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Add error checking to the pci_find_cap(, PCIY_MSIX,) call that is returns

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success and a good value.  Only then try to use it and set the MSIX_ENABLE
bit.

With the current em(4) driver we have observed failures in this case in a
specific environment when pci_find_cap() would not return the assumed
value, which meant we ended up writing to PCI register 2 (PCI_DEVICE_ID)
which is read-only.

PR:		216456
Submitted by:	bz
This commit is contained in:
sbruno 2017-01-25 14:37:05 +00:00
parent 9b6046a549
commit da4174dcdb
1 changed files with 15 additions and 6 deletions
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21
sys/net/iflib.c
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@ -3733,6 +3733,10 @@ iflib_device_register(device_t dev, void *sc, if_shared_ctx_t sctx, if_ctx_t *ct
if (sctx->isc_flags & IFLIB_SKIP_MSIX) {
msix = scctx->isc_vectors;
} else if (scctx->isc_msix_bar != 0)
/*
* The simple fact that isc_msix_bar is not 0 does not mean we
* we have a good value there that is known to work.
*/
msix = iflib_msix_init(ctx);
else {
scctx->isc_vectors = 1;
@ -4779,15 +4783,20 @@ iflib_msix_init(if_ctx_t ctx)
uint16_t pci_cmd_word;
int msix_ctrl, rid;
rid = 0;
pci_cmd_word = pci_read_config(dev, PCIR_COMMAND, 2);
pci_cmd_word |= PCIM_CMD_BUSMASTEREN;
pci_write_config(dev, PCIR_COMMAND, pci_cmd_word, 2);
pci_find_cap(dev, PCIY_MSIX, &rid);
rid += PCIR_MSIX_CTRL;
msix_ctrl = pci_read_config(dev, rid, 2);
msix_ctrl |= PCIM_MSIXCTRL_MSIX_ENABLE;
pci_write_config(dev, rid, msix_ctrl, 2);
rid = 0;
if (pci_find_cap(dev, PCIY_MSIX, &rid) == 0 && rid != 0) {
rid += PCIR_MSIX_CTRL;
msix_ctrl = pci_read_config(dev, rid, 2);
msix_ctrl |= PCIM_MSIXCTRL_MSIX_ENABLE;
pci_write_config(dev, rid, msix_ctrl, 2);
} else {
device_printf(dev, "PCIY_MSIX capability not found; "
"or rid %d == 0.\n", rid);
goto msi;
}
}
/*