On Wed, Jul 25, 2018 at 03:57:33PM +0200, Andrew Jones wrote: > On Wed, Jul 25, 2018 at 12:50:45PM +0100, Dave Martin wrote: > > > > + if (system_supports_sve() && guest_has_sve) > > > > As elsewhere, the system_supports_sve() check uses a static key and > > should be very cheap (or free in a CONFIG_ARM64_SVE=n kernel). > > > > Yup, I'm clear on that now. Thanks again for explaining. It might > be nice for a small helper function in this case in order to avoid > the 'system_supports_sve() &&' everywhere and the chance that the > order of the checks gets swapped during some code refactoring someday. This is what guest_has_sve() is for. In hyp_switch_fpsimd() I wanted to avoid runtime checks wherever possible, but it may be overkill to keep checking system_supports_sve() like this. It might take some benchmarking to figure out whether the extra checks have any merit here... Cheers ---Dave _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
