33af3a7ef9
Performing a WBINVD and DF_FLUSH are expensive operations. Currently, a WBINVD/DF_FLUSH is performed every time an SEV guest terminates. However, the WBINVD/DF_FLUSH is only required when an ASID is being re-allocated to a new SEV guest. Also, a single WBINVD/DF_FLUSH can enable all ASIDs that have been disassociated from guests through DEACTIVATE. To reduce the number of WBINVD/DF_FLUSH invocations, introduce a new ASID bitmap to track ASIDs that need to be reclaimed. When an SEV guest is terminated, add its ASID to the reclaim bitmap instead of clearing the bitmap in the existing SEV ASID bitmap. This delays the need to perform a WBINVD/DF_FLUSH invocation when an SEV guest terminates until all of the available SEV ASIDs have been used. At that point, the WBINVD/DF_FLUSH invocation can be performed and all ASIDs in the reclaim bitmap moved to the available ASIDs bitmap. The semaphore around DEACTIVATE can be changed to a read semaphore with the semaphore taken in write mode before performing the WBINVD/DF_FLUSH. Tested-by: David Rientjes <rientjes@google.com> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.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.