linux-kernel - Re: [GIT PULL] x86/mm changes for v4.14: PCID support, 5-level paging support, Secure Memory Encryption support

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Date:   Wed, 6 Sep 2017 23:16:02 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     Ingo Molnar <mingo@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [GIT PULL] x86/mm changes for v4.14: PCID support, 5-level paging
 support, Secure Memory Encryption support

On Wed, 6 Sep 2017, Jiri Kosina wrote:

> This is a "me too", observed on my Lenovo thinkpad x270 (so it's not 
> specific to that XPS 13 system at all).
> 
> The symptom I observe is that an attempt to resume from hibernation 
> proceeds up to reading 100% of the hibernation image, and then reboot 
> happens (IOW looks like triple fault).
> 
> nopcid cures it, I haven't tried to revert 10af6235e0d3 yet, but looks 
> like it's the same thing.

[ reposting the information again with LKML re-introduced to CC ]

As suggested by Andy off-list, I tested with this change to always force 
ASID 0

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 5ca71d1..c3b0811 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -35,7 +35,7 @@ static void choose_new_asid(struct mm_struct *next, u64 next_tlb_gen,
 {
 	u16 asid;
 
-	if (!static_cpu_has(X86_FEATURE_PCID)) {
+	if (true || !static_cpu_has(X86_FEATURE_PCID)) {
 		*new_asid = 0;
 		*need_flush = true;
 		return;

and that fixes the issue on my system.

-- 
Jiri Kosina
SUSE Labs