From: "Wu, Feng" <feng.wu@intel.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
"keir@xen.org" <keir@xen.org>,
"george.dunlap@eu.citrix.com" <george.dunlap@eu.citrix.com>,
"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
"Zhang, Yang Z" <yang.z.zhang@intel.com>,
"Wu, Feng" <feng.wu@intel.com>
Subject: Re: [v3 10/15] vt-d: Add API to update IRTE when VT-d PI is used
Date: Wed, 15 Jul 2015 06:04:41 +0000 [thread overview]
Message-ID: <E959C4978C3B6342920538CF579893F0026113FF@SHSMSX104.ccr.corp.intel.com> (raw)
In-Reply-To: <559FEC77020000780008F8DA@mail.emea.novell.com>
> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@suse.com]
> Sent: Friday, July 10, 2015 10:02 PM
> To: Wu, Feng
> Cc: andrew.cooper3@citrix.com; george.dunlap@eu.citrix.com; Tian, Kevin;
> Zhang, Yang Z; xen-devel@lists.xen.org; keir@xen.org
> Subject: Re: [v3 10/15] vt-d: Add API to update IRTE when VT-d PI is used
>
> >>> On 24.06.15 at 07:18, <feng.wu@intel.com> wrote:
> > This patch adds an API which is used to update the IRTE
> > for posted-interrupt when guest changes MSI/MSI-X information.
>
> This is again an example where adding a dead function complicates
> review: How will I know here why this statement is correct, namely
> why MSI/MSI-X are affected but IO-APIC isn't?
>
> > +int pi_update_irte(struct vcpu *v, struct pirq *pirq, uint8_t gvec)
> > +{
> > + struct irq_desc *desc;
> > + struct msi_desc *msi_desc;
> > + int remap_index;
> > + int rc = 0;
> > + struct pci_dev *pci_dev;
> > + struct acpi_drhd_unit *drhd;
> > + struct iommu *iommu;
> > + struct ir_ctrl *ir_ctrl;
> > + struct iremap_entry *iremap_entries = NULL, *p = NULL;
> > + struct iremap_entry new_ire;
> > + struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
>
> I suppose some of the pointers above could become pointers to
> const?
>
> > + unsigned long flags;
> > + uint128_t old_ire, ret;
> > +
> > + desc = pirq_spin_lock_irq_desc(pirq, NULL);
> > + if ( !desc )
> > + return -ENOMEM;
> > +
> > + msi_desc = desc->msi_desc;
> > + if ( !msi_desc )
> > + {
> > + rc = -EBADSLT;
> > + goto unlock_out;
> > + }
> > +
> > + pci_dev = msi_desc->dev;
> > + if ( !pci_dev )
> > + {
> > + rc = -ENODEV;
> > + goto unlock_out;
> > + }
> > +
> > + remap_index = msi_desc->remap_index;
> > + drhd = acpi_find_matched_drhd_unit(pci_dev);
> > + if ( !drhd )
> > + {
> > + rc = -ENODEV;
> > + goto unlock_out;
> > + }
> > +
> > + iommu = drhd->iommu;
> > + ir_ctrl = iommu_ir_ctrl(iommu);
> > + if ( !ir_ctrl )
> > + {
> > + rc = -ENODEV;
> > + goto unlock_out;
> > + }
> > +
> > + spin_lock_irqsave(&ir_ctrl->iremap_lock, flags);
>
> Interrupts are unconditionally disabled here already. Question
> though is whether you really need to hold on to the IRQ descriptor
> lock across the entire function. Much of course depends on what
> other locks you maybe imply to be held by the caller.
I search lots of current code where the irq desc lock is used, and
I think the unlock operate can be placed before acquiring iremap_lock.
>
> I'm particularly worried by the call to acpi_find_matched_drhd_unit()
> - is it maybe worth storing the iommu pointer in struct msi_desc?
I think it worth, Like Andrew also mentioned this point before. I tend
to make this a independent work and do it later, since the 4.6 release
is coming, I am still try my best to target it. Could you please share
your concern here, performance? Or other things? Thanks!
>
> > + GET_IREMAP_ENTRY(ir_ctrl->iremap_maddr, remap_index,
> iremap_entries, p);
> > + new_ire = *p;
> > +
> > + /* Setup/Update interrupt remapping table entry. */
> > + setup_posted_irte(&new_ire, pi_desc, gvec);
> > +
> > + do {
> > + old_ire = *(uint128_t *)p;
>
> This cast suggests that you might want to go beyond what Andrew
> said on cmpxchg16b()'s parameters: Perhaps they'd better be
> void * instead of uint128_t *.
In that case, I need to do the cast in __cmpxchg16b(), right?
>
> > + ret = cmpxchg16b(p, &old_ire, &new_ire);
> > + } while ( memcmp(&ret, &old_ire, sizeof(old_ire)) );
>
> Doesn't setup_posted_irte() need to move inside this loop, as it
> tries to preserve certain fields? Or else, what is the cmpxchg16b
> loop guarding against (i.e. why isn't this just a single one)?
Why need we move setup_posted_irte() inside the loop? "new_ire"
will not be changed after setup, right? Here we need to make sure
the 128b IRTE is updated atomically, especially for the high part
of posted-interrupt descriptor address and the low part of it.
Thanks,
Feng
>
> > + iommu_flush_cache_entry(p, sizeof(struct iremap_entry));
>
> sizeof(*p)
>
> Jan
next prev parent reply other threads:[~2015-07-15 6:04 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
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 [this message]
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
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