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From: Andrew Cooper <Andrew.Cooper3@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Bobby Eshleman <bobby.eshleman@gmail.com>,
	Roger Pau Monne <roger.pau@citrix.com>, Wei Liu <wl@xen.org>,
	Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v5 2/6] x86/gdbsx: Rename debug.c to gdbsx.c
Date: Thu, 21 Apr 2022 17:29:35 +0000	[thread overview]
Message-ID: <c7feeb73-78fb-136e-2dac-4a3f87e0ae93@citrix.com> (raw)
In-Reply-To: <bb1961c1-af89-0220-6328-aa8cb98a1d84@suse.com>

On 21/04/2022 14:06, Jan Beulich wrote:
> On 20.04.2022 16:13, Andrew Cooper wrote:
>> From: Bobby Eshleman <bobby.eshleman@gmail.com>
>>
>> debug.c contains only dbg_rw_mem().  Rename it to gdbsx.c.
>>
>> Move gdbsx_guest_mem_io(), and the prior setup of iop->remain, from domctl.c
>> to gdbsx.c, merging it with dbg_rw_mem().
>>
>> Signed-off-by: Bobby Eshleman <bobby.eshleman@gmail.com>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>

Thanks.

>
>> The semantics are rather broken.  XEN_DOMCTL_gdbsx_guestmemio only sets
>> copyback when there's nothing to copy back, and skips copying back in the
>> -EFAULT case when the iop->remain field is relevant.  Furthermore, it can be
>> asked to move up to 4GB in one go, with no continuability whatsoever.
> The last point perhaps isn't overly much of a problem for this specific
> operation.

It's also not terribly hard to fix, but I really don't have time to get
bogged down in "make the gdbsx hypercalls sane". 
XEN_DOMCTL_gdbsx_domstatus is a disaster, and there are far better ways
of doing this.  https://www.youtube.com/watch?v=osZeioYKsxA is one which
was presented at XenSummit in 2019.

~Andrew

  reply	other threads:[~2022-04-21 17:30 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-20 14:13 [PATCH v5 0/6] Clean up common/arch split for debugger.h Andrew Cooper
2022-04-20 14:13 ` [PATCH v5 1/6] x86/debugger: Remove debugger_trap_entry() Andrew Cooper
2022-04-21 13:02   ` Jan Beulich
2022-04-21 17:23     ` Andrew Cooper
2022-04-22  7:27       ` Jan Beulich
2022-04-20 14:13 ` [PATCH v5 2/6] x86/gdbsx: Rename debug.c to gdbsx.c Andrew Cooper
2022-04-21 13:06   ` Jan Beulich
2022-04-21 17:29     ` Andrew Cooper [this message]
2022-04-25 13:40   ` Jan Beulich
2022-04-20 14:13 ` [PATCH v5 3/6] x86/gdbsx: Move domain_pause_for_debugger() into gdbsx Andrew Cooper
2022-04-21 13:08   ` Jan Beulich
2022-04-20 14:13 ` [PATCH v5 4/6] x86/gdbstub: Clean up includes Andrew Cooper
2022-04-21 13:09   ` Jan Beulich
2022-04-20 14:13 ` [PATCH v5 5/6] x86/debugger: Misc cleanup prior to splitting Andrew Cooper
2022-04-21 13:10   ` Jan Beulich
2022-04-20 14:13 ` [PATCH v5 6/6] xen: Split x86/debugger.h into common and arch specific parts Andrew Cooper
2022-04-21 13:12   ` Jan Beulich

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