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commit 98c25ead5eda5e9d41abe57839ad3e8caf19500c upstream. Handle the switch to/from the hypervisor/software timer when a vCPU is blocking in common x86 instead of in VMX. Even though VMX is the only user of a hypervisor timer, the logic and all functions involved are generic x86 (unless future CPUs do something completely different and implement a hypervisor timer that runs regardless of mode). Handling the switch in common x86 will allow for the elimination of the pre/post_blocks hooks, and also lets KVM switch back to the hypervisor timer if and only if it was in use (without additional params). Add a comment explaining why the switch cannot be deferred to kvm_sched_out() or kvm_vcpu_block(). Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20211208015236.1616697-8-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [ta: Fix conflicts in vmx_pre_block and vmx_post_block as per Paolo's suggestion. Add Reported-by and Link tags.] Reported-by: syzbot+b6a74be92b5063a0f1ff@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=489beb3d76ef14cc6cd18125782dc6f86051a605 Tested-by: Tudor Ambarus <tudor.ambarus@linaro.org> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.