Hi Ryan, On Tue, Dec 06, 2022 at 01:59:28PM +0000, Ryan Roberts wrote: > In order to support 5 level translation, FEAT_LPA2 introduces the 1-bit > SL2 field within VTCR_EL2 to extend the existing 2-bit SL0 field. The > SL2[0]:SL0[1:0] encodings have no simple algorithmic relationship to the > start levels they represent (that I can find, at least), so replace the > existing macros with functions that do lookups to encode and decode the > values. These new functions no longer make hardcoded assumptions about > the maximum level and instead rely on KVM_PGTABLE_FIRST_LEVEL and > KVM_PGTABLE_LAST_LEVEL. > > This is preparatory work for enabling 52-bit IPA for 4KB and 16KB pages > with FEAT_LPA2. > > No functional change intended. > > Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> Why do we need to support 5-level paging at stage-2? A configuration of start_level = 0, T0SZ = 12 with 4K paging would result in 16 concatenated tables at level 0, avoiding the level -1 lookup altogether. -- Thanks, Oliver _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
