RE: [Xen-devel][VTD][PATCH][RESEND]add a timer for the sharedinterrupt issue for vt-d - Xin, Xiaohui - com.xensource.lists.xen-devel

8 messages in com.xensource.lists.xen-develRE: [Xen-devel][VTD][PATCH][RESEND]ad...

From	Sent On	Attachments
Xin, Xiaohui	17 Oct 2007 06:44	.diff
Keir Fraser	18 Oct 2007 02:35
Xin, Xiaohui	18 Oct 2007 20:46	.diff
Keir Fraser	19 Oct 2007 03:24
Xin, Xiaohui	20 Oct 2007 04:04
Xin, Xiaohui	20 Oct 2007 04:09
Keir Fraser	20 Oct 2007 04:23
Xin, Xiaohui	20 Oct 2007 04:32

Subject:	RE: [Xen-devel][VTD][PATCH][RESEND]add a timer for the sharedinterrupt issue for vt-d
From:	Xin, Xiaohui (xiao...@intel.com)
Date:	10/20/2007 04:09:39 AM
List:	com.xensource.lists.xen-devel

Sorry, last mail, For 2) there still one or more interrupt CAN NOT be scheduled
for HVM after “is_paused_by_controller” changed

Thanks

Xiaohui.

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From: Xin, Xiaohui Sent: 2007年10月20日 19:05 To: 'Keir Fraser'; xen-...@lists.xensource.com Subject: RE: [Xen-devel][VTD][PATCH][RESEND]add a timer for the sharedinterrupt
issue for vt-d

Keir,

For 1) I have changes the hvm_pci_intx_assert() to be untouched. The reason is
that, I want to get the result of the hvm_pci_intx_assert() since I think I
could get some hints of the failure of the assertion quickly, and I do get the
hints, so in the patches sent out before, I just do pirq_guest_eoi() quickly.
But from your response, seems you don’t like any change to the
hvm_pci_intx_assert(). So I think another way, I can still use timer to deal
with that though that it should be a little slower to call pirq_guest_eoi() at
last, you know, in that situation, if the assert failure, the timer will be
functional still.

For 2) Yes, firstly I think to use the flag of the domain as
“is_pasued_by_controller”, but from the experience and from the log file, at the
situation which IDE shares interrupt with NIC card, and when the NIC is assigned
to HVM guest, “is pasued_by_controller” can deal with most cases, but after
unpaused, there are still one or more interrupts can be scheduled. The
“is_paused_by_controller” can not deal with all the cases. So I still use timer
to deal with that because timer is simple.

Any other comments?

Thanks

Xiaohui

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From: xen-...@lists.xensource.com
[mailto:xen-...@lists.xensource.com] On Behalf Of Keir Fraser Sent: 2007年10月19日 18:25 To: Xin, Xiaohui; xen-...@lists.xensource.com Subject: Re: [Xen-devel][VTD][PATCH][RESEND]add a timer for the sharedinterrupt
issue for vt-d

Applied, but I have the following questions:

1. Your changes to hvm_pci_intx_assert() have completely disappeared. Did you
decide you didn’t need them after all, or have you simply resolved to do without
them to get the patch in more quickly? 2. You set_timer() in hvm_do_IRQ_dpci(). Why is this necessary, given that
vmx_dirq_assist() does the same, and should run shortly after since you
vcpu_kick()? Is this to solve the delay between assigning a device to a new HVM
guest and when that HVM guest gets unpaused after it is fully constructed? In
that case we would be better to bail from hvm_do_IRQ_dpci() if the domain
‘is_paused_by_controller’, and return 0.

Thanks, Keir

On 19/10/07 04:46, "Xin, Xiaohui" <xiao...@intel.com> wrote:

Keir, Thanks for your points. This is the updated patch. I have fixed 1,2,3,4 of your
comments.

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From: Keir Fraser [mailto:Keir...@cl.cam.ac.uk]
<mailto:Keir...@cl.cam.ac.uk%5d> Sent: 2007年10月18日 17:36 To: Xin, Xiaohui; xen-...@lists.xensource.com Subject: Re: [Xen-devel][VTD][RESEND]add a timer for the shared interrupt issue
for vt-d

Getting better, some more points: 1. The timeout values are bizarrely non-round (8192000). Do you really need 4
significant figures of precision? Do you really mean for an 8ms timeout? It
would then be better to define as MILLISECS(8). Much clearer as it shows the
units. 2. You can’t stick timer_hvm[] in the generic common domain.c. It belongs in
the hvm_irq_dpci structure, making it clear it is HVM-specific, and also meaning
that memory for the array is only allocated for those domains that actually have
devices passed through to them. 3. The extra argument to hvm_dpci_eoi() is used only to decide whether to
stop_timer() or not. You’re aware you can call stop_timer() quite safely from
within the timeout callback handler? I think that means this extra argument is
unnecessary. 4. The comment added to hvm_pci_intx_assert() is delightfully vague. Also I
think it may be wrong ― do you really mean “before the driver loading, the
vioapic redir entry may be unmasked”?

So you need another spin. I’m still unconvinced that the hvm_pci_intx_assert()
changes are the right way to go, but I need to consider the patch some more to
see if there is a cleaner way. If there is I will modify the patch myself before
I check it in. The other points listed above you need to address yourself.

-- Keir

On 17/10/07 14:44, "Xin, Xiaohui" <xiao...@intel.com> wrote: Keir, It’s a resending patch for the timeout mechanism to deal with the shared
interrupt issue for vt-d enabled hvm guest. We modify the patch following your comments last time and make some other small
fix: 1) We don’t touch the locking around the hvm_dpci_eoi(). 2) Remove the HZ from the TIME_OUT_PERIOD macro which may confuse others. 3) Add some explanation to the return value for the hvm_pci_intx_assert(),
and the has_timer parameter for the hvm_dpci_eoi. We have tested it with shared interrupt between dom0/HVM(pcie/disk) and
HVM/HVM(pcie/pcie).

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