From: "Roger Pau Monné" <roger.pau@citrix.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "Nakajima, Jun" <jun.nakajima@intel.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Jan Beulich <jbeulich@suse.com>, Wei Liu <wl@xen.org>,
Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [Xen-devel] [PATCH 2/3] x86/nvmx: clarify and fix usage of nvmx_update_apicv
Date: Tue, 24 Mar 2020 13:18:31 +0100 [thread overview]
Message-ID: <20200324121831.GL24458@Air-de-Roger.citrite.net> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19D7E629A@SHSMSX104.ccr.corp.intel.com>
On Tue, Mar 24, 2020 at 11:33:00AM +0000, Tian, Kevin wrote:
> > From: Roger Pau Monné <roger.pau@citrix.com>
> > Sent: Tuesday, March 24, 2020 7:23 PM
> >
> > On Tue, Mar 24, 2020 at 10:11:15AM +0000, Tian, Kevin wrote:
> > > > From: Roger Pau Monné <roger.pau@citrix.com>
> > > > Sent: Tuesday, March 24, 2020 5:51 PM
> > > >
> > > > On Tue, Mar 24, 2020 at 06:03:28AM +0000, Tian, Kevin wrote:
> > > > > > From: Roger Pau Monne <roger.pau@citrix.com>
> > > > > > Sent: Saturday, March 21, 2020 3:08 AM
> > > > > >
> > > > > > The current usage of nvmx_update_apicv is not clear: it is deeply
> > > > > > intertwined with the Ack interrupt on exit VMEXIT control.
> > > > > >
> > > > > > The code in nvmx_update_apicv should update the SVI (in service
> > > > interrupt)
> > > > > > field of the guest interrupt status only when the Ack interrupt on
> > > > > > exit is set, as it is used to record that the interrupt being
> > > > > > serviced is signaled in a vmcs field, and hence hasn't been injected
> > > > > > as on native. It's important to record the current in service
> > > > > > interrupt on the guest interrupt status field, or else further
> > > > > > interrupts won't respect the priority of the in service one.
> > > > > >
> > > > > > While clarifying the usage make sure that the SVI is only updated
> > when
> > > > > > Ack on exit is set and the nested vmcs interrupt info field is valid. Or
> > > > > > else a guest not using the Ack on exit feature would loose interrupts
> > as
> > > > > > they would be signaled as being in service on the guest interrupt
> > > > > > status field but won't actually be recorded on the interrupt info vmcs
> > > > > > field, neither injected in any other way.
> > > > >
> > > > > It is insufficient. You also need to update RVI to enable virtual injection
> > > > > when Ack on exit is cleared.
> > > >
> > > > But RVI should be updated in vmx_intr_assist in that case, since
> > > > nvmx_intr_intercept shouldn't intercept the interrupt, as it should be
> > > > handled normally.
> > >
> > > As we discussed before, vmx_intr_assist is invoked before
> > nvmx_switch_guest.
> > >
> > > It is incorrectly to update RVI at that time since it might be still vmcs02
> > being
> > > active (if no pending softirq to make it invoked again).
> > >
> > > Also nvmx_intr_intercept does intercept Ack-on-exit=0 case:
> > >
> > > if ( intack.source == hvm_intsrc_pic ||
> > > intack.source == hvm_intsrc_lapic )
I've realized that nvmx_intr_intercept will return 1 for interrupts
originating from the lapic or the pic, while nvmx_update_apicv will
only update GUEST_INTR_STATUS for interrupts originating from the
lapic. Is this correct?
Shouldn't both be in sync and handle the same interrupt sources?
Thanks, Roger.
next prev parent reply other threads:[~2020-03-24 12:19 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 19:07 [Xen-devel] [PATCH 0/3] x86/nvmx: attempt to fix interrupt injection Roger Pau Monne
2020-03-20 19:07 ` [Xen-devel] [PATCH 1/3] Revert "x86/vvmx: fix virtual interrupt injection when Ack on exit control is used" Roger Pau Monne
2020-03-23 8:09 ` Jan Beulich
2020-03-23 14:48 ` Roger Pau Monné
2020-03-24 5:41 ` Tian, Kevin
2020-03-24 8:10 ` Jan Beulich
2020-03-24 8:49 ` Tian, Kevin
2020-03-24 10:47 ` Roger Pau Monné
2020-03-24 11:00 ` Tian, Kevin
2020-03-20 19:07 ` [Xen-devel] [PATCH 2/3] x86/nvmx: clarify and fix usage of nvmx_update_apicv Roger Pau Monne
2020-03-24 6:03 ` Tian, Kevin
2020-03-24 9:50 ` Roger Pau Monné
2020-03-24 10:11 ` Tian, Kevin
2020-03-24 11:22 ` Roger Pau Monné
2020-03-24 11:33 ` Tian, Kevin
2020-03-24 12:18 ` Roger Pau Monné [this message]
2020-03-26 5:49 ` Tian, Kevin
2020-03-20 19:07 ` [Xen-devel] [PATCH 3/3] x86/nvmx: update exit bitmap on vmexit Roger Pau Monne
2020-03-24 6:22 ` Tian, Kevin
2020-03-24 9:59 ` Roger Pau Monné
2020-03-24 10:16 ` Tian, Kevin
2020-03-24 11:24 ` Roger Pau Monné
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