core: Rework PCI config space access handling

Move more logic into generic code by extending the write handler to
pci_cfg_write_moderate and introducing pci_cfg_read_moderate. These
handlers are responsible for any config space access, including to
unowned or non-existent devices. They can reject the access, return an
emulated value on read or a real value to be written to hardware, or
they instruct the caller to perform the access directly.

We already pass a reference to the issuing cell to the access handlers.
It stays unused for now but will be needed by succeeding changes. So
add it now to avoid changing API and callers once again later on.

This commit lays the foundation for capability access moderation and,
specifically, MSI/MSI-X emulation.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
x86: Minimize scope of pci_lock

Move PIO accesses and the related spinlock into data_port_in/out_handler
in order to reduce the lock contention time.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
x86: Enable unwinding from exception handler

Preserve the .eh_frame section for the linked hypervisor objection and
only remove it from the binary. Then add .cfi directives to the
exception entry code. This enables to use a debugger for unwinding from
the exception handler to the causing function and beyond (not perfect
due to missing stack frames, though).

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
core: Fix error handling of MMCONFIG setup

If we have an MMCONFIG region, we must either successfully map it or
fail the initialization. Succeeding without setting up pci_space will
cause crashes later on when accessing it on behalf of a cell.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
core: Don't match MMIO accesses if there is no MMCONFIG space

Without this additional check, we will use addr >= (u64)-1 as upper
boundary if there is no MMCONFIG, which is almost always true.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
x86: Increase remapping region size

If we have to map the MMCONFIG space of a complete PCI section, we run
out of remapping space. 4 means 128K pages, more than enough for now.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
configs: Enable MMCONFIG moderation for QEMU Q35 and H87i

Exclude the MMCONFIG regions from memory regions so that Jailhouse can
intercept accesses. Not yet converted is the H700 config.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Update TODO list

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
configs: Tune memory regions of H87i

ACPI was off by one page, and two regions overlapped, exposing too much
access.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>