On Fri, Dec 18 2020 at 13:58, Dan Williams wrote:
> On Fri, Dec 18, 2020 at 1:06 PM Thomas Gleixner wrote:
>> kmap_local() is fine. That can work automatically because it's strict
>> local to the context which does the mapping.
>>
>> kmap() is dubious because it's a 'global' mapping as dictated pe
On Fri, Dec 18, 2020 at 1:06 PM Thomas Gleixner wrote:
>
> On Fri, Dec 18 2020 at 11:20, Dan Williams wrote:
> > On Fri, Dec 18, 2020 at 5:58 AM Thomas Gleixner wrote:
> > [..]
> >> 5) The DAX case which you made "work" with dev_access_enable() and
> >> dev_access_disable(), i.e. with yet
On Fri, Dec 18 2020 at 11:42, Ira Weiny wrote:
> On Fri, Dec 18, 2020 at 02:57:51PM +0100, Thomas Gleixner wrote:
>> 2) Modify kmap() so that it marks the to be mapped page as 'globaly
>> unprotected' instead of doing this global unprotect PKS dance.
>> kunmap() undoes that. That obviou
On Fri, Dec 18 2020 at 11:20, Dan Williams wrote:
> On Fri, Dec 18, 2020 at 5:58 AM Thomas Gleixner wrote:
> [..]
>> 5) The DAX case which you made "work" with dev_access_enable() and
>> dev_access_disable(), i.e. with yet another lazy approach of
>> avoiding to change a handful of usa
On 12/18/20 11:42 AM, Ira Weiny wrote:
> Another problem would be if the kmap and kunmap happened in different
> contexts... :-/ I don't think that is done either but I don't know for
> certain.
It would be really nice to put together some surveillance patches to
help become more certain about t
On Fri, Dec 18, 2020 at 02:57:51PM +0100, Thomas Gleixner wrote:
> On Thu, Dec 17 2020 at 23:43, Thomas Gleixner wrote:
> > The only use case for this in your tree is: kmap() and the possible
> > usage of that mapping outside of the thread context which sets it up.
> >
> > The only hint for doing t
On Fri, Dec 18, 2020 at 5:58 AM Thomas Gleixner wrote:
[..]
> 5) The DAX case which you made "work" with dev_access_enable() and
> dev_access_disable(), i.e. with yet another lazy approach of
> avoiding to change a handful of usage sites.
>
> The use cases are strictly context loc
On 12/17/20 8:10 PM, Ira Weiny wrote:
> On Thu, Dec 17, 2020 at 12:41:50PM -0800, Dave Hansen wrote:
>> On 11/6/20 3:29 PM, ira.we...@intel.com wrote:
>>> void disable_TSC(void)
>>> @@ -644,6 +668,8 @@ void __switch_to_xtra(struct task_struct *prev_p,
>>> struct task_struct *next_p)
>>>
>>>
On Thu, Dec 17 2020 at 23:43, Thomas Gleixner wrote:
> The only use case for this in your tree is: kmap() and the possible
> usage of that mapping outside of the thread context which sets it up.
>
> The only hint for doing this at all is:
>
> Some users, such as kmap(), sometimes requires PKS t
On Thu, Dec 17, 2020 at 12:41:50PM -0800, Dave Hansen wrote:
> On 11/6/20 3:29 PM, ira.we...@intel.com wrote:
> > void disable_TSC(void)
> > @@ -644,6 +668,8 @@ void __switch_to_xtra(struct task_struct *prev_p,
> > struct task_struct *next_p)
> >
> > if ((tifp ^ tifn) & _TIF_SLD)
> >
On Thu, Dec 17, 2020 at 03:50:55PM +0100, Thomas Gleixner wrote:
> On Fri, Nov 06 2020 at 15:29, ira weiny wrote:
> > --- a/arch/x86/kernel/process.c
> > +++ b/arch/x86/kernel/process.c
> > @@ -43,6 +43,7 @@
> > #include
> > #include
> > #include
> > +#include
> >
> > #include "process.h"
On Thu, Dec 17 2020 at 15:50, Thomas Gleixner wrote:
> On Fri, Nov 06 2020 at 15:29, ira weiny wrote:
>
>> +void write_pkrs(u32 new_pkrs)
>> +{
>> +u32 *pkrs;
>> +
>> +if (!static_cpu_has(X86_FEATURE_PKS))
>> +return;
>> +
>> +pkrs = get_cpu_ptr(&pkrs_cache);
>
> So this is
On 11/6/20 3:29 PM, ira.we...@intel.com wrote:
> void disable_TSC(void)
> @@ -644,6 +668,8 @@ void __switch_to_xtra(struct task_struct *prev_p, struct
> task_struct *next_p)
>
> if ((tifp ^ tifn) & _TIF_SLD)
> switch_to_sld(tifn);
> +
> + pks_sched_in();
> }
Does the s
On Fri, Nov 06 2020 at 15:29, ira weiny wrote:
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -43,6 +43,7 @@
> #include
> #include
> #include
> +#include
>
> #include "process.h"
>
> @@ -187,6 +188,27 @@ int copy_thread(unsigned long clone_flags, unsigned long
From: Ira Weiny
The PKRS MSR is defined as a per-logical-processor register. This
isolates memory access by logical CPU. Unfortunately, the MSR is not
managed by XSAVE. Therefore, tasks must save/restore the MSR value on
context switch.
Define a saved PKRS value in the task struct, as well as
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