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From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
	Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Tim Deegan <tim@xen.org>, Ian Jackson <Ian.Jackson@eu.citrix.com>,
	Julien Grall <julien.grall@arm.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [PATCH 1/3] xen: drop in_atomic()
Date: Wed, 22 May 2019 04:10:28 -0600	[thread overview]
Message-ID: <5CE52014020000780023147E@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <20190522094549.28397-2-jgross@suse.com>

>>> On 22.05.19 at 11:45, <jgross@suse.com> wrote:
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -3185,22 +3185,6 @@ static enum hvm_translation_result __hvm_copy(
>  
>      ASSERT(is_hvm_vcpu(v));
>  
> -    /*
> -     * XXX Disable for 4.1.0: PV-on-HVM drivers will do grant-table ops
> -     * such as query_size. Grant-table code currently does copy_to/from_guest
> -     * accesses under the big per-domain lock, which this test would disallow.
> -     * The test is not needed until we implement sleeping-on-waitqueue when
> -     * we access a paged-out frame, and that's post 4.1.0 now.
> -     */
> -#if 0
> -    /*
> -     * If the required guest memory is paged out, this function may sleep.
> -     * Hence we bail immediately if called from atomic context.
> -     */
> -    if ( in_atomic() )
> -        return HVMTRANS_unhandleable;
> -#endif

Dealing with this TODO item is of course much appreciated, but
should it really be deleted altogether? The big-domain-lock issue
is gone afair, in which case dropping the #if 0 would seem
possible to me, even if it's not strictly needed without the sleep-
on-waitqueue behavior mentioned.

Jan



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Xen-devel mailing list
Xen-devel@lists.xenproject.org
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WARNING: multiple messages have this Message-ID (diff)
From: "Jan Beulich" <JBeulich@suse.com>
To: "Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Juergen Gross" <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Tim Deegan <tim@xen.org>, Ian Jackson <Ian.Jackson@eu.citrix.com>,
	Julien Grall <julien.grall@arm.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 1/3] xen: drop in_atomic()
Date: Wed, 22 May 2019 04:10:28 -0600	[thread overview]
Message-ID: <5CE52014020000780023147E@prv1-mh.provo.novell.com> (raw)
Message-ID: <20190522101028.7wr7_EPooM5CqH8_QjmZdcXimAAMtkvlAeSzJsrGzDc@z> (raw)
In-Reply-To: <20190522094549.28397-2-jgross@suse.com>

>>> On 22.05.19 at 11:45, <jgross@suse.com> wrote:
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -3185,22 +3185,6 @@ static enum hvm_translation_result __hvm_copy(
>  
>      ASSERT(is_hvm_vcpu(v));
>  
> -    /*
> -     * XXX Disable for 4.1.0: PV-on-HVM drivers will do grant-table ops
> -     * such as query_size. Grant-table code currently does copy_to/from_guest
> -     * accesses under the big per-domain lock, which this test would disallow.
> -     * The test is not needed until we implement sleeping-on-waitqueue when
> -     * we access a paged-out frame, and that's post 4.1.0 now.
> -     */
> -#if 0
> -    /*
> -     * If the required guest memory is paged out, this function may sleep.
> -     * Hence we bail immediately if called from atomic context.
> -     */
> -    if ( in_atomic() )
> -        return HVMTRANS_unhandleable;
> -#endif

Dealing with this TODO item is of course much appreciated, but
should it really be deleted altogether? The big-domain-lock issue
is gone afair, in which case dropping the #if 0 would seem
possible to me, even if it's not strictly needed without the sleep-
on-waitqueue behavior mentioned.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  parent reply	other threads:[~2019-05-22 10:10 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22  9:45 [PATCH 0/3] tune preempt_[dis|en]able() Juergen Gross
2019-05-22  9:45 ` [Xen-devel] " Juergen Gross
2019-05-22  9:45 ` [PATCH 1/3] xen: drop in_atomic() Juergen Gross
2019-05-22  9:45   ` [Xen-devel] " Juergen Gross
2019-05-22  9:58   ` Andrew Cooper
2019-05-22  9:58     ` [Xen-devel] " Andrew Cooper
2019-05-22 10:10   ` Jan Beulich [this message]
2019-05-22 10:10     ` Jan Beulich
2019-05-24  5:41     ` Juergen Gross
2019-05-24  5:41       ` [Xen-devel] " Juergen Gross
2019-05-24  6:38       ` Jan Beulich
2019-05-24  6:38         ` [Xen-devel] " Jan Beulich
2019-05-24  8:34         ` Juergen Gross
2019-05-24  8:34           ` [Xen-devel] " Juergen Gross
2019-05-24  8:39           ` Jan Beulich
2019-05-24  8:39             ` [Xen-devel] " Jan Beulich
2019-05-24 12:30             ` Andrew Cooper
2019-05-24 12:30               ` [Xen-devel] " Andrew Cooper
2019-05-24 12:35               ` Jan Beulich
2019-05-24 12:35                 ` [Xen-devel] " Jan Beulich
     [not found]   ` <5CE52014020000780023147E@suse.com>
2019-05-22 10:19     ` Juergen Gross
2019-05-22 10:19       ` [Xen-devel] " Juergen Gross
2019-05-22 12:34       ` Jan Beulich
2019-05-22 12:34         ` [Xen-devel] " Jan Beulich
2019-05-22  9:45 ` [PATCH 2/3] xen: drop preempt_count() for non-debug builds Juergen Gross
2019-05-22  9:45   ` [Xen-devel] " Juergen Gross
2019-05-22 10:00   ` Andrew Cooper
2019-05-22 10:00     ` [Xen-devel] " Andrew Cooper
2019-05-22 10:17     ` Juergen Gross
2019-05-22 10:17       ` [Xen-devel] " Juergen Gross
2019-05-22 10:18     ` Jan Beulich
2019-05-22 10:18       ` [Xen-devel] " Jan Beulich
2019-05-22 10:39       ` Andrew Cooper
2019-05-22 10:39         ` [Xen-devel] " Andrew Cooper
2019-05-22 10:12   ` Jan Beulich
2019-05-22 10:12     ` [Xen-devel] " Jan Beulich
     [not found]   ` <5CE5207A0200007800231481@suse.com>
2019-05-22 10:17     ` Juergen Gross
2019-05-22 10:17       ` [Xen-devel] " Juergen Gross
2019-05-22  9:45 ` [PATCH 3/3] xen: build common/preempt.c only with CONFIG_DEBUG Juergen Gross
2019-05-22  9:45   ` [Xen-devel] " Juergen Gross
2019-05-22 13:01 [PATCH 1/3] xen: drop in_atomic() Juergen Gross

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