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> Bug: 274862109 Change-Id: I90ce94d984f90df38f935ce7aca18736d127b2ae Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>