Re: [V3 PATCH 09/16] powerpc/pseries/vas: Implement to get all capabilities

Nicholas Piggin
2021-05-10T06:13:16Z

Excerpts from Haren Myneni's message of April 18, 2021 7:08 am:
>
> pHyp provides various VAS capabilities such as GZIP default and QoS
> capabilities which are used to determine total number of credits
> available in LPAR, maximum window credits, maximum LPAR credits,
> whether usermode copy/paste is supported, and etc.
>
> So first retrieve overall vas capabilities using
> H_QUERY_VAS_CAPABILITIES HCALL which tells the specific features that
> are available. Then retrieve the specific capabilities by using the
> feature type in H_QUERY_VAS_CAPABILITIES HCALL.
>
> pHyp supports only GZIP default and GZIP QoS capabilities right now.

Changelog and title could use a bit of work.

>
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> ---
> arch/powerpc/platforms/pseries/vas.c | 130 +++++++++++++++++++++++++++
> 1 file changed, 130 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
> index 06960151477c..35946fb02995 100644
> --- a/arch/powerpc/platforms/pseries/vas.c
> +++ b/arch/powerpc/platforms/pseries/vas.c
> @@ -30,6 +30,13 @@
> /* phyp allows one credit per window right now */
> #define DEF_WIN_CREDS 1
>
> +static struct vas_all_capabs capabs_all;

Does this name come from PAPR? If not, capabilities or caps are better
for readability than capabs.

> +static int copypaste_feat;

Should be a bool? And what does it mean? copy-paste is a host core
capability.

> +
> +struct vas_capabs vcapabs[VAS_MAX_FEAT_TYPE];
> +
> +DEFINE_MUTEX(vas_pseries_mutex);

Can these be made static if they're only used here, and export them if a
future patch uses them (or add the header declaration now).

> +
> static int64_t hcall_return_busy_check(int64_t rc)
> {
> /* Check if we are stalled for some time */
> @@ -215,3 +222,126 @@ int plpar_vas_query_capabilities(const u64 hcall, u8 query_type,
> return -EIO;
> }
> }
> +
> +/*
> + * Get the specific capabilities based on the feature type.
> + * Right now supports GZIP default and GZIP QoS capabilities.
> + */
> +static int get_vas_capabilities(u8 feat, enum vas_cop_feat_type type,
> + struct vas_ct_capabs_be *capab_be)
> +{
> + struct vas_ct_capabs *capab;
> + struct vas_capabs *vcapab;
> + int rc = 0;
> +
> + vcapab = &vcapabs[type];
> + memset(vcapab, 0, sizeof(*vcapab));
> + INIT_LIST_HEAD(&vcapab->list);
> +
> + capab = &vcapab->capab;
> +
> + rc = plpar_vas_query_capabilities(H_QUERY_VAS_CAPABILITIES, feat,
> + (u64)virt_to_phys(capab_be));
> + if (rc)
> + return rc;
> +
> + capab->user_mode = capab_be->user_mode;
> + if (!(capab->user_mode & VAS_COPY_PASTE_USER_MODE)) {
> + pr_err("User space COPY/PASTE is not supported\n");
> + return -ENOTSUPP;
> + }
> +
> + snprintf(capab->name, VAS_DESCR_LEN + 1, "%.8s",
> + (char *)&capab_be->descriptor);
> + capab->descriptor = be64_to_cpu(capab_be->descriptor);
> + capab->win_type = capab_be->win_type;
> + if (capab->win_type >= VAS_MAX_FEAT_TYPE) {
> + pr_err("Unsupported window type %u\n", capab->win_type);
> + return -EINVAL;
> + }
> + capab->max_lpar_creds = be16_to_cpu(capab_be->max_lpar_creds);
> + capab->max_win_creds = be16_to_cpu(capab_be->max_win_creds);
> + atomic_set(&capab->target_lpar_creds,
> + be16_to_cpu(capab_be->target_lpar_creds));
> + if (feat == VAS_GZIP_DEF_FEAT) {
> + capab->def_lpar_creds = be16_to_cpu(capab_be->def_lpar_creds);
> +
> + if (capab->max_win_creds < DEF_WIN_CREDS) {
> + pr_err("Window creds(%u) > max allowed window creds(%u)\n",
> + DEF_WIN_CREDS, capab->max_win_creds);
> + return -EINVAL;
> + }
> + }
> +
> + copypaste_feat = 1;
> +
> + return 0;
> +}
> +
> +static int __init pseries_vas_init(void)
> +{
> + struct vas_ct_capabs_be *ct_capabs_be;
> + struct vas_all_capabs_be *capabs_be;
> + int rc;
> +
> + /*
> + * Linux supports user space COPY/PASTE only with Radix
> + */
> + if (!radix_enabled()) {
> + pr_err("API is supported only with radix page tables\n");
> + return -ENOTSUPP;
> + }
> +
> + capabs_be = kmalloc(sizeof(*capabs_be), GFP_KERNEL);
> + if (!capabs_be)
> + return -ENOMEM;
> + /*
> + * Get VAS overall capabilities by passing 0 to feature type.
> + */
> + rc = plpar_vas_query_capabilities(H_QUERY_VAS_CAPABILITIES, 0,
> + (u64)virt_to_phys(capabs_be));
> + if (rc)
> + goto out;
> +
> + snprintf(capabs_all.name, VAS_DESCR_LEN, "%.7s",
> + (char *)&capabs_be->descriptor);
> + capabs_all.descriptor = be64_to_cpu(capabs_be->descriptor);
> + capabs_all.feat_type = be64_to_cpu(capabs_be->feat_type);
> +
> + ct_capabs_be = kmalloc(sizeof(*ct_capabs_be), GFP_KERNEL);
> + if (!ct_capabs_be) {
> + rc = -ENOMEM;
> + goto out;
> + }
> + /*
> + * QOS capabilities available
> + */
> + if (capabs_all.feat_type & VAS_GZIP_QOS_FEAT_BIT) {
> + rc = get_vas_capabilities(VAS_GZIP_QOS_FEAT,
> + VAS_GZIP_QOS_FEAT_TYPE, ct_capabs_be);
> +
> + if (rc)
> + goto out_ct;
> + }
> + /*
> + * Default capabilities available
> + */
> + if (capabs_all.feat_type & VAS_GZIP_DEF_FEAT_BIT) {
> + rc = get_vas_capabilities(VAS_GZIP_DEF_FEAT,
> + VAS_GZIP_DEF_FEAT_TYPE, ct_capabs_be);
> + if (rc)
> + goto out_ct;
> + }

Using the same buffer for two hcalls? Do they fill in different parts of
it?

> +
> + if (!copypaste_feat)
> + pr_err("GZIP feature is not supported\n");

This is dead code AFAIKS, because errors will always branch to out.

Thanks,
Nick

> +
> + pr_info("GZIP feature is available\n");
> +
> +out_ct:
> + kfree(ct_capabs_be);
> +out:
> + kfree(capabs_be);
> + return rc;
> +}
> +machine_device_initcall(pseries, pseries_vas_init);
> --
> 2.18.2
>
>
>