Reported-by: dexuan@
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Details
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- Repository
- rS FreeBSD src repository - subversion
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Lint Not Applicable - Unit
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We need this patch to make PCIe pass-through work for Hyper-V UEFI VM (Generation 2 VM).
Hyper-V UEFI VM has no legacy pcib0, so pci_cfgregopen() doesn't have a chance to be called to initialize 'pcicfg_mtx.
Some unusual drivers (like hptiop/hptmv/hptnr/hptrr/hpt27xx), which don't conform to Newbus, call pcireg_cfgread() directly e.g. in hpt_match() -> get_controller_count() -> ... -> pcireg_cfgread() -> mtx_lock_spin(&pcicfg_mtx) hangs!!! The patch fixes the issue.
Comment Actions
I'd kind of prefer we fix the drivers, though I think this patch is fine for now. I have an open item to refactor even the ACPI code to not use pci_cfgreg* directly but instead punt that up to the parent of acpi0 (nexus0) to support arm64 (and to support systems with multiple domains).
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Well, all of the problematic drivers are blob ones. I am not even quite sure about why they want to read config space directly, instead of using pci_{read,write}_config. And with in the increasing number of vendor maintained/imported drivers, it's becoming difficult to fix drivers or audit the drivers before importing them. So that's why I prefer to fix it in the pci.
If no objection comes, I will commit it tomorrow.