Commit Graph

64 Commits

Author SHA1 Message Date
Glen Barber
317cec3c43 MFH
Sponsored by:	The FreeBSD Foundation
2016-02-22 12:28:23 +00:00
Svatopluk Kraus
d6849317c5 As <machine/param.h> is included from <sys/param.h>, there is no need
to include it explicitly when <sys/param.h> is already included.

Reviewed by:	alc, kib
Differential Revision:	https://reviews.freebsd.org/D5378
2016-02-22 09:04:36 +00:00
Glen Barber
a70cba9582 First pass through library packaging.
Sponsored by:	The FreeBSD Foundation
2016-02-04 21:16:35 +00:00
Bryan Drewery
7b3ea376a2 META MODE: Prefer INSTALL=tools/install.sh to lessen the need for xinstall.host.
This both avoids some dependencies on xinstall.host and allows
bootstrapping on older releases to work due to lack of at least 'install -l'
support.

Sponsored by:	EMC / Isilon Storage Division
2015-11-25 19:10:28 +00:00
Neel Natu
5e4f29c037 Move the 'devmem' device nodes from /dev/vmm to /dev/vmm.io
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
2015-07-06 19:41:43 +00:00
Simon J. Gerraty
96a11afdff Updated depends 2015-07-03 06:11:54 +00:00
Neel Natu
36e8356e99 Fix a regression in "movs" emulation after r284539. The regression was caused
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
2015-06-22 00:30:34 +00:00
Neel Natu
9b1aa8d622 Restructure memory allocation in bhyve to support "devmem".
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
2015-06-18 06:00:17 +00:00
Simon J. Gerraty
ccfb965433 Add META_MODE support.
Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.

Still need to add real targets under targets/ to build packages.

Differential Revision:       D2796
Reviewed by: brooks imp
2015-06-13 19:20:56 +00:00
Simon J. Gerraty
98e0ffaefb Merge sync of head 2015-05-27 01:19:58 +00:00
Neel Natu
9c4d547896 Deprecate the 3-way return values from vm_gla2gpa() and vm_copy_setup().
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
2015-05-06 16:25:20 +00:00
Baptiste Daroussin
ea4a4d8a2e Fix overlinking in bhyve:
libvmmapi is actually needed to be linked to libutil, not bhyve nor bhyveload
2015-04-09 21:38:40 +00:00
Tycho Nightingale
ef7c2a82ed Fix "MOVS" instruction memory to MMIO emulation. Currently updates to
%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
2015-04-01 00:15:31 +00:00
Neel Natu
009e2acba6 Fix a bug in libvmmapi 'vm_copy_setup()' where it would return success even if
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
2015-01-19 06:51:04 +00:00
Neel Natu
d087a39935 Simplify instruction restart logic in bhyve.
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
2015-01-18 03:08:30 +00:00
Neel Natu
0dafa5cd4b Replace bhyve's minimal RTC emulation with a fully featured one in vmm.ko.
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
2014-12-30 22:19:34 +00:00
Simon J. Gerraty
ee7b0571c2 Merge head from 7/28 2014-08-19 06:50:54 +00:00
Neel Natu
d37f2adb38 Fix fault injection in bhyve.
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 *'.
2014-07-24 01:38:11 +00:00
Neel Natu
d665d229ce Emulate instructions emitted by OpenBSD/i386 version 5.5:
- CMP REG, r/m
- MOV AX/EAX/RAX, moffset
- MOV moffset, AX/EAX/RAX
- PUSH r/m
2014-07-23 04:28:51 +00:00
Neel Natu
091d453222 Handle nested exceptions in bhyve.
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.
2014-07-19 20:59:08 +00:00
Neel Natu
be679db4cd Provide APIs to directly get 'lowmem' and 'highmem' size directly.
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).
2014-06-24 02:02:51 +00:00
Neel Natu
5fcf252f41 Add ioctl(VM_REINIT) to reinitialize the virtual machine state maintained
by vmm.ko. This allows the virtual machine to be restarted without having
to destroy it first.

Reviewed by:	grehan
2014-06-07 21:36:52 +00:00
Neel Natu
95ebc360ef Activate vcpus from bhyve(8) using the ioctl VM_ACTIVATE_CPU instead of doing
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.
2014-05-31 23:37:34 +00:00
Neel Natu
6303b65d35 Fix issue with restarting an "insb/insw/insl" instruction because of a page
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.
2014-05-26 18:21:08 +00:00
Neel Natu
da11f4aa1d Add libvmmapi functions vm_copyin() and vm_copyout() to copy into and out
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).
2014-05-24 23:12:30 +00:00
Simon J. Gerraty
fae50821ae Updated dependencies 2014-05-16 14:09:51 +00:00
John Baldwin
b3e9732a76 Implement a PCI interrupt router to route PCI legacy INTx interrupts to
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
2014-05-15 14:16:55 +00:00
Neel Natu
0dd10c0047 Don't include the guest memory segments in the bhyve(8) process core dump.
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
2014-05-13 16:40:27 +00:00
Simon J. Gerraty
76b28ad6ab Updated dependencies 2014-05-10 05:16:28 +00:00
Simon J. Gerraty
cc3f4b9965 Merge from head 2014-05-08 23:54:15 +00:00
Neel Natu
f0fdcfe247 Allow a virtual machine to be forcibly reset or powered off. This is done
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@
2014-04-28 22:06:40 +00:00
Simon J. Gerraty
3b8f084595 Merge head 2014-04-28 07:50:45 +00:00
Simon J. Gerraty
9d2ab4a62d Merge head 2014-04-27 08:13:43 +00:00
Tycho Nightingale
b96be57a2d Add support for emulating the slave PIC.
Reviewed by:	grehan, jhb
Approved by:	grehan (co-mentor)
2014-04-14 19:00:20 +00:00
Neel Natu
b15a09c05e Add an ioctl to suspend a virtual machine (VM_SUSPEND). The ioctl can be called
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
2014-03-26 23:34:27 +00:00
Tycho Nightingale
762fd20804 Replace the userspace atpic stub with a more functional vmm.ko model.
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)
2014-03-11 16:56:00 +00:00
Neel Natu
dc50650607 Queue pending exceptions in the 'struct vcpu' instead of directly updating the
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
2014-02-26 00:52:05 +00:00
John Baldwin
00f3efe1bd Add support for FreeBSD/i386 guests under bhyve.
- Similar to the hack for bootinfo32.c in userboot, define
  _MACHINE_ELF_WANT_32BIT in the load_elf32 file handlers in userboot.
  This allows userboot to load 32-bit kernels and modules.
- Copy the SMAP generation code out of bootinfo64.c and into its own
  file so it can be shared with bootinfo32.c to pass an SMAP to the i386
  kernel.
- Use uint32_t instead of u_long when aligning module metadata in
  bootinfo32.c in userboot, as otherwise the metadata used 64-bit
  alignment which corrupted the layout.
- Populate the basemem and extmem members of the bootinfo struct passed
  to 32-bit kernels.
- Fix the 32-bit stack in userboot to start at the top of the stack
  instead of the bottom so that there is room to grow before the
  kernel switches to its own stack.
- Push a fake return address onto the 32-bit stack in addition to the
  arguments normally passed to exec() in the loader.  This return
  address is needed to convince recover_bootinfo() in the 32-bit
  locore code that it is being invoked from a "new" boot block.
- Add a routine to libvmmapi to setup a 32-bit flat mode register state
  including a GDT and TSS that is able to start the i386 kernel and
  update bhyveload to use it when booting an i386 kernel.
- Use the guest register state to determine the CPU's current instruction
  mode (32-bit vs 64-bit) and paging mode (flat, 32-bit, PAE, or long
  mode) in the instruction emulation code.  Update the gla2gpa() routine
  used when fetching instructions to handle flat mode, 32-bit paging, and
  PAE paging in addition to long mode paging.  Don't look for a REX
  prefix when the CPU is in 32-bit mode, and use the detected mode to
  enable the existing 32-bit mode code when decoding the mod r/m byte.

Reviewed by:	grehan, neel
MFC after:	1 month
2014-02-05 04:39:03 +00:00
John Baldwin
3cbf3585cb Enhance the support for PCI legacy INTx interrupts and enable them in
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
2014-01-29 14:56:48 +00:00
John Baldwin
330baf58c6 Extend the support for local interrupts on the local APIC:
- 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)
2013-12-23 19:29:07 +00:00
Neel Natu
55888cfaa2 Rename the ambiguously named 'vm_setup_msi()' and 'vm_setup_msix()' to
'vm_setup_pptdev_msi()' and 'vm_setup_pptdev_msix()' respectively.

It should now be clear that these functions operate on passthru devices.
2013-12-18 03:58:51 +00:00
Neel Natu
4f8be175d5 Add an API to deliver message signalled interrupts to vcpus. This allows
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@
2013-12-16 19:59:31 +00:00
Neel Natu
08e3ff329a Add HPET device emulation to bhyve.
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).
2013-11-25 19:04:51 +00:00
Neel Natu
ac7304a758 Add an ioctl to assert and deassert an ioapic pin atomically. This will be used
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)
2013-11-23 03:56:03 +00:00
Neel Natu
565bbb8698 Move the ioapic device model from userspace into vmm.ko. This is needed for
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)
2013-11-12 22:51:03 +00:00
Simon J. Gerraty
09127a3637 New/updated dependencies 2013-10-17 19:59:51 +00:00
Neel Natu
49cc03da31 Add a new capability, VM_CAP_ENABLE_INVPCID, that can be enabled to expose
'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
2013-10-16 18:20:27 +00:00
Neel Natu
200758f114 Parse the memory size parameter using expand_number() to allow specifying
the memory size more intuitively (e.g. 512M, 4G etc).

Submitted by:	rodrigc
Reviewed by:	grehan
Approved by:	re (blanket)
2013-10-09 03:56:07 +00:00
Neel Natu
318224bbe6 Merge projects/bhyve_npt_pmap into head.
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
2013-10-05 21:22:35 +00:00
Neel Natu
ade4af668a Remove deprecated APIs to get the total and free memory available to vmm.ko.
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
2013-04-25 20:42:21 +00:00