On 08/24/2018 09:32 AM, Vlastimil Babka wrote: > On 08/23/2018 09:27 PM, Michal Hocko wrote: >> On Thu 23-08-18 16:28:12, Vlastimil Babka wrote: >>> Two users have reported [1] that they have an "extremely unlikely" system >>> with more than MAX_PA/2 memory and L1TF mitigation is not effective. Let's >>> make the warning more helpful by suggesting the proper mem=X kernel boot param, >>> a rough calculation of how much RAM can be lost (not precise if there's holes >>> between MAX_PA/2 and max_pfn in the e820 map) and a link to the L1TF document >>> to help decide if the mitigation is worth the unusable RAM. >>> >>> [1] https://bugzilla.suse.com/show_bug.cgi?id=1105536 >>> >>> Suggested-by: Michal Hocko <mhocko@xxxxxxxx> >>> Cc: stable@xxxxxxxxxxxxxxx >>> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> >> >> I wouldn't bother with max_pfn-half_pa part but other than that this is >> much more useful than the original message. > > Right, and it causes build failures on some configs. > >> Acked-by: Michal Hocko <mhocko@xxxxxxxx> > > Thanks! Here's a v2: Just realized that kvm printk's refer to the online version at https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html which should be easier for the users of distro kernels, should I change that?
