Paolo Bonzini a104e0a305 Merge tag 'kvm-x86-svm-6.18' of https://github.com/kvm-x86/linux into HEAD
KVM SVM changes for 6.18

 - Require a minimum GHCB version of 2 when starting SEV-SNP guests via
   KVM_SEV_INIT2 so that invalid GHCB versions result in immediate errors
   instead of latent guest failures.

 - Add support for Secure TSC for SEV-SNP guests, which prevents the untrusted
   host from tampering with the guest's TSC frequency, while still allowing the
   the VMM to configure the guest's TSC frequency prior to launch.

 - Mitigate the potential for TOCTOU bugs when accessing GHCB fields by
   wrapping all accesses via READ_ONCE().

 - Validate the XCR0 provided by the guest (via the GHCB) to avoid tracking a
   bogous XCR0 value in KVM's software model.

 - Save an SEV guest's policy if and only if LAUNCH_START fully succeeds to
   avoid leaving behind stale state (thankfully not consumed in KVM).

 - Explicitly reject non-positive effective lengths during SNP's LAUNCH_UPDATE
   instead of subtly relying on guest_memfd to do the "heavy" lifting.

 - Reload the pre-VMRUN TSC_AUX on #VMEXIT for SEV-ES guests, not the host's
   desired TSC_AUX, to fix a bug where KVM could clobber a different vCPU's
   TSC_AUX due to hardware not matching the value cached in the user-return MSR
   infrastructure.

 - Enable AVIC by default for Zen4+ if x2AVIC (and other prereqs) is supported,
   and clean up the AVIC initialization code along the way.
2025-09-30 13:34:12 -04:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2025-09-21 15:08:52 -07:00
2024-03-18 03:36:32 -06:00

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.
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