mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-03 20:34:23 -04:00
0e0ab73c9a
...except RSP, which is restored by hardware as part of VM-Exit.
Paolo theorized that restoring registers from the stack after a VM-Exit
in lieu of zeroing them could lead to speculative execution with the
guest's values, e.g. if the stack accesses miss the L1 cache[1].
Zeroing XORs are dirt cheap, so just be ultra-paranoid.
Note that the scratch register (currently RCX) used to save/restore the
guest state is also zeroed as its host-defined value is loaded via the
stack, just with a MOV instead of a POP.
[1] https://patchwork.kernel.org/patch/10771539/#22441255
Fixes: 0cb5b30698 ("kvm: vmx: Scrub hardware GPRs at VM-exit")
Cc: <stable@vger.kernel.org>
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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.