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| author | Michael Brown <mcb30@ipxe.org> | 2021-04-10 13:14:30 +0100 |
|---|---|---|
| committer | Michael Brown <mcb30@ipxe.org> | 2021-04-10 15:05:05 +0100 |
| commit | 0be8491b717fec6697dbf6ef8ac07604e062ecb1 (patch) | |
| tree | 1f5d84a13dbd6113e7e884a2795e6e01cdda3a31 | |
| parent | c0346dbb49de0bb6c7637c511a175ce478aca9b9 (diff) | |
| download | ipxe-0be8491b717fec6697dbf6ef8ac07604e062ecb1.zip ipxe-0be8491b717fec6697dbf6ef8ac07604e062ecb1.tar.gz ipxe-0be8491b717fec6697dbf6ef8ac07604e062ecb1.tar.bz2 | |
[pci] Avoid scanning nonexistent buses when using PCIAPI_DIRECT
There is no method for obtaining the number of PCI buses when using
PCIAPI_DIRECT, and we therefore currently scan all possible bus
numbers. This can cause a several-second startup delay in some
virtualised environments, since PCI configuration space access will
necessarily require the involvement of the hypervisor.
Ameliorate this situation by defaulting to scanning only a single bus,
and expanding the number of PCI buses to accommodate any subordinate
buses that are detected during enumeration.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
| -rw-r--r-- | src/arch/x86/include/ipxe/pcidirect.h | 4 | ||||
| -rw-r--r-- | src/drivers/bus/pci.c | 27 | ||||
| -rw-r--r-- | src/include/ipxe/pci.h | 3 |
3 files changed, 30 insertions, 4 deletions
diff --git a/src/arch/x86/include/ipxe/pcidirect.h b/src/arch/x86/include/ipxe/pcidirect.h index 9570fd7..decdc81 100644 --- a/src/arch/x86/include/ipxe/pcidirect.h +++ b/src/arch/x86/include/ipxe/pcidirect.h @@ -32,8 +32,8 @@ extern void pcidirect_prepare ( struct pci_device *pci, int where ); */ static inline __always_inline int PCIAPI_INLINE ( direct, pci_num_bus ) ( void ) { - /* No way to work this out via Type 1 accesses */ - return 0x100; + /* Scan first bus and rely on bridge detection to find higher buses */ + return 1; } /** diff --git a/src/drivers/bus/pci.c b/src/drivers/bus/pci.c index 06b36a7..1b7350c 100644 --- a/src/drivers/bus/pci.c +++ b/src/drivers/bus/pci.c @@ -228,6 +228,9 @@ int pci_read_config ( struct pci_device *pci ) { */ int pci_find_next ( struct pci_device *pci, unsigned int busdevfn ) { static unsigned int end; + unsigned int sub_end; + uint8_t hdrtype; + uint8_t sub; int rc; /* Determine number of PCI buses */ @@ -236,10 +239,30 @@ int pci_find_next ( struct pci_device *pci, unsigned int busdevfn ) { /* Find next PCI device, if any */ for ( ; busdevfn < end ; busdevfn++ ) { + + /* Check for PCI device existence */ memset ( pci, 0, sizeof ( *pci ) ); pci_init ( pci, busdevfn ); - if ( ( rc = pci_read_config ( pci ) ) == 0 ) - return busdevfn; + if ( ( rc = pci_read_config ( pci ) ) != 0 ) + continue; + + /* If device is a bridge, expand the number of PCI + * buses as needed. + */ + pci_read_config_byte ( pci, PCI_HEADER_TYPE, &hdrtype ); + hdrtype &= PCI_HEADER_TYPE_MASK; + if ( hdrtype == PCI_HEADER_TYPE_BRIDGE ) { + pci_read_config_byte ( pci, PCI_SUBORDINATE, &sub ); + sub_end = PCI_BUSDEVFN ( 0, ( sub + 1 ), 0, 0 ); + if ( end < sub_end ) { + DBGC ( pci, PCI_FMT " found subordinate bus " + "%#02x\n", PCI_ARGS ( pci ), sub ); + end = sub_end; + } + } + + /* Return this device */ + return busdevfn; } return -ENODEV; diff --git a/src/include/ipxe/pci.h b/src/include/ipxe/pci.h index 6632c57..933f485 100644 --- a/src/include/ipxe/pci.h +++ b/src/include/ipxe/pci.h @@ -135,6 +135,9 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); #define PCI_CLASS_SERIAL_USB_EHCI 0x20 /**< ECHI USB controller */ #define PCI_CLASS_SERIAL_USB_XHCI 0x30 /**< xHCI USB controller */ +/** Subordinate bus number */ +#define PCI_SUBORDINATE 0x1a + /** Construct PCI class * * @v base Base class (or PCI_ANY_ID) |