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From: Ira Weiny <ira.weiny@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	nvdimm@lists.linux.dev, linux-mm@kvack.org
Subject: Re: [PATCH V7 08/18] x86/entry: Preserve PKRS MSR across exceptions
Date: Mon, 6 Dec 2021 20:45:22 -0800	[thread overview]
Message-ID: <20211207044522.GE3538886@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20211207015423.GA4012679@iweiny-DESK2.sc.intel.com>

On Mon, Dec 06, 2021 at 05:54:23PM -0800, 'Ira Weiny' wrote:

[snip]

> > 
> > Though, if you look at the xen_pv_evtchn_do_upcall() part where you
> > added this extra invocation you might figure out that adding
> > pkrs_restore_irq() to irqentry_exit_cond_resched() and explicitely to
> > the 'else' path in irqentry_exit() makes it magically consistent for
> > both use cases.
> > 
> 
> Thank you, yes good catch.  However, I think I need at least 1 more call in the
> !regs_irqs_disabled() && state.exit_rcu case right?
> 
> 11:29:48 > git di
> diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
> index 717091910ebc..667676ebc129 100644
> --- a/arch/x86/entry/common.c
> +++ b/arch/x86/entry/common.c
> @@ -363,8 +363,6 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs)
>  
>         inhcall = get_and_clear_inhcall();
>         if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) {
> -               /* Normally called by irqentry_exit, restore pkrs here */
> -               pkrs_restore_irq(regs);
>                 irqentry_exit_cond_resched();
>                 instrumentation_end();
>                 restore_inhcall(inhcall);
> diff --git a/kernel/entry/common.c b/kernel/entry/common.c
> index 1c0a70a17e93..60ae3d4c9cc0 100644
> --- a/kernel/entry/common.c
> +++ b/kernel/entry/common.c
> @@ -385,6 +385,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs)
>  
>  void irqentry_exit_cond_resched(void)

Opps...  Of course regs will need to be passed in here now...

Ira

>  {
> +       pkrs_restore_irq(regs);
>         if (!preempt_count()) {
>                 /* Sanity check RCU and thread stack */
>                 rcu_irq_exit_check_preempt();
> @@ -408,8 +409,6 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
>                 return;
>         }
>  
> -       pkrs_restore_irq(regs);
> -
>         if (!regs_irqs_disabled(regs)) {
>                 /*
>                  * If RCU was not watching on entry this needs to be done
> @@ -421,6 +420,7 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
>                         /* Tell the tracer that IRET will enable interrupts */
>                         trace_hardirqs_on_prepare();
>                         lockdep_hardirqs_on_prepare(CALLER_ADDR0);
> +                       pkrs_restore_irq(regs);
>                         instrumentation_end();
>                         rcu_irq_exit();
>                         lockdep_hardirqs_on(CALLER_ADDR0);
> @@ -439,6 +439,10 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
>                 trace_hardirqs_on();
>                 instrumentation_end();
>         } else {
> +               instrumentation_begin();
> +               pkrs_restore_irq(regs);
> +               instrumentation_end();
> +
>                 /*
>                  * IRQ flags state is correct already. Just tell RCU if it
>                  * was not watching on entry.
> @@ -470,8 +474,8 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
>  
>  void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
>  {
> -       pkrs_restore_irq(regs);
>         instrumentation_begin();
> +       pkrs_restore_irq(regs);
>         ftrace_nmi_exit();
>         if (irq_state.lockdep) {
>                 trace_hardirqs_on_prepare();
> 
> 
> Thank you again for the review,
> Ira
> 
> 
> [0] https://lore.kernel.org/lkml/20210804043231.2655537-5-ira.weiny@intel.com/
> [1] https://lore.kernel.org/lkml/20201217131924.GW3040@hirez.programming.kicks-ass.net/
> [2] https://lore.kernel.org/lkml/20201216013202.GY1563847@iweiny-DESK2.sc.intel.com/
> [3] https://lore.kernel.org/lkml/87y2hwqwng.fsf@nanos.tec.linutronix.de/
> 
> > Thanks,
> > 
> >         tglx

  reply	other threads:[~2021-12-07  4:45 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-04  4:32 [PATCH V7 00/18] PKS/PMEM: Add Stray Write Protection ira.weiny
2021-08-04  4:32 ` [PATCH V7 01/18] x86/pkeys: Create pkeys_common.h ira.weiny
2021-08-04  4:32 ` [PATCH V7 02/18] x86/fpu: Refactor arch_set_user_pkey_access() ira.weiny
2021-11-25 14:23   ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 03/18] x86/pks: Add additional PKEY helper macros ira.weiny
2021-11-25 14:25   ` Thomas Gleixner
2021-11-25 16:58     ` Thomas Gleixner
2021-12-08  0:51     ` Ira Weiny
2021-12-08 15:11       ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 04/18] x86/pks: Add PKS defines and Kconfig options ira.weiny
2021-08-04  4:32 ` [PATCH V7 05/18] x86/pks: Add PKS setup code ira.weiny
2021-11-25 15:15   ` Thomas Gleixner
2021-11-26  3:11     ` taoyi.ty
2021-11-26  9:57       ` Thomas Gleixner
2021-11-26 11:03     ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 06/18] x86/fault: Adjust WARN_ON for PKey fault ira.weiny
2021-08-04  4:32 ` [PATCH V7 07/18] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2021-11-25 15:25   ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 08/18] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2021-11-13  0:50   ` Ira Weiny
2021-11-25 11:19     ` Thomas Gleixner
2021-12-03  1:13     ` Andy Lutomirski
2021-11-25 14:12   ` Thomas Gleixner
2021-12-07  1:54     ` Ira Weiny
2021-12-07  4:45       ` Ira Weiny [this message]
2021-12-08  0:21       ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 09/18] x86/pks: Add PKS kernel API ira.weiny
2021-08-04  4:32 ` [PATCH V7 10/18] x86/pks: Introduce pks_abandon_protections() ira.weiny
2021-08-04  4:32 ` [PATCH V7 11/18] x86/pks: Add PKS Test code ira.weiny
2021-08-04  4:32 ` [PATCH V7 12/18] x86/pks: Add PKS fault callbacks ira.weiny
2021-08-11 21:18   ` Edgecombe, Rick P
2021-08-17  3:21     ` Ira Weiny
2021-08-04  4:32 ` [PATCH V7 13/18] memremap_pages: Add access protection via supervisor Protection Keys (PKS) ira.weiny
2021-08-04  4:32 ` [PATCH V7 14/18] memremap_pages: Add memremap.pks_fault_mode ira.weiny
2021-08-04  4:57   ` Randy Dunlap
2021-08-07 19:32     ` Ira Weiny
2021-08-11 19:01   ` Edgecombe, Rick P
2021-08-17  3:12     ` Ira Weiny
2021-08-04  4:32 ` [PATCH V7 15/18] kmap: Add stray access protection for devmap pages ira.weiny
2021-08-04  4:32 ` [PATCH V7 16/18] dax: Stray access protection for dax_direct_access() ira.weiny
2021-08-04  4:32 ` [PATCH V7 17/18] nvdimm/pmem: Enable stray access protection ira.weiny
2021-08-04  4:32 ` [PATCH V7 18/18] devdax: " ira.weiny

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