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

Haren Myneni
2021-05-11T02:10:26Z

On Mon, 2021-05-10 at 16:13 +1000, Nicholas Piggin wrote:
> 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.

No capabs is not from PAPR, I just added capabs as short name for
capabilities. I will change it to caps as suggested.

>
> > +static int copypaste_feat;
>
> Should be a bool? And what does it mean? copy-paste is a host core
> capability.

copypaste_feat can be bool. But is it used to export user space API if
reading all capabilities are successful.
>
> > +
> > +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?

Yes, ct_capabs_be buffer is passed to HCALL to get capabilities for DEF
and QOS types.

Thanks
Haren

>
> > +
> > + 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
> >
> >
> >