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This patch adds a new pseudo-register KVM_REG_ARM64_SVE_VLS to allow userspace to set and query the set of vector lengths visible to the guest. In the future, multiple register slices per SVE register may be visible through the ioctl interface. Once the set of slices has been determined we would not be able to allow the vector length set to be changed any more, in order to avoid userspace seeing inconsistent sets of registers. For this reason, this patch adds support for explicit finalization of the SVE configuration via the KVM_ARM_VCPU_FINALIZE ioctl. Finalization is the proper place to allocate the SVE register state storage in vcpu->arch.sve_state, so this patch adds that as appropriate. The data is freed via kvm_arch_vcpu_uninit(), which was previously a no-op on arm64. To simplify the logic for determining what vector lengths can be supported, some code is added to KVM init to work this out, in the kvm_arm_init_arch_resources() hook. The KVM_REG_ARM64_SVE_VLS pseudo-register is not exposed yet. Subsequent patches will allow SVE to be turned on for guest vcpus, making it visible. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Julien Thierry <julien.thierry@arm.com> Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.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.