We use 4-level EPT pages, correct the upper bound.
Reviewed by: grehan
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D27402
There is no need for these to be function pointers since they are
never modified post-module load.
Rename AMD/Intel ops to be more consistent.
Submitted by: adam_fenn.io
Reviewed by: markj, grehan
Approved by: grehan (bhyve)
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D27375
This is a relic from when these instructions weren't supported by the toolchain.
No functional change.
Submitted by: adam_fenn.io
Reviewed by: grehan
Approved by: grehan (bhyve)
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D27130
This reduces some code duplication. One behavior change is that
ppt_assign_device() will now only succeed if the device is unowned.
Previously, a device could be assigned to the same VM multiple times,
but each time it was assigned, the device's state was reset.
Reviewed by: markj, grehan
MFC after: 2 weeks
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D27301
Add a new ioctl to disable all MSI-X interrupts for a PCI passthrough
device and invoke it if a write to the MSI-X capability registers
disables MSI-X. This avoids leaving MSI-X interrupts enabled on the
host if a guest device driver has disabled them (e.g. as part of
detaching a guest device driver).
This was found by Chelsio QA when testing that a Linux guest could
switch from MSI-X to MSI interrupts when using the cxgb4vf driver.
While here, explicitly fail requests to enable MSI on a passthrough
device if MSI-X is enabled and vice versa.
Reported by: Sony Arpita Das @ Chelsio
Reviewed by: grehan, markj
MFC after: 2 weeks
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D27212
Currently EPT TLB invalidation is done by incrementing a generation
counter and issuing an IPI to all CPUs currently running vCPU threads.
The VMM inner loop caches the most recently observed generation on each
host CPU and invalidates TLB entries before executing the VM if the
cached generation number is not the most recent value.
pmap_invalidate_ept() issues IPIs to force each vCPU to stop executing
guest instructions and reload the generation number. However, it does
not actually wait for vCPUs to exit, potentially creating a window where
guests may continue to reference stale TLB entries.
Fix the problem by bracketing guest execution with an SMR read section
which is entered before loading the invalidation generation. Then,
pmap_invalidate_ept() increments the current write sequence before
loading pm_active and sending IPIs, and polls readers to ensure that all
vCPUs potentially operating with stale TLB entries have exited before
pmap_invalidate_ept() returns.
Also ensure that unsynchronized loads of the generation counter are
wrapped with atomic(9), and stop (inconsistently) updating the
invalidation counter and pm_active bitmask with acquire semantics.
Reviewed by: grehan, kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26910
Rewrite the code that maintains pm_active and invalidates EPTP-tagged
TLB entries in C. Previously this work was done in vmx_enter_guest(),
in assembly, but there is no good reason for that and it makes the TLB
invalidation algorithm for nested page tables harder to review.
No functional change intended. Now, an error from the invept
instruction results in a kernel panic rather than a vmexit. Such errors
should occur only as a result of VMM bugs.
Reviewed by: grehan, kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26830
Per the Intel manuals, CPUID is supposed to unconditionally zero the
upper 32 bits of the involved (rax/rbx/rcx/rdx) registers.
Previously, the emulation would cast pointers to the 64-bit register
values down to `uint32_t`, which while properly manipulating the lower
bits, would leave any garbage in the upper bits uncleared. While no
existing guest OSes seem to stumble over this in practice, the bhyve
emulation should match x86 expectations.
This was discovered through alignment warnings emitted by gcc9, while
testing it against SmartOS/bhyve.
SmartOS bug: https://smartos.org/bugview/OS-8168
Submitted by: Patrick Mooney
Reviewed by: rgrimes
Differential Revision: https://reviews.freebsd.org/D24727
Intercept and report #UD to VM on SVM/AMD in case VM tried to execute an
SVM instruction. Otherwise, SVM allows execution of them, and instructions
operate on host physical addresses despite being executed in guest mode.
Reported by: Maxime Villard <max@m00nbsd.net>
admbug: 972
CVE: CVE-2020-7467
Reviewed by: grehan, markj
Differential revision: https://reviews.freebsd.org/D26313
Since LA57 was moved to the main SDM document with revision 072, it
seems that we should have a support for it, and silicons are coming.
This patch makes pmap support both LA48 and LA57 hardware. The
selection of page table level is done at startup, kernel always
receives control from loader with 4-level paging. It is not clear how
UEFI spec would adapt LA57, for instance it could hand out control in
LA57 mode sometimes.
To switch from LA48 to LA57 requires turning off long mode, requesting
LA57 in CR4, then re-entering long mode. This is somewhat delicate
and done in pmap_bootstrap_la57(). AP startup in LA57 mode is much
easier, we only need to toggle a bit in CR4 and load right value in CR3.
I decided to not change kernel map for now. Single PML5 entry is
created that points to the existing kernel_pml4 (KML4Phys) page, and a
pml5 entry to create our recursive mapping for vtopte()/vtopde().
This decision is motivated by the fact that we cannot overcommit for
KVA, so large space there is unusable until machines start providing
wider physical memory addressing. Another reason is that I do not
want to break our fragile autotuning, so the KVA expansion is not
included into this first step. Nice side effect is that minidumps are
compatible.
On the other hand, (very) large address space is definitely
immediately useful for some userspace applications.
For userspace, numbering of pte entries (or page table pages) is
always done for 5-level structures even if we operate in 4-level mode.
The pmap_is_la57() function is added to report the mode of the
specified pmap, this is done not to allow simultaneous 4-/5-levels
(which is not allowed by hw), but to accomodate for EPT which has
separate level control and in principle might not allow 5-leve EPT
despite x86 paging supports it. Anyway, it does not seems critical to
have 5-level EPT support now.
Tested by: pho (LA48 hardware)
Reviewed by: alc
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D25273
Recent versions of UEFI have moved local APIC timer initialization into
the early SEC phase which runs out of ROM, prior to self-relocating
into RAM. This results in a hypervisor exit.
Currently bhyve prevents instruction emulation from segments that aren't
marked as "sysmem" aka guest RAM, with the vm_gpa_hold() routine failing.
However, there is no reason for this restriction: the hypervisor already
controls whether EPT mappings are marked as executable.
Fix by dropping the redundant check of sysmem.
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D25955
If userspace has a newer bhyve than the kernel, it may be able to decode
and emulate some instructions vmm.ko is unaware of. In this scenario,
reset decoder state and try again.
Reviewed by: grehan
Differential Revision: https://reviews.freebsd.org/D24464
Expose the special kernel LAPIC, IOAPIC, and HPET devices to userspace
for use in, e.g., fallback instruction emulation (when userspace has a
newer instruction decode/emulation layer than the kernel vmm(4)).
Plumb the ioctl through libvmmapi and register the memory ranges in
bhyve(8).
Reviewed by: grehan
Differential Revision: https://reviews.freebsd.org/D24525
In recent Linux (5.3+) and OpenBSD (6.6+) kernels, and with hosts that
support CPUID 0x15, the local APIC frequency is determined directly
from the reported crystal clock to avoid calibration against the 8254
timer.
However, the local APIC frequency implemented by bhyve is 128MHz, where
most h/w systems report frequencies around 25MHz. This shows up on
OpenBSD guests as repeated keystrokes on the emulated PS2 keyboard
when using VNC, since the kernel's timers are now much shorter.
Fix by reporting all-zeroes for CPUID 0x15. This allows guests to fall
back to using the 8254 to calibrate the local APIC frequency.
Future work could be to compute values returned for 0x15 that would
match the host TSC and bhyve local APIC frequency, though all dependencies
on this would need to be examined (for example, Linux will start using
0x16 for some hosts).
PR: 246321
Reported by: Jason Tubnor (and tested)
Reviewed by: jhb
Approved by: jhb, bz (mentor)
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D24837
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
As a short term solution for the problem reported by Shawn Webb re: r359950,
bump the maximum number of memmaps per VM. This structure is 40 bytes, and the
additional four (fixed array embedded in the struct vm) members increase the
size of struct vm by 3%.
(The vast majority of struct vm is the embedded struct vcpu array, which
accounts for 84% of the size -- over 4 kB.)
Reported by: Shawn Webb <shawn.webb AT hardenedbsd.org>
Reviewed by: grehan
X-MFC-With: r359950
Differential Revision: https://reviews.freebsd.org/D24507
Permit instruction decoding logic to be compiled outside of the kernel for
rapid iteration and validation.
Reviewed by: grehan
Differential Revision: https://reviews.freebsd.org/D24439
This speeds up Windows guests tremendously.
The patch does:
Add a new tuneable 'hw.vmm.vmx.use_tpr_shadowing' to disable TLP shadowing.
Also add 'hw.vmm.vmx.cap.tpr_shadowing' to be able to query if TPR shadowing is used.
Detach the initialization of TPR shadowing from the initialization of APIC virtualization.
APIC virtualization still needs TPR shadowing, but not vice versa.
Any CPU that supports APIC virtualization should also support TPR shadowing.
When TPR shadowing is used, the APIC page of each vCPU is written to the VMCS_VIRTUAL_APIC field of the VMCS
so that the CPU can write directly to the page without intercept.
On vm exit, vlapic_update_ppr() is called to update the PPR.
Submitted by: Yamagi Burmeister
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D22942
r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked). Use it in
preparation for a general review of all nodes.
This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.
Reviewed by: kib
Approved by: kib (mentor)
Differential Revision: https://reviews.freebsd.org/D23625
X-Generally looks fine: jhb
- Allow the userland hypervisor to intercept breakpoint exceptions
(BP#) in the guest. A new capability (VM_CAP_BPT_EXIT) is used to
enable this feature. These exceptions are reported to userland via
a new VM_EXITCODE_BPT that includes the length of the original
breakpoint instruction. If userland wishes to pass the exception
through to the guest, it must be explicitly re-injected via
vm_inject_exception().
- Export VMCS_ENTRY_INST_LENGTH as a VM_REG_GUEST_ENTRY_INST_LENGTH
pseudo-register. Injecting a BP# on Intel requires setting this to
the length of the breakpoint instruction. AMD SVM currently ignores
writes to this register (but reports success) and fails to read it.
- Rework the per-vCPU state tracked by the debug server. Rather than
a single 'stepping_vcpu' global, add a structure for each vCPU that
tracks state about that vCPU ('stepping', 'stepped', and
'hit_swbreak'). A global 'stopped_vcpu' tracks which vCPU is
currently reporting an event. Event handlers for MTRAP and
breakpoint exits loop until the associated event is reported to the
debugger.
Breakpoint events are discarded if the breakpoint is not present
when a vCPU resumes in the breakpoint handler to retry submitting
the breakpoint event.
- Maintain a linked-list of active breakpoints in response to the GDB
'Z0' and 'z0' packets.
Reviewed by: markj (earlier version)
MFC after: 2 months
Differential Revision: https://reviews.freebsd.org/D20309
No need to log all the commands in command ring but only the last one for which completion failed.
Reported by: np@freebsd.org
Reviewed by: np, markj
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D22566
After removing wmb(), vm_set_rendezvous_func() became super trivial, so
there was no point in keeping it.
The wmb (sfence on amd64, lock nop on i386) was not needed. This can be
explained from several points of view.
First, wmb() is used for store-store ordering (although, the primitive
is undocumented). There was no obvious subsequent store that needed the
barrier.
Second, x86 has a memory model with strong ordering including total
store order. An explicit store barrier may be needed only when working
with special memory (device, special caching mode) or using special
instructions (non-temporal stores). That was not the case for this
code.
Third, I believe that there is a misconception that sfence "flushes" the
store buffer in a sense that it speeds up the propagation of stores from
the store buffer to the global visibility. I think that such
propagation always happens as fast as possible. sfence only makes
subsequent stores wait for that propagation to complete. So, sfence is
only useful for ordering of stores and only in the situations described
above.
Reviewed by: jhb
MFC after: 23 days
Differential Revision: https://reviews.freebsd.org/D21978
Centralize calculation of signal and ucode delivered on unhandled page
fault in new function vm_fault_trap(). MD trap_pfault() now almost
always uses the signal numbers and error codes calculated in
consistent MI way.
This introduces the protection fault compatibility sysctls to all
non-x86 architectures which did not have that bug, but apparently they
were already much more wrong in selecting delivered signals on
protection violations.
Change the delivered signal for accesses to mapped area after the
backing object was truncated. According to POSIX description for
mmap(2):
The system shall always zero-fill any partial page at the end of an
object. Further, the system shall never write out any modified
portions of the last page of an object which are beyond its
end. References within the address range starting at pa and
continuing for len bytes to whole pages following the end of an
object shall result in delivery of a SIGBUS signal.
An implementation may generate SIGBUS signals when a reference
would cause an error in the mapped object, such as out-of-space
condition.
Adjust according to the description, keeping the existing
compatibility code for SIGSEGV/SIGBUS on protection failures.
For situations where kernel cannot handle page fault due to resource
limit enforcement, SIGBUS with a new error code BUS_OBJERR is
delivered. Also, provide a new error code SEGV_PKUERR for SIGSEGV on
amd64 due to protection key access violation.
vm_fault_hold() is renamed to vm_fault(). Fixed some nits in
trap_pfault()s like mis-interpreting Mach errors as errnos. Removed
unneeded truncations of the fault addresses reported by hardware.
PR: 211924
Reviewed by: alc
Discussed with: jilles, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D21566
There are several mechanisms by which a vm_page reference is held,
preventing the page from being freed back to the page allocator. In
particular, holding the page's object lock is sufficient to prevent the
page from being freed; holding the busy lock or a wiring is sufficent as
well. These references are protected by the page lock, which must
therefore be acquired for many per-page operations. This results in
false sharing since the page locks are external to the vm_page
structures themselves and each lock protects multiple structures.
Transition to using an atomically updated per-page reference counter.
The object's reference is counted using a flag bit in the counter. A
second flag bit is used to atomically block new references via
pmap_extract_and_hold() while removing managed mappings of a page.
Thus, the reference count of a page is guaranteed not to increase if the
page is unbusied, unmapped, and the object's write lock is held. As
a consequence of this, the page lock no longer protects a page's
identity; operations which move pages between objects are now
synchronized solely by the objects' locks.
The vm_page_wire() and vm_page_unwire() KPIs are changed. The former
requires that either the object lock or the busy lock is held. The
latter no longer has a return value and may free the page if it releases
the last reference to that page. vm_page_unwire_noq() behaves the same
as before; the caller is responsible for checking its return value and
freeing or enqueuing the page as appropriate. vm_page_wire_mapped() is
introduced for use in pmap_extract_and_hold(). It fails if the page is
concurrently being unmapped, typically triggering a fallback to the
fault handler. vm_page_wire() no longer requires the page lock and
vm_page_unwire() now internally acquires the page lock when releasing
the last wiring of a page (since the page lock still protects a page's
queue state). In particular, synchronization details are no longer
leaked into the caller.
The change excises the page lock from several frequently executed code
paths. In particular, vm_object_terminate() no longer bounces between
page locks as it releases an object's pages, and direct I/O and
sendfile(SF_NOCACHE) completions no longer require the page lock. In
these latter cases we now get linear scalability in the common scenario
where different threads are operating on different files.
__FreeBSD_version is bumped. The DRM ports have been updated to
accomodate the KPI changes.
Reviewed by: jeff (earlier version)
Tested by: gallatin (earlier version), pho
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20486
The bhyve virtual local APIC uses an instance-global flag to indicate
when an error LVT is being delivered to prevent infinite recursion.
Use a function argument instead to reduce the amount of instance-global
state.
This was inspired by reviewing the bhyve save/restore work, which
saves a copy of the instance-global state for each vlapic.
Smart OS bug: https://smartos.org/bugview/OS-7777
Submitted by: Patrick Mooney
Reviewed by: markj, rgrimes
Obtained from: SmartOS / Joyent
Differential Revision: https://reviews.freebsd.org/D20365
physical destination mode.
This is mostly a nop, because the vmm initializes all vCPUs up to
vm_maxcpus, so even if the target CPU is not active, lapic/vlapic code
still has the valid data to use. As John notes, dropping such
interrupts more closely matches the real harware, which ignores all
interrupts for not started APs.
Reviewed by: jhb
admbugs: 837
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Bhyve's vmm is a self-contained modern component and thus a good
candidate for use of C99 types.
Reviewed by: jhb, kib, markj, Patrick Mooney
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21036
Use 'struct bintime' instead of 'sbintime_t' to manage times in vPIT
to postpone rounding to final results rather than intermediate
results. In tests performed by Joyent, this reduced the error measured
by Linux guests by 59 ppm.
Smart OS bug: https://smartos.org/bugview/OS-6923
Submitted by: Patrick Mooney
Reviewed by: rgrimes
Obtained from: SmartOS / Joyent
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20335
hard-coded value. Don't allocate space for it from the kernel stack.
Account for prefix, suffix, and separator space in the name. This
takes the effective length up to 229 bytes on 13-current, and 37 bytes
on 12-stable. 37 bytes is enough to hold a full GUID string.
PR: 234134
MFC after: 1 week
Differential Revision: http://reviews.freebsd.org/D20924
The hold_count and wire_count fields of struct vm_page are separate
reference counters with similar semantics. The remaining essential
differences are that holds are not counted as a reference with respect
to LRU, and holds have an implicit free-on-last unhold semantic whereas
vm_page_unwire() callers must explicitly determine whether to free the
page once the last reference to the page is released.
This change removes the KPIs which directly manipulate hold_count.
Functions such as vm_fault_quick_hold_pages() now return wired pages
instead. Since r328977 the overhead of maintaining LRU for wired pages
is lower, and in many cases vm_fault_quick_hold_pages() callers would
swap holds for wirings on the returned pages anyway, so with this change
we remove a number of page lock acquisitions.
No functional change is intended. __FreeBSD_version is bumped.
Reviewed by: alc, kib
Discussed with: jeff
Discussed with: jhb, np (cxgbe)
Tested by: pho (previous version)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D19247
This adds emulation for:
test r/m16, imm16
test r/m32, imm32
test r/m64, imm32 sign-extended to 64
OpenBSD guests compiled with clang 8.0.0 use TEST directly against a
Local APIC register instead of separate read via MOV followed by a
TEST against the register.
PR: 238794
Submitted by: jhb
Reported by: Jason Tubnor jason@tubnor.net
Tested by: Jason Tubnor jason@tubnor.net
Reviewed by: markj, Patrick Mooney patrick.mooney@joyent.com
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D20755
