forked from luck/tmp_suning_uos_patched
831a301129
In the vCPU-run asm blob, the guest's RCX is temporarily saved onto the stack after VM-Exit as the exit flow must first load a register with a pointer to the vCPU's save area in order to save the guest's registers. RCX is arbitrarily designated as the scratch register. Since the stack usage is to (1)save host, (2)save guest, (3)load host and (4)load guest, the code can't conform to the stack's natural FIFO semantics, i.e. it can't simply do PUSH/POP. Regardless of whether it is done for the host's value or guest's value, at some point the code needs to access the stack using a non-traditional method, e.g. MOV instead of POP. vCPU-run opts to create a placeholder on the stack for guest's RCX (by adjusting RSP) and saves RCX to its place immediately after VM-Exit (via MOV). In other words, the purpose of the first 'PUSH RCX' at the start of the vCPU-run asm blob is to adjust RSP down, i.e. there's no need to actually access memory. Use 'SUB $wordsize, RSP' instead of 'PUSH RCX' to make it more obvious that the intent is simply to create a gap on the stack for the guest's RCX. Reviewed-by: Jim Mattson <jmattson@google.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.