Re: [PATCH 6/8] pseries/plpks: add HCALLs for PKWM wrapping key life cycle management

[Srish Srinivasan <ssrish@linux.ibm.com>]

Hi Nageswara,
Thanks for taking a look.

On 8/28/26 4:34 PM, R Nageswara Sastry wrote:
> On 27. 08. 2026 11: 53 AM, Srish Srinivasan wrote: The PKWM trusted 
> source uses a single wrapping key per LPAR, created only once during 
> trust source initialization. All the wrap and unwrap requests are 
> bound to this default wrapping key. Implement
> 
>
>
> On 27.08.2026 11:53 AM, Srish Srinivasan wrote:
>> The PKWM trusted source uses a single wrapping key per LPAR, created only
>> once during trust source initialization. All the wrap and unwrap requests
>> are bound to this default wrapping key.
>>
>> Implement H_PKS_REVOKE_OBJECT, H_PKS_UNREVOKE_OBJECT, and
>> H_PKS_GET_OBJECTLABELS HCALLs to enable support for revoking and unrevoking
>> PKWM wrapping keys, and for retrieving wrapping key labels. The label
>> retrieval operation (H_PKS_GET_OBJECTLABELS) applies to all wrapping keys
>> including the default one, while the life cycle operations
>> (H_PKS_REVOKE_OBJECT/H_PKS_UNREVOKE_OBJECT) apply only to user-created
>> wrapping keys.
>>
>> Signed-off-by: Srish Srinivasan<ssrish@linux.ibm.com>
>> ---
>>   Documentation/arch/powerpc/papr_hcalls.rst |  33 ++
>>   arch/powerpc/include/asm/hvcall.h          |   5 +-
>>   arch/powerpc/include/asm/plpks.h           |  15 +
>>   arch/powerpc/platforms/pseries/plpks.c     | 475 ++++++++++++++++++++-
>>   4 files changed, 524 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/arch/powerpc/papr_hcalls.rst b/Documentation/arch/powerpc/papr_hcalls.rst
>> index 44c9c8b32ae3..3455b403a048 100644
>> --- a/Documentation/arch/powerpc/papr_hcalls.rst
>> +++ b/Documentation/arch/powerpc/papr_hcalls.rst
>> @@ -343,6 +343,39 @@ is returned to the caller.
>>   H_PKS_UNWRAP_OBJECT is used to unwrap an object that was previously wrapped with
>>   H_PKS_WRAP_OBJECT.
>>   
>> +**H_PKS_REVOKE_OBJECT**
>> +
>> +| Input: authorization, objectlabel, objectlabellen, flags
>> +| Out: *object policy*
>> +| Return Value: *H_Success, H_Function, H_State, H_Parameter, H_P2, H_P3, H_P4,
>> +                H_Authority, H_Not_Found, H_Busy, H_Aborted*
>> +
>> +H_PKS_REVOKE_OBJECT is used to revoke an object in Platform Keystore.
>> +
>> +
>> +**H_PKS_UNREVOKE_OBJECT**
>> +
>> +| Input: authorization, objectlabel, objectlabellen, flags
>> +| Out: *object policy*
>> +| Return Value: *H_Success, H_Function, H_State, H_Parameter, H_P2, H_P3, H_P4,
>> +                H_Authority, H_Not_Found, H_Busy, H_Aborted*
>> +
>> +H_PKS_UNREVOKE_OBJECT is used to unrevoke an object that was previously revoked
>> +with H_PKS_REVOKE_OBJECT in Platform Keystore.
>> +
>> +
>> +**H_PKS_GET_OBJECTLABELS**
>> +
>> +| Input: authorization, continueToken, out, outlen
>> +| Out: *continue-token, number of object labels in the returned list, object
>> +        label list*
>> +| Return Value: *H_Success, H_Function, H_State, H_Parameter, H_P2, H_P3, H_P4,
>> +                H_Authority, H_Busy, H_Aborted, H_Continue*
>> +
>> +H_PKS_GET_OBJECTLABELS is used to retrieve a list of object labels owned by the
>> +specified consumer.
>> +
>> +
>>   References
>>   ==========
>>   .. [1] "Power Architecture Platform Reference"
>> diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
>> index dff90a7d7f70..4d4c2ce1dd87 100644
>> --- a/arch/powerpc/include/asm/hvcall.h
>> +++ b/arch/powerpc/include/asm/hvcall.h
>> @@ -340,6 +340,7 @@
>>   #define H_PKS_GET_CONFIG	0x41C
>>   #define H_PKS_SET_PASSWORD	0x420
>>   #define H_PKS_GEN_PASSWORD	0x424
>> +#define H_PKS_GET_OBJECTLABELS	0x428
>>   #define H_PKS_WRITE_OBJECT	0x42C
>>   #define H_PKS_GEN_KEY		0x430
>>   #define H_PKS_READ_OBJECT	0x434
>> @@ -362,7 +363,9 @@
>>   #define H_GUEST_DELETE		0x488
>>   #define H_PKS_WRAP_OBJECT	0x490
>>   #define H_PKS_UNWRAP_OBJECT	0x494
>> -#define MAX_HCALL_OPCODE	H_PKS_UNWRAP_OBJECT
>> +#define H_PKS_REVOKE_OBJECT	0x4AC
>> +#define H_PKS_UNREVOKE_OBJECT	0x4B0
>> +#define MAX_HCALL_OPCODE	H_PKS_UNREVOKE_OBJECT
>>   
>>   /* Scope args for H_SCM_UNBIND_ALL */
>>   #define H_UNBIND_SCOPE_ALL (0x1)
>> diff --git a/arch/powerpc/include/asm/plpks.h b/arch/powerpc/include/asm/plpks.h
>> index 8b2ffb27db5a..c39d1f07017e 100644
>> --- a/arch/powerpc/include/asm/plpks.h
>> +++ b/arch/powerpc/include/asm/plpks.h
>> @@ -25,6 +25,7 @@
>>   #define PLPKS_SIGNEDUPDATE	PPC_BIT32(7) // Object can only be modified by signed updates
>>   #define PLPKS_WRAPPINGKEY	PPC_BIT32(8) // Object contains a wrapping key
>>   #define PLPKS_HVPROVISIONED	PPC_BIT32(28) // Hypervisor has provisioned this object
>> +#define PLPKS_REVOKED		PPC_BIT32(30) // Object is revoked
>>   
>>   // Signature algorithm flags from signed_update_algorithms
>>   #define PLPKS_ALG_RSA2048	PPC_BIT(0)
>> @@ -123,6 +124,20 @@ int plpks_wrap_object(u8 **input_buf, u64 input_len, u16 wrap_flags,
>>   
>>   int plpks_unwrap_object(u8 **input_buf, u64 input_len,
>>   			u8 **output_buf, u64 *output_len);
>> +
>> +int plpks_revoke_wrapping_key(struct plpks_var *var);
>> +
>> +int plpks_unrevoke_wrapping_key(struct plpks_var *var);
>> +
>> +int plpks_del_wrapping_key(struct plpks_var *var);
>> +
>> +int plpks_is_wrapping_key_revoked(struct plpks_var *var);
>> +
>> +int plpks_get_object_labels(u8 **output_buf, u64 *output_len,
>> +			    char *comp_prefix);
>> +
>> +bool plpks_revoke_is_supported(void);
>> +
>>   #else // CONFIG_PSERIES_PLPKS
>>   static inline bool plpks_is_available(void) { return false; }
>>   static inline u16 plpks_get_passwordlen(void) { BUILD_BUG(); }
>> diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
>> index b553f7b130b6..48a86497eb2b 100644
>> --- a/arch/powerpc/platforms/pseries/plpks.c
>> +++ b/arch/powerpc/platforms/pseries/plpks.c
>> @@ -23,8 +23,17 @@
>>    */
>>   #define PLPKS_WRAPPING_BUF_DIFF	1024
>>   
>> +/*
>> + * Maximum length for the buffer to store the retrieved object labels
>> + */
>> +#define PLPKS_OBJLABEL_BUF_MAX	2550
>> +
>> +#define PLPKS_OBJLABEL_LEN_FIELD_SIZE	2
>> +#define PLPKS_OBJLABEL_PREFIX_LEN	8
>> +
>>   #define PLPKS_WRAP_INTERFACE_BIT	3
>>   #define PLPKS_WRAPPING_KEY_LENGTH	32
>> +#define PLPKS_REVOKE_INTERFACE_BIT	4
>>   
>>   #define WRAPFLAG_BE_BIT_SET(be_bit) \
>>   	BIT_ULL(63 - (be_bit))
>> @@ -46,6 +55,7 @@
>>   #include <linux/libfdt.h>
>>   #include <linux/memblock.h>
>>   #include <linux/bitfield.h>
>> +#include <linux/unaligned.h>
>>   #include <asm/hvcall.h>
>>   #include <asm/machdep.h>
>>   #include <asm/plpks.h>
>> @@ -67,6 +77,7 @@ static u32 maxlargeobjectsize;
>>   static u64 signedupdatealgorithms;
>>   static u64 wrappingfeatures;
>>   static bool wrapsupport;
>> +static bool revokesupport;
>>   
>>   struct plpks_auth {
>>   	u8 version;
>> @@ -146,6 +157,9 @@ static int pseries_status_to_err(int rc)
>>   	case H_ABORTED:
>>   		err = -EIO;
>>   		break;
>> +	case H_CONTINUE:
>> +		err = -EAGAIN;
>> +		break;
>>   	default:
>>   		err = -EINVAL;
>>   	}
>> @@ -312,6 +326,7 @@ static int _plpks_get_config(void)
>>   	signedupdatealgorithms = be64_to_cpu(config->signedupdatealgorithms);
>>   	wrappingfeatures = be64_to_cpu(config->wrappingfeatures);
>>   	wrapsupport = config->flags & PPC_BIT8(PLPKS_WRAP_INTERFACE_BIT);
>> +	revokesupport = config->flags & PPC_BIT8(PLPKS_REVOKE_INTERFACE_BIT);
>>   
>>   	// Validate that the numbers we get back match the requirements of the spec
>>   	if (maxpwsize < 32) {
>> @@ -831,9 +846,6 @@ static int plpks_read_var(u8 consumer, struct plpks_var *var)
>>   	if (var->namelen > PLPKS_MAX_NAME_SIZE)
>>   		return -EINVAL;
>>   
>> -	if (var->policy & PLPKS_WRAPPINGKEY)
>> -		return -EPERM;
>> -
>>   	auth = construct_auth(consumer);
>>   	if (IS_ERR(auth))
>>   		return PTR_ERR(auth);
>> @@ -903,6 +915,23 @@ bool plpks_wrapping_is_supported(void)
>>   }
>>   EXPORT_SYMBOL_GPL(plpks_wrapping_is_supported);
>>   
>> +/**
>> + * plpks_revoke_is_supported() - Get the H_PKS_REVOKE_OBJECT and
>> + * H_PKS_UNREVOKE_OBJECT interfaces availability status for the LPAR.
>> + *
>> + * Successful execution of the H_PKS_GET_CONFIG HCALL during initialization
>> + * sets bit 4 of the flags variable in the PLPKS config structure if the
>> + * H_PKS_REVOKE_OBJECT and H_PKS_UNREVOKE_OBJECT interfaces are supported.
>> + *
>> + * Returns: true if the H_PKS_REVOKE_OBJECT and H_PKS_UNREVOKE_OBJECT interfaces
>> + * are supported, false if not.
>> + */
>> +bool plpks_revoke_is_supported(void)
>> +{
>> +	return revokesupport;
>> +}
>> +EXPORT_SYMBOL_GPL(plpks_revoke_is_supported);
>> +
>>   /**
>>    * plpks_gen_wrapping_key() - Generate a new random key with the 'wrapping key'
>>    * policy set.
>> @@ -1189,6 +1218,446 @@ int plpks_unwrap_object(u8 **input_buf, u64 input_len, u8 **output_buf,
>>   }
>>   EXPORT_SYMBOL_GPL(plpks_unwrap_object);
>>   
>> +/**
>> + * plpks_revoke_wrapping_key() - Revoke a wrapping key stored in the PLPKS.
>> + * @var: variable representing the wrapping key to be revoked
>> + *
>> + * The H_PKS_REVOKE_OBJECT HCALL revokes an object stored in the PLPKS.
>> + *
>> + * Possible reasons for the returned errno values:
>> + *
>> + * -ENXIO	if PLPKS is not supported
>> + * -EIO		if PLPKS access is blocked due to the LPAR's state
>> + *		if PLPKS modification is blocked due to the LPAR's state
>> + *		if an error occurred while processing the request
>> + * -EINVAL	if invalid authorization parameter
>> + *		if invalid wrapping key label parameter
>> + *		if invalid wrapping key label length parameter
>> + *		if invalid or unsupported wrapping key revoking flags
>> + * -EPERM	if access is denied
>> + * -ENOENT	if the requested wrapping key was not found
>> + * -EBUSY	if unable to handle the request or long running operation
>> + *		initiated, retry later.
>> + *
>> + * Returns: On success 0 is returned, a negative errno if not.
>> + */
>> +int plpks_revoke_wrapping_key(struct plpks_var *var)
>> +{
>> +	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
>> +	struct plpks_auth *auth = NULL;
>> +	struct label *label;
>> +	u64 objrevokeflags = 0;
>> +	int rc = 0, pseries_status = 0;
>> +
>> +	if (!var->name || !*var->name) {
>
> Can you please add null check for 'var' also.
>
> if (! var || !var->name || !*var->name)
>

Noted.
I will fix this.


>> +		pr_err("key label cannot be NULL/empty\n");
>> +		rc = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	if (!strcmp((char *)var->name, PLPKS_DEFAULT_WRAPKEY_LABEL)) {
>> +		pr_warn("the default wrapping key must not be revoked!\n");
>> +		rc = -EPERM;
>> +		goto out;
>> +	}
>> +
>> +	auth = construct_auth(PLPKS_OS_OWNER);
>> +	if (IS_ERR(auth)) {
>> +		rc = PTR_ERR(auth);
>> +		goto out;
>> +	}
>> +
>> +	label = construct_label(var->component, var->os, var->name,
>> +				var->namelen);
>> +	if (IS_ERR(label)) {
>> +		rc = PTR_ERR(label);
>> +		goto out;
>> +	}
>> +
>> +	rc = plpar_hcall(H_PKS_REVOKE_OBJECT, retbuf, virt_to_phys(auth),
>> +			 virt_to_phys(label), label->size, objrevokeflags);
>> +
>> +	pseries_status = rc;
>> +	rc = pseries_status_to_err(rc);
>> +
>> +	if (rc) {
>> +		pr_err("H_PKS_REVOKE_OBJECT failed. pseries_status=%d, rc=%d\n",
>> +		       pseries_status, rc);
>> +	}
>> +
>> +	if (!rc || (rc == -EPERM && retbuf[0]))
>> +		var->policy = (u32)retbuf[0];
>> +
>> +	kfree(label);
>> +out:
>> +	kfree(auth);
>> +	return rc;
>> +}
>> +EXPORT_SYMBOL_GPL(plpks_revoke_wrapping_key);
>> +
>> +/**
>> + * plpks_unrevoke_wrapping_key() - Unrevoke a revoked wrapping key in the PLPKS.
>> + * @var: variable representing the revoked wrapping key to be unrevoked
>> + *
>> + * The H_PKS_UNREVOKE_OBJECT HCALL unrevokes a revoked object stored in the
>> + * PLPKS.
>> + *
>> + * Possible reasons for the returned errno values:
>> + *
>> + * -ENXIO	if PLPKS is not supported
>> + * -EIO		if PLPKS access is blocked due to the LPAR's state
>> + *		if PLPKS modification is blocked due to the LPAR's state
>> + *		if an error occurred while processing the request
>> + * -EINVAL	if invalid authorization parameter
>> + *		if invalid object label parameter
>> + *		if invalid object label length parameter
>> + *		if invalid or unsupported object revoking flags
>> + * -EPERM	if access is denied
>> + * -ENOENT	if the requested object was not found
>> + * -EBUSY	if unable to handle the request or long running operation
>> + *		initiated, retry later.
>> + *
>> + * Returns: On success 0 is returned, a negative errno if not.
>> + */
>> +int plpks_unrevoke_wrapping_key(struct plpks_var *var)
>> +{
>> +	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
>> +	struct plpks_auth *auth = NULL;
>> +	struct label *label;
>> +	u64 objrevokeflags = 0;
>> +	int rc = 0, pseries_status = 0;
>> +
>> +	if (!var->name || !*var->name) {
> same comment as above


Yup. I will fix this.


>> +		pr_err("key label cannot be NULL/empty\n");
>> +		rc = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	if (!strcmp((char *)var->name, PLPKS_DEFAULT_WRAPKEY_LABEL)) {
>> +		pr_warn("unrevoke on the default wrapping key is invalid\n");
>> +		rc = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	auth = construct_auth(PLPKS_OS_OWNER);
>> +	if (IS_ERR(auth)) {
>> +		rc = PTR_ERR(auth);
>> +		goto out;
>> +	}
>> +
>> +	label = construct_label(var->component, var->os, var->name,
>> +				var->namelen);
>> +	if (IS_ERR(label)) {
>> +		rc = PTR_ERR(label);
>> +		goto out;
>> +	}
>> +
>> +	rc = plpar_hcall(H_PKS_UNREVOKE_OBJECT, retbuf,
>> +			 virt_to_phys(auth), virt_to_phys(label),
>> +			 label->size, objrevokeflags);
>> +
>> +	pseries_status = rc;
>> +	rc = pseries_status_to_err(rc);
>> +
>> +	if (rc)
>> +		pr_err("H_PKS_UNREVOKE_OBJECT failed. pseries_status=%d, rc=%d\n",
>> +		       pseries_status, rc);
>> +
>> +	if (!rc || (rc == -EPERM && retbuf[0]))
>> +		var->policy = (u32)retbuf[0];
>> +
>> +	kfree(label);
>> +out:
>> +	kfree(auth);
>> +	return rc;
>> +}
>> +EXPORT_SYMBOL_GPL(plpks_unrevoke_wrapping_key);
>> +
>> +/**
>> + * plpks_is_wrapping_key_revoked() - Check if a given wrapping key has been
>> + * revoked.
>> + * @var: variable representing the wrapping key to be checked
>> + *
>> + * When the H_PKS_READ_OBJECT HCALL tries reads an object that exists but when
>> + * the policy is not met, it returns H_AUTHORITY along with the 4-byte object
>> + * policy. This policy is inspected to determine if the object has been revoked.
>> + *
>> + * Possible reasons for the returned errno values:
>> + *
>> + * -ENXIO	if PLPKS is not supported
>> + * -EIO		if PLPKS access is blocked due to the LPAR's state
>> + *		if an error occurred while processing the request
>> + * -EINVAL	if invalid authorization parameter
>> + *		if invalid object label parameter
>> + *		if invalid object label len parameter
>> + *		if invalid output data parameter
>> + *		if invalid output data len parameter
>> + * -EPERM	if access is denied
>> + * -ENOENT	if the requested object was not found
>> + * -EFBIG	if the requested object couldn't be
>> + *		stored in the buffer provided
>> + * -EBUSY	if unable to handle the request
>> + *
>> + * Returns: 1 is returned if the wrapping key has been revoked. 0 is returned if
>> + *	    the wrapping key has not been revoked. Otherwise, a negative errno
>> + *	    is returned.
>> + */
>> +int plpks_is_wrapping_key_revoked(struct plpks_var *var)
>> +{
>> +	int rc;
>> +
>> +	if (!var->name || !*var->name) {
> same comment as above


Yup. I will fix this.


>> +		pr_err("key label cannot be NULL/empty\n");
>> +		rc = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	rc = plpks_read_var(PLPKS_OS_OWNER, var);
>> +	if (!rc) {
>> +		pr_err("unexpected successful read of wrapping key\n");
>> +		rc = -EIO;
>> +	} else if (rc == -EPERM) {
>> +		if (var->policy & PLPKS_WRAPPINGKEY) {
>> +			if (var->policy & PLPKS_REVOKED)
>> +				rc = 1;
>> +			else
>> +				rc = 0;
>> +		}
>> +	}
>> +
>> +out:
>> +	return rc;
>> +}
>> +EXPORT_SYMBOL_GPL(plpks_is_wrapping_key_revoked);
>> +
>> +/**
>> + * plpks_del_wrapping_key() - Delete a wrapping key from the PLPKS.
>> + * @var: variable representing the revoked wrapping key to be deleted
>> + *
>> + * The plpks_remove_var function removes the specified variable and its data
>> + * from the PLPKS by invoking the H_PKS_REMOVE_OBJECT HCALL.
>> + *
>> + * Possible reasons for the returned errno values:
>> + *
>> + * -ENXIO	if PLPKS is not supported
>> + * -EIO		if PLPKS access is blocked due to the LPAR's state
>> + *		if PLPKS modification is blocked due to the LPAR's state
>> + *		if an error occurred while processing the request
>> + * -EINVAL	if invalid authorization parameter
>> + *		if invalid object label parameter
>> + *		if invalid object label len parameter
>> + * -EPERM	if access is denied
>> + * -ENOENT	if the requested object was not found
>> + * -EBUSY	if unable to handle the request
>> + *
>> + * Returns: On success 0 is returned, a negative errno if not.
>> + */
>> +int plpks_del_wrapping_key(struct plpks_var *var)
>> +{
>> +	int rc;
>> +	struct plpks_var_name vname;
>> +
>> +	if (!var->name || !*var->name) {
> same comment as above


Yup. I will fix this.


Thanks,
Srish.


>> +		pr_err("key label cannot be NULL/empty\n");
>> +		rc = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	if (!strcmp((char *)var->name, PLPKS_DEFAULT_WRAPKEY_LABEL)) {
>> +		pr_warn("the default wrapping key must not be deleted!\n");
>> +		rc = -EPERM;
>> +		goto out;
>> +	}
>> +
>> +	rc = plpks_is_wrapping_key_revoked(var);
>> +	if (rc == 1) {
>> +		vname = (struct plpks_var_name) {
>> +			.name = var->name,
>> +			.namelen = var->namelen
>> +		};
>> +
>> +		rc = plpks_remove_var(PLPKS_WRAPKEY_COMPONENT, var->os,
>> +				      vname);
>> +		if (rc)
>> +			pr_err("deletion of <%s> failed. rc=%d\n",
>> +			       (char *)var->name, rc);
>> +		goto out;
>> +	} else if (!rc) {
>> +		pr_err("revoke <%s> before deletion\n", (char *)var->name);
>> +		rc = -EPERM;
>> +		goto out;
>> +	} else {
>> +		pr_err("revocation status check failed for <%s>. rc = %d\n",
>> +		       (char *)var->name, rc);
>> +	}
>> +
>> +out:
>> +	return rc;
>> +}
>> +EXPORT_SYMBOL_GPL(plpks_del_wrapping_key);
>> +
>> +/**
>> + * plpks_get_object_labels() - retrieve a list of object labels for the objects
>> + * stored in the PLPKS
>> + * @output_buf: buffer to store the retrieved object labels
>> + * @output_len: number of object labels retrieved
>> + * @comp_prefix: component prefix string
>> + *
>> + * The H_PKS_GET_OBJECTLABELS HCALL retrieves a list of object labels for the
>> + * objects with the given component prefix stored in the PLPKS.
>> + *
>> + * Possible reasons for the returned errno values:
>> + *
>> + * -ENXIO	if PLPKS is not supported
>> + * -EIO		if PLPKS access is blocked due to the LPAR's state
>> + *		if PLPKS modification is blocked due to the LPAR's state
>> + *		if an error occurred while processing the request
>> + * -EINVAL	if invalid authorization parameter
>> + *		if invalid output buffer parameter
>> + *		if invalid output buffer length parameter
>> + *		if invalid continue token parameter
>> + *		if the provided component prefix is NULL
>> + * -EPERM	if access is denied
>> + * -EBUSY	if unable to handle the request or long running operation
>> + *		initiated, retry later.
>> + *
>> + * Returns: On success 0 is returned, a negative errno if not.
>> + */
>> +int plpks_get_object_labels(u8 **output_buf, u64 *output_len,
>> +			    char *comp_prefix)
>> +{
>> +	unsigned long retbuf[PLPAR_HCALL_BUFSIZE] = { 0 };
>> +	u8 *labels_buf = NULL;
>> +	u8 *tmp_buf = NULL;
>> +	struct plpks_auth *auth = NULL;
>> +	struct label_attr *metadata = NULL;
>> +	u16 label_len;
>> +	u64 labels_count;
>> +	u64 continuetoken = 0, output_buf_len = 0;
>> +	int rc = 0, pseries_status = 0;
>> +	size_t labels_buf_offset = 0, output_buf_offset = 0;
>> +	size_t obj_label_entry_size, i;
>> +
>> +	*output_buf = NULL;
>> +	*output_len = 0;
>> +
>> +	if (!comp_prefix) {
>> +		rc = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	auth = construct_auth(PLPKS_OS_OWNER);
>> +	if (IS_ERR(auth)) {
>> +		rc = PTR_ERR(auth);
>> +		goto out;
>> +	}
>> +
>> +	do {
>> +		labels_buf =
>> +			kzalloc(roundup_pow_of_two(PLPKS_OBJLABEL_BUF_MAX),
>> +				GFP_KERNEL);
>> +
>> +		if (!labels_buf) {
>> +			pr_err("labels_buf buffer allocation failed\n");
>> +			rc = -ENOMEM;
>> +			goto out_free_output_buf;
>> +		}
>> +
>> +		rc = plpar_hcall(H_PKS_GET_OBJECTLABELS, retbuf,
>> +				 virt_to_phys(auth), continuetoken,
>> +				 virt_to_phys(labels_buf),
>> +				 roundup_pow_of_two(PLPKS_OBJLABEL_BUF_MAX));
>> +
>> +		pseries_status = rc;
>> +		rc = pseries_status_to_err(rc);
>> +
>> +		if (rc && rc != -EAGAIN) {
>> +			pr_err("H_PKS_GET_OBJECTLABELS failed. pseries_status=%d rc=%d\n",
>> +			       pseries_status, rc);
>> +			goto out_free_labels_buf;
>> +		} else {
>> +			/*
>> +			 * Setting an incorrect countinuetoken upon
>> +			 * receiving H_CONTINUE would result in H_P2. Since
>> +			 * the continuetoken is being set to the expected
>> +			 * value from the previous call, H_P2 must not be
>> +			 * returned.
>> +			 */
>> +			continuetoken = retbuf[1];
>> +
>> +			labels_count = retbuf[0];
>> +			if (!labels_count) {
>> +				kfree(labels_buf);
>> +				labels_buf = NULL;
>> +				goto out;
>> +			}
>> +
>> +			/*
>> +			 * Filter out object labels that don't have the provided
>> +			 * component prefix.
>> +			 */
>> +
>> +			output_buf_len +=
>> +				roundup_pow_of_two(PLPKS_OBJLABEL_BUF_MAX);
>> +
>> +			tmp_buf = krealloc(*output_buf, output_buf_len,
>> +					   GFP_KERNEL);
>> +
>> +			if (!tmp_buf) {
>> +				pr_err("output buffer re-allocation failed\n");
>> +				rc = -ENOMEM;
>> +				goto out_free_labels_buf;
>> +			}
>> +
>> +			*output_buf = tmp_buf;
>> +
>> +			for (i = 0; i < labels_count; ++i) {
>> +				label_len =
>> +					get_unaligned_be16(labels_buf +
>> +							   labels_buf_offset);
>> +
>> +				obj_label_entry_size =
>> +					PLPKS_OBJLABEL_LEN_FIELD_SIZE +
>> +					label_len;
>> +
>> +				metadata =
>> +					(struct label_attr *)(labels_buf +
>> +					labels_buf_offset +
>> +					PLPKS_OBJLABEL_LEN_FIELD_SIZE);
>> +
>> +				if (!memcmp(metadata->prefix, comp_prefix,
>> +					    PLPKS_OBJLABEL_PREFIX_LEN)) {
>> +					memcpy(*output_buf + output_buf_offset,
>> +					       labels_buf + labels_buf_offset,
>> +					       obj_label_entry_size);
>> +
>> +					output_buf_offset +=
>> +						obj_label_entry_size;
>> +					(*output_len) += 1;
>> +				}
>> +				labels_buf_offset += obj_label_entry_size;
>> +			}
>> +			kfree(labels_buf);
>> +			labels_buf = NULL;
>> +			labels_buf_offset = 0;
>> +		}
>> +	} while (rc == -EAGAIN);
>> +
>> +	goto out;
>> +
>> +out_free_labels_buf:
>> +	kfree(labels_buf);
>> +	labels_buf = NULL;
>> +out_free_output_buf:
>> +	kfree(*output_buf);
>> +	*output_buf = NULL;
>> +	*output_len = 0;
>> +out:
>> +	kfree(auth);
>> +	return rc;
>> +}
>> +EXPORT_SYMBOL_GPL(plpks_get_object_labels);
>> +
>>   /**
>>    * plpks_read_os_var() - Fetch the data for the specified variable that is owned
>>    * by the OS consumer.
> -- 
> Thanks and Regards
> R.Nageswara Sastry