This function can then be used by the TDX code to allocate the memory at
specific locations required for the TDVF to run from.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Use the newly added hugepages_size option if provided by the user to
pick a huge page size when creating the memfd region. If none is
specified use the system default.
Sadly different huge pages cannot be tested by an integration test as
creating a pool of the non-default size cannot be done at runtime
(requires kernel to be booted with certain parameters.)
TETS=Manually tested with a kernel booted with both 1GiB and 2MiB huge
pages (hugepagesz=1G hugepages=1 hugepagesz=2M hugepages=512)
Fixes: #2230
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This allows the user to use an alternative huge page size otherwise the
default size will be used.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This commit introduces a new information to the VirtioMemZone structure
in order to know if the memory zone is backed by hugepages.
Based on this new information, the virtio-mem device is now able to
determine if madvise(MADV_DONTNEED) should be performed or not. The
madvise documentation specifies that MADV_DONTNEED advice will fail if
the memory range has been allocated with some hugepages.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Hui Zhu <teawater@antfin.com>
The mutex timeout should be 0xffff rather than 0xfff to disable the
timeout feature.
dsdt.dsl 745: Acquire (\_SB.PRES.CPLK, 0x0FFF)
Warning 3130 - ^ Result is not used, possible operator timeout will be missed
dsdt.dsl 767: Acquire (\_SB.PRES.CPLK, 0x0FFF)
Warning 3130 - ^ Result is not used, possible operator timeout will be missed
dsdt.dsl 775: Acquire (\_SB.PRES.CPLK, 0x0FFF)
Warning 3130 - ^ Result is not used, possible operator timeout will be missed
Fixes: #2216
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Based on the LKML feedback, the devices under /dev/sgx/* are
not justified. SGX RFC v40 moves the SGX device nodes to /dev/sgx_*
and this is reflected in kvm-sgx (next branch) too.
Update cloud-hypervisor code and documentation to follow this.
Signed-off-by: Mikko Ylinen <mikko.ylinen@intel.com>
With Rust 1.49 using attributes on a function parameter is not allowed.
The recommended workaround is to put it in a new block.
error[E0658]: attributes on expressions are experimental
--> vmm/src/memory_manager.rs:698:17
|
698 | #[cfg(target_arch = "x86_64")]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
error: removing an expression is not supported in this position
--> vmm/src/memory_manager.rs:698:17
|
698 | #[cfg(target_arch = "x86_64")]
|
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This can be uses to indicate to the caller that it should wait on the
barrier before returning as there is some asynchronous activity
triggered by the write which requires the KVM exit to block until it's
completed.
This is useful for having vCPU thread wait for the VMM thread to proceed
to activate the virtio devices.
See #1863
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
In order to do this we must extend the MemoryManager API to add the
ability to specify the tracking of the dirty pages when creating the
userspace mappings and also keep track of the userspace mappings that
have been created for RAM regions.
Currently the dirty pages are collected into ranges based on a block
level of 64 pages. The algorithm could be tweaked to create smaller
ranges but for now if any page in the block of 64 is dirty the whole
block is added to the range.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
While the addressable space size reduction of 4k in necessary due to
the Linux bug, the 64k alignment of the addressable space size is
required by Windows. This patch satisfies both.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
This allows the code to be reused when creating the VM from a snapshot
when doing VM migration.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Rather than filling the guest memory from a file at the point of the the
guest memory region being created instead fill from the file later. This
simplifies the region creation code but also adds flexibility for
sourcing the guest memory from a source other than an on disk file.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
As a mirror of bdbea19e23 which ensured
that GuestMemoryMmap::read_exact_from() was used to read all the file to
the region ensure that all the guest memory region is written to disk.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Any occurrence of of a variable containing `ext_region` is replaced with
the less confusing name `saved_region`. The point is to clearly identify
the memory regions that might have been saved during a snapshot, while
the `ext` standing for `external` was pretty unclear.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In the context of saving the memory regions content through snapshot,
using the term "backing file" brings confusion with the actual backing
file that might back the memory mapping.
To avoid such conflicting naming, the 'backing_file' field from the
MemoryRegion structure gets replaced with 'content', as this is
designating the potential file containing the memory region data.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Use GuestRegionMmap::read_exact_from() to ensure that all of the file is
read into the guest. This addresses an issue where
GuestRegionMmap::read_from() was only copying the first 2GiB of the
memory and so lead to snapshot-restore was failing when the guest RAM
was 2GiB or greater.
This change also propagates any error from the copying upwards.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
When restoring if a region of RAM is backed by anonymous memory i.e from
memfd_create() then copy the contents of the ram from the file that has
been saved to disk.
Previously the code would map the memory from that file into the guest
using a MAP_PRIVATE mapping. This has the effect of
minimising the restore time but provides an issue where the restored VM
does not have the same structure as the snapshotted VM, in particular
memory is backed by files in the restored VM that were anonymously
backed in the original.
This creates two problems:
* The snapshot data is mapped from files for the pages of the guest
which prevents the storage from being reclaimed.
* When snapshotting again the guest memory will not be correctly saved
as it will have looked like it was backed by a file so it will not be
written to disk but as it is a MAP_PRIVATE mapping the changes will
never be written to the disk again. This results in incorrect
behaviour.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Now that we have a new dedicated way of asking for a balloon through the
CLI and the REST API, we can move all the balloon code to the device
manager. This allows us to simplify the memory manager, which is already
quite complex.
It also simplifies the behavior of the balloon resizing command. Instead
of providing the expected size for the RAM, which is complex when memory
zones are involved, it now expects the balloon size. This is a much more
straightforward behavior as it really resizes the balloon to the desired
size. Additionally to the simplication, the benefit of this approach is
that it does not need to be tied to the memory manager at all.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
If the user provided a maximum physical bits value for the vCPUs, the
memory manager will adapt the guest physical address space accordingly
so that devices are not placed further than the specified value.
It's important to note that if the number exceed what is available on
the host, the smaller number will be picked.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The 'GuestAddress::unchecked_add' function has undefined behavior when
an overflow occurs. Its alternative 'checked_add' requires use to handle
the overflow explicitly.
Signed-off-by: Bo Chen <chen.bo@intel.com>
We are now reserving a 256M gap in the guest address space each time
when hotplugging memory with ACPI, which prevents users from hotplugging
memory to the maximum size they requested. We confirm that there is no
need to reserve this gap.
This patch removes the 'reserved gaps'. It also refactors the
'MemoryManager::start_addr' so that it is rounding-up to 128M alignment
when hotplugged memory is allowed with ACPI.
Signed-off-by: Bo Chen <chen.bo@intel.com>
We now try to create a ram region of size 0 when the requested memory
size is the same as current memory size. It results in an error of
`GuestMemoryRegion(Mmap(Os { code: 22, kind: InvalidInput, message:
"Invalid argument" }))`. This error is not meaningful to users and we
should not report it.
Signed-off-by: Bo Chen <chen.bo@intel.com>
The virtio-balloon change the memory size is asynchronous.
VirtioBalloonConfig.actual of balloon device show current balloon size.
This commit add memory_actual_size to vm.info to show memory actual size.
Signed-off-by: Hui Zhu <teawater@antfin.com>
Misspellings were identified by https://github.com/marketplace/actions/check-spelling
* Initial corrections suggested by Google Sheets
* Additional corrections by Google Chrome auto-suggest
* Some manual corrections
Signed-off-by: Josh Soref <jsoref@users.noreply.github.com>
Use zone.host_numa_node to create memory zone, so that memory zone
can apply memory policy in according with host numa node ID
Signed-off-by: Jiangbo Wu <jiangbo.wu@intel.com>
Based on all the preparatory work achieved through previous commits,
this patch updates the 'hotplugged_size' field for both MemoryConfig and
MemoryZoneConfig structures when either the whole memory is resized, or
simply when a memory zone is resized.
This fixes the lack of support for rebooting a VM with the right amount
of memory plugged in.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Adding a new field to VirtioMemZone structure, as it lets us associate
with a particular virtio-mem region the amount of memory that should be
plugged in at boot.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This patch simplifies the code as we have one single Option for the
VirtioMemZone. This also prepares for storing additional information
related to the virtio-mem region.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Add the new option 'hotplugged_size' to both --memory-zone and --memory
parameters so that we can let the user specify a certain amount of
memory being plugged at boot.
This is also part of making sure we can store the virtio-mem size over a
reboot of the VM.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that e820 tables are created from the 'boot_guest_memory', we can
simplify the memory manager code by adding the virtio-mem regions when
they are created. There's no need to wait for the first hotplug to
insert these regions.
This also anticipates the need for starting a VM with some memory
already plugged into the virtio-mem region.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In order to differentiate the 'boot' memory regions from the virtio-mem
regions, we store what we call 'boot_guest_memory'. This is useful to
provide the adequate list of regions to the configure_system() function
as it expects only the list of regions that should be exposed through
the e820 table.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The virtio-mem driver is generating some warnings regarding both size
and alignment of the virtio-mem region if not based on 128MiB:
The alignment of the physical start address can make some memory
unusable.
The alignment of the physical end address can make some memory
unusable.
For these reasons, the current patch enforces virtio-mem regions to be
128MiB aligned and checks the size provided by the user is a multiple of
128MiB.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
For more consistency and help reading the code better, this commit
renames all 'virtiomem*' variables into 'virtio_mem*'.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Implement a new VM action called 'resize-zone' allowing the user to
resize one specific memory zone at a time. This relies on all the
preliminary work from the previous commits to resize each virtio-mem
device independently from each others.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
By adding a new parameter 'id' to the virtiomem_resize() function, we
prepare this function to be usable for both global memory resizing and
memory zone resizing.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
It's important to return the region covered by virtio-mem the first time
it is inserted as the device manager must update all devices with this
information.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Based on the previous code changes, we can now update the MemoryManager
code to create one virtio-mem region and resizing handler per memory
zone. This will naturally create one virtio-mem device per memory zone
from the DeviceManager's code which has been previously updated as well.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In anticipation for resizing support of an individual memory zone,
this commit introduces a new option 'hotplug_size' to '--memory-zone'
parameter. This defines the amount of memory that can be added through
each specific memory zone.
Because memory zone resize is tied to virtio-mem, make sure the user
selects 'virtio-mem' hotplug method, otherwise return an error.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Both MemoryManager and DeviceManager are updated through this commit to
handle the creation of multiple virtio-mem devices if needed. For now,
only the framework is in place, but the behavior remains the same, which
means only the memory zone created from '--memory' generates a
virtio-mem region that can be used for resize.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In order to anticipate the need for storing memory regions along with
virtio-mem information for each memory zone, we create a new structure
MemoryZone that will replace Vec<Arc<GuestRegionMmap>> in the hash map
MemoryZones.
This makes thing more logical as MemoryZones becomes a list of
MemoryZone sorted by their identifier.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This removes the dependency of the pci crate on the devices crate which
now only contains the device implementations themselves.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The way to describe guest NUMA nodes has been updated through previous
commits, letting the user describe the full NUMA topology through the
--numa parameter (or NumaConfig).
That's why we can remove the deprecated and unused 'guest_numa_node'
option.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Based on the previous changes introducing new options for both memory
zones and NUMA configuration, this patch changes the behavior of the
NUMA node definition. Instead of relying on the memory zones to define
the guest NUMA nodes, everything goes through the --numa parameter. This
allows for defining NUMA nodes without associating any particular memory
range to it. And in case one wants to associate one or multiple memory
ranges to it, the expectation is to describe a list of memory zone
through the --numa parameter.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that we have an identifier per memory zone, and in order to keep
track of the memory regions associated with the memory zones, we create
and store a map referencing list of memory regions per memory zone ID.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In anticipation for allowing memory zones to be removed, but also in
anticipation for refactoring NUMA parameter, we introduce a mandatory
'id' option to the --memory-zone parameter.
This forces the user to provide a unique identifier for each memory zone
so that we can refer to these.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Based on the NumaConfig which now provides distance information, we can
internally update the list of NUMA nodes with the exact distances they
should be located from other nodes.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Relying on the list of CPUs defined through the NumaConfig, this patch
will update the internal list of CPUs attached to each NUMA node.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Based on the 'guest_numa_node' option, we create and store a list of
NUMA nodes in the MemoryManager. The point being to associate a list of
memory regions to each node, so that we can later create the ACPI tables
with the proper memory range information.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
With the introduction of this new option, the user will be able to
describe if a particular memory zone should belong to a specific NUMA
node from a guest perspective.
For instance, using '--memory-zone size=1G,guest_numa_node=2' would let
the user describe that a memory zone of 1G in the guest should be
exposed as being associated with the NUMA node 2.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Given that ACPI uses u32 as the type for the Proximity Domain, we can
use u32 instead of u64 as the type for 'host_numa_node' option.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Let's narrow down the limitation related to mbind() by allowing shared
mappings backed by a file backed by RAM. This leaves the restriction on
only for mappings backed by a regular file.
With this patch, host NUMA node can be specified even if using
vhost-user devices.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Relying on the new option 'host_numa_node' from the 'memory-zone'
parameter, the user can now define which NUMA node from the host
should be used to back the current memory zone.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Since memory zones have been introduced, it is now possible for a user
to specify multiple backends for the guest RAM. By adding a new option
'host_numa_node' to the 'memory-zone' parameter, we allow the guest RAM
to be backed by memory that might come from a specific NUMA node on the
host.
The option expects a node identifier, specifying which NUMA node should
be used to allocate the memory associated with a specific memory zone.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The flag 'mergeable' should only apply to the entire guest RAM, which is
why it is removed from the MemoryZoneConfig as it is defined as a global
parameter at the MemoryConfig level.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Factorize the codepath between simple memory and multiple memory zones.
This simplifies the way regions are memory mapped, as everything relies
on the same codepath. This is performed by creating a memory zone on the
fly for the specific use case where --memory is used with size being
different from 0. Internally, the code can rely on memory zones to
create the memory regions forming the guest memory.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
After the introduction of user defined memory zones, we can now remove
the deprecated 'file' option from --memory parameter. This makes this
parameter simpler, letting more advanced users define their own custom
memory zones through the dedicated parameter.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
User defined memory regions can now support being snapshot and restored,
therefore this commit removes the restrictions that were applied through
earlier commit.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
By factorizing a lot of code into create_ram_region(), this commit
achieves the simplification of the restore codepath. Additionally, it
makes user defined memory zones compatible with snapshot/restore.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
First thing, this patch introduces a new function to identify if a file
descriptor is linked to any hard link on the system. This can let the
VMM know if the file can be accessed by the user, or if the file will
be destroyed as soon as the VMM releases the file descriptor.
Based on this information, and associated with the knowledge about the
region being MAP_SHARED or not, the VMM can now decide to skip the copy
of the memory region content. If the user has access to the file from
the filesystem, and if the file has been mapped as MAP_SHARED, we can
consider the guest memory region content to be present in this file at
any point in time. That's why in this specific case, there's no need for
performing the copy of the memory region content into a dedicated file.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Let's not assume that a backing file is going to be the result from
a snapshot for each memory region. These regions might be backed by
a file on the host filesystem (not a temporary file in host RAM), which
means they don't need to be copied and stored into dedicated files.
That's why this commit prepares for further changes by introducing an
optional PathBuf associated with the snapshot of each memory region.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
There will be some cases where the implementation of the snapshot()
function from the Snapshottable trait will require to modify some
internal data, therefore we make this possible by updating the trait
definition with snapshot(&mut self).
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In case the memory size is 0, this means the user defined memory
zones are used as a way to specify how to back the guest memory.
This is the first step in supporting complex use cases where the user
can define exactly which type of memory from the host should back the
memory from the guest.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In anticipation for the need to map part of a file with the function
create_ram_region(), it is extended to accept a file offset as argument.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In case the provided backing file is an actual file and not a directory,
we should not truncate it, as we expect the file to already be the right
size.
This change will be important once we try to map the same file through
multiple memory mappings. We can't let the file be truncated as the
second mapping wouldn't work properly.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Some OS might check for duplicates and bail out, if it can't create a
distinct mapping. According to ACPI 5.0 section 6.1.12, while _UID is
optional, it becomes required when there are multiple devices with the
same _HID.
Signed-off-by: Anatol Belski <ab@php.net>
The SGX EPC region must be exposed through the ACPI tables so that the
guest can detect its presence. The guest only get the full range from
ACPI, as the specific EPC sections are directly described through the
CPUID of each vCPU.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Based on the presence of one or multiple SGX EPC sections from the VM
configuration, the MemoryManager will allocate a contiguous block of
guest address space to hold the entire EPC region. Within this EPC
region, each EPC section is memory mapped.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit store balloon size to MemoryConfig.
After reboot, virtio-balloon can use this size to inflate back to
the size before reboot.
Signed-off-by: Hui Zhu <teawater@antfin.com>
The code is purely for maintaining an internal counter. It is not really
tied to KVM.
No functional change.
Signed-off-by: Wei Liu <liuwe@microsoft.com>
The fd naming is quite KVM specific. Since we're now using the
hypervisor crate abstractions, we can rename those into something more
readable and meaningful.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Split the generic virtio code (queues and device type) from the
VirtioDevice trait, transport and device implementations.
This also simplifies the feature handling in vhost_user_backend as the
vm-virtio crate is no longer has any features.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
That removes one more KVM-ism in VMM crate.
Note that there are more KVM specific code in those files to be split
out, but we're not at that stage yet.
No functional change.
Signed-off-by: Wei Liu <liuwe@microsoft.com>
Start moving the vmm, arch and pci crates to being hypervisor agnostic
by using the hypervisor trait and abstractions. This is not a complete
switch and there are still some remaining KVM dependencies.
Signed-off-by: Muminul Islam <muislam@microsoft.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Implemented GSI allocator and system allocator for AArch64.
Renamed some layout definitions to align more code between architectures.
Signed-off-by: Michael Zhao <michael.zhao@arm.com>
In order to workaround a Linux bug that happens when we place devices at
the end of the physical address space on recent hardware (52 bits limit)
we reduce the MMIO address space by one 4k page. This way, nothing gets
allocated in the last 4k of the address space, which is negligible given
the amount of space in the address space.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This is a preparing commit to build and test CH on AArch64. All building
issues were fixed, but no functionality was introduced.
For X86, the logic of code was not changed at all.
For ARM, the architecture specific part is still empty. And we applied
some tricks to workaround lint warnings. But such code will be replaced
later by other commits with real functionality.
Signed-off-by: Michael Zhao <michael.zhao@arm.com>
The new 'shared' and 'hugepages' controls aim to replace the 'file'
option in MemoryConfig. This patch also updated all related integration
tests to use the new controls (instead of providing explicit paths to
"/dev/shm" or "/dev/hugepages").
Fixes: #1011
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Signed-off-by: Bo Chen <chen.bo@intel.com>
Replace alignment calculation of start address with functionally
equivalent version that does not assume that the block size is a power
of two.
Signed-off-by: Martin Xu <martin.xu@intel.com>
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The same way we added a helper for creating userspace memory mappings
from the MemoryManager, this patch adds a new helper to remove some
previously added mappings.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that the restore path uses RestoreConfig structure, we add a new
parameter called "prefault" to it. This will give the user the ability
to populate the pages corresponding to the mapped regions backed by the
snapshotted memory files.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
When CoW can be used, the VM restoration time is reduced, but the pages
are not populated. This can lead to some slowness from the guest when
accessing these pages.
Depending on the use case, we might prefer a slower boot time for better
performances from guest runtime. The way to achieve this is to prefault
the pages in this case, using the MAP_POPULATE flag along with CoW.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This patch extends the previous behavior on the restore codepath.
Instead of copying the memory regions content from the snapshot files
into the new memory regions, the VMM will use the snapshot region files
as the backing files behind each mapped region. This is done in order to
reduce the time for the VM to be restored.
When the source VM has been initially started with a backing file, this
means it has been mapped with the MAP_SHARED flag. For this case, we
cannot use the CoW trick to speed up the VM restore path and we simply
fallback onto the copy of the memory regions content.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Whenever a MemoryManager is restored from a snapshot, the memory regions
associated with it might need to directly back the mapped memory for
increased performances. If that's the case, a list of external regions
is provided and the MemoryManager should simply ignore what's coming
from the MemoryConfig.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that we can choose specific mmap flags for the guest RAM, we create
a new parameter "copy_on_write" meaning that the memory mappings backed
by a file should be performed with MAP_PRIVATE instead of MAP_SHARED.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
