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. Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> --- 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
