Re: Stack switching plan of attack (Re: [PATCH v2 00/18] Entry stack switching)

2017-11-23 Thread Borislav Petkov
On Thu, Nov 23, 2017 at 07:50:59AM -0800, Andy Lutomirski wrote: > 1. There needs to be a way to turn it off to get the performance hit > under control. I'm leaning toward a boot-time switch, and we can turn > it into a runtime switch later on. Thoughts? Yes, we need a runtime switch off for mac

Re: [PATCH v2 00/18] Entry stack switching

2017-11-23 Thread Thomas Gleixner
On Thu, 23 Nov 2017, Andy Lutomirski wrote: > On Wed, Nov 22, 2017 at 10:58 PM, Ingo Molnar wrote: > > * Ingo Molnar wrote: > >> * Ingo Molnar wrote: > >> > >> > > Anyway, I booted your config (more or less -- I munged it through > >> > > virtme-configkernel --update first) with 17 vCPUs and it

Stack switching plan of attack (Re: [PATCH v2 00/18] Entry stack switching)

2017-11-23 Thread Andy Lutomirski
On Tue, Nov 21, 2017 at 8:43 PM, Andy Lutomirski wrote: > This sets up stack switching, including for SYSCALL. I think it's > in decent shape. What's the plan of attack? is the goal to get this thing in -rc1 or as soon as possible thereafter? If so, I think there are two things that need fixin

Re: [PATCH v2 00/18] Entry stack switching

2017-11-23 Thread Andy Lutomirski
On Wed, Nov 22, 2017 at 10:58 PM, Ingo Molnar wrote: > > * Ingo Molnar wrote: > >> >> * Ingo Molnar wrote: >> >> > > Anyway, I booted your config (more or less -- I munged it through >> > > virtme-configkernel --update first) with 17 vCPUs and it seems fine. >> > > Is the issue reliable enough t

Re: [PATCH v2 00/18] Entry stack switching

2017-11-22 Thread Ingo Molnar
* Ingo Molnar wrote: > > * Ingo Molnar wrote: > > > > Anyway, I booted your config (more or less -- I munged it through > > > virtme-configkernel --update first) with 17 vCPUs and it seems fine. > > > Is the issue reliable enough to bisect? > > > > Ok, it should be bisectable, will try to bi

Re: [PATCH v2 00/18] Entry stack switching

2017-11-22 Thread Ingo Molnar
* Ingo Molnar wrote: > > Anyway, I booted your config (more or less -- I munged it through > > virtme-configkernel --update first) with 17 vCPUs and it seems fine. > > Is the issue reliable enough to bisect? > > Ok, it should be bisectable, will try to bisect it. The latestest entry-stack code

Re: [PATCH v2 00/18] Entry stack switching

2017-11-22 Thread Ingo Molnar
* Andy Lutomirski wrote: > On Tue, Nov 21, 2017 at 10:22 PM, Ingo Molnar wrote: > > > > * Andy Lutomirski wrote: > > > >> This sets up stack switching, including for SYSCALL. I think it's > >> in decent shape. > >> > >> Known issues: > >> - I think we're going to want a way to turn the stack

Re: WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0 (Re: [PATCH v2 00/18] Entry stack switching)

2017-11-22 Thread Andy Lutomirski
On Wed, Nov 22, 2017 at 7:56 AM, Ingo Molnar wrote: > > * Andy Lutomirski wrote: > >> > .Lerror_entry_from_usermode_after_swapgs: >> > /* Put us onto the real thread stack. */ >> > - leaq8(%rsp), %rdi /* pt_regs pointer */ >> > - movq(%rsp), %r12 >>

Re: [PATCH v2 00/18] Entry stack switching

2017-11-22 Thread Andy Lutomirski
On Tue, Nov 21, 2017 at 10:22 PM, Ingo Molnar wrote: > > * Andy Lutomirski wrote: > >> This sets up stack switching, including for SYSCALL. I think it's >> in decent shape. >> >> Known issues: >> - I think we're going to want a way to turn the stack switching on and >>off either at boot tim

Re: WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0 (Re: [PATCH v2 00/18] Entry stack switching)

2017-11-22 Thread Ingo Molnar
* Andy Lutomirski wrote: > > .Lerror_entry_from_usermode_after_swapgs: > > /* Put us onto the real thread stack. */ > > - leaq8(%rsp), %rdi /* pt_regs pointer */ > > - movq(%rsp), %r12 > > + popq%r12/* function

Re: WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0 (Re: [PATCH v2 00/18] Entry stack switching)

2017-11-22 Thread Andy Lutomirski
On Wed, Nov 22, 2017 at 5:55 AM, Josh Poimboeuf wrote: > On Wed, Nov 22, 2017 at 08:39:07AM +0100, Ingo Molnar wrote: >> >> * Andy Lutomirski wrote: >> >> > This sets up stack switching, including for SYSCALL. I think it's >> > in decent shape. >> > >> > Known issues: >> > - I think we're going

Re: WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0 (Re: [PATCH v2 00/18] Entry stack switching)

2017-11-22 Thread Josh Poimboeuf
On Wed, Nov 22, 2017 at 08:39:07AM +0100, Ingo Molnar wrote: > > * Andy Lutomirski wrote: > > > This sets up stack switching, including for SYSCALL. I think it's > > in decent shape. > > > > Known issues: > > - I think we're going to want a way to turn the stack switching on and > >off ei

Re: WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0 (Re: [PATCH v2 00/18] Entry stack switching)

2017-11-21 Thread Ingo Molnar
* Ingo Molnar wrote: > > * Andy Lutomirski wrote: > > > This sets up stack switching, including for SYSCALL. I think it's > > in decent shape. > > > > Known issues: > > - I think we're going to want a way to turn the stack switching on and > >off either at boot time or at runtime. It

WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0 (Re: [PATCH v2 00/18] Entry stack switching)

2017-11-21 Thread Ingo Molnar
* Andy Lutomirski wrote: > This sets up stack switching, including for SYSCALL. I think it's > in decent shape. > > Known issues: > - I think we're going to want a way to turn the stack switching on and >off either at boot time or at runtime. It should be fairly straightforward >to m

Re: [PATCH v2 00/18] Entry stack switching

2017-11-21 Thread Ingo Molnar
* Ingo Molnar wrote: > > * Andy Lutomirski wrote: > > > This sets up stack switching, including for SYSCALL. I think it's > > in decent shape. > > > > Known issues: > > - I think we're going to want a way to turn the stack switching on and > >off either at boot time or at runtime. It

Re: [PATCH v2 00/18] Entry stack switching

2017-11-21 Thread Ingo Molnar
* Andy Lutomirski wrote: > This sets up stack switching, including for SYSCALL. I think it's > in decent shape. > > Known issues: > - I think we're going to want a way to turn the stack switching on and >off either at boot time or at runtime. It should be fairly straightforward >to m

[PATCH v2 00/18] Entry stack switching

2017-11-21 Thread Andy Lutomirski
This sets up stack switching, including for SYSCALL. I think it's in decent shape. Known issues: - I think we're going to want a way to turn the stack switching on and off either at boot time or at runtime. It should be fairly straightforward to make it work. - I think the ORC unwinder