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[pci] Allow PCI configuration space access mechanism to vary by range

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On some systems (observed on an AWS EC2 c7a.medium instance in
eu-west-2), there is no single PCI configuration space access
mechanism that covers all PCI devices.  For example: the ECAM may
provide access only to bus 01 and above, with type 1 accesses required
to access bus 00.

Allow the choice of PCI configuration space access mechanism to be
made on a per-range basis, rather than being made just once in an
initialisation function.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2025-11-24 14:44:53 +00:00
parent 81496315f2
commit 0cf2f8028c
1 changed files with 121 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

169
src/arch/x86/interface/pcbios/pcicloud.c
View File

@@ -24,7 +24,7 @@
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <ipxe/init.h>
#include <string.h>
#include <ipxe/pci.h>
#include <ipxe/ecam.h>
#include <ipxe/pcibios.h>
@@ -37,8 +37,70 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
*
*/
/** Selected PCI configuration space access API */
static struct pci_api *pcicloud = &ecam_api;
/** Underlying PCI configuration space access APIs */
static struct pci_api *pcicloud_apis[] = {
&ecam_api, &pcibios_api, &pcidirect_api
};
/** Cached PCI configuration space access API */
static struct {
/** PCI bus:dev.fn address range */
struct pci_range range;
/** API for this bus:dev.fn address */
struct pci_api *api;
} pcicloud;
/**
* Find PCI configuration space access API for address
*
* @v busdevfn Starting PCI bus:dev.fn address
* @v range PCI bus:dev.fn address range to fill in
* @ret api Configuration space access API, or NULL
*/
static struct pci_api * pcicloud_find ( uint32_t busdevfn,
struct pci_range *range ) {
struct pci_range candidate;
struct pci_api *api;
uint32_t best = 0;
uint32_t index;
uint32_t first;
uint32_t last;
unsigned int i;
/* Return empty range on error */
range->count = 0;
/* Try discovery via all known APIs */
for ( i = 0 ; i < ( sizeof ( pcicloud_apis ) /
sizeof ( pcicloud_apis[0] ) ) ; i++ ) {
/* Discover via this API */
api = pcicloud_apis[i];
api->pci_discover ( busdevfn, &candidate );
/* Check for a matching or new closest allocation */
index = ( busdevfn - candidate.start );
if ( ( index < candidate.count ) || ( index > best ) ) {
memcpy ( range, &candidate, sizeof ( *range ) );
best = index;
}
/* Stop if this range contains the target bus:dev.fn address */
if ( index < candidate.count ) {
first = range->start;
last = ( range->start + range->count - 1 );
DBGC ( &pcicloud, "PCICLOUD [" PCI_FMT "," PCI_FMT ") "
"using %s API\n", PCI_SEG ( first ),
PCI_BUS ( first ), PCI_SLOT ( first ),
PCI_FUNC ( first ), PCI_SEG ( last ),
PCI_BUS ( last ), PCI_SLOT ( last ),
PCI_FUNC ( last ), api->name );
return api;
}
}
return NULL;
}
/**
* Find next PCI bus:dev.fn address range in system
@@ -48,7 +110,48 @@ static struct pci_api *pcicloud = &ecam_api;
*/
static void pcicloud_discover ( uint32_t busdevfn, struct pci_range *range ) {
pcicloud->pci_discover ( busdevfn, range );
/* Find new range, if any */
pcicloud_find ( busdevfn, range );
}
/**
* Find configuration space access API for PCI device
*
* @v pci PCI device
* @ret api Configuration space access API
*/
static struct pci_api * pcicloud_api ( struct pci_device *pci ) {
struct pci_range *range = &pcicloud.range;
struct pci_api *api;
uint32_t first;
uint32_t last;
/* Reuse cached API if applicable */
if ( ( pci->busdevfn - range->start ) < range->count )
return pcicloud.api;
/* Find highest priority API claiming this range */
api = pcicloud_find ( pci->busdevfn, range );
/* Fall back to lowest priority API for any unclaimed gaps in ranges */
if ( ! api ) {
api = pcicloud_apis[ ( sizeof ( pcicloud_apis ) /
sizeof ( pcicloud_apis[0] ) ) - 1 ];
range->count = ( range->start - pci->busdevfn );
range->start = pci->busdevfn;
first = range->start;
last = ( range->start + range->count - 1 );
DBGC ( &pcicloud, "PCICLOUD [" PCI_FMT "," PCI_FMT ") falling "
"back to %s API\n", PCI_SEG ( first ),
PCI_BUS ( first ), PCI_SLOT ( first ),
PCI_FUNC ( first ), PCI_SEG ( last ), PCI_BUS ( last ),
PCI_SLOT ( last ), PCI_FUNC ( last ), api->name );
}
/* Cache API for this range */
pcicloud.api = api;
return api;
}
/**
@@ -61,8 +164,9 @@ static void pcicloud_discover ( uint32_t busdevfn, struct pci_range *range ) {
*/
static int pcicloud_read_config_byte ( struct pci_device *pci,
unsigned int where, uint8_t *value ) {
struct pci_api *api = pcicloud_api ( pci );
return pcicloud->pci_read_config_byte ( pci, where, value );
return api->pci_read_config_byte ( pci, where, value );
}
/**
@@ -75,8 +179,9 @@ static int pcicloud_read_config_byte ( struct pci_device *pci,
*/
static int pcicloud_read_config_word ( struct pci_device *pci,
unsigned int where, uint16_t *value ) {
struct pci_api *api = pcicloud_api ( pci );
return pcicloud->pci_read_config_word ( pci, where, value );
return api->pci_read_config_word ( pci, where, value );
}
/**
@@ -89,8 +194,9 @@ static int pcicloud_read_config_word ( struct pci_device *pci,
*/
static int pcicloud_read_config_dword ( struct pci_device *pci,
unsigned int where, uint32_t *value ) {
struct pci_api *api = pcicloud_api ( pci );
return pcicloud->pci_read_config_dword ( pci, where, value );
return api->pci_read_config_dword ( pci, where, value );
}
/**
@@ -103,8 +209,9 @@ static int pcicloud_read_config_dword ( struct pci_device *pci,
*/
static int pcicloud_write_config_byte ( struct pci_device *pci,
unsigned int where, uint8_t value ) {
struct pci_api *api = pcicloud_api ( pci );
return pcicloud->pci_write_config_byte ( pci, where, value );
return api->pci_write_config_byte ( pci, where, value );
}
/**
@@ -117,8 +224,9 @@ static int pcicloud_write_config_byte ( struct pci_device *pci,
*/
static int pcicloud_write_config_word ( struct pci_device *pci,
unsigned int where, uint16_t value ) {
struct pci_api *api = pcicloud_api ( pci );
return pcicloud->pci_write_config_word ( pci, where, value );
return api->pci_write_config_word ( pci, where, value );
}
/**
@@ -131,8 +239,9 @@ static int pcicloud_write_config_word ( struct pci_device *pci,
*/
static int pcicloud_write_config_dword ( struct pci_device *pci,
unsigned int where, uint32_t value ) {
struct pci_api *api = pcicloud_api ( pci );
return pcicloud->pci_write_config_dword ( pci, where, value );
return api->pci_write_config_dword ( pci, where, value );
}
/**
@@ -144,8 +253,9 @@ static int pcicloud_write_config_dword ( struct pci_device *pci,
*/
static void * pcicloud_ioremap ( struct pci_device *pci,
unsigned long bus_addr, size_t len ) {
struct pci_api *api = pcicloud_api ( pci );
return pcicloud->pci_ioremap ( pci, bus_addr, len );
return api->pci_ioremap ( pci, bus_addr, len );
}
PROVIDE_PCIAPI_INLINE ( cloud, pci_can_probe );
@@ -157,40 +267,3 @@ PROVIDE_PCIAPI ( cloud, pci_write_config_byte, pcicloud_write_config_byte );
PROVIDE_PCIAPI ( cloud, pci_write_config_word, pcicloud_write_config_word );
PROVIDE_PCIAPI ( cloud, pci_write_config_dword, pcicloud_write_config_dword );
PROVIDE_PCIAPI ( cloud, pci_ioremap, pcicloud_ioremap );
/**
* Initialise cloud VM PCI configuration space access
*
*/
static void pcicloud_init ( void ) {
static struct pci_api *apis[] = {
&ecam_api, &pcibios_api, &pcidirect_api
};
struct pci_device pci;
uint32_t busdevfn;
unsigned int i;
int rc;
/* Select first API that successfully discovers a PCI device */
for ( i = 0 ; i < ( sizeof ( apis ) / sizeof ( apis[0] ) ) ; i++ ) {
pcicloud = apis[i];
busdevfn = 0;
if ( ( rc = pci_find_next ( &pci, &busdevfn ) ) == 0 ) {
DBGC ( pcicloud, "PCICLOUD selected %s API (found "
PCI_FMT ")\n", pcicloud->name,
PCI_ARGS ( &pci ) );
return;
}
}
/* Fall back to using final attempted API if no devices found */
pcicloud = apis[ i - 1 ];
DBGC ( pcicloud, "PCICLOUD selected %s API (nothing detected)\n",
pcicloud->name );
}
/** Cloud VM PCI configuration space access initialisation function */
struct init_fn pcicloud_init_fn __init_fn ( INIT_EARLY ) = {
.name = "pcicloud",
.initialise = pcicloud_init,
};