From: "Wu, Feng" <feng.wu@intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Cc: "Wu, Feng" <feng.wu@intel.com>,
"george.dunlap@eu.citrix.com" <george.dunlap@eu.citrix.com>,
"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
"jbeulich@suse.com" <jbeulich@suse.com>,
"Zhang, Yang Z" <yang.z.zhang@intel.com>,
"keir@xen.org" <keir@xen.org>
Subject: Re: [v3 08/15] Suppress posting interrupts when 'SN' is set
Date: Wed, 8 Jul 2015 11:58:01 +0000 [thread overview]
Message-ID: <E959C4978C3B6342920538CF579893F0025F92D8@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D1262B8D49@SHSMSX101.ccr.corp.intel.com>
> -----Original Message-----
> From: Tian, Kevin
> Sent: Wednesday, July 08, 2015 7:31 PM
> To: Wu, Feng; xen-devel@lists.xen.org
> Cc: keir@xen.org; jbeulich@suse.com; andrew.cooper3@citrix.com; Zhang,
> Yang Z; george.dunlap@eu.citrix.com
> Subject: RE: [v3 08/15] Suppress posting interrupts when 'SN' is set
>
> > From: Wu, Feng
> > Sent: Wednesday, July 08, 2015 6:11 PM
> > > From: Tian, Kevin
> > > Sent: Wednesday, July 08, 2015 5:06 PM
> > >
> > > > From: Wu, Feng
> > > > Sent: Wednesday, June 24, 2015 1:18 PM
> > > >
> > > > Currently, we don't support urgent interrupt, all interrupts
> > > > are recognized as non-urgent interrupt, so we cannot send
> > > > posted-interrupt when 'SN' is set.
> > > >
> > > > Signed-off-by: Feng Wu <feng.wu@intel.com>
> > > > ---
> > > > v3:
> > > > use cmpxchg to test SN/ON and set ON
> > > >
> > > > xen/arch/x86/hvm/vmx/vmx.c | 32
> > ++++++++++++++++++++++++++++----
> > > > 1 file changed, 28 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> > > > index 0837627..b94ef6a 100644
> > > > --- a/xen/arch/x86/hvm/vmx/vmx.c
> > > > +++ b/xen/arch/x86/hvm/vmx/vmx.c
> > > > @@ -1686,6 +1686,8 @@ static void
> __vmx_deliver_posted_interrupt(struct
> > > vcpu *v)
> > > >
> > > > static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
> > > > {
> > > > + struct pi_desc old, new, prev;
> > > > +
> > >
> > > move to 'else if'.
> > >
> > > > if ( pi_test_and_set_pir(vector, &v->arch.hvm_vmx.pi_desc) )
> > > > return;
> > > >
> > > > @@ -1698,13 +1700,35 @@ static void vmx_deliver_posted_intr(struct
> vcpu
> > > *v, u8
> > > > vector)
> > > > */
> > > > pi_set_on(&v->arch.hvm_vmx.pi_desc);
> > > > }
> > > > - else if ( !pi_test_and_set_on(&v->arch.hvm_vmx.pi_desc) )
> > > > + else
> > > > {
> > > > + prev.control = 0;
> > > > +
> > > > + do {
> > > > + old.control = v->arch.hvm_vmx.pi_desc.control &
> > > > + ~(1 << POSTED_INTR_ON | 1 <<
> > > POSTED_INTR_SN);
> > > > + new.control = v->arch.hvm_vmx.pi_desc.control |
> > > > + 1 << POSTED_INTR_ON;
> > > > +
> > > > + /*
> > > > + * Currently, we don't support urgent interrupt, all
> > > > + * interrupts are recognized as non-urgent interrupt,
> > > > + * so we cannot send posted-interrupt when 'SN' is set.
> > > > + * Besides that, if 'ON' is already set, we cannot set
> > > > + * posted-interrupts as well.
> > > > + */
> > > > + if ( prev.sn || prev.on )
> > > > + {
> > > > + vcpu_kick(v);
> > > > + return;
> > > > + }
> > >
> > > would it make more sense to move above check after cmpxchg?
> >
> > My original idea is that, we only need to do the check when
> > prev.control != old.control, which means the cmpxchg is not
> > successful completed. If we add the check between cmpxchg
> > and while ( prev.control != old.control ), it seems the logic is
> > not so clear, since we don't need to check prev.sn and prev.on
> > when cmxchg succeeds in setting the new value.
> >
> > Thanks,
> > Feng
> >
>
> Then it'd be clearer if you move the check the start of the loop, so
> you can avoid two additional reads when the prev.on/sn is set. :-)
Good idea!
Thanks,
Feng
>
> Thanks
> Kevin
next prev parent reply other threads:[~2015-07-08 11:58 UTC|newest]
Thread overview: 155+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-24 5:18 [v3 00/15] Add VT-d Posted-Interrupts support Feng Wu
2015-06-24 5:18 ` [v3 01/15] Vt-d Posted-intterrupt (PI) design Feng Wu
2015-06-24 6:15 ` Meng Xu
2015-06-24 6:19 ` Wu, Feng
2015-07-08 7:21 ` Tian, Kevin
2015-07-08 7:29 ` Wu, Feng
2015-06-24 5:18 ` [v3 02/15] Add helper macro for X86_FEATURE_CX16 feature detection Feng Wu
2015-06-24 17:31 ` Andrew Cooper
2015-07-08 7:23 ` Tian, Kevin
2015-06-24 5:18 ` [v3 03/15] Add cmpxchg16b support for x86-64 Feng Wu
2015-06-24 18:35 ` Andrew Cooper
2015-07-08 7:06 ` Wu, Feng
2015-07-08 8:12 ` Jan Beulich
2015-07-08 8:33 ` Wu, Feng
2015-07-08 8:43 ` Jan Beulich
2015-07-08 8:50 ` Wu, Feng
2015-07-08 8:50 ` Andrew Cooper
2015-07-10 12:57 ` Jan Beulich
2015-06-24 5:18 ` [v3 04/15] iommu: Add iommu_intpost to control VT-d Posted-Interrupts feature Feng Wu
2015-06-25 9:06 ` Andrew Cooper
2015-06-25 9:47 ` Wu, Feng
2015-06-25 10:16 ` Andrew Cooper
2015-06-25 12:47 ` Wu, Feng
2015-07-08 7:30 ` Tian, Kevin
2015-06-24 5:18 ` [v3 05/15] vt-d: VT-d Posted-Interrupts feature detection Feng Wu
2015-06-25 10:21 ` Andrew Cooper
2015-06-25 13:02 ` Wu, Feng
2015-07-08 7:32 ` Tian, Kevin
2015-07-08 8:00 ` Wu, Feng
2015-06-24 5:18 ` [v3 06/15] vmx: Extend struct pi_desc to support VT-d Posted-Interrupts Feng Wu
2015-06-29 15:04 ` Andrew Cooper
2015-07-08 7:48 ` Tian, Kevin
2015-07-10 13:08 ` Jan Beulich
2015-07-15 2:40 ` Wu, Feng
2015-07-15 8:20 ` Jan Beulich
2015-07-15 8:26 ` Wu, Feng
2015-07-15 8:36 ` Jan Beulich
2015-07-15 8:43 ` Wu, Feng
2015-07-15 9:28 ` Jan Beulich
2015-07-15 9:30 ` Wu, Feng
2015-07-15 3:13 ` Wu, Feng
2015-06-24 5:18 ` [v3 07/15] vmx: Initialize VT-d Posted-Interrupts Descriptor Feng Wu
2015-06-29 15:32 ` Andrew Cooper
2015-06-30 1:46 ` Wu, Feng
2015-06-30 2:32 ` Dario Faggioli
2015-07-08 7:53 ` Tian, Kevin
2015-06-24 5:18 ` [v3 08/15] Suppress posting interrupts when 'SN' is set Feng Wu
2015-06-29 15:41 ` Andrew Cooper
2015-06-30 1:48 ` Wu, Feng
2015-07-08 9:06 ` Tian, Kevin
2015-07-08 10:11 ` Wu, Feng
2015-07-08 11:31 ` Tian, Kevin
2015-07-08 11:58 ` Wu, Feng [this message]
2015-07-10 13:20 ` Jan Beulich
2015-06-24 5:18 ` [v3 09/15] vt-d: Extend struct iremap_entry to support VT-d Posted-Interrupts Feng Wu
2015-06-29 16:04 ` Andrew Cooper
2015-06-30 1:52 ` Wu, Feng
2015-07-08 9:10 ` Tian, Kevin
2015-07-10 13:27 ` Jan Beulich
2015-06-24 5:18 ` [v3 10/15] vt-d: Add API to update IRTE when VT-d PI is used Feng Wu
2015-06-29 16:22 ` Andrew Cooper
2015-07-08 9:59 ` Tian, Kevin
2015-07-08 10:12 ` Wu, Feng
2015-07-10 14:01 ` Jan Beulich
2015-07-15 6:04 ` Wu, Feng
2015-07-15 8:24 ` Jan Beulich
2015-07-15 8:38 ` Wu, Feng
2015-07-15 8:46 ` Jan Beulich
2015-07-15 8:55 ` Wu, Feng
2015-07-15 9:32 ` Jan Beulich
2015-06-24 5:18 ` [v3 11/15] Update IRTE according to guest interrupt config changes Feng Wu
2015-06-29 16:46 ` Andrew Cooper
2015-07-08 10:22 ` Tian, Kevin
2015-07-08 10:31 ` Wu, Feng
2015-07-08 11:46 ` Tian, Kevin
2015-07-08 11:52 ` Wu, Feng
2015-07-08 11:54 ` Tian, Kevin
2015-07-10 14:23 ` Jan Beulich
2015-06-24 5:18 ` [v3 12/15] vmx: posted-interrupt handling when vCPU is blocked Feng Wu
2015-06-29 17:07 ` Andrew Cooper
2015-07-08 10:36 ` Wu, Feng
2015-07-08 10:48 ` Jan Beulich
[not found] ` <559181F9.6020106@citrix.com>
2015-06-30 2:51 ` Fwd: " Dario Faggioli
2015-06-30 2:59 ` Wu, Feng
2015-06-30 9:46 ` Dario Faggioli
2015-06-30 10:11 ` Andrew Cooper
2015-07-01 13:26 ` Dario Faggioli
2015-07-02 4:27 ` Wu, Feng
2015-07-02 8:30 ` Dario Faggioli
2015-07-02 8:58 ` Wu, Feng
2015-07-02 10:09 ` Dario Faggioli
2015-07-02 10:41 ` Wu, Feng
2015-07-02 10:30 ` Andrew Cooper
2015-07-02 10:56 ` Wu, Feng
2015-07-02 12:04 ` Dario Faggioli
2015-07-02 12:10 ` Wu, Feng
2015-07-02 12:16 ` Andrew Cooper
2015-07-02 12:38 ` Dario Faggioli
2015-07-02 12:59 ` Andrew Cooper
2015-07-03 1:33 ` Wu, Feng
2015-07-02 4:25 ` Wu, Feng
2015-07-08 11:00 ` Tian, Kevin
2015-07-08 11:02 ` Wu, Feng
2015-07-08 12:46 ` Jan Beulich
2015-07-08 13:09 ` Andrew Cooper
2015-07-08 22:49 ` Tian, Kevin
2015-07-09 7:25 ` Jan Beulich
2015-07-10 6:21 ` Wu, Feng
2015-07-10 6:32 ` Jan Beulich
2015-07-10 7:29 ` Wu, Feng
2015-07-10 8:49 ` Jan Beulich
2015-07-10 8:57 ` Wu, Feng
2015-07-08 22:31 ` Tian, Kevin
2015-06-24 5:18 ` [v3 13/15] vmx: Properly handle notification event when vCPU is running Feng Wu
2015-07-08 11:03 ` Tian, Kevin
2015-07-10 14:40 ` Jan Beulich
2015-06-24 5:18 ` [v3 14/15] Update Posted-Interrupts Descriptor during vCPU scheduling Feng Wu
[not found] ` <55918214.4030102@citrix.com>
2015-06-30 2:58 ` Fwd: " Dario Faggioli
2015-07-02 4:32 ` Wu, Feng
2015-07-02 4:34 ` Wu, Feng
2015-07-02 8:20 ` Dario Faggioli
2015-07-09 3:09 ` Wu, Feng
2015-07-09 8:18 ` Dario Faggioli
2015-07-09 11:19 ` George Dunlap
2015-07-09 11:29 ` George Dunlap
2015-07-09 11:38 ` Wu, Feng
2015-07-09 12:42 ` Dario Faggioli
2015-07-10 0:07 ` Wu, Feng
2015-07-10 12:40 ` Dario Faggioli
2015-07-10 13:47 ` Konrad Rzeszutek Wilk
2015-07-10 13:59 ` Dario Faggioli
2015-07-09 12:53 ` George Dunlap
2015-07-09 13:44 ` Jan Beulich
2015-07-09 14:18 ` Dario Faggioli
2015-07-09 14:27 ` George Dunlap
2015-07-09 14:47 ` Dario Faggioli
2015-07-10 5:59 ` Wu, Feng
2015-07-10 6:22 ` Jan Beulich
2015-07-10 11:05 ` Dario Faggioli
2015-07-14 5:44 ` Wu, Feng
2015-07-14 14:08 ` Wu, Feng
2015-07-14 14:54 ` Jan Beulich
2015-07-14 15:20 ` Dario Faggioli
2015-07-14 16:41 ` George Dunlap
2015-07-14 16:02 ` Dario Faggioli
2015-07-15 0:54 ` Wu, Feng
2015-07-17 7:46 ` Wu, Feng
2015-07-17 10:13 ` Dario Faggioli
2015-07-17 22:57 ` Wu, Feng
2015-07-18 13:43 ` Dario Faggioli
2015-07-10 0:15 ` Wu, Feng
2015-07-08 11:24 ` Tian, Kevin
2015-07-10 14:48 ` Jan Beulich
2015-06-24 5:18 ` [v3 15/15] Add a command line parameter for VT-d posted-interrupts Feng Wu
2015-07-08 11:25 ` Tian, Kevin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=E959C4978C3B6342920538CF579893F0025F92D8@SHSMSX104.ccr.corp.intel.com \
--to=feng.wu@intel.com \
--cc=andrew.cooper3@citrix.com \
--cc=george.dunlap@eu.citrix.com \
--cc=jbeulich@suse.com \
--cc=keir@xen.org \
--cc=kevin.tian@intel.com \
--cc=xen-devel@lists.xen.org \
--cc=yang.z.zhang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.