LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Ingo Molnar <mingo@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>,
	linux-tip-commits@vger.kernel.org, linux-kernel@vger.kernel.org,
	keescook@chromium.org, ast@plumgrid.com, fweisbec@gmail.com,
	oleg@redhat.com, tglx@linutronix.de,
	torvalds@linux-foundation.org, hpa@zytor.com, wad@chromium.org,
	rostedt@goodmis.org
Subject: Re: [tip:x86/asm] x86/asm/entry/64: Remove unused thread_struct::usersp
Date: Tue, 17 Mar 2015 08:51:39 +0100	[thread overview]
Message-ID: <20150317075139.GA27898@gmail.com> (raw)
In-Reply-To: <20150317072118.GA26864@gmail.com>


* Ingo Molnar <mingo@kernel.org> wrote:

> Assuming this does not fix the regression, could you apply the 
> minimal patch below - which reverts the old_rsp handling change.

Assuming this solves the regression (it really should, it's now 
equivalent to a full revert minus comments):

> @@ -395,6 +398,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
>  	/*
>  	 * Switch the PDA and FPU contexts.
>  	 */
> +	prev->usersp = this_cpu_read(old_rsp);
> +	this_cpu_write(old_rsp, next->usersp);
>  	this_cpu_write(current_task, next_p);
>  
>  	/*

can you confirm that your guest (sometimes) uses SYSENTER to do 
syscalls?

If yes then my theory is that we broke SYSENTER (or SYSEXIT) support - 
and that this would not be visible in our normal tests of KVM because 
SYSCALL is used most of the time.

Thanks,

	Ingo

  parent reply	other threads:[~2015-03-17  7:52 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-10 10:45 [PATCH 2/4] x86: entry_64.S: remove stub_iopl Denys Vlasenko
2015-03-10 10:45 ` [PATCH 4/4] x86: entry_64.S: remove unused thread_struct::usersp Denys Vlasenko
2015-03-11 12:55   ` Borislav Petkov
2015-03-11 15:19     ` Denys Vlasenko
2015-03-16 12:05   ` [tip:x86/asm] x86/asm/entry/64: Remove unused thread_struct:: usersp tip-bot for Denys Vlasenko
2015-03-16 16:47     ` Borislav Petkov
2015-03-16 22:20       ` [tip:x86/asm] x86/asm/entry/64: Remove unused thread_struct::usersp Denys Vlasenko
2015-03-17  7:08         ` Borislav Petkov
2015-03-17  7:13           ` Ingo Molnar
2015-03-17  7:21             ` Ingo Molnar
2015-03-17  7:39               ` Borislav Petkov
2015-03-17 12:22                 ` Denys Vlasenko
2015-03-17 12:51                   ` Denys Vlasenko
2015-03-17  7:51               ` Ingo Molnar [this message]
2015-03-17  8:06                 ` Borislav Petkov
2015-03-17  8:27                   ` Ingo Molnar
2015-03-17  9:01                     ` Borislav Petkov
2015-03-11 12:08 ` [PATCH 2/4] x86: entry_64.S: remove stub_iopl Borislav Petkov
2015-03-16 12:05 ` [tip:x86/asm] x86/asm/entry/64: Remove stub_iopl tip-bot for Denys Vlasenko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20150317075139.GA27898@gmail.com \
    --to=mingo@kernel.org \
    --cc=ast@plumgrid.com \
    --cc=bp@alien8.de \
    --cc=dvlasenk@redhat.com \
    --cc=fweisbec@gmail.com \
    --cc=hpa@zytor.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-tip-commits@vger.kernel.org \
    --cc=oleg@redhat.com \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --cc=wad@chromium.org \
    --subject='Re: [tip:x86/asm] x86/asm/entry/64: Remove unused thread_struct::usersp' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).