
> +#define RMI_REALM_PARAM_FLAG_SVE		BIT(1)
> +
> +#define RMI_HASH_SHA_256			0
> +#define RMI_HASH_SHA_512			1
> +#define RMI_HASH_SHA_384			2
> +
> +struct realm_params {
> +	union { /* 0x0 */
> +		struct {
> +			u64 flags0;
> +			u64 s2sz;
> +			u64 sve_vl;
> +			u64 num_bps;
> +			u64 num_wps;
> +			u64 pmu_num_ctrs;
> +			u64 hash_algo;
> +			u64 num_aux_planes;
> +		};
> +		u8 padding0[0x400];

The union + sizer concept is cool. Technically this one isn't a padding,
it's also a sizer? (same for the other structs below.

> +	};
> +	union { /* 0x400 */
> +		struct {
> +			u8 rpv[64];
> +			u64 ats_plane;
> +		};
> +		u8 padding1[0x400];
> +	};
> +	union { /* 0x800 */
> +		struct {
> +			u64 padding2;
> +			u64 rtt_base;
> +			s64 rtt_level_start;
> +			u64 rtt_num_start;
> +			u64 flags1;
> +			u64 max_num_vdevs;
> +		};
> +		u8 padding3[0x700];
> +	};
> +	union { /* 0xf00 */
> +		struct {
> +			u8 padding4[0x80];
> +			u64 aux_rtt_base[3];
> +		};
> +		u8 padding5[0x100];
> +	};
> +};
> +
> +static_assert(sizeof(struct realm_params) == SZ_4K);
> +

Does declaring this struct as packed matter? I guess the static_assert()
has the same effect.

>
> [...snip...]
>