On Tue, Oct 10, 2017 at 07:38:41PM +0100, Dave P Martin wrote: > KVM guests cannot currently use SVE, because SVE is always > configured to trap to EL2. > > However, a guest that sees SVE reported as present in > ID_AA64PFR0_EL1 may legitimately expect that SVE works and try to > use it. Instead of working, the guest will receive an injected > undef exception, which may cause the guest to oops or go into a > spin. > > To avoid misleading the guest into believing that SVE will work, > this patch masks out the SVE field from ID_AA64PFR0_EL1 when a > guest attempts to read this register. No support is explicitly > added for ID_AA64ZFR0_EL1 either, so that is still emulated as > reading as zero, which is consistent with SVE not being > implemented. > > This is a temporary measure, and will be removed in a later series > when full KVM support for SVE is implemented. > > Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> > Reviewed-by: Alex Bennée <alex.bennee@xxxxxxxxxx> > Cc: Marc Zyngier <marc.zyngier@xxxxxxx> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
