Address a syzkaller splat by restricting the Xen hypercall MSR index to the de facto standard synthetic range, 0x40000000 - 0x4fffffff. This obviously has the potential to break userspace, but I'm fairly confident it'll be fine (knock wood), and doing nothing is not an option as letting userspace redirect any WRMSR is at best completely broken, and at worst could be used to exploit paths in KVM that directly write hardcoded MSRs. Patches 2-5 are tangentially related cleanups. Sean Christopherson (5): KVM: x86/xen: Restrict hypercall MSR to unofficial synthetic range KVM: x86/xen: Add an #ifdef'd helper to detect writes to Xen MSR KVM: x86/xen: Consult kvm_xen_enabled when checking for Xen MSR writes KVM: x86/xen: Bury xen_hvm_config behind CONFIG_KVM_XEN=y KVM: x86/xen: Move kvm_xen_hvm_config field into kvm_xen arch/x86/include/asm/kvm_host.h | 4 ++-- arch/x86/kvm/x86.c | 4 ++-- arch/x86/kvm/xen.c | 28 ++++++++++++++++++---------- arch/x86/kvm/xen.h | 17 +++++++++++++++-- 4 files changed, 37 insertions(+), 16 deletions(-) base-commit: eb723766b1030a23c38adf2348b7c3d1409d11f0 -- 2.48.1.362.g079036d154-goog
