• Mark Rutland's avatar
    arm: KVM: Survive unknown traps from guests · f050fe7a
    Mark Rutland authored
    Currently we BUG() if we see a HSR.EC value we don't recognise. As
    configurable disables/enables are added to the architecture (controlled
    by RES1/RES0 bits respectively), with associated synchronous exceptions,
    it may be possible for a guest to trigger exceptions with classes that
    we don't recognise.
    
    While we can't service these exceptions in a manner useful to the guest,
    we can avoid bringing down the host. Per ARM DDI 0406C.c, all currently
    unallocated HSR EC encodings are reserved, and per ARM DDI
    0487A.k_iss10775, page G6-4395, EC values within the range 0x00 - 0x2c
    are reserved for future use with synchronous exceptions, and EC values
    within the range 0x2d - 0x3f may be used for either synchronous or
    asynchronous exceptions.
    
    The patch makes KVM handle any unknown EC by injecting an UNDEFINED
    exception into the guest, with a corresponding (ratelimited) warning in
    the host dmesg. We could later improve on this with with a new (opt-in)
    exit to the host userspace.
    
    Cc: Dave Martin <dave.martin@arm.com>
    Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
    Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
    Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
    Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
    f050fe7a
handle_exit.c 4.43 KB