xenstore.c File Reference

XenStore interface. More...

#include <stdint.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ipxe/io.h>
#include <ipxe/nap.h>
#include <ipxe/malloc.h>
#include <ipxe/xen.h>
#include <ipxe/xenevent.h>
#include <ipxe/xenstore.h>
#include <xen/io/xs_wire.h>
#include <errno.h>

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static void	xenstore_send (struct xen_hypervisor *xen, const void *data, size_t len)
	Send XenStore request raw data. More...
static void	xenstore_send_string (struct xen_hypervisor *xen, const char *string)
	Send XenStore request string (excluding terminating NUL) More...
static void	xenstore_recv (struct xen_hypervisor *xen, void *data, size_t len)
	Receive XenStore response raw data. More...
static int	xenstore_request (struct xen_hypervisor *xen, enum xsd_sockmsg_type type, uint32_t req_id, const char *value, va_list key)
	Send XenStore request. More...
static int	xenstore_response (struct xen_hypervisor *xen, uint32_t req_id, char **value, size_t *len)
	Receive XenStore response. More...
static int	xenstore_message (struct xen_hypervisor *xen, enum xsd_sockmsg_type type, char **response, size_t *len, const char *request, va_list key)
	Issue a XenStore message. More...
static int	xenstore_vread (struct xen_hypervisor *xen, char **value, va_list key)
	Read XenStore value. More...
int	xenstore_read (struct xen_hypervisor *xen, char **value,...)
	Read XenStore value. More...
int	xenstore_read_num (struct xen_hypervisor *xen, unsigned long *num,...)
	Read XenStore numeric value. More...
static int	xenstore_vwrite (struct xen_hypervisor *xen, const char *value, va_list key)
	Write XenStore value. More...
int	xenstore_write (struct xen_hypervisor *xen, const char *value,...)
	Write XenStore value. More...
int	xenstore_write_num (struct xen_hypervisor *xen, unsigned long num,...)
	Write XenStore numeric value. More...
int	xenstore_rm (struct xen_hypervisor *xen,...)
	Delete XenStore value. More...
int	xenstore_directory (struct xen_hypervisor *xen, char **children, size_t *len,...)
	Read XenStore directory. More...
void	xenstore_dump (struct xen_hypervisor *xen, const char *key)
	Dump XenStore directory contents (for debugging) More...

Variables
static uint32_t	xenstore_req_id
	Request identifier. More...

Detailed Description

XenStore interface.

Definition in file xenstore.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

xenstore_send()

static void xenstore_send ( struct xen_hypervisor *  xen, const void *  data, size_t  len  )

static

Send XenStore request raw data.

Parameters

xen	Xen hypervisor
data	Data buffer
len	Length of data

Definition at line 64 of file xenstore.c.

                                         {
        struct xenstore_domain_interface *intf = xen->store.intf;
        XENSTORE_RING_IDX prod = readl ( &intf->req_prod );
        XENSTORE_RING_IDX cons;
        XENSTORE_RING_IDX idx;
        const char *bytes = data;
        size_t offset;
        size_t fill;

        DBGCP ( intf, "XENSTORE raw request:\n" );
        DBGCP_HDA ( intf, MASK_XENSTORE_IDX ( prod ), data, len );

        /* Write one byte at a time */
        for ( offset = 0 ; offset < len ; offset++ ) {

                /* Wait for space to become available */
                while ( 1 ) {
                        cons = readl ( &intf->req_cons );
                        fill = ( prod - cons );
                        if ( fill < XENSTORE_RING_SIZE )
                                break;
                        DBGC2 ( xen, "." );
                        cpu_nap();
                        rmb();
                }

                /* Write byte */
                idx = MASK_XENSTORE_IDX ( prod++ );
                writeb ( bytes[offset], &intf->req[idx] );
        }

        /* Update producer counter */
        wmb();
        writel ( prod, &intf->req_prod );
        wmb();
}

References bytes, cons, cpu_nap(), data, DBGC2, DBGCP, DBGCP_HDA, fill, xen_store::intf, len, MASK_XENSTORE_IDX, offset, readl(), xenstore_domain_interface::req, xenstore_domain_interface::req_cons, xenstore_domain_interface::req_prod, rmb, xen_hypervisor::store, wmb(), writeb(), writel(), and XENSTORE_RING_SIZE.

Referenced by xenstore_request(), and xenstore_send_string().

xenstore_send_string()

static void xenstore_send_string ( struct xen_hypervisor *  xen, const char *  string  )

static

Send XenStore request string (excluding terminating NUL)

Parameters

xen	Xen hypervisor
string	String

Definition at line 108 of file xenstore.c.

                                                        {

        xenstore_send ( xen, string, strlen ( string ) );
}

References strlen(), and xenstore_send().

Referenced by xenstore_request().

xenstore_recv()

static void xenstore_recv ( struct xen_hypervisor *  xen, void *  data, size_t  len  )

static

Receive XenStore response raw data.

Parameters

xen	Xen hypervisor
data	Data buffer, or NULL to discard data
len	Length of data

Definition at line 121 of file xenstore.c.

                                         {
        struct xenstore_domain_interface *intf = xen->store.intf;
        XENSTORE_RING_IDX cons = readl ( &intf->rsp_cons );
        XENSTORE_RING_IDX prod;
        XENSTORE_RING_IDX idx;
        char *bytes = data;
        size_t offset;
        size_t fill;

        DBGCP ( intf, "XENSTORE raw response:\n" );

        /* Read one byte at a time */
        for ( offset = 0 ; offset < len ; offset++ ) {

                /* Wait for data to be ready */
                while ( 1 ) {
                        prod = readl ( &intf->rsp_prod );
                        fill = ( prod - cons );
                        if ( fill > 0 )
                                break;
                        DBGC2 ( xen, "." );
                        cpu_nap();
                        rmb();
                }

                /* Read byte */
                idx = MASK_XENSTORE_IDX ( cons++ );
                if ( data )
                        bytes[offset] = readb ( &intf->rsp[idx] );
        }
        if ( data )
                DBGCP_HDA ( intf, MASK_XENSTORE_IDX ( cons - len ), data, len );

        /* Update consumer counter */
        writel ( cons, &intf->rsp_cons );
        wmb();
}

References bytes, cons, cpu_nap(), data, DBGC2, DBGCP, DBGCP_HDA, fill, xen_store::intf, len, MASK_XENSTORE_IDX, offset, readb(), readl(), rmb, xenstore_domain_interface::rsp, xenstore_domain_interface::rsp_cons, xenstore_domain_interface::rsp_prod, xen_hypervisor::store, wmb(), and writel().

Referenced by xenstore_response().

xenstore_request()

static int xenstore_request ( struct xen_hypervisor *  xen, enum xsd_sockmsg_type  type, uint32_t  req_id, const char *  value, va_list  key  )

static

Send XenStore request.

Parameters

xen	Xen hypervisor
type	Message type
req_id	Request ID
value	Value, or NULL to omit
key	Key path components

Return values

rc	Return status code

Definition at line 170 of file xenstore.c.

                                                               {
        struct xsd_sockmsg msg;
        struct evtchn_send event;
        const char *string;
        va_list tmp;
        int xenrc;
        int rc;

        /* Construct message header */
        msg.type = type;
        msg.req_id = req_id;
        msg.tx_id = 0;
        msg.len = 0;
        DBGC2 ( xen, "XENSTORE request ID %d type %d ", req_id, type );

        /* Calculate total length */
        va_copy ( tmp, key );
        while ( ( string = va_arg ( tmp, const char * ) ) != NULL ) {
                DBGC2 ( xen, "%s%s", ( msg.len ? "/" : "" ), string );
                msg.len += ( strlen ( string ) + 1 /* '/' or NUL */ );
        }
        va_end ( tmp );
        if ( value ) {
                DBGC2 ( xen, " = \"%s\"", value );
                msg.len += strlen ( value );
        }
        DBGC2 ( xen, "\n" );

        /* Send message */
        xenstore_send ( xen, &msg, sizeof ( msg ) );
        string = va_arg ( key, const char * );
        assert ( string != NULL );
        xenstore_send_string ( xen, string );
        while ( ( string = va_arg ( key, const char * ) ) != NULL ) {
                xenstore_send_string ( xen, "/" );
                xenstore_send_string ( xen, string );
        }
        xenstore_send ( xen, "", 1 ); /* Separating NUL */
        if ( value )
                xenstore_send_string ( xen, value );

        /* Notify the back end */
        event.port = xen->store.port;
        if ( ( xenrc = xenevent_send ( xen, &event ) ) != 0 ) {
                rc = -EXEN ( xenrc );
                DBGC ( xen, "XENSTORE could not notify back end: %s\n",
                       strerror ( rc ) );
                return rc;
        }

        return 0;
}

References assert(), DBGC, DBGC2, EXEN, key, msg(), NULL, xen_store::port, rc, xen_hypervisor::store, strerror(), string, strlen(), tmp, type, va_arg, va_copy, va_end, value, xenstore_send(), and xenstore_send_string().

Referenced by xenstore_message().

xenstore_response()

static int xenstore_response ( struct xen_hypervisor *  xen, uint32_t  req_id, char **  value, size_t *  len  )

static

Receive XenStore response.

Parameters

xen	Xen hypervisor
req_id	Request ID
value	Value to fill in
len	Length to fill in

Return values

rc	Return status code

The caller is responsible for eventually calling free() on the returned value. Note that the value may comprise multiple NUL-terminated strings concatenated together. A terminating NUL will always be appended to the returned value.

Definition at line 239 of file xenstore.c.

                                                           {
        struct xsd_sockmsg msg;
        char *string;
        int rc;

        /* Wait for response to become available */
        while ( ! xenevent_pending ( xen, xen->store.port ) )
                cpu_nap();

        /* Receive message header */
        xenstore_recv ( xen, &msg, sizeof ( msg ) );
        *len = msg.len;

        /* Allocate space for response */
        *value = zalloc ( msg.len + 1 /* terminating NUL */ );

        /* Receive data.  Do this even if allocation failed, or if the
         * request ID was incorrect, to avoid leaving data in the
         * ring.
         */
        xenstore_recv ( xen, *value, msg.len );

        /* Validate request ID */
        if ( msg.req_id != req_id ) {
                DBGC ( xen, "XENSTORE response ID mismatch (got %d, expected "
                       "%d)\n", msg.req_id, req_id );
                rc = -EPROTO;
                goto err_req_id;
        }

        /* Check for allocation failure */
        if ( ! *value ) {
                DBGC ( xen, "XENSTORE could not allocate %d bytes for "
                       "response\n", msg.len );
                rc = -ENOMEM;
                goto err_alloc;
        }

        /* Check for explicit errors */
        if ( msg.type == XS_ERROR ) {
                DBGC ( xen, "XENSTORE response error \"%s\"\n", *value );
                rc = -EIO;
                goto err_explicit;
        }

        DBGC2 ( xen, "XENSTORE response ID %d\n", req_id );
        if ( DBG_EXTRA ) {
                for ( string = *value ; string < ( *value + msg.len ) ;
                      string += ( strlen ( string ) + 1 /* NUL */ ) ) {
                        DBGC2 ( xen, " - \"%s\"\n", string );
                }
        }
        return 0;

 err_explicit:
 err_alloc:
 err_req_id:
        free ( *value );
        *value = NULL;
        return rc;
}

References cpu_nap(), DBG_EXTRA, DBGC, DBGC2, EIO, ENOMEM, EPROTO, free, len, msg(), NULL, xen_store::port, rc, xsd_sockmsg::req_id, xen_hypervisor::store, string, strlen(), value, xenstore_recv(), XS_ERROR, and zalloc().

Referenced by xenstore_message().

xenstore_message()

static int xenstore_message ( struct xen_hypervisor *  xen, enum xsd_sockmsg_type  type, char **  response, size_t *  len, const char *  request, va_list  key  )

static

Issue a XenStore message.

Parameters

xen	Xen hypervisor
type	Message type
response	Response value to fill in, or NULL to discard
len	Response length to fill in, or NULL to ignore
request	Request value, or NULL to omit
key	Key path components

Return values

rc	Return status code

Definition at line 313 of file xenstore.c.

                                                                              {
        char *response_value;
        size_t response_len;
        int rc;

        /* Send request */
        if ( ( rc = xenstore_request ( xen, type, ++xenstore_req_id,
                                       request, key ) ) != 0 )
                return rc;

        /* Receive response */
        if ( ( rc = xenstore_response ( xen, xenstore_req_id, &response_value,
                                        &response_len ) ) != 0 )
                return rc;

        /* Return response, if applicable */
        if ( response ) {
                *response = response_value;
        } else {
                free ( response_value );
        }
        if ( len )
                *len = response_len;

        return 0;
}

References free, key, len, rc, request, type, xenstore_req_id, xenstore_request(), and xenstore_response().

Referenced by xenstore_directory(), xenstore_rm(), xenstore_vread(), and xenstore_vwrite().

xenstore_vread()

static int xenstore_vread ( struct xen_hypervisor *  xen, char **  value, va_list  key  )

static

Read XenStore value.

Parameters

xen	Xen hypervisor
value	Value to fill in
key	Key path components

Return values

rc	Return status code

On a successful return, the caller is responsible for calling free() on the returned value.

Definition at line 353 of file xenstore.c.

                                          {

        return xenstore_message ( xen, XS_READ, value, NULL, NULL, key );
}

References key, NULL, value, xenstore_message(), and XS_READ.

Referenced by xenstore_read(), and xenstore_read_num().

xenstore_read()

int xenstore_read	(	struct xen_hypervisor *	xen,
		char **	value,
			...
	)

Read XenStore value.

Parameters

xen	Xen hypervisor
value	Value to fill in
...	Key path components

Return values

rc	Return status code

On a successful return, the caller is responsible for calling free() on the returned value.

Definition at line 371 of file xenstore.c.

                                                                {
        va_list key;
        int rc;

        va_start ( key, value );
        rc = xenstore_vread ( xen, value, key );
        va_end ( key );
        return rc;
}

References key, rc, va_end, va_start, value, and xenstore_vread().

Referenced by hvm_map_xenstore(), netfront_read_mac(), xenbus_probe_device(), and xenstore_dump().

xenstore_read_num()

int xenstore_read_num	(	struct xen_hypervisor *	xen,
		unsigned long *	num,
			...
	)

Read XenStore numeric value.

Parameters

xen	Xen hypervisor
num	Numeric value to fill in
...	Key path components

Return values

rc	Return status code

Definition at line 390 of file xenstore.c.

                                                                          {
        va_list key;
        char *value;
        char *endp;
        int rc;

        /* Try to read text value */
        va_start ( key, num );
        rc = xenstore_vread ( xen, &value, key );
        va_end ( key );
        if ( rc != 0 )
                goto err_read;

        /* Try to parse as numeric value */
        *num = strtoul ( value, &endp, 10 );
        if ( ( *value == '\0' ) || ( *endp != '\0' ) ) {
                DBGC ( xen, "XENSTORE found invalid numeric value \"%s\"\n",
                       value );
                rc = -EINVAL;
                goto err_strtoul;
        }

 err_strtoul:
        free ( value );
 err_read:
        return rc;
}

References DBGC, EINVAL, free, key, num, rc, strtoul(), va_end, va_start, value, and xenstore_vread().

Referenced by xenbus_backend_state(), and xenbus_probe_device().

xenstore_vwrite()

static int xenstore_vwrite ( struct xen_hypervisor *  xen, const char *  value, va_list  key  )

static

Write XenStore value.

Parameters

xen	Xen hypervisor
value	Value
key	Key path components

Return values

rc	Return status code

Definition at line 426 of file xenstore.c.

                                           {

        return xenstore_message ( xen, XS_WRITE, NULL, NULL, value, key );
}

References key, NULL, value, xenstore_message(), and XS_WRITE.

Referenced by xenstore_write(), and xenstore_write_num().

xenstore_write()

int xenstore_write	(	struct xen_hypervisor *	xen,
		const char *	value,
			...
	)

Write XenStore value.

Parameters

xen	Xen hypervisor
value	Value
...	Key path components

Return values

rc	Return status code

Definition at line 441 of file xenstore.c.

                                                                      {
        va_list key;
        int rc;

        va_start ( key, value );
        rc = xenstore_vwrite ( xen, value, key );
        va_end ( key );
        return rc;
}

References key, rc, va_end, va_start, value, and xenstore_vwrite().

xenstore_write_num()

int xenstore_write_num	(	struct xen_hypervisor *	xen,
		unsigned long	num,
			...
	)

Write XenStore numeric value.

Parameters

xen	Xen hypervisor
num	Numeric value
...	Key path components

Return values

rc	Return status code

Definition at line 460 of file xenstore.c.

                                                                          {
        char value[ 21 /* "18446744073709551615" + NUL */ ];
        va_list key;
        int rc;

        /* Construct value */
        snprintf ( value, sizeof ( value ), "%ld", num );

        /* Write value */
        va_start ( key, num );
        rc = xenstore_vwrite ( xen, value, key );
        va_end ( key );
        return rc;
}

References key, num, rc, snprintf(), va_end, va_start, value, and xenstore_vwrite().

Referenced by netfront_write_num(), and xenbus_set_state().

xenstore_rm()

int xenstore_rm	(	struct xen_hypervisor *	xen,
			...
	)

Delete XenStore value.

Parameters

xen	Xen hypervisor
...	Key path components

Return values

rc	Return status code

Definition at line 483 of file xenstore.c.

                                                {
        va_list key;
        int rc;

        va_start ( key, xen );
        rc = xenstore_message ( xen, XS_RM, NULL, NULL, NULL, key );
        va_end ( key );
        return rc;
}

References key, NULL, rc, va_end, va_start, xenstore_message(), and XS_RM.

Referenced by netfront_rm().

xenstore_directory()

int xenstore_directory	(	struct xen_hypervisor *	xen,
		char **	children,
		size_t *	len,
			...
	)

Read XenStore directory.

Parameters

xen	Xen hypervisor
children	Child key names to fill in
len	Length of child key names to fill in
...	Key path components

Return values

rc	Return status code

Definition at line 503 of file xenstore.c.

                           {
        va_list key;
        int rc;

        va_start ( key, len );
        rc = xenstore_message ( xen, XS_DIRECTORY, children, len, NULL, key );
        va_end ( key );
        return rc;
}

References children, key, len, NULL, rc, va_end, va_start, xenstore_message(), and XS_DIRECTORY.

Referenced by xenbus_probe(), xenbus_probe_type(), and xenstore_dump().

xenstore_dump()

void xenstore_dump	(	struct xen_hypervisor *	xen,
		const char *	key
	)

Dump XenStore directory contents (for debugging)

Parameters

xen	Xen hypervisor
key	Key

Definition at line 520 of file xenstore.c.

                                                                   {
        char *value;
        char *children;
        char *child;
        char *child_key;
        size_t len;
        int rc;

        /* Try to dump current key as a value */
        if ( ( rc = xenstore_read ( xen, &value, key, NULL ) ) == 0 ) {
                DBGC ( xen, "%s = \"%s\"\n", key, value );
                free ( value );
        }

        /* Try to recurse into each child in turn */
        if ( ( rc = xenstore_directory ( xen, &children, &len, key,
                                         NULL ) ) == 0 ) {
                for ( child = children ; child < ( children + len ) ;
                      child += ( strlen ( child ) + 1 /* NUL */ ) ) {

                        /* Construct child key */
                        if ( asprintf ( &child_key, "%s/%s", key, child ) < 0 ){
                                DBGC ( xen, "XENSTORE could not allocate child "
                                       "key \"%s/%s\"\n", key, child );
                                rc = -ENOMEM;
                                break;
                        }

                        /* Recurse into child key, continuing on error */
                        xenstore_dump ( xen, child_key );
                        free ( child_key );
                }
                free ( children );
        }
}

References asprintf(), children, DBGC, ENOMEM, free, key, len, NULL, rc, strlen(), value, xenstore_directory(), xenstore_dump(), and xenstore_read().

Referenced by xenstore_dump().

Variable Documentation

xenstore_req_id

uint32_t xenstore_req_id

static

Request identifier.

Definition at line 55 of file xenstore.c.

Referenced by xenstore_message().