The save/restore feature uses a unix domain socket to send messages
from bhyvectl(8) to a bhyve(8) process. A datagram socket will suffice
for this.
An added benefit of using a datagram socket is simplified code. For
bhyve, the listen/accept calls are dropped; and for bhyvectl, the
connect() call is dropped.
EPRINTLN handles raw mode for bhyve(8), use it to print error messages.
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D28983
Use errno to print a more descriptive error message when vm_open() fails
libvmm: preserve errno when vm_device_open() fails
vm_destroy() squashes errno by making a dive into sysctlbyname() - we
can safely skip vm_destroy() here since it's not doing any critical
clean up at this point. Replace vm_destroy() with a free() call.
PR: 250671
MFC after: 3 days
Submitted by: marko@apache.org
Reviewed by: grehan
Differential Revision: https://reviews.freebsd.org/D29109
MAX_SNAPSHOT_VMNAME is a macro used to set the size of a character
buffer that stores a filename or the path to a file - this file is used
by the save/restore feature.
Since the file doesn't have anything to do with a vm name, rename
MAX_SNAPSHOT_VMNAME to MAX_SNAPSHOT_FILENAME. Bump the size to PATH_MAX
while here.
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D28879
Combine send_start_checkpoint() and send_start_suspend() into a
single function named snapshot_request().
snapshot_request() is equivalent to send_start_checkpoint() and
send_start_suspend() except that it takes an additional argument. The
additional argument, enum ipc_opcode, is used to determine the type of
snapshot request being performed. Also, switch to using strlcpy instead
of strncpy.
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D28878
Add /var/run/bhyve/ to BSD.var.dist so we don't have to call mkdir when
creating the unix domain socket for a given bhyve vm.
The path to the unix domain socket for a bhyve vm will now be
/var/run/bhyve/vmname instead of /var/run/bhyve/checkpoint/vmname
Move BHYVE_RUN_DIR from snapshot.c to snapshot.h so it can be shared
to bhyvectl(8).
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D28783
struct checkpoint_op, enum checkpoint_opcodes, and
MAX_SNAPSHOT_VMNAME are not vmm specific, move them out of the vmmapi
header.
They are used for the save/restore functionality that bhyve(8)
provides and are better suited in usr.sbin/bhyve/snapshot.h
Since bhyvectl(8) requires these, the Makefile for bhyvectl has been
modified to include usr.sbin/bhyve/snapshot.h
Reviewed by: kevans, grehan
Differential Revision: https://reviews.freebsd.org/D28410
Don't permit setting the exception bitmap or VMCS entry interrupt
information. These are not generally useful to set. If it is needed
in the future, dedicated pseudo registers can be added for these that
would be used with vm_set_register().
Discussed with: grehan
MFC after: 1 week
Save and restore (also known as suspend and resume) permits a snapshot
to be taken of a guest's state that can later be resumed. In the
current implementation, bhyve(8) creates a UNIX domain socket that is
used by bhyvectl(8) to send a request to save a snapshot (and
optionally exit after the snapshot has been taken). A snapshot
currently consists of two files: the first holds a copy of guest RAM,
and the second file holds other guest state such as vCPU register
values and device model state.
To resume a guest, bhyve(8) must be started with a matching pair of
command line arguments to instantiate the same set of device models as
well as a pointer to the saved snapshot.
While the current implementation is useful for several uses cases, it
has a few limitations. The file format for saving the guest state is
tied to the ABI of internal bhyve structures and is not
self-describing (in that it does not communicate the set of device
models present in the system). In addition, the state saved for some
device models closely matches the internal data structures which might
prove a challenge for compatibility of snapshot files across a range
of bhyve versions. The file format also does not currently support
versioning of individual chunks of state. As a result, the current
file format is not a fixed binary format and future revisions to save
and restore will break binary compatiblity of snapshot files. The
goal is to move to a more flexible format that adds versioning,
etc. and at that point to commit to providing a reasonable level of
compatibility. As a result, the current implementation is not enabled
by default. It can be enabled via the WITH_BHYVE_SNAPSHOT=yes option
for userland builds, and the kernel option BHYVE_SHAPSHOT.
Submitted by: Mihai Tiganus, Flavius Anton, Darius Mihai
Submitted by: Elena Mihailescu, Mihai Carabas, Sergiu Weisz
Relnotes: yes
Sponsored by: University Politehnica of Bucharest
Sponsored by: Matthew Grooms (student scholarships)
Sponsored by: iXsystems
Differential Revision: https://reviews.freebsd.org/D19495
from userland without the need to use sysctls, it allows the old
sysctls to continue to function, but deprecates them at
FreeBSD_version 1200060 (Relnotes for deprecate).
The command line of bhyve is maintained in a backwards compatible way.
The API of libvmmapi is maintained in a backwards compatible way.
The sysctl's are maintained in a backwards compatible way.
Added command option looks like:
bhyve -c [[cpus=]n][,sockets=n][,cores=n][,threads=n][,maxcpus=n]
The optional parts can be specified in any order, but only a single
integer invokes the backwards compatible parse. [,maxcpus=n] is
hidden by #ifdef until kernel support is added, though the api
is put in place.
bhyvectl --get-cpu-topology option added.
Reviewed by: grehan (maintainer, earlier version),
Reviewed by: bcr (manpages)
Approved by: bde (mentor), phk (mentor)
Tested by: Oleg Ginzburg <olevole@olevole.ru> (cbsd)
MFC after: 1 week
Relnotes: Y
Differential Revision: https://reviews.freebsd.org/D9930
Currently most of the debug registers are not saved and restored
during VM transitions allowing guest and host debug register values to
leak into the opposite context. One result is that hardware
watchpoints do not work reliably within a guest under VT-x.
Due to differences in SVM and VT-x, slightly different approaches are
used.
For VT-x:
- Enable debug register save/restore for VM entry/exit in the VMCS for
DR7 and MSR_DEBUGCTL.
- Explicitly save DR0-3,6 of the guest.
- Explicitly save DR0-3,6-7, MSR_DEBUGCTL, and the trap flag from
%rflags for the host. Note that because DR6 is "software" managed
and not stored in the VMCS a kernel debugger which single steps
through VM entry could corrupt the guest DR6 (since a single step
trap taken after loading the guest DR6 could alter the DR6
register). To avoid this, explicitly disable single-stepping via
the trace flag before loading the guest DR6. A determined debugger
could still defeat this by setting a breakpoint after the guest DR6
was loaded and then single-stepping.
For SVM:
- Enable debug register caching in the VMCB for DR6/DR7.
- Explicitly save DR0-3 of the guest.
- Explicitly save DR0-3,6-7, and MSR_DEBUGCTL for the host. Since SVM
saves the guest DR6 in the VMCB, the race with single-stepping
described for VT-x does not exist.
For both platforms, expose all of the guest DRx values via --get-drX
and --set-drX flags to bhyvectl.
Discussed with: avg, grehan
Tested by: avg (SVM), myself (VT-x)
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D13229
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
No functional change intended.
This is not properly respecting WITHOUT or ARCH dependencies in target/.
Doing so requires a massive effort to rework targets/ to do so. A
better approach will be to either include the SUBDIR Makefiles directly
and map to DIRDEPS or just dynamically lookup the SUBDIR. These lose
the benefit of having a userland/lib, userland/libexec, etc, though and
results in a massive package. The current implementation of targets/ is
very unmaintainable.
Currently rescue/rescue and sys/modules are still not connected.
Sponsored by: EMC / Isilon Storage Division
devmem is used to represent MMIO devices like the boot ROM or a VESA framebuffer
where doing a trap-and-emulate for every access is impractical. devmem is a
hybrid of system memory (sysmem) and emulated device models.
devmem is mapped in the guest address space via nested page tables similar
to sysmem. However the address range where devmem is mapped may be changed
by the guest at runtime (e.g. by reprogramming a PCI BAR). Also devmem is
usually mapped RO or RW as compared to RWX mappings for sysmem.
Each devmem segment is named (e.g. "bootrom") and this name is used to
create a device node for the devmem segment (e.g. /dev/vmm/testvm.bootrom).
The device node supports mmap(2) and this decouples the host mapping of
devmem from its mapping in the guest address space (which can change).
Reviewed by: tychon
Discussed with: grehan
Differential Revision: https://reviews.freebsd.org/D2762
MFC after: 4 weeks
Keep track of the next instruction to be executed by the vcpu as 'nextrip'.
As a result the VM_RUN ioctl no longer takes the %rip where a vcpu should
start execution.
Also, instruction restart happens implicitly via 'vm_inject_exception()' or
explicitly via 'vm_restart_instruction()'. The APIs behave identically in
both kernel and userspace contexts. The main beneficiary is the instruction
emulation code that executes in both contexts.
bhyve(8) VM exit handlers now treat 'vmexit->rip' and 'vmexit->inst_length'
as readonly:
- Restarting an instruction is now done by calling 'vm_restart_instruction()'
as opposed to setting 'vmexit->inst_length' to 0 (e.g. emulate_inout())
- Resuming vcpu at an arbitrary %rip is now done by setting VM_REG_GUEST_RIP
as opposed to changing 'vmexit->rip' (e.g. vmexit_task_switch())
Differential Revision: https://reviews.freebsd.org/D1526
Reviewed by: grehan
MFC after: 2 weeks
The new RTC emulation supports all interrupt modes: periodic, update ended
and alarm. It is also capable of maintaining the date/time and NVRAM contents
across virtual machine reset. Also, the date/time fields can now be modified
by the guest.
Since bhyve now emulates both the PIT and the RTC there is no need for
"Legacy Replacement Routing" in the HPET so get rid of it.
The RTC device state can be inspected via bhyvectl as follows:
bhyvectl --vm=vm --get-rtc-time
bhyvectl --vm=vm --set-rtc-time=<unix_time_secs>
bhyvectl --vm=vm --rtc-nvram-offset=<offset> --get-rtc-nvram
bhyvectl --vm=vm --rtc-nvram-offset=<offset> --set-rtc-nvram=<value>
Reviewed by: tychon
Discussed with: grehan
Differential Revision: https://reviews.freebsd.org/D1385
MFC after: 2 weeks
options to display some key VMCB fields.
The set of valid options that can be passed to bhyvectl now depends on the
processor type. AMD-specific options are identified by a "--vmcb" or "--avic"
in the option name. Intel-specific options are identified by a "--vmcs" in
the option name.
Submitted by: Anish Gupta (akgupt3@gmail.com)
A nested exception condition arises when a second exception is triggered while
delivering the first exception. Most nested exceptions can be handled serially
but some are converted into a double fault. If an exception is generated during
delivery of a double fault then the virtual machine shuts down as a result of
a triple fault.
vm_exit_intinfo() is used to record that a VM-exit happened while an event was
being delivered through the IDT. If an exception is triggered while handling
the VM-exit it will be treated like a nested exception.
vm_entry_intinfo() is used by processor-specific code to get the event to be
injected into the guest on the next VM-entry. This function is responsible for
deciding the disposition of nested exceptions.
it implicitly in vmm.ko.
Add ioctl VM_GET_CPUS to get the current set of 'active' and 'suspended' cpus
and display them via /usr/sbin/bhyvectl using the "--get-active-cpus" and
"--get-suspended-cpus" options.
This is in preparation for being able to reset virtual machine state without
having to destroy and recreate it.
by adding an argument to the VM_SUSPEND ioctl that specifies how the virtual
machine should be suspended, viz. VM_SUSPEND_RESET or VM_SUSPEND_POWEROFF.
The disposition of VM_SUSPEND is also made available to the exit handler
via the 'u.suspended' member of 'struct vm_exit'.
This capability is exposed via the '--force-reset' and '--force-poweroff'
arguments to /usr/sbin/bhyvectl.
Discussed with: grehan@
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.
hides the setjmp/longjmp semantics of VM enter/exit. vmx_enter_guest() is used
to enter guest context and vmx_exit_guest() is used to transition back into
host context.
Fix a longstanding race where a vcpu interrupt notification might be ignored
if it happens after vmx_inject_interrupts() but before host interrupts are
disabled in vmx_resume/vmx_launch. We now called vmx_inject_interrupts() with
host interrupts disabled to prevent this.
Suggested by: grehan@
- Add a generic routine to trigger an LVT interrupt that supports both
fixed and NMI delivery modes.
- Add an ioctl and bhyvectl command to trigger local interrupts inside a
guest. In particular, a global NMI similar to that raised by SERR# or
PERR# can be simulated by asserting LINT1 on all vCPUs.
- Extend the LVT table in the vCPU local APIC to support CMCI.
- Flesh out the local APIC error reporting a bit to cache errors and
report them via ESR when ESR is written to. Add support for asserting
the error LVT when an error occurs. Raise illegal vector errors when
attempting to signal an invalid vector for an interrupt or when sending
an IPI.
- Ignore writes to reserved bits in LVT entries.
- Export table entries the MADT and MP Table advertising the stock x86
config of LINT0 set to ExtInt and LINT1 wired to NMI.
Reviewed by: neel (earlier version)
'invpcid' instruction to the guest. Currently bhyve will try to enable this
capability unconditionally if it is available.
Consolidate code in bhyve to set the capabilities so it is no longer
duplicated in BSP and AP bringup.
Add a sysctl 'vm.pmap.invpcid_works' to display whether the 'invpcid'
instruction is available.
Reviewed by: grehan
MFC after: 3 days
Make the amd64/pmap code aware of nested page table mappings used by bhyve
guests. This allows bhyve to associate each guest with its own vmspace and
deal with nested page faults in the context of that vmspace. This also
enables features like accessed/dirty bit tracking, swapping to disk and
transparent superpage promotions of guest memory.
Guest vmspace:
Each bhyve guest has a unique vmspace to represent the physical memory
allocated to the guest. Each memory segment allocated by the guest is
mapped into the guest's address space via the 'vmspace->vm_map' and is
backed by an object of type OBJT_DEFAULT.
pmap types:
The amd64/pmap now understands two types of pmaps: PT_X86 and PT_EPT.
The PT_X86 pmap type is used by the vmspace associated with the host kernel
as well as user processes executing on the host. The PT_EPT pmap is used by
the vmspace associated with a bhyve guest.
Page Table Entries:
The EPT page table entries as mostly similar in functionality to regular
page table entries although there are some differences in terms of what
bits are used to express that functionality. For e.g. the dirty bit is
represented by bit 9 in the nested PTE as opposed to bit 6 in the regular
x86 PTE. Therefore the bitmask representing the dirty bit is now computed
at runtime based on the type of the pmap. Thus PG_M that was previously a
macro now becomes a local variable that is initialized at runtime using
'pmap_modified_bit(pmap)'.
An additional wrinkle associated with EPT mappings is that older Intel
processors don't have hardware support for tracking accessed/dirty bits in
the PTE. This means that the amd64/pmap code needs to emulate these bits to
provide proper accounting to the VM subsystem. This is achieved by using
the following mapping for EPT entries that need emulation of A/D bits:
Bit Position Interpreted By
PG_V 52 software (accessed bit emulation handler)
PG_RW 53 software (dirty bit emulation handler)
PG_A 0 hardware (aka EPT_PG_RD)
PG_M 1 hardware (aka EPT_PG_WR)
The idea to use the mapping listed above for A/D bit emulation came from
Alan Cox (alc@).
The final difference with respect to x86 PTEs is that some EPT implementations
do not support superpage mappings. This is recorded in the 'pm_flags' field
of the pmap.
TLB invalidation:
The amd64/pmap code has a number of ways to do invalidation of mappings
that may be cached in the TLB: single page, multiple pages in a range or the
entire TLB. All of these funnel into a single EPT invalidation routine called
'pmap_invalidate_ept()'. This routine bumps up the EPT generation number and
sends an IPI to the host cpus that are executing the guest's vcpus. On a
subsequent entry into the guest it will detect that the EPT has changed and
invalidate the mappings from the TLB.
Guest memory access:
Since the guest memory is no longer wired we need to hold the host physical
page that backs the guest physical page before we can access it. The helper
functions 'vm_gpa_hold()/vm_gpa_release()' are available for this purpose.
PCI passthru:
Guest's with PCI passthru devices will wire the entire guest physical address
space. The MMIO BAR associated with the passthru device is backed by a
vm_object of type OBJT_SG. An IOMMU domain is created only for guest's that
have one or more PCI passthru devices attached to them.
Limitations:
There isn't a way to map a guest physical page without execute permissions.
This is because the amd64/pmap code interprets the guest physical mappings as
user mappings since they are numerically below VM_MAXUSER_ADDRESS. Since PG_U
shares the same bit position as EPT_PG_EXECUTE all guest mappings become
automatically executable.
Thanks to Alan Cox and Konstantin Belousov for their rigorous code reviews
as well as their support and encouragement.
Thanks for John Baldwin for reviewing the use of OBJT_SG as the backing
object for pci passthru mmio regions.
Special thanks to Peter Holm for testing the patch on short notice.
Approved by: re
Discussed with: grehan
Reviewed by: alc, kib
Tested by: pho
