This fixes the panic caused by deadlocking when grant-table free
callbacks are used.
The cause of the recursion is: check_free_callbacks() is always called
with the lock gnttab_list_lock held. In turn the callback function is
also called with the lock held. Then when the client uses any of the grant
reference methods which also attempt the lock the gnttab_list_lock
mutex from within the free callback a deadlock happens.
Fix this by making the gnttab_list_lock recursive.
Submitted by: Pratyush Yadav <pratyush@freebsd.org>
Differential Revision: https://reviews.freebsd.org/D16505
Without a call to check_free_callbacks() clients waiting for grant
references would not be woken up even when there are sufficient grant
references available.
The check was likely left out as a mistake when the function was first
added.
Note that other functions used to free grant references already call
check_free_callbacks.
Submitted by: pratyush
Reviewed by: royger
Differential review: https://reviews.freebsd.org/D15899
xen/hypervisor.h:
- Remove unused helpers: MULTI_update_va_mapping, is_initial_xendomain,
is_running_on_xen
- Remove unused define CONFIG_X86_PAE
- Remove unused variable xen_start_info: note that it's used inpcifront
which is not built at all
- Remove forward declaration of HYPERVISOR_crash
xen/xen-os.h:
- Remove unused define CONFIG_X86_PAE
- Drop unused helpers: test_and_clear_bit, clear_bit,
force_evtchn_callback
- Implement a generic version (based on ofed/include/linux/bitops.h) of
set_bit and test_bit and prefix them by xen_ to avoid any use by other
code than Xen. Note that It would be worth to investigate a generic
implementation in FreeBSD.
- Replace barrier() by __compiler_membar()
- Replace cpu_relax() by cpu_spinwait(): it's exactly the same as rep;nop
= pause
xen/xen_intr.h:
- Move the prototype of xen_intr_handle_upcall in it: Use by all the
platform
x86/xen/xen_intr.c:
- Use BITSET* for the enabledbits: Avoid to use custom helpers
- test_bit/set_bit has been renamed to xen_test_bit/xen_set_bit
- Don't export the variable xen_intr_pcpu
dev/xen/blkback/blkback.c:
- Fix the string format when XBB_DEBUG is enabled: host_addr is typed
uint64_t
dev/xen/balloon/balloon.c:
- Remove set but not used variable
- Use the correct type for frame_list: xen_pfn_t represents the frame
number on any architecture
dev/xen/control/control.c:
- Return BUS_PROBE_WILDCARD in xs_probe: Returning 0 in a probe callback
means the driver can handle this device. If by any chance xenstore is the
first driver, every new device with the driver is unset will use
xenstore.
dev/xen/grant-table/grant_table.c:
- Remove unused cmpxchg
- Drop unused include opt_pmap.h: Doesn't exist on ARM64 and it doesn't
contain anything required for the code on x86
dev/xen/netfront/netfront.c:
- Use the correct type for rx_pfn_array: xen_pfn_t represents the frame
number on any architecture
dev/xen/netback/netback.c:
- Use the correct type for gmfn: xen_pfn_t represents the frame number on
any architecture
dev/xen/xenstore/xenstore.c:
- Return BUS_PROBE_WILDCARD in xctrl_probe: Returning 0 in a probe callback
means the driver can handle this device. If by any chance xenstore is the
first driver, every new device with the driver is unset will use xenstore.
Note that with the changes, x86/include/xen/xen-os.h doesn't contain anymore
arch-specific code. Although, a new series will add some helpers that differ
between x86 and ARM64, so I've kept the headers for now.
Submitted by: Julien Grall <julien.grall@citrix.com>
Reviewed by: royger
Differential Revision: https://reviews.freebsd.org/D3921
Sponsored by: Citrix Systems R&D
In order to map memory from other domains when running on Xen FreeBSD uses
unused physical memory regions. Until now this memory has been allocated
using bus_alloc_resource, but this is not completely safe as we can end up
using unreclaimed MMIO or ACPI regions.
Fix this by introducing a new newbus method that can be used by Xen drivers
to request for unused memory regions. On amd64 we make sure this memory
comes from regions above 4GB in order to prevent clashes with MMIO/ACPI
regions. On i386 there's nothing we can do, so just fall back to the
previous mechanism.
Sponsored by: Citrix Systems R&D
Tested by: Gustau Pérez <gperez@entel.upc.edu>
remains. Xen is planning to phase out support for PV upstream since it
is harder to maintain and has more overhead. Modern x86 CPUs include
virtualization extensions that support HVM guests instead of PV guests.
In addition, the PV code was i386 only and not as well maintained recently
as the HVM code.
- Remove the i386-only NATIVE option that was used to disable certain
components for PV kernels. These components are now standard as they
are on amd64.
- Remove !XENHVM bits from PV drivers.
- Remove various shims required for XEN (e.g. PT_UPDATES_FLUSH, LOAD_CR3,
etc.)
- Remove duplicate copy of <xen/features.h>.
- Remove unused, i386-only xenstored.h.
Differential Revision: https://reviews.freebsd.org/D2362
Reviewed by: royger
Tested by: royger (i386/amd64 HVM domU and amd64 PVH dom0)
Relnotes: yes
This allows the Grant-table code to attach directly to the xenpv bus,
allowing us to remove the grant-table initialization done in xenpv.
Sponsored by: Citrix Systems R&D
Mave the grant table code into the dev/xen folder in preparation for turning
it into a device using the newbus interface. This is just code motion, no
functional changes.
Sponsored by: Citrix Systems R&D
