Re: [PATCH v6 15/17] crypto/nx: Get NX capabilities for GZIP coprocessor type

[Nicholas Piggin <npiggin@gmail.com>]

Excerpts from Haren Myneni's message of June 18, 2021 6:38 am:
> 
> The hypervisor provides different NX capabilities that it
> supports. These capabilities such as recommended minimum
> compression / decompression lengths and the maximum request
> buffer size in bytes are used to define the user space NX
> request.
> 
> NX will reject the request if the buffer size is more than
> the maximum buffer size. Whereas compression / decompression
> lengths are recommended values for better performance.
> 
> Changes to get NX overall capabilities which points to the
> specific features that the hypervisor supports. Then retrieve
> the capabilities for the specific feature (available only
> for NXGZIP).
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

Acked-by: Nicholas Piggin <npiggin@gmail.com>

> ---
>  drivers/crypto/nx/nx-common-pseries.c | 87 +++++++++++++++++++++++++++
>  1 file changed, 87 insertions(+)
> 
> diff --git a/drivers/crypto/nx/nx-common-pseries.c b/drivers/crypto/nx/nx-common-pseries.c
> index cc8dd3072b8b..9fc2abb56019 100644
> --- a/drivers/crypto/nx/nx-common-pseries.c
> +++ b/drivers/crypto/nx/nx-common-pseries.c
> @@ -9,6 +9,8 @@
>   */
>  
>  #include <asm/vio.h>
> +#include <asm/hvcall.h>
> +#include <asm/vas.h>
>  
>  #include "nx-842.h"
>  #include "nx_csbcpb.h" /* struct nx_csbcpb */
> @@ -19,6 +21,29 @@ MODULE_DESCRIPTION("842 H/W Compression driver for IBM Power processors");
>  MODULE_ALIAS_CRYPTO("842");
>  MODULE_ALIAS_CRYPTO("842-nx");
>  
> +/*
> + * Coprocessor type specific capabilities from the hypervisor.
> + */
> +struct hv_nx_cop_caps {
> +	__be64	descriptor;
> +	__be64	req_max_processed_len;	/* Max bytes in one GZIP request */
> +	__be64	min_compress_len;	/* Min compression size in bytes */
> +	__be64	min_decompress_len;	/* Min decompression size in bytes */
> +} __packed __aligned(0x1000);
> +
> +/*
> + * Coprocessor type specific capabilities.
> + */
> +struct nx_cop_caps {
> +	u64	descriptor;
> +	u64	req_max_processed_len;	/* Max bytes in one GZIP request */
> +	u64	min_compress_len;	/* Min compression in bytes */
> +	u64	min_decompress_len;	/* Min decompression in bytes */
> +};
> +
> +static u64 caps_feat;
> +static struct nx_cop_caps nx_cop_caps;
> +
>  static struct nx842_constraints nx842_pseries_constraints = {
>  	.alignment =	DDE_BUFFER_ALIGN,
>  	.multiple =	DDE_BUFFER_LAST_MULT,
> @@ -1065,6 +1090,64 @@ static void nx842_remove(struct vio_dev *viodev)
>  	kfree(old_devdata);
>  }
>  
> +/*
> + * Get NX capabilities from the hypervisor.
> + * Only NXGZIP capabilities are provided by the hypersvisor right
> + * now and these values are available to user space with sysfs.
> + */
> +static void __init nxcop_get_capabilities(void)
> +{
> +	struct hv_vas_all_caps *hv_caps;
> +	struct hv_nx_cop_caps *hv_nxc;
> +	int rc;
> +
> +	hv_caps = kmalloc(sizeof(*hv_caps), GFP_KERNEL);
> +	if (!hv_caps)
> +		return;
> +	/*
> +	 * Get NX overall capabilities with feature type=0
> +	 */
> +	rc = h_query_vas_capabilities(H_QUERY_NX_CAPABILITIES, 0,
> +					  (u64)virt_to_phys(hv_caps));
> +	if (rc)
> +		goto out;
> +
> +	caps_feat = be64_to_cpu(hv_caps->feat_type);
> +	/*
> +	 * NX-GZIP feature available
> +	 */
> +	if (caps_feat & VAS_NX_GZIP_FEAT_BIT) {
> +		hv_nxc = kmalloc(sizeof(*hv_nxc), GFP_KERNEL);
> +		if (!hv_nxc)
> +			goto out;
> +		/*
> +		 * Get capabilities for NX-GZIP feature
> +		 */
> +		rc = h_query_vas_capabilities(H_QUERY_NX_CAPABILITIES,
> +						  VAS_NX_GZIP_FEAT,
> +						  (u64)virt_to_phys(hv_nxc));
> +	} else {
> +		pr_err("NX-GZIP feature is not available\n");
> +		rc = -EINVAL;
> +	}
> +
> +	if (!rc) {
> +		nx_cop_caps.descriptor = be64_to_cpu(hv_nxc->descriptor);
> +		nx_cop_caps.req_max_processed_len =
> +				be64_to_cpu(hv_nxc->req_max_processed_len);
> +		nx_cop_caps.min_compress_len =
> +				be64_to_cpu(hv_nxc->min_compress_len);
> +		nx_cop_caps.min_decompress_len =
> +				be64_to_cpu(hv_nxc->min_decompress_len);
> +	} else {
> +		caps_feat = 0;
> +	}
> +
> +	kfree(hv_nxc);
> +out:
> +	kfree(hv_caps);
> +}
> +
>  static const struct vio_device_id nx842_vio_driver_ids[] = {
>  	{"ibm,compression-v1", "ibm,compression"},
>  	{"", ""},
> @@ -1092,6 +1175,10 @@ static int __init nx842_pseries_init(void)
>  		return -ENOMEM;
>  
>  	RCU_INIT_POINTER(devdata, new_devdata);
> +	/*
> +	 * Get NX capabilities from the hypervisor.
> +	 */
> +	nxcop_get_capabilities();
>  
>  	ret = vio_register_driver(&nx842_vio_driver);
>  	if (ret) {
> -- 
> 2.18.2
> 
> 
>