Current, Xen isn't aware of device reset (initiated by dom0). Xen may access the device while device cannot respond to config requests normally (e.g. after device reset, device may respond to config requests with CRS completions to indicate it needs more time to complete a reset, refer to pci_dev_wait() in linux kernel for more detail). Here, don't assume msix capability is always visible and return -EAGAIN to the caller.
Signed-off-by: Chao Gao <[email protected]> --- I didn't find a way to trigger the assertion in normal usages. It is found by an internal test: echo 1 to /sys/bus/pci/<sbdf>/reset when the device is being used by a guest. Although the test is a little insane, it is better to avoid crashing Xen even for this case. --- xen/arch/x86/msi.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c index 76d4034..e2f3c6c 100644 --- a/xen/arch/x86/msi.c +++ b/xen/arch/x86/msi.c @@ -1265,7 +1265,13 @@ int pci_msi_conf_write_intercept(struct pci_dev *pdev, unsigned int reg, pos = entry ? entry->msi_attrib.pos : pci_find_cap_offset(seg, bus, slot, func, PCI_CAP_ID_MSIX); - ASSERT(pos); + if ( unlikely(!pos) ) + { + printk_once(XENLOG_WARNING + "%04x:%02x:%02x.%u MSI-X capability is missing\n", + seg, bus, slot, func); + return -EAGAIN; + } if ( reg >= pos && reg < msix_pba_offset_reg(pos) + 4 ) { -- 1.8.3.1 _______________________________________________ Xen-devel mailing list [email protected] https://lists.xenproject.org/mailman/listinfo/xen-devel
