Re: [PATCH v5 11/17] powerpc/pseries/vas: Implement getting capabilities from hypervisor

[Nicholas Piggin <npiggin@gmail.com>]

Excerpts from Haren Myneni's message of June 13, 2021 9:01 pm:
> 
> The hypervisor provides VAS capabilities for GZIP default and QoS
> features. These capabilities gives information for the specific
> features such as total number of credits available in LPAR,
> maximum credits allowed per window, maximum credits allowed in
> LPAR, whether usermode copy/paste is supported, and etc.
> 
> This patch adds the following:
> - Retrieve all features that are provided by hypervisor using
>   H_QUERY_VAS_CAPABILITIES hcall with 0 as feature type.
> - Retrieve capabilities for the specific feature using the same
>   hcall and the feature type (1 for QoS and 2 for default type).
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> ---
>  arch/powerpc/platforms/pseries/vas.c | 124 +++++++++++++++++++++++++++
>  1 file changed, 124 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
> index fec280979d50..98109a13f1c2 100644
> --- a/arch/powerpc/platforms/pseries/vas.c
> +++ b/arch/powerpc/platforms/pseries/vas.c
> @@ -10,6 +10,7 @@
>  #include <linux/export.h>
>  #include <linux/types.h>
>  #include <linux/delay.h>
> +#include <asm/machdep.h>
>  #include <asm/hvcall.h>
>  #include <asm/plpar_wrappers.h>
>  #include <asm/vas.h>
> @@ -20,6 +21,13 @@
>  /* phyp allows one credit per window right now */
>  #define DEF_WIN_CREDS		1
>  
> +static struct vas_all_caps caps_all;
> +static bool copypaste_feat;
> +
> +static struct vas_caps vascaps[VAS_MAX_FEAT_TYPE];

If these will all be read by later patches I think that's okay, 
however:

> +
> +static DEFINE_MUTEX(vas_pseries_mutex);

This is not used at all. It should be added in the patch that uses it.

Thanks,
Nick

> +
>  static long hcall_return_busy_check(long rc)
>  {
>  	/* Check if we are stalled for some time */
> @@ -179,3 +187,119 @@ int h_query_vas_capabilities(const u64 hcall, u8 query_type, u64 result)
>  		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 hv_vas_ct_caps *hv_caps)
> +{
> +	struct vas_ct_caps *caps;
> +	struct vas_caps *vcaps;
> +	int rc = 0;
> +
> +	vcaps = &vascaps[type];
> +	memset(vcaps, 0, sizeof(*vcaps));
> +	INIT_LIST_HEAD(&vcaps->list);
> +
> +	caps = &vcaps->caps;
> +
> +	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES, feat,
> +					  (u64)virt_to_phys(hv_caps));
> +	if (rc)
> +		return rc;
> +
> +	caps->user_mode = hv_caps->user_mode;
> +	if (!(caps->user_mode & VAS_COPY_PASTE_USER_MODE)) {
> +		pr_err("User space COPY/PASTE is not supported\n");
> +		return -ENOTSUPP;
> +	}
> +
> +	caps->descriptor = be64_to_cpu(hv_caps->descriptor);
> +	caps->win_type = hv_caps->win_type;
> +	if (caps->win_type >= VAS_MAX_FEAT_TYPE) {
> +		pr_err("Unsupported window type %u\n", caps->win_type);
> +		return -EINVAL;
> +	}
> +	caps->max_lpar_creds = be16_to_cpu(hv_caps->max_lpar_creds);
> +	caps->max_win_creds = be16_to_cpu(hv_caps->max_win_creds);
> +	atomic_set(&caps->target_lpar_creds,
> +		   be16_to_cpu(hv_caps->target_lpar_creds));
> +	if (feat == VAS_GZIP_DEF_FEAT) {
> +		caps->def_lpar_creds = be16_to_cpu(hv_caps->def_lpar_creds);
> +
> +		if (caps->max_win_creds < DEF_WIN_CREDS) {
> +			pr_err("Window creds(%u) > max allowed window creds(%u)\n",
> +			       DEF_WIN_CREDS, caps->max_win_creds);
> +			return -EINVAL;
> +		}
> +	}
> +
> +	copypaste_feat = true;
> +
> +	return 0;
> +}
> +
> +static int __init pseries_vas_init(void)
> +{
> +	struct hv_vas_ct_caps *hv_ct_caps;
> +	struct hv_vas_all_caps *hv_caps;
> +	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;
> +	}
> +
> +	hv_caps = kmalloc(sizeof(*hv_caps), GFP_KERNEL);
> +	if (!hv_caps)
> +		return -ENOMEM;
> +	/*
> +	 * Get VAS overall capabilities by passing 0 to feature type.
> +	 */
> +	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES, 0,
> +					  (u64)virt_to_phys(hv_caps));
> +	if (rc)
> +		goto out;
> +
> +	caps_all.descriptor = be64_to_cpu(hv_caps->descriptor);
> +	caps_all.feat_type = be64_to_cpu(hv_caps->feat_type);
> +
> +	hv_ct_caps = kmalloc(sizeof(*hv_ct_caps), GFP_KERNEL);
> +	if (!hv_ct_caps) {
> +		rc = -ENOMEM;
> +		goto out;
> +	}
> +	/*
> +	 * QOS capabilities available
> +	 */
> +	if (caps_all.feat_type & VAS_GZIP_QOS_FEAT_BIT) {
> +		rc = get_vas_capabilities(VAS_GZIP_QOS_FEAT,
> +					  VAS_GZIP_QOS_FEAT_TYPE, hv_ct_caps);
> +
> +		if (rc)
> +			goto out_ct;
> +	}
> +	/*
> +	 * Default capabilities available
> +	 */
> +	if (caps_all.feat_type & VAS_GZIP_DEF_FEAT_BIT) {
> +		rc = get_vas_capabilities(VAS_GZIP_DEF_FEAT,
> +					  VAS_GZIP_DEF_FEAT_TYPE, hv_ct_caps);
> +		if (rc)
> +			goto out_ct;
> +	}
> +
> +	pr_info("GZIP feature is available\n");
> +
> +out_ct:
> +	kfree(hv_ct_caps);
> +out:
> +	kfree(hv_caps);
> +	return rc;
> +}
> +machine_device_initcall(pseries, pseries_vas_init);
> -- 
> 2.18.2
> 
> 
>