[MODERATED] Re: [PATCH v2 4/8] MDSv2 0

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Dec 12, 2018 at 02:09:46PM -0800, speck for Andi Kleen wrote:
> On Wed, Dec 12, 2018 at 04:45:06PM -0500, speck for Konrad Rzeszutek Wilk wrote:
> > On Mon, Dec 10, 2018 at 09:53:36AM -0800, speck for Andi Kleen wrote:
> > > From: Andi Kleen <ak@linux.intel.com>
> > > Subject:  x86/speculation/mds: Add sysfs reporting
> > > 
> > > Report mds mitigation state in sysfs vulnerabilities.
> > > 
> > > Signed-off-by: Andi Kleen <ak@linux.intel.com>
> > > ---
> > >  .../ABI/testing/sysfs-devices-system-cpu         |  1 +
> > >  arch/x86/kernel/cpu/bugs.c                       | 16 ++++++++++++++++
> > >  drivers/base/cpu.c                               |  8 ++++++++
> > >  3 files changed, 25 insertions(+)
> > > 
> > > diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
> > > index 73318225a368..02b7bb711214 100644
> > > --- a/Documentation/ABI/testing/sysfs-devices-system-cpu
> > > +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
> > > @@ -477,6 +477,7 @@ What:		/sys/devices/system/cpu/vulnerabilities
> > >  		/sys/devices/system/cpu/vulnerabilities/spectre_v2
> > >  		/sys/devices/system/cpu/vulnerabilities/spec_store_bypass
> > >  		/sys/devices/system/cpu/vulnerabilities/l1tf
> > > +		/sys/devices/system/cpu/vulnerabilities/mds
> > >  Date:		January 2018
> > >  Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
> > >  Description:	Information about CPU vulnerabilities
> > > diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> > > index 8200b41b8db9..accab3279068 100644
> > > --- a/arch/x86/kernel/cpu/bugs.c
> > > +++ b/arch/x86/kernel/cpu/bugs.c
> > > @@ -1175,6 +1175,16 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
> > >  		if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))
> > >  			return l1tf_show_state(buf);
> > >  		break;
> > > +
> > > +	case X86_BUG_MDS:
> > > +		/* Assumes Hypervisor exposed HT state to us if in guest */
> > > +		if (boot_cpu_has(X86_FEATURE_MB_CLEAR)) {
> > > +			if (cpu_smt_control != CPU_SMT_ENABLED)
> > > +				return sprintf(buf, "Mitigation: MB_CLEAR\n");
> > 
> > I am not sure if a normal system admin would understand what MB_CLEAR means. Is there a way to
> > make this more ..grokked?
> 
> You mean they are somehow unable to use Google?

Why do we want to have sharp corners? What is so wrong with making
it well rounded and self explanatory?