From: Paul Durrant <Paul.Durrant@citrix.com>
To: Andrew Cooper <Andrew.Cooper3@citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Cc: Kevin Tian <kevin.tian@intel.com>, "Tim (Xen.org)" <tim@xen.org>,
Jun Nakajima <jun.nakajima@intel.com>,
Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH v2 17/19] x86/hvm: Avoid __hvm_copy() raising #PF behind the emulators back
Date: Mon, 28 Nov 2016 13:01:34 +0000 [thread overview]
Message-ID: <a87c82c66dd844318a680f574af16b99@AMSPEX02CL03.citrite.net> (raw)
In-Reply-To: <845d41d8-ac7a-899a-d15b-90012ea3c03d@citrix.com>
> -----Original Message-----
> From: Andrew Cooper
> Sent: 28 November 2016 12:58
> To: Paul Durrant <Paul.Durrant@citrix.com>; Xen-devel <xen-
> devel@lists.xen.org>
> Cc: Jan Beulich <JBeulich@suse.com>; Tim (Xen.org) <tim@xen.org>; Jun
> Nakajima <jun.nakajima@intel.com>; Kevin Tian <kevin.tian@intel.com>
> Subject: Re: [PATCH v2 17/19] x86/hvm: Avoid __hvm_copy() raising #PF
> behind the emulators back
>
> On 28/11/16 11:56, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Andrew Cooper [mailto:andrew.cooper3@citrix.com]
> >> Sent: 28 November 2016 11:14
> >> To: Xen-devel <xen-devel@lists.xen.org>
> >> Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>; Jan Beulich
> >> <JBeulich@suse.com>; Paul Durrant <Paul.Durrant@citrix.com>; Tim
> >> (Xen.org) <tim@xen.org>; Jun Nakajima <jun.nakajima@intel.com>;
> Kevin
> >> Tian <kevin.tian@intel.com>
> >> Subject: [PATCH v2 17/19] x86/hvm: Avoid __hvm_copy() raising #PF
> behind
> >> the emulators back
> >>
> >> Drop the call to hvm_inject_page_fault() in __hvm_copy(), and require
> >> callers
> >> to inject the pagefault themselves.
> >>
> >> No functional change.
> > That's not the way it looks on the face of it. You've indeed removed the call
> to hvm_inject_page_fault() but some of the callers now call
> x86_emul_pagefault(). I'd call that a functional change... clearly the change
> you intended, but still a functional change.
>
> Hmm - I suppose I am confusing no functional change in the hypervisor
> with no functional change as observed by a guest.
>
Yes, I was thinking from the PoV of someone looking at this patch years later and saying 'hang on a minute...'. Saying 'no guest-observable behavioural change' is much clearer I think.
Paul
> ~Andrew
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next prev parent reply other threads:[~2016-11-28 13:01 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-28 11:13 [PATCH for-4.9 v2 00/19] XSA-191 followup Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 01/19] x86/shadow: Fix #PFs from emulated writes crossing a page boundary Andrew Cooper
2016-11-28 11:55 ` Tim Deegan
2016-11-29 15:24 ` Jan Beulich
2016-11-28 11:13 ` [PATCH v2 02/19] x86/emul: Drop X86EMUL_CMPXCHG_FAILED Andrew Cooper
2016-11-28 11:55 ` Tim Deegan
2016-11-29 15:29 ` Jan Beulich
2016-11-28 11:13 ` [PATCH v2 03/19] x86/emul: Simplfy emulation state setup Andrew Cooper
2016-11-28 11:58 ` Paul Durrant
2016-11-28 12:54 ` Paul Durrant
2016-11-28 11:13 ` [PATCH v2 04/19] x86/emul: Rename hvm_trap to x86_event and move it into the emulation infrastructure Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 05/19] x86/emul: Rename HVM_DELIVER_NO_ERROR_CODE to X86_EVENT_NO_EC Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 06/19] x86/pv: Implement pv_inject_{event, page_fault, hw_exception}() Andrew Cooper
2016-11-28 11:58 ` Tim Deegan
2016-11-28 11:59 ` Andrew Cooper
2016-11-29 16:00 ` Jan Beulich
2016-11-29 16:50 ` Andrew Cooper
2016-11-30 8:41 ` Jan Beulich
2016-11-30 13:17 ` Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 07/19] x86/emul: Remove opencoded exception generation Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 08/19] x86/emul: Rework emulator event injection Andrew Cooper
2016-11-28 12:04 ` Tim Deegan
2016-11-28 12:48 ` Andrew Cooper
2016-11-28 14:24 ` Tim Deegan
2016-11-28 14:34 ` Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 09/19] x86/vmx: Use hvm_{get, set}_segment_register() rather than vmx_{get, set}_segment_register() Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 10/19] x86/hvm: Reposition the modification of raw segment data from the VMCB/VMCS Andrew Cooper
2016-11-28 14:18 ` Boris Ostrovsky
2016-11-28 11:13 ` [PATCH v2 11/19] x86/emul: Avoid raising faults behind the emulators back Andrew Cooper
2016-11-28 12:47 ` Paul Durrant
2016-11-29 16:02 ` Jan Beulich
2016-11-28 11:13 ` [PATCH v2 12/19] x86/pv: " Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 13/19] x86/shadow: " Andrew Cooper
2016-11-28 14:49 ` Tim Deegan
2016-11-28 16:04 ` Andrew Cooper
2016-11-28 17:21 ` Tim Deegan
2016-11-28 17:36 ` Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 14/19] x86/hvm: Extend the hvm_copy_*() API with a pagefault_info pointer Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 15/19] x86/hvm: Reimplement hvm_copy_*_nofault() in terms of no pagefault_info Andrew Cooper
2016-11-28 12:56 ` Paul Durrant
2016-11-28 11:13 ` [PATCH v2 16/19] x86/hvm: Rename hvm_copy_*_guest_virt() to hvm_copy_*_guest_linear() Andrew Cooper
2016-11-28 11:59 ` Paul Durrant
2016-11-28 11:13 ` [PATCH v2 17/19] x86/hvm: Avoid __hvm_copy() raising #PF behind the emulators back Andrew Cooper
2016-11-28 11:56 ` Paul Durrant
2016-11-28 12:58 ` Andrew Cooper
2016-11-28 13:01 ` Paul Durrant [this message]
2016-11-28 13:03 ` Andrew Cooper
2016-11-28 14:56 ` Tim Deegan
2016-11-28 16:32 ` Andrew Cooper
2016-11-28 16:42 ` Tim Deegan
2016-11-29 1:22 ` Tian, Kevin
2016-11-29 16:24 ` Jan Beulich
2016-11-29 16:30 ` Andrew Cooper
2016-11-29 16:36 ` Jan Beulich
2016-11-29 16:38 ` Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 18/19] x86/hvm: Prepare to allow use of system segments for memory references Andrew Cooper
2016-11-28 11:13 ` [PATCH v2 19/19] x86/hvm: Use system-segment relative memory accesses Andrew Cooper
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