Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1271581

Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit

Show all headers | View raw

On 17/11/15 18:49, Andy Lutomirski wrote:
> On Nov 17, 2015 6:40 AM, "Boris Ostrovsky" <boris.ostrovsky@oracle.com> wrote:
>> On 11/16/2015 04:55 PM, H. Peter Anvin wrote:
>>> On 11/16/15 12:22, Borislav Petkov wrote:
>>>> Huh, so what's wrong with a jump:
>>>>
>>>>         jmp 1f
>>>>         swapgs
>>>>         1:
>>>>
>>> What is the point of that jump?
>>>
>>>>> If it would make you feel better, it could be X86_BUG_XENPV :-p
>>>> That doesn't matter - I just don't want to open the flood gates on
>>>> pseudo feature bits.
>>>>
>>>> hpa, what do you think?
>>> Pseudo feature bits are fine, we already have plenty of them.  They make
>>> sense as they let us reuse a lot of infrastructure.
>>
>>
>> So how about something like this? And then I think we can remove usergs_sysret32 and irq_enable_sysexit pv ops completely as noone will use them (lguest doesn't set them)
>>
> Looks good to me.  Does Xen have any sysexit/sysret32 equivalent to
> return to 32-bit user mode?  If so, it could be worth trying to wire
> it up by patching the jz instead of the test instruction.

From the guests point of view, there is only hypercall_iret.

>
> Also, I'd prefer X86_FEATURE_XENPV.  IMO "PV" means too many things to
> too many people.

I agree - PV on its own is too generic.

An alternative might be X86_FEATURE_XEN_PV_GUEST which is very clear an
unambiguous, although rather longer.

~Andrew
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-16 17:30 +0100
  Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andy Lutomirski <luto@amacapital.net> - 2015-11-16 20:10 +0100
    Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Borislav Petkov <bp@alien8.de> - 2015-11-16 21:00 +0100
      Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andy Lutomirski <luto@amacapital.net> - 2015-11-16 21:20 +0100
        Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Borislav Petkov <bp@alien8.de> - 2015-11-16 21:30 +0100
          Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-16 21:50 +0100
            Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andy Lutomirski <luto@amacapital.net> - 2015-11-16 22:00 +0100
              Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andy Lutomirski <luto@amacapital.net> - 2015-11-16 22:10 +0100
                Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Joao Martins <joao.m.martins@oracle.com> - 2015-11-17 12:00 +0100
              Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Borislav Petkov <bp@alien8.de> - 2015-11-16 22:10 +0100
          Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit "H. Peter Anvin" <hpa@zytor.com> - 2015-11-16 23:00 +0100
            Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-17 15:50 +0100
              Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andy Lutomirski <luto@amacapital.net> - 2015-11-17 20:00 +0100
                Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andy Lutomirski <luto@amacapital.net> - 2015-11-17 20:20 +0100
                Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Borislav Petkov <bp@alien8.de> - 2015-11-17 20:30 +0100
                Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andrew Cooper <andrew.cooper3@citrix.com> - 2015-11-17 20:30 +0100
                Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andy Lutomirski <luto@amacapital.net> - 2015-11-17 20:40 +0100
                Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-17 20:40 +0100
                Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-17 20:40 +0100
                Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Andrew Cooper <andrew.cooper3@citrix.com> - 2015-11-17 20:20 +0100
    Re: [PATCH] xen/x86: Adjust stack pointer in xen_sysexit Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-16 21:40 +0100

csiph-web