All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jarkko Sakkinen <jarkko@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>,
	Sean Christopherson <seanjc@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Dan Williams <dan.j.williams@intel.com>,
	Borislav Petkov <bp@alien8.de>,
	LKML <linux-kernel@vger.kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [patch 01/10] x86/fpu/signal: Clarify exception handling in restore_fpregs_from_user()
Date: Fri, 03 Sep 2021 09:00:16 +0300	[thread overview]
Message-ID: <23bd92e159dba35f74fc3d3a8186dfbb3ff84f66.camel@kernel.org> (raw)
In-Reply-To: <871r67cbp6.ffs@tglx>

On Thu, 2021-09-02 at 16:08 +0200, Thomas Gleixner wrote:
> On Thu, Sep 02 2021 at 16:08, Jarkko Sakkinen wrote:
> > On Wed, 2021-09-01 at 16:47 +0000, Sean Christopherson wrote:
> > > As for SGX consuming the trap number in general, it's correct.  For non-KVM usage,
> > > it's nice to have but not strictly necessary.  Any fault except #PF on ENCLS is
> > > guaranteed to be a kernel or hardware bug; SGX uses the trap number to WARN on a
> > > !#PF exception, e.g. on #GP or #UD.  Not having the trap number would mean losing
> > > those sanity checks, which have been useful in the past.
> > 
> > AFAIK, we do not consider #UD as a bug. Agree with the conclusion that SGX
> > should never #MC, I just did not get this part. #UD is something that is
> > useful for SGX run-time.
> 
> I understood that storing the trap number is useful. I was just
> questioning the #MC angle. I.e. pretending that the #MC caused by ENCLS
> is recoverable.

Absolutely not. 

I mixed up #UD caused by CPU executing inside enclave and ENCLS causing
#UD. Sorry about that.

Because of KVM we have to catch #PF's, given that a new power cycle
in the host resets the state of SGX protected memory in the guest.

> 
> Thanks,
> 
>         tglx

/Jarkko


  reply	other threads:[~2021-09-03  6:00 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30 16:27 [patch 00/10] x86/fpu: Clean up error handling in sigframe related code Thomas Gleixner
2021-08-30 16:27 ` [patch 01/10] x86/fpu/signal: Clarify exception handling in restore_fpregs_from_user() Thomas Gleixner
2021-08-30 19:33   ` Borislav Petkov
2021-08-30 20:07     ` Borislav Petkov
2021-08-30 20:09     ` Thomas Gleixner
2021-08-30 21:02       ` Al Viro
2021-08-30 21:26         ` Linus Torvalds
2021-08-30 21:30           ` Al Viro
2021-08-30 22:00             ` Linus Torvalds
2021-08-30 22:12               ` Thomas Gleixner
2021-08-30 22:26                 ` Linus Torvalds
2021-08-31  0:06               ` Al Viro
2021-08-31  0:34               ` Thomas Gleixner
2021-08-31  7:39                 ` Borislav Petkov
2021-08-31 18:39                   ` Luck, Tony
2021-09-01  7:27                     ` Borislav Petkov
2021-08-30 22:01           ` Thomas Gleixner
2021-08-30 22:11             ` Linus Torvalds
2021-09-01 12:00           ` Thomas Gleixner
2021-09-01 15:52             ` Thomas Gleixner
2021-09-01 16:47               ` Sean Christopherson
2021-09-01 19:22                 ` Thomas Gleixner
2021-09-01 19:22                 ` Dave Hansen
2021-09-02 13:08                 ` Jarkko Sakkinen
2021-09-02 14:08                   ` Thomas Gleixner
2021-09-03  6:00                     ` Jarkko Sakkinen [this message]
2021-09-03  6:05                       ` Jarkko Sakkinen
2021-08-30 16:27 ` [patch 02/10] x86/fpu/signal: Move header zeroing out of xsave_to_user_sigframe() Thomas Gleixner
2021-08-30 16:27 ` [patch 03/10] x86/fpu/signal: Move xstate clearing out of copy_fpregs_to_sigframe() Thomas Gleixner
2021-08-30 16:27 ` [patch 04/10] x86/fpu/signal: Change return type of copy_fpstate_to_sigframe() to boolean Thomas Gleixner
2021-08-30 16:27 ` [patch 05/10] x86/fpu/signal: Change return type of copy_fpregs_to_sigframe() helpers " Thomas Gleixner
2021-08-30 16:27 ` [patch 06/10] x86/signal: Change return type of restore_sigcontext() " Thomas Gleixner
2021-08-30 16:27 ` [patch 07/10] x86/fpu/signal: Change return type of fpu__restore_sig() " Thomas Gleixner
2021-08-30 16:27 ` [patch 08/10] x86/fpu/signal: Change return type of __fpu_restore_sig() " Thomas Gleixner
2021-08-30 16:27 ` [patch 09/10] x86/fpu/signal: Change return code of check_xstate_in_sigframe() " Thomas Gleixner
2021-08-30 16:27 ` [patch 10/10] x86/fpu/signal: Change return code of restore_fpregs_from_user() " Thomas Gleixner
2021-08-30 17:39 ` [patch 00/10] x86/fpu: Clean up error handling in sigframe related code Linus Torvalds
2021-08-30 18:51   ` Thomas Gleixner

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=23bd92e159dba35f74fc3d3a8186dfbb3ff84f66.camel@kernel.org \
    --to=jarkko@kernel.org \
    --cc=bp@alien8.de \
    --cc=dan.j.williams@intel.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=seanjc@google.com \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=x86@kernel.org \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.