Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest

From	Andrew Cooper <andrew.cooper3@citrix.com>
Newsgroups	linux.kernel
Subject	Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest
Date	2016-01-23 01:40 +0100
Message-ID	<qTUpb-3iD-1@gated-at.bofh.it> (permalink)
References	<qTRB0-1oj-3@gated-at.bofh.it> <qTRB0-1oj-1@gated-at.bofh.it> <qTTt7-2G5-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 22/01/2016 23:32, Luis R. Rodriguez wrote:
> On Fri, Jan 22, 2016 at 04:35:50PM -0500, Boris Ostrovsky wrote:
>> +	/*
>> +	 * See Documentation/x86/boot.txt.
>> +	 *
>> +	 * Version 2.12 supports Xen entry point but we will use default x86/PC
>> +	 * environment (i.e. hardware_subarch 0).
>> +	 */
>> +	xen_hvmlite_boot_params.hdr.version = 0x212;
>> +	xen_hvmlite_boot_params.hdr.type_of_loader = 9; /* Xen loader */
>> +}
> I realize PV got away with setting up boot_params on C code but best
> ask now that this new code is being introduced: why can't we just have
> the Xen hypervisor fill this in? It'd save us all this code.

I agree that this looks to be a mess.  Having said that, the DMLite boot
protocol is OS agnostic, and will be staying that way.

It happens to look suspiciously like multiboot; a flat 32bit protected
mode entry (at a location chosen in an ELF note), with %ebx pointing to
an in-ram structure containing things like a command line and module list.

I would have though the correct way to do direct Linux support would be
to have a very small init stub which constructs an appropriate zero
page, and lets the native entry point get on with things.

This covers the usecase where people wish to boot a specific Linux
kernel straight out of the dom0 filesystem.

For the alternative usecase of general OS support, dom0 would boot
something such as grub2 as the DMLite "kernel", at which point all
stooging around in the guests filesystem is done from guest context,
rather than control context (mitigating a substantial attack surface).

~Andrew

Thread

[PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-22 22:40 +0100
  Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-23 00:40 +0100
    Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Andrew Cooper <andrew.cooper3@citrix.com> - 2016-01-23 01:40 +0100
      Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-23 01:50 +0100
      Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-23 02:00 +0100
        Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Andrew Cooper <andrew.cooper3@citrix.com> - 2016-01-23 15:50 +0100
          Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "H. Peter Anvin" <hpa@zytor.com> - 2016-01-23 17:10 +0100
            Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-01-23 17:20 +0100
              Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "H. Peter Anvin" <hpa@zytor.com> - 2016-01-23 19:30 +0100
              Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Roger Pau Monné <royger@FreeBSD.org> - 2016-01-25 11:40 +0100
          Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-25 23:20 +0100
            Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-26 00:00 +0100
              Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-26 21:40 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-26 23:00 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-27 01:10 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-27 03:20 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest David Vrabel <david.vrabel@citrix.com> - 2016-01-27 16:00 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-27 16:10 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest David Vrabel <david.vrabel@citrix.com> - 2016-01-27 16:10 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-27 16:20 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-27 17:20 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-01-27 19:50 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-01-27 20:10 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Borislav Petkov <bp@suse.de> - 2016-01-27 17:20 +0100
          Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-01-26 17:20 +0100
      Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-25 16:10 +0100
    Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-25 17:10 +0100
      Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-25 22:20 +0100
        Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "H. Peter Anvin" <hpa@zytor.com> - 2016-01-25 22:30 +0100
          Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-25 23:30 +0100
            Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-26 19:40 +0100
              Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Andy Lutomirski <luto@amacapital.net> - 2016-01-26 19:50 +0100
                Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-01-26 20:10 +0100
                Re: [Xen-devel] [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-01-26 20:20 +0100

csiph-web