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From: Ira Weiny <ira.weiny@intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, Andrew Morton <akpm@linux-foundation.org>,
	Fenghua Yu <fenghua.yu@intel.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH RFC V3 7/9] x86/entry: Preserve PKRS MSR across exceptions
Date: Wed, 14 Oct 2020 20:46:45 -0700	[thread overview]
Message-ID: <20201015034645.GQ2046448@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <6006a4c8-32bd-04ca-95cc-b2736a5cef72@intel.com>

On Tue, Oct 13, 2020 at 11:52:32AM -0700, Dave Hansen wrote:
> On 10/9/20 12:42 PM, ira.weiny@intel.com wrote:
> > @@ -341,6 +341,9 @@ noinstr void irqentry_enter(struct pt_regs *regs, irqentry_state_t *state)
> >  	/* Use the combo lockdep/tracing function */
> >  	trace_hardirqs_off();
> >  	instrumentation_end();
> > +
> > +done:
> > +	irq_save_pkrs(state);
> >  }
> 
> One nit: This saves *and* sets PKRS.  It's not obvious from the call
> here that PKRS is altered at this site.  Seems like there could be a
> better name.
> 
> Even if we did:
> 
> 	irq_save_set_pkrs(state, INIT_VAL);
> 
> It would probably compile down to the same thing, but be *really*
> obvious what's going on.

I suppose that is true.  But I think it is odd having a parameter which is the
same for every call site.

But I'm not going to quibble over something like this.

Changed,
Ira

> 
> >  void irqentry_exit_cond_resched(void)
> > @@ -362,7 +365,12 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t *state)
> >  	/* Check whether this returns to user mode */
> >  	if (user_mode(regs)) {
> >  		irqentry_exit_to_user_mode(regs);
> > -	} else if (!regs_irqs_disabled(regs)) {
> > +		return;
> > +	}
> > +
> > +	irq_restore_pkrs(state);
> > +
> > +	if (!regs_irqs_disabled(regs)) {
> >  		/*
> >  		 * If RCU was not watching on entry this needs to be done
> >  		 * carefully and needs the same ordering of lockdep/tracing
> > 
> 
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WARNING: multiple messages have this Message-ID (diff)
From: Ira Weiny <ira.weiny@intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, Dan Williams <dan.j.williams@intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Fenghua Yu <fenghua.yu@intel.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH RFC V3 7/9] x86/entry: Preserve PKRS MSR across exceptions
Date: Wed, 14 Oct 2020 20:46:45 -0700	[thread overview]
Message-ID: <20201015034645.GQ2046448@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <6006a4c8-32bd-04ca-95cc-b2736a5cef72@intel.com>

On Tue, Oct 13, 2020 at 11:52:32AM -0700, Dave Hansen wrote:
> On 10/9/20 12:42 PM, ira.weiny@intel.com wrote:
> > @@ -341,6 +341,9 @@ noinstr void irqentry_enter(struct pt_regs *regs, irqentry_state_t *state)
> >  	/* Use the combo lockdep/tracing function */
> >  	trace_hardirqs_off();
> >  	instrumentation_end();
> > +
> > +done:
> > +	irq_save_pkrs(state);
> >  }
> 
> One nit: This saves *and* sets PKRS.  It's not obvious from the call
> here that PKRS is altered at this site.  Seems like there could be a
> better name.
> 
> Even if we did:
> 
> 	irq_save_set_pkrs(state, INIT_VAL);
> 
> It would probably compile down to the same thing, but be *really*
> obvious what's going on.

I suppose that is true.  But I think it is odd having a parameter which is the
same for every call site.

But I'm not going to quibble over something like this.

Changed,
Ira

> 
> >  void irqentry_exit_cond_resched(void)
> > @@ -362,7 +365,12 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t *state)
> >  	/* Check whether this returns to user mode */
> >  	if (user_mode(regs)) {
> >  		irqentry_exit_to_user_mode(regs);
> > -	} else if (!regs_irqs_disabled(regs)) {
> > +		return;
> > +	}
> > +
> > +	irq_restore_pkrs(state);
> > +
> > +	if (!regs_irqs_disabled(regs)) {
> >  		/*
> >  		 * If RCU was not watching on entry this needs to be done
> >  		 * carefully and needs the same ordering of lockdep/tracing
> > 
> 

  reply	other threads:[~2020-10-15  3:46 UTC|newest]

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09 19:42 [PATCH RFC V3 0/9] PKS: Add Protection Keys Supervisor (PKS) support RFC v3 ira.weiny
2020-10-09 19:42 ` ira.weiny
2020-10-09 19:42 ` [PATCH RFC V3 1/9] x86/pkeys: Create pkeys_common.h ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-13 17:46   ` Dave Hansen
2020-10-13 17:46     ` Dave Hansen
2020-10-13 19:44     ` Ira Weiny
2020-10-13 19:44       ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 2/9] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-13 17:50   ` Dave Hansen
2020-10-13 17:50     ` Dave Hansen
2020-10-13 23:56     ` Ira Weiny
2020-10-13 23:56       ` Ira Weiny
2020-10-16 10:57   ` Peter Zijlstra
2020-10-16 10:57     ` Peter Zijlstra
2020-10-17  3:32     ` Ira Weiny
2020-10-17  3:32       ` Ira Weiny
2020-10-19  9:35       ` Peter Zijlstra
2020-10-19  9:35         ` Peter Zijlstra
2020-10-09 19:42 ` [PATCH RFC V3 3/9] x86/pks: Enable Protection Keys Supervisor (PKS) ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-13 18:23   ` Dave Hansen
2020-10-13 18:23     ` Dave Hansen
2020-10-14  2:08     ` Ira Weiny
2020-10-14  2:08       ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 4/9] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-13 18:31   ` Dave Hansen
2020-10-13 18:31     ` Dave Hansen
2020-10-14 22:36     ` Ira Weiny
2020-10-14 22:36       ` Ira Weiny
2020-10-16 11:12     ` Peter Zijlstra
2020-10-16 11:12       ` Peter Zijlstra
2020-10-17  5:14       ` Ira Weiny
2020-10-17  5:14         ` Ira Weiny
2020-10-19  9:37         ` Peter Zijlstra
2020-10-19  9:37           ` Peter Zijlstra
2020-10-19 18:48           ` Ira Weiny
2020-10-19 18:48             ` Ira Weiny
2020-10-16 11:06   ` Peter Zijlstra
2020-10-16 11:06     ` Peter Zijlstra
2020-10-17  5:37     ` Ira Weiny
2020-10-17  5:37       ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 5/9] x86/pks: Add PKS kernel API ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-13 18:43   ` Dave Hansen
2020-10-13 18:43     ` Dave Hansen
2020-10-15  1:08     ` Ira Weiny
2020-10-15  1:08       ` Ira Weiny
2020-10-16 11:07   ` Peter Zijlstra
2020-10-16 11:07     ` Peter Zijlstra
2020-10-17  5:42     ` Ira Weiny
2020-10-17  5:42       ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 6/9] x86/entry: Pass irqentry_state_t by reference ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-16 11:45   ` Peter Zijlstra
2020-10-16 11:45     ` Peter Zijlstra
2020-10-16 12:55     ` Thomas Gleixner
2020-10-16 12:55       ` Thomas Gleixner
2020-10-19  5:37       ` Ira Weiny
2020-10-19  5:37         ` Ira Weiny
2020-10-19  9:32         ` Thomas Gleixner
2020-10-19  9:32           ` Thomas Gleixner
2020-10-19 20:26           ` Ira Weiny
2020-10-19 20:26             ` Ira Weiny
2020-10-19 21:12             ` Thomas Gleixner
2020-10-19 21:12               ` Thomas Gleixner
2020-10-20 14:10               ` Ira Weiny
2020-10-20 14:10                 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 7/9] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-13 18:52   ` Dave Hansen
2020-10-13 18:52     ` Dave Hansen
2020-10-15  3:46     ` Ira Weiny [this message]
2020-10-15  3:46       ` Ira Weiny
2020-10-15  4:06       ` Dave Hansen
2020-10-15  4:06         ` Dave Hansen
2020-10-15  4:18         ` Ira Weiny
2020-10-15  4:18           ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 8/9] x86/fault: Report the PKRS state on fault ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-13 18:56   ` Dave Hansen
2020-10-13 18:56     ` Dave Hansen
2020-10-15  4:13     ` Ira Weiny
2020-10-15  4:13       ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 9/9] x86/pks: Add PKS test code ira.weiny
2020-10-09 19:42   ` ira.weiny
2020-10-13 19:02   ` Dave Hansen
2020-10-13 19:02     ` Dave Hansen
2020-10-15  4:46     ` Ira Weiny
2020-10-15  4:46       ` Ira Weiny
2020-10-09 20:18 ` [PATCH RFC V3 0/9] PKS: Add Protection Keys Supervisor (PKS) support RFC v3 Ira Weiny
2020-10-09 20:18   ` Ira Weiny

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