• Marc Zyngier's avatar
    KVM: arm64: Handle PtrAuth traps early · 29eb5a3c
    Marc Zyngier authored
    The current way we deal with PtrAuth is a bit heavy handed:
    
    - We forcefully save the host's keys on each vcpu_load()
    - Handling the PtrAuth trap forces us to go all the way back
      to the exit handling code to just set the HCR bits
    
    Overall, this is pretty cumbersome. A better approach would be
    to handle it the same way we deal with the FPSIMD registers:
    
    - On vcpu_load() disable PtrAuth for the guest
    - On first use, save the host's keys, enable PtrAuth in the
      guest
    
    Crucially, this can happen as a fixup, which is done very early
    on exit. We can then reenter the guest immediately without
    leaving the hypervisor role.
    
    Another thing is that it simplify the rest of the host handling:
    exiting all the way to the host means that the only possible
    outcome for this trap is to inject an UNDEF.
    Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
    Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
    29eb5a3c
sys_regs.c 79.2 KB