From: Juergen Gross <jgross@suse.com>
To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
x86@kernel.org
Cc: boris.ostrovsky@oracle.com, hpa@zytor.com, tglx@linutronix.de,
mingo@redhat.com, Juergen Gross <jgross@suse.com>
Subject: [PATCH 0/2] x86/xen: avoid 32-bit writes to PTEs in PV PAE guests
Date: Mon, 20 Aug 2018 07:14:54 +0200 [thread overview]
Message-ID: <20180820051456.20779-1-jgross@suse.com> (raw)
While the hypervisor emulates plain writes to PTEs happily, this is
much slower than issuing a hypercall for PTE modifcations. And writing
a PTE via two 32-bit write instructions (especially when clearing the
PTE) will result in an intermediate L1TF vulnerable PTE.
Writes to PAE PTEs should always be done with 64-bit writes or via
hypercalls.
Juergen Gross (2):
x86/xen: don't write ptes directly in 32-bit PV guests
x86/pae: use 64 bit atomic xchg function in native_ptep_get_and_clear
arch/x86/include/asm/pgtable-3level.h | 14 ++++++++------
arch/x86/xen/mmu_pv.c | 7 +++----
2 files changed, 11 insertions(+), 10 deletions(-)
--
2.13.7
next reply other threads:[~2018-08-20 5:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-20 5:14 Juergen Gross [this message]
2018-08-20 5:14 ` [PATCH 1/2] x86/xen: don't write ptes directly in 32-bit PV guests Juergen Gross
2018-08-20 8:38 ` [Xen-devel] " Jan Beulich
2018-08-20 5:14 ` [PATCH 2/2] x86/pae: use 64 bit atomic xchg function in native_ptep_get_and_clear Juergen Gross
2018-08-20 8:40 ` [Xen-devel] " Jan Beulich
2018-08-20 8:56 ` Juergen Gross
2018-08-20 13:26 ` Thomas Gleixner
2018-08-20 14:55 ` Juergen Gross
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=20180820051456.20779-1-jgross@suse.com \
--to=jgross@suse.com \
--cc=boris.ostrovsky@oracle.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=xen-devel@lists.xenproject.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 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).