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Project ACRN hypervisor
ea4eadf0a5
The current permission-checking and dispatching mechanism of hypercalls is
not unified because:
1. Some hypercalls require the exact vCPU initiating the call, while the
others only need to know the VM.
2. Different hypercalls have different permission requirements: the
trusty-related ones are enabled by a guest flag, while the others
require the initiating VM to be the Service OS.
Without a unified logic it could be hard to scale when more kinds of
hypercalls are added later.
The objectives of this patch are as follows.
1. All hypercalls have the same prototype and are dispatched by a unified
logic.
2. Permissions are checked by a unified logic without consulting the
hypercall ID.
To achieve the first objective, this patch modifies the type of the first
parameter of hcall_* functions (which are the callbacks implementing the
hypercalls) from `struct acrn_vm *` to `struct acrn_vcpu *`. The
doxygen-style documentations are updated accordingly.
To achieve the second objective, this patch adds to `struct hc_dispatch` a
`permission_flags` field which specifies the guest flags that must ALL be
set for a VM to be able to invoke the hypercall. The default value (which
is 0UL) indicates that this hypercall is for SOS only. Currently only the
`permission_flag` of trusty-related hypercalls have the non-zero value
GUEST_FLAG_SECURE_WORLD_ENABLED.
With `permission_flag`, the permission checking logic of hypercalls is
unified as follows.
1. General checks
i. If the VM is neither SOS nor having any guest flag that allows
certain hypercalls, it gets #UD upon executing the `vmcall`
instruction.
ii. If the VM is allowed to execute the `vmcall` instruction, but
attempts to execute it in ring 1, 2 or 3, the VM gets #GP(0).
2. Hypercall-specific checks
i. If the hypercall is for SOS (i.e. `permission_flag` is 0), the
initiating VM must be SOS and the specified target VM cannot be a
pre-launched VM. Otherwise the hypercall returns -EINVAL without
further actions.
ii. If the hypercall requires certain guest flags, the initiating VM
must have all the required flags. Otherwise the hypercall returns
-EINVAL without further actions.
iii. A hypercall with an unknown hypercall ID makes the hypercall
returns -EINVAL without further actions.
The logic above is different from the current implementation in the
following aspects.
1. A pre-launched VM now gets #UD (rather than #GP(0)) when it attempts
to execute `vmcall` in ring 1, 2 or 3.
2. A pre-launched VM now gets #UD (rather than the return value -EPERM)
when it attempts to execute a trusty hypercall in ring 0.
3. The SOS now gets the return value -EINVAL (rather than -EPERM) when it
attempts to invoke a trusty hypercall.
4. A post-launched VM with trusty support now gets the return value
-EINVAL (rather than #UD) when it attempts to invoke a non-trusty
hypercall or an invalid hypercall.
v1 -> v2:
- Update documentation that describe hypercall behavior.
- Fix Doxygen warnings
Tracked-On: #5924
Signed-off-by: Junjie Mao <junjie.mao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
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| .github/ISSUE_TEMPLATE | ||
| devicemodel | ||
| doc | ||
| hypervisor | ||
| misc | ||
| .checkpatch.conf | ||
| .clang-format | ||
| .gitignore | ||
| CODEOWNERS | ||
| LICENSE | ||
| Makefile | ||
| paths.make | ||
| README.rst | ||
| VERSION | ||
Project ACRN Embedded Hypervisor ################################ .. raw:: html <img src="doc/images/ACRN_Logo_PrimaryLockup_COLOR-300x300-1.png" height="175px" align="right"> The open source project ACRN defines a device hypervisor reference stack and an architecture for running multiple software subsystems, managed securely, on a consolidated system by means of a virtual machine manager. It also defines a reference framework implementation for virtual device emulation, called the "ACRN Device Model". The ACRN Hypervisor is a Type 1 reference hypervisor stack, running directly on the bare-metal hardware, and is suitable for a variety of IoT and embedded device solutions. The ACRN hypervisor addresses the gap that currently exists between datacenter hypervisors, and hard partitioning hypervisors. The ACRN hypervisor architecture partitions the system into different functional domains, with carefully selected guest OS sharing optimizations for IoT and embedded devices. .. start_include_here Community Support ***************** The Project ACRN Developer Community includes developers from member organizations and the general community all joining in the development of software within the project. Members contribute and discuss ideas, submit bugs and bug fixes. They also help those in need through the community's forums such as mailing lists and IRC channels. Anyone can join the developer community and the community is always willing to help its members and the User Community to get the most out of Project ACRN. Welcome to the project ARCN community! We're now holding weekly Technical Community Meetings and encourage you to call in and learn more about the project. Meeting information is on the `TCM Meeting page`_ in our `ACRN wiki <https://wiki.projectacrn.org/>`_. .. _TCM Meeting page: https://github.com/projectacrn/acrn-hypervisor/wiki/ACRN-Committee-and-Working-Group-Meetings#technical-community-meetings Resources ********* Here's a quick summary of resources to find your way around the Project ACRN support systems: * **Project ACRN Website**: The https://projectacrn.org website is the central source of information about the project. On this site, you'll find background and current information about the project as well as relevant links to project material. For a quick start, refer to the `Introduction`_ and `Getting Started Guide`_. * **Source Code in GitHub**: Project ACRN source code is maintained on a public GitHub repository at https://github.com/projectacrn/acrn-hypervisor. You'll find information about getting access to the repository and how to contribute to the project in this `Contribution Guide`_ document. * **Documentation**: Project technical documentation is developed along with the project's code, and can be found at https://projectacrn.github.io. Additional documentation is maintained in the `Project ACRN GitHub wiki`_. * **Issue Reporting and Tracking**: Requirements and Issue tracking is done in the Github issues system: https://github.com/projectacrn/acrn-hypervisor/issues. You can browse through the reported issues and submit issues of your own. * **Reporting a Potential Security Vulnerability**: If you have discovered potential security vulnerability in ACRN, please send an e-mail to secure@intel.com. For issues related to Intel Products, please visit https://security-center.intel.com. It is important to include the following details: - The projects and versions affected - Detailed description of the vulnerability - Information on known exploits Vulnerability information is extremely sensitive. Please encrypt all security vulnerability reports using our `PGP key`_. A member of the Intel Product Security Team will review your e-mail and contact you to to collaborate on resolving the issue. For more information on how Intel works to resolve security issues, see: `vulnerability handling guidelines`_. * **Mailing List**: The `Project ACRN Development mailing list`_ is perhaps the most convenient way to track developer discussions and to ask your own support questions to the project ACRN community. There are also specific `ACRN mailing list subgroups`_ for builds, users, and Technical Steering Committee notes, for example. You can read through the message archives to follow past posts and discussions, a good thing to do to discover more about the project. .. _Introduction: https://projectacrn.github.io/latest/introduction/ .. _Getting Started Guide: https://projectacrn.github.io/latest/getting-started/ .. _Contribution Guide: https://projectacrn.github.io/latest/contribute.html .. _Project ACRN GitHub wiki: https://github.com/projectacrn/acrn-hypervisor/wiki .. _PGP Key: https://www.intel.com/content/www/us/en/security-center/pgp-public-key.html .. _vulnerability handling guidelines: https://www.intel.com/content/www/us/en/security-center/vulnerability-handling-guidelines.html .. _Project ACRN Development mailing list: https://lists.projectacrn.org/g/acrn-dev .. _ACRN mailing list subgroups: https://lists.projectacrn.org/g/main/subgroups