lead to access from the virtual machine to the heap of the bhyve(8) process.
Submitted by: Felix Wilhelm <fwilhelm ernw.de>
Patch by: grehan
Security: FreeBSD-SA-16:38.bhyve
Some external tools just do a 'ls /dev/vmm' to figure out the bhyve virtual
machines on the host. These tools break if the devmem device nodes also
appear in /dev/vmm.
Requested by: grehan
due to a change in behavior of the 'vm_map_gpa()'.
Prior to r284539 if 'vm_map_gpa()' was called to map an address range in the
guest MMIO region then it would return NULL. This was used by the "movs"
emulation to detect if the 'src' or 'dst' operand was in MMIO space.
Post r284539 'vm_map_gpa()' started returning a non-NULL pointer even when
mapping the guest MMIO region.
Fix this by returning non-NULL only if [gaddr, gaddr+len) is entirely
within the 'lowmem' or 'highmem' regions and NULL otherwise.
Pointy hat to: neel
Reviewed by: grehan
Reported by: tychon, Ben Perrault (ben.perrault@gmail.com)
MFC after: 1 week
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
Prior to this change both functions returned 0 for success, -1 for failure
and +1 to indicate that an exception was injected into the guest.
The numerical value of ERESTART also happens to be -1 so when these functions
returned -1 it had to be translated to a positive errno value to prevent the
VM_RUN ioctl from being inadvertently restarted. This made it easy to introduce
bugs when writing emulation code.
Fix this by adding an 'int *guest_fault' parameter and setting it to '1' if
an exception was delivered to the guest. The return value is 0 or EFAULT so
no additional translation is needed.
Reviewed by: tychon
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D2428
%rdi, %rsi, etc are inadvertently bypassed along with the check to
see if the instruction needs to be repeated per the 'rep' prefix.
Add "MOVS" instruction support for the 'MMIO to MMIO' case.
Reviewed by: neel
the 'gpa' was in the guest MMIO region. This would manifest as a segmentation
fault in 'vm_map_copyin()' or 'vm_map_copyout()' because 'vm_map_gpa()' would
return NULL for this 'gpa'.
Fix this by calling 'vm_map_gpa()' in 'vm_copy_setup' and returning a failure
if the 'gpa' cannot be mapped. This matches the behavior of 'vm_copy_setup()'
in vmm.ko.
MFC after: 1 week
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
The faulting instruction needs to be restarted when the exception handler
is done handling the fault. bhyve now does this correctly by setting
'vmexit[vcpu].inst_length' to zero so the %rip is not advanced.
A minor complication is that the fault injection APIs are used by instruction
emulation code that is shared by vmm.ko and bhyve. Thus the argument that
refers to 'struct vm *' in kernel or 'struct vmctx *' in userspace needs to
be loosely typed as a 'void *'.
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.
Previously the sizes were inferred indirectly based on the size of the mappings
at 0 and 4GB respectively. This works fine as long as size of the allocation is
identical to the size of the mapping in the guest's address space. However, if
the mapping is disjoint then this assumption falls apart (e.g., due to the
legacy BIOS hole between 640KB and 1MB).
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.
fault on the destination buffer.
Prior to this change a page fault would be detected in vm_copyout(). This
was done after the I/O port access was done. If the I/O port access had
side-effects (e.g. reading the uart FIFO) then restarting the instruction
would result in incorrect behavior.
Fix this by validating the guest linear address before doing the I/O port
emulation. If the validation results in a page fault exception being injected
into the guest then the instruction can now be restarted without any
side-effects.
of the guest linear address space. These APIs in turn use a new ioctl
'VM_GLA2GPA' to convert the guest linear address to guest physical.
Use the new copyin/copyout APIs when emulating ins/outs instruction in
bhyve(8).
the legacy 8259A PICs.
- Implement an ICH-comptabile PCI interrupt router on the lpc device with
8 steerable pins configured via config space access to byte-wide
registers at 0x60-63 and 0x68-6b.
- For each configured PCI INTx interrupt, route it to both an I/O APIC
pin and a PCI interrupt router pin. When a PCI INTx interrupt is
asserted, ensure that both pins are asserted.
- Provide an initial routing of PCI interrupt router (PIRQ) pins to
8259A pins (ISA IRQs) and initialize the interrupt line config register
for the corresponding PCI function with the ISA IRQ as this matches
existing hardware.
- Add a global _PIC method for OSPM to select the desired interrupt routing
configuration.
- Update the _PRT methods for PCI bridges to provide both APIC and legacy
PRT tables and return the appropriate table based on the configured
routing configuration. Note that if the lpc device is not configured, no
routing information is provided.
- When the lpc device is enabled, provide ACPI PCI link devices corresponding
to each PIRQ pin.
- Add a VMM ioctl to adjust the trigger mode (edge vs level) for 8259A
pins via the ELCR.
- Mark the power management SCI as level triggered.
- Don't hardcode the number of elements in Packages in the source for
the DSDT. iasl(8) will fill in the actual number of elements, and
this makes it simpler to generate a Package with a variable number of
elements.
Reviewed by: tycho
This has not added a lot of value when debugging bhyve issues while greatly
increasing the time and space required to store the core file.
Passing the "-C" option to bhyve(8) will change the default and dump guest
memory in the core dump.
Requested by: grehan
Reviewed by: grehan
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@
from any context i.e., it is not required to be called from a vcpu thread. The
ioctl simply sets a state variable 'vm->suspend' to '1' and returns.
The vcpus inspect 'vm->suspend' in the run loop and if it is set to '1' the
vcpu breaks out of the loop with a reason of 'VM_EXITCODE_SUSPENDED'. The
suspend handler waits until all 'vm->active_cpus' have transitioned to
'vm->suspended_cpus' before returning to userspace.
Discussed with: grehan
New ioctls VM_ISA_ASSERT_IRQ, VM_ISA_DEASSERT_IRQ and VM_ISA_PULSE_IRQ
can be used to manipulate the pic, and optionally the ioapic, pin state.
Reviewed by: jhb, neel
Approved by: neel (co-mentor)
processor-specific VMCS or VMCB. The pending exception will be delivered right
before entering the guest.
The order of event injection into the guest is:
- hardware exception
- NMI
- maskable interrupt
In the Intel VT-x case, a pending NMI or interrupt will enable the interrupt
window-exiting and inject it as soon as possible after the hardware exception
is injected. Also since interrupts are inherently asynchronous, injecting
them after the hardware exception should not affect correctness from the
guest perspective.
Rename the unused ioctl VM_INJECT_EVENT to VM_INJECT_EXCEPTION and restrict
it to only deliver x86 hardware exceptions. This new ioctl is now used to
inject a protection fault when the guest accesses an unimplemented MSR.
Discussed with: grehan, jhb
Reviewed by: jhb
the virtio backends.
- Add a new ioctl to export the count of pins on the I/O APIC from vmm
to the hypervisor.
- Use pins on the I/O APIC >= 16 for PCI interrupts leaving 0-15 for
ISA interrupts.
- Populate the MP Table with I/O interrupt entries for any PCI INTx
interrupts.
- Create a _PRT table under the PCI root bridge in ACPI to route any
PCI INTx interrupts appropriately.
- Track which INTx interrupts are in use per-slot so that functions
that share a slot attempt to distribute their INTx interrupts across
the four available pins.
- Implicitly mask INTx interrupts if either MSI or MSI-X is enabled
and when the INTx DIS bit is set in a function's PCI command register.
Either assert or deassert the associated I/O APIC pin when the
state of one of those conditions changes.
- Add INTx support to the virtio backends.
- Always advertise the MSI capability in the virtio backends.
Submitted by: neel (7)
Reviewed by: neel
MFC after: 2 weeks
- 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)
callers treat the MSI 'addr' and 'data' fields as opaque and also lets
bhyve implement multiple destination modes: physical, flat and clustered.
Submitted by: Tycho Nightingale (tycho.nightingale@pluribusnetworks.com)
Reviewed by: grehan@
bhyve supports a single timer block with 8 timers. The timers are all 32-bit
and capable of being operated in periodic mode. All timers support interrupt
delivery using MSI. Timers 0 and 1 also support legacy interrupt routing.
At the moment the timers are not connected to any ioapic pins but that will
be addressed in a subsequent commit.
This change is based on a patch from Tycho Nightingale (tycho.nightingale@pluribusnetworks.com).
to inject edge triggered legacy interrupts into the guest.
Start using the new API in device models that use edge triggered interrupts:
viz. the 8254 timer and the LPC/uart device emulation.
Submitted by: Tycho Nightingale (tycho.nightingale@pluribusnetworks.com)
upcoming in-kernel device emulations like the HPET.
The ioctls VM_IOAPIC_ASSERT_IRQ and VM_IOAPIC_DEASSERT_IRQ are used to
manipulate the ioapic pin state.
Discussed with: grehan@
Submitted by: Tycho Nightingale (tycho.nightingale@pluribusnetworks.com)
'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
These APIs were relevant when memory for virtual machine allocation was
hard partitioned away from the rest of the system but that is no longer
the case. The sysctls that provided this information were garbage collected
a while back.
Obtained from: NetApp
command line option "-m <memsize in MB>" to specify the memory size.
Prior to this change the user needed to explicitly specify the amount of
memory allocated below 4G (-m <lowmem>) and the amount above 4G (-M <highmem>).
The "-M" option is no longer supported by 'bhyveload' and 'bhyve'.
The start of the PCI hole is fixed at 3GB and cannot be directly changed
using command line options. However it is still possible to change this in
special circumstances via the 'vm_set_lowmem_limit()' API provided by
libvmmapi.
Submitted by: Dinakar Medavaram (initial version)
Reviewed by: grehan
Obtained from: NetApp
Prior to this change pinning was implemented via an ioctl (VM_SET_PINNING)
that called 'sched_bind()' on behalf of the user thread.
The ULE implementation of 'sched_bind()' bumps up 'td_pinned' which in turn
runs afoul of the assertion '(td_pinned == 0)' in userret().
Using the cpuset affinity to implement pinning of the vcpu threads works with
both 4BSD and ULE schedulers and has the happy side-effect of getting rid
of a bunch of code in vmm.ko.
Discussed with: grehan
Firmware tables require too much knowledge of system configuration,
and it's difficult to pass that information in general terms to a library.
The upcoming ACPI work exposed this - it will also livein bhyve.
Also, remove code specific to NetApp from the mptable name, and remove
the -n option from bhyve.
Reviewed by: neel
Obtained from: NetApp
address associated with the guest memory segment. This is because there is
no longer a 1:1 mapping between GPA and HPA.
As a result 'vmmctl' can only display the guest physical address and the
length of the lowmem and highmem segments.
chunks. This breaks the assumption that the entire memory segment is
contiguously allocated in the host physical address space.
This also paves the way to satisfy the 4KB page allocations by requesting
free pages from the VM subsystem as opposed to hard-partitioning host memory
at boot time.
CR4. This bit is specific to the Intel VTX and removing it makes the library
more portable to AMD/SVM.
In the Intel VTX implementation, the hypervisor will ensure that this bit is
always set. See vmx_fix_cr4() for details.
Suggested by: grehan
Includes instruction emulation for memory r/w access. This
opens the door for io-apic, local apic, hpet timer, and
legacy device emulation.
Submitted by: ryan dot berryhill at sandvine dot com
Reviewed by: grehan
Obtained from: Sandvine
vmm.ko - kernel module for VT-x, VT-d and hypervisor control
bhyve - user-space sequencer and i/o emulation
vmmctl - dump of hypervisor register state
libvmm - front-end to vmm.ko chardev interface
bhyve was designed and implemented by Neel Natu.
Thanks to the following folk from NetApp who helped to make this available:
Joe CaraDonna
Peter Snyder
Jeff Heller
Sandeep Mann
Steve Miller
Brian Pawlowski
