On Fri 24-08-18 14:10:54, Vlastimil Babka wrote: > On 08/24/2018 12:36 PM, Vlastimil Babka wrote: > > 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? > > FWIW, if it's not possible to amend anymore... > ----8<---- > >From a650e6a4b989c6e029ac1ab4e0a68553e074ba7a Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka <vbabka@xxxxxxx> > Date: Fri, 24 Aug 2018 14:05:45 +0200 > Subject: [PATCH] x86/speculation/l1tf: replace Documentation path with > kernel.org URL > > The URL might be easier to reach for users of distro kernels without unpacked > source, and be more up-to-date. It's also used in KVM warnings related to L1TF. Yes, URL is much more convenient than a reference to the kernel source documentation. If the link below is meant to be long lived then sure. > Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > arch/x86/kernel/cpu/bugs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c > index 5c32b5006738..4c2313d0b9ca 100644 > --- a/arch/x86/kernel/cpu/bugs.c > +++ b/arch/x86/kernel/cpu/bugs.c > @@ -705,7 +705,7 @@ static void __init l1tf_select_mitigation(void) > pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n", > half_pa); > pr_info("However, doing so will make a part of your RAM unusable.\n"); > - pr_info("Reading Documentation/admin-guide/l1tf.rst might help you decide.\n"); > + pr_info("Reading https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html might help you decide.\n"); > return; > } > > -- > 2.18.0 > > > -- Michal Hocko SUSE Labs
