Re: [PATCH] x86:pvclock: add missing barriers

2016-06-12 Thread Minfei Huang
On 06/08/16 at 09:45P, Borislav Petkov wrote: > On Wed, Jun 08, 2016 at 09:11:39PM +0300, Roman Kagan wrote: > > Gradual removal of excessive barriers in pvclock reading functions > > (commits 502dfeff239e8313bfbe906ca0a1a6827ac8481b, > > a3eb97bd80134ba07864ca00747466c02118aca1) ended up removing

Re: [PATCH] x86:pvclock: add missing barriers

2016-06-12 Thread Minfei Huang
On 06/08/16 at 09:45P, Borislav Petkov wrote: > On Wed, Jun 08, 2016 at 09:11:39PM +0300, Roman Kagan wrote: > > Gradual removal of excessive barriers in pvclock reading functions > > (commits 502dfeff239e8313bfbe906ca0a1a6827ac8481b, > > a3eb97bd80134ba07864ca00747466c02118aca1) ended up removing

Re: [PATCH] x86:pvclock: add missing barriers

2016-06-09 Thread Roman Kagan
On Thu, Jun 09, 2016 at 12:01:13AM +0300, Roman Kagan wrote: > On Wed, Jun 08, 2016 at 09:45:09PM +0200, Borislav Petkov wrote: > > On Wed, Jun 08, 2016 at 09:11:39PM +0300, Roman Kagan wrote: > > > --- a/arch/x86/include/asm/pvclock.h > > > +++ b/arch/x86/include/asm/pvclock.h > > > @@ -80,18

Re: [PATCH] x86:pvclock: add missing barriers

2016-06-09 Thread Roman Kagan
On Thu, Jun 09, 2016 at 12:01:13AM +0300, Roman Kagan wrote: > On Wed, Jun 08, 2016 at 09:45:09PM +0200, Borislav Petkov wrote: > > On Wed, Jun 08, 2016 at 09:11:39PM +0300, Roman Kagan wrote: > > > --- a/arch/x86/include/asm/pvclock.h > > > +++ b/arch/x86/include/asm/pvclock.h > > > @@ -80,18

Re: [PATCH] x86:pvclock: add missing barriers

2016-06-08 Thread Roman Kagan
On Wed, Jun 08, 2016 at 09:45:09PM +0200, Borislav Petkov wrote: > On Wed, Jun 08, 2016 at 09:11:39PM +0300, Roman Kagan wrote: > > Gradual removal of excessive barriers in pvclock reading functions > > (commits 502dfeff239e8313bfbe906ca0a1a6827ac8481b, > >

Re: [PATCH] x86:pvclock: add missing barriers

2016-06-08 Thread Roman Kagan
On Wed, Jun 08, 2016 at 09:45:09PM +0200, Borislav Petkov wrote: > On Wed, Jun 08, 2016 at 09:11:39PM +0300, Roman Kagan wrote: > > Gradual removal of excessive barriers in pvclock reading functions > > (commits 502dfeff239e8313bfbe906ca0a1a6827ac8481b, > >

Re: [PATCH] x86:pvclock: add missing barriers

2016-06-08 Thread Borislav Petkov
On Wed, Jun 08, 2016 at 09:11:39PM +0300, Roman Kagan wrote: > Gradual removal of excessive barriers in pvclock reading functions > (commits 502dfeff239e8313bfbe906ca0a1a6827ac8481b, > a3eb97bd80134ba07864ca00747466c02118aca1) ended up removing too much: > although rdtsc is now orderd WRT other

[PATCH] x86:pvclock: add missing barriers

2016-06-08 Thread Roman Kagan
Gradual removal of excessive barriers in pvclock reading functions (commits 502dfeff239e8313bfbe906ca0a1a6827ac8481b, a3eb97bd80134ba07864ca00747466c02118aca1) ended up removing too much: although rdtsc is now orderd WRT other loads, there's no protection against the compiler reordering the loads

Re: [PATCH] x86:pvclock: add missing barriers

2016-06-08 Thread Borislav Petkov
On Wed, Jun 08, 2016 at 09:11:39PM +0300, Roman Kagan wrote: > Gradual removal of excessive barriers in pvclock reading functions > (commits 502dfeff239e8313bfbe906ca0a1a6827ac8481b, > a3eb97bd80134ba07864ca00747466c02118aca1) ended up removing too much: > although rdtsc is now orderd WRT other

[PATCH] x86:pvclock: add missing barriers

2016-06-08 Thread Roman Kagan
Gradual removal of excessive barriers in pvclock reading functions (commits 502dfeff239e8313bfbe906ca0a1a6827ac8481b, a3eb97bd80134ba07864ca00747466c02118aca1) ended up removing too much: although rdtsc is now orderd WRT other loads, there's no protection against the compiler reordering the loads