From: Jarkko Sakkinen <jarkko@kernel.org>
To: Sean Christopherson <seanjc@google.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
linux-sgx@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH] x86/sgx: Synchronize encl->srcu in sgx_encl_release().
Date: Tue, 15 Dec 2020 07:55:56 +0200 [thread overview]
Message-ID: <20201215055556.GA28278@kernel.org> (raw)
In-Reply-To: <X9e2jOWz1hfXVpQ5@google.com>
On Mon, Dec 14, 2020 at 11:01:32AM -0800, Sean Christopherson wrote:
> On Fri, Dec 11, 2020, Jarkko Sakkinen wrote:
> > Each sgx_mmun_notifier_release() starts a grace period, which means that
>
> Should be sgx_mmu_notifier_release(), here and in the comment.
Thanks.
> > one extra synchronize_rcu() in sgx_encl_release(). Add it there.
> >
> > sgx_release() has the loop that drains the list but with bad luck the
> > entry is already gone from the list before that loop processes it.
>
> Why not include the actual analysis that "proves" the bug? The splat that
> Haitao reported would also be useful info.
True. I can include a snippet of dmesg to the commit message.
> > Fixes: 1728ab54b4be ("x86/sgx: Add a page reclaimer")
> > Cc: Borislav Petkov <bp@alien8.de>
> > Cc: Dave Hansen <dave.hansen@linux.intel.com>
> > Reported-by: Sean Christopherson <seanjc@google.com>
>
> Haitao reported the bug, and for all intents and purposes provided the fix. I
> just did the analysis to verify that there was a legitimate bug and that the
> synchronization in sgx_encl_release() was indeed necessary.
Good and valid point. The way I see it, the tags should be:
Reported-by: Haitao Huang <haitao.huang@linux.intel.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Haitao pointed out the bug but from your analysis I could resolve that
this is the fix to implement, and was able to write the long
description for the commit.
Does this make sense to you?
/Jarkko
next prev parent reply other threads:[~2020-12-15 5:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-11 11:32 [PATCH] x86/sgx: Synchronize encl->srcu in sgx_encl_release() Jarkko Sakkinen
2020-12-14 19:01 ` Sean Christopherson
2020-12-15 5:55 ` Jarkko Sakkinen [this message]
2020-12-15 5:59 ` Jarkko Sakkinen
2020-12-15 17:34 ` Haitao Huang
2020-12-15 21:35 ` Jarkko Sakkinen
2020-12-15 22:04 ` Sean Christopherson
2020-12-16 12:25 ` Jarkko Sakkinen
-- strict thread matches above, loose matches on Subject: below --
2020-12-15 21:40 Jarkko Sakkinen
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