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Paolo Bonzini 10ef74c06b KVM SEV-SNP CipherText Hiding support for 6.18
Add support for SEV-SNP's CipherText Hiding, an opt-in feature that prevents
 unauthorized CPU accesses from reading the ciphertext of SNP guest private
 memory, e.g. to attempt an offline attack.  Instead of ciphertext, the CPU
 will always read back all FFs when CipherText Hiding is enabled.
 
 Add new module parameter to the KVM module to enable CipherText Hiding and
 control the number of ASIDs that can be used for VMs with CipherText Hiding,
 which is in effect the number of SNP VMs.  When CipherText Hiding is enabled,
 the hared SEV-ES/SEV-SNP ASID space is split into separate ranges for SEV-ES
 and SEV-SNP guests, i.e. ASIDs that can be used for CipherText Hiding cannot
 be used to run SEV-ES guests.
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Merge tag 'kvm-x86-ciphertext-6.18' of https://github.com/kvm-x86/linux into HEAD

KVM SEV-SNP CipherText Hiding support for 6.18

Add support for SEV-SNP's CipherText Hiding, an opt-in feature that prevents
unauthorized CPU accesses from reading the ciphertext of SNP guest private
memory, e.g. to attempt an offline attack.  Instead of ciphertext, the CPU
will always read back all FFs when CipherText Hiding is enabled.

Add new module parameter to the KVM module to enable CipherText Hiding and
control the number of ASIDs that can be used for VMs with CipherText Hiding,
which is in effect the number of SNP VMs.  When CipherText Hiding is enabled,
the shared SEV-ES/SEV-SNP ASID space is split into separate ranges for SEV-ES
and SEV-SNP guests, i.e. ASIDs that can be used for CipherText Hiding cannot
be used to run SEV-ES guests.
History 2025-09-30 13:34:32 -04:00
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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 reStructuredText 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.