From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
Nadav Amit <namit@vmware.com>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Stephane Eranian <eranian@google.com>,
Feng Tang <feng.tang@intel.com>
Subject: Re: [patch V2 04/25] x86/apic: Make apic_pending_intr_clear() more robust
Date: Sun, 7 Jul 2019 10:27:29 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1907071025440.3648@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CALCETrXPX5CXOOVHhN2Npvxh=ZRSA4ttC+VaNekF1W13Z=FLkA@mail.gmail.com>
On Fri, 5 Jul 2019, Andy Lutomirski wrote:
> On Fri, Jul 5, 2019 at 1:36 PM Thomas Gleixner <tglx@linutronix.de> wrote:
> > No. We can map the APIC into the user space visible page tables for PTI
> > without compromising the PTI isolation and it can be read very early on
> > before SWAPGS. All you need is a register to clobber not more. It the ISR
> > is set, then go into an error path, yell loudly, issue EOI and return.
> > The only issue I can see is: It's slow :)
> >
> I think this will be really extremely slow. If we can restrict this
> to x2apic machines, then maybe it's not so awful.
x2apic machines have working iommu/interrupt remapping.
> FWIW, if we just patch up the GS thing, then we are still vulnerable:
> the bad guy can arrange for a privileged process to have register
> state corresponding to a dangerous syscall and then send an int $0x80
> via the APIC.
Right, that's why you want to read the APIC:ISR to check where that thing
came from.
Thanks,
tglx
next prev parent reply other threads:[~2019-07-07 8:27 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-04 15:51 [patch V2 00/25] x86/apic: Support for IPI shorthands Thomas Gleixner
2019-07-04 15:51 ` [patch V2 01/25] x86/kgbd: Use NMI_VECTOR not APIC_DM_NMI Thomas Gleixner
2019-07-05 21:43 ` Thomas Gleixner
2019-07-04 15:51 ` [patch V2 02/25] x86/apic: Invoke perf_events_lapic_init() after enabling APIC Thomas Gleixner
2019-07-04 15:51 ` [patch V2 03/25] x86/apic: Soft disable APIC before initializing it Thomas Gleixner
2019-07-04 15:51 ` [patch V2 04/25] x86/apic: Make apic_pending_intr_clear() more robust Thomas Gleixner
2019-07-05 15:47 ` Andrew Cooper
2019-07-05 19:06 ` Andy Lutomirski
2019-07-05 20:17 ` Andrew Cooper
2019-07-05 20:36 ` Thomas Gleixner
2019-07-05 20:39 ` Andy Lutomirski
2019-07-07 8:27 ` Thomas Gleixner [this message]
2019-07-05 19:19 ` Nadav Amit
2019-07-05 20:47 ` Andrew Cooper
2019-07-05 20:25 ` Thomas Gleixner
2019-07-05 20:37 ` Andy Lutomirski
2019-07-05 20:49 ` Paolo Bonzini
2019-07-05 21:16 ` Andrew Cooper
2019-07-07 8:37 ` Thomas Gleixner
2019-07-09 14:43 ` Thomas Gleixner
2019-07-04 15:51 ` [patch V2 05/25] x86/apic: Move IPI inlines into ipi.c Thomas Gleixner
2019-07-04 15:51 ` [patch V2 06/25] x86/apic: Cleanup the include maze Thomas Gleixner
2019-07-04 15:51 ` [patch V2 07/25] x86/apic: Move ipi header into apic directory Thomas Gleixner
2019-07-04 15:51 ` [patch V2 08/25] x86/apic: Move apic_flat_64 " Thomas Gleixner
2019-07-04 15:51 ` [patch V2 09/25] x86/apic: Consolidate the apic local headers Thomas Gleixner
2019-07-04 15:51 ` [patch V2 10/25] x86/apic/uv: Make x2apic_extra_bits static Thomas Gleixner
2019-07-04 15:51 ` [patch V2 11/25] smp/hotplug: Track booted once CPUs in a cpumask Thomas Gleixner
2019-07-04 15:51 ` [patch V2 12/25] x86/cpu: Move arch_smt_update() to a neutral place Thomas Gleixner
2019-07-04 15:51 ` [patch V2 13/25] x86/hotplug: Silence APIC and NMI when CPU is dead Thomas Gleixner
2019-07-04 15:51 ` [patch V2 14/25] x86/apic: Remove dest argument from __default_send_IPI_shortcut() Thomas Gleixner
2019-07-04 15:52 ` [patch V2 15/25] x86/apic: Add NMI_VECTOR wait to IPI shorthand Thomas Gleixner
2019-07-04 15:52 ` [patch V2 16/25] x86/apic: Move no_ipi_broadcast() out of 32bit Thomas Gleixner
2019-07-04 15:52 ` [patch V2 17/25] x86/apic: Add static key to Control IPI shorthands Thomas Gleixner
2019-07-04 15:52 ` [patch V2 18/25] x86/apic: Provide and use helper for send_IPI_allbutself() Thomas Gleixner
2019-07-04 15:52 ` [patch V2 19/25] cpumask: Implement cpumask_or_equal() Thomas Gleixner
2019-07-04 15:52 ` [patch V2 20/25] x86/smp: Move smp_function_call implementations into IPI code Thomas Gleixner
2019-07-04 15:52 ` [patch V2 21/25] x86/smp: Enhance native_send_call_func_ipi() Thomas Gleixner
2019-07-05 1:26 ` Nadav Amit
2019-07-04 15:52 ` [patch V2 22/25] x86/apic: Remove the shorthand decision logic Thomas Gleixner
2019-07-04 15:52 ` [patch V2 23/25] x86/apic: Share common IPI helpers Thomas Gleixner
2019-07-04 15:52 ` [patch V2 24/25] x86/apic/flat64: Remove the IPI shorthand decision logic Thomas Gleixner
2019-07-04 15:52 ` [patch V2 25/25] x86/apic/x2apic: Implement IPI shorthands support Thomas Gleixner
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