From: "Jan Beulich" <JBeulich@suse.com>
To: "Andrew Cooper" <andrew.cooper3@citrix.com>
Cc: "David Vrabel" <david.vrabel@citrix.com>, <x86@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>, <lguest@lists.ozlabs.org>,
"Xen-devel" <xen-devel@lists.xen.org>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Rusty Russell" <rusty@rustcorp.com.au>,
<linux-kernel@vger.kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [Xen-devel] [PATCH] [RFC] x86/cpu: Fix SMAP check in PVOPS environments
Date: Tue, 21 Apr 2015 09:36:20 +0100 [thread overview]
Message-ID: <553628240200007800074272@mail.emea.novell.com> (raw)
In-Reply-To: <1429549782-12962-1-git-send-email-andrew.cooper3@citrix.com>
>>> On 20.04.15 at 19:09, <andrew.cooper3@citrix.com> wrote:
> A different approach, given the dual nature of the AC flag now is to gate
> setup_smap() on a kernel rpl of 0. SMAP necessarily can't be used in a
> paravirtual situation where the kernel runs in cpl > 0.
"Can't" isn't true here - for 64-bit PV Xen guests, which already
toggle between two page table variants for kernel and user mode,
it would be possible (but perhaps expensive) to mimic the needed
behavior by introducing a 3rd set of page tables, containing only
the kernel mappings. You may recall that I had even posted an
RFC patch to tat effect about a year ago.
Jan
prev parent reply other threads:[~2015-04-21 8:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-20 17:09 Andrew Cooper
2015-04-20 17:11 ` David Vrabel
2015-04-21 0:35 ` Andy Lutomirski
2015-04-21 5:07 ` Rusty Russell
2015-04-21 8:26 ` Andrew Cooper
2015-04-21 12:45 ` [RFC PATCH] x86/asm/irq: Don't use POPF but STI Ingo Molnar
2015-04-21 13:09 ` Borislav Petkov
2015-04-21 15:22 ` Ingo Molnar
2015-04-21 16:12 ` Linus Torvalds
2015-04-21 22:39 ` Andy Lutomirski
2015-04-21 8:36 ` Jan Beulich [this message]
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