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 <ha...@linux.ibm.com>
> Acked-by: Herbert Xu <herb...@gondor.apana.org.au>
Acked-by: Nicholas Piggin <npig...@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
>
>
>
