Re: [Xen-devel] [PATCH v9 3/9] xen/x86: support per-domain flag for xpti

[Juergen Gross <jgross@xxxxxxxx>]

On 27/04/18 09:55, Sergey Dyasli wrote:
> On Thu, 2018-04-26 at 13:33 +0200, Juergen Gross wrote:
>> Instead of switching XPTI globally on or off add a per-domain flag for
>> that purpose. This allows to modify the xpti boot parameter to support
>> running dom0 without Meltdown mitigations. Using "xpti=no-dom0" as boot
> 
> "xpti=dom0=0"

Both variants are valid.

> 
>> parameter will achieve that.
>>
>> Move the xpti boot parameter handling to xen/arch/x86/pv/domain.c as
>> it is pv-domain specific.
>>
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
>> ---
>> V9:
>> - adjust boot message (Sergey Dyasli)
>> - adjust boot parameter documentation (Sergey Dyasli)
>>
>> V6.1:
>> - address some minor comments (Jan Beulich)
>>
>> V6:
>> - modify xpti boot parameter options (Andrew Cooper)
>> - move xpti_init() code to spec_ctrl.c (Andrew Cooper)
>> - irework init of per-domain xpti flag (Andrew Cooper)
>>
>> V3:
>> - latch get_cpu_info() return value in variable (Jan Beulich)
>> - call always xpti_domain_init() for pv dom0 (Jan Beulich)
>> - add __init annotations (Jan Beulich)
>> - drop per domain XPTI message (Jan Beulich)
>> - document xpti=default support (Jan Beulich)
>> - move domain xpti flag into a padding hole (Jan Beulich)
>> ---
>>  docs/misc/xen-command-line.markdown | 14 ++++++-
>>  xen/arch/x86/mm.c                   | 17 ++++++++-
>>  xen/arch/x86/pv/dom0_build.c        |  1 +
>>  xen/arch/x86/pv/domain.c            |  6 +++
>>  xen/arch/x86/setup.c                | 19 ----------
>>  xen/arch/x86/smpboot.c              |  4 +-
>>  xen/arch/x86/spec_ctrl.c            | 75 
>> ++++++++++++++++++++++++++++++++++++-
>>  xen/include/asm-x86/current.h       |  3 +-
>>  xen/include/asm-x86/domain.h        |  3 ++
>>  xen/include/asm-x86/flushtlb.h      |  2 +-
>>  xen/include/asm-x86/spec_ctrl.h     |  4 ++
>>  11 files changed, 119 insertions(+), 29 deletions(-)
>>
>> diff --git a/docs/misc/xen-command-line.markdown 
>> b/docs/misc/xen-command-line.markdown
>> index b353352adf..220d1ba020 100644
>> --- a/docs/misc/xen-command-line.markdown
>> +++ b/docs/misc/xen-command-line.markdown
>> @@ -1955,14 +1955,24 @@ clustered mode.  The default, given no hint from the 
>> **FADT**, is cluster
>>  mode.
>>  
>>  ### xpti
>> -> `= <boolean>`
>> +> `= List of [ default | <boolean> | dom0=<bool> | domu=<bool> ]`
>>  
>> -> Default: `false` on AMD hardware
>> +> Default: `false` on hardware not to be vulnerable to Meltdown (e.g. AMD)
>                                  ^
>                                  known

Yes, indeed.


Juergen

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