Re: [RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2019-01-15 Thread Waiman Long
On 01/15/2019 04:48 AM, Thomas Gleixner wrote: > On Mon, 14 Jan 2019, Waiman Long wrote: >> On 01/11/2019 02:52 PM, Thomas Gleixner wrote: >>> On Wed, 19 Dec 2018, Waiman Long wrote: >>> With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode, the TIF_SSBD bit will be

Re: [RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2019-01-15 Thread Thomas Gleixner
On Mon, 14 Jan 2019, Waiman Long wrote: > On 01/11/2019 02:52 PM, Thomas Gleixner wrote: > > On Wed, 19 Dec 2018, Waiman Long wrote: > > > >> With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode, > >> the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned. > >>

Re: [RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2019-01-14 Thread Waiman Long
On 01/11/2019 02:52 PM, Thomas Gleixner wrote: > On Wed, 19 Dec 2018, Waiman Long wrote: > >> With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode, >> the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned. >> >> As only certain class of applications (like Java)

Re: [RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2019-01-11 Thread Thomas Gleixner
On Wed, 19 Dec 2018, Waiman Long wrote: > With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode, > the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned. > > As only certain class of applications (like Java) requires disabling > speculative store bypass for

Re: [RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2019-01-07 Thread Waiman Long
On 12/19/2018 02:09 PM, Waiman Long wrote: > With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode, > the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned. > > As only certain class of applications (like Java) requires disabling > speculative store bypass for

Re: [RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2018-12-19 Thread Andi Kleen
> You can always force disable SSB. In that case, all the child processes > will have SSBD on. Okay that sounds reasonable, given the below. Thanks. -Andi > > > > > Do you have a real use case where this behavior is a problem? > > > > -Andi > > Yes, we have an enterprise application partner

Re: [RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2018-12-19 Thread Waiman Long
On 12/19/2018 02:38 PM, Andi Kleen wrote: > On Wed, Dec 19, 2018 at 02:09:50PM -0500, Waiman Long wrote: >> With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode, >> the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned. >> >> As only certain class of

Re: [RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2018-12-19 Thread Andi Kleen
On Wed, Dec 19, 2018 at 02:09:50PM -0500, Waiman Long wrote: > With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode, > the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned. > > As only certain class of applications (like Java) requires disabling > speculative

[RFC PATCH] x86/speculation: Don't inherit TIF_SSBD on execve()

2018-12-19 Thread Waiman Long
With the default SPEC_STORE_BYPASS_SECCOMP/SPEC_STORE_BYPASS_PRCTL mode, the TIF_SSBD bit will be inherited when a new task is fork'ed or cloned. As only certain class of applications (like Java) requires disabling speculative store bypass for security purpose, it may not make sense to allow the