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From: "Jan Beulich" <JBeulich@suse.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH 1/4] x86/vMSI-X: defer intercept handler registration
Date: Fri, 17 Jun 2016 10:38:30 -0600	[thread overview]
Message-ID: <576443A602000078000F6445@prv-mh.provo.novell.com> (raw)
In-Reply-To: <20160617161358.GM1340@char.us.oracle.com>

>>> On 17.06.16 at 18:13, <konrad.wilk@oracle.com> wrote:
> On Wed, Jun 08, 2016 at 06:52:58AM -0600, Jan Beulich wrote:
>> There's no point in registering the internal MSI-X table intercept
>> functions on all domains - it is sufficient to do so once a domain gets
>> an MSI-X capable device assigned.
> 
> I think this will break on SR-IOV devices that are created and we
> had not setup MCFG.

How does MCFG get into the picture here? (And anyway, this series
is about vMSI-X, not host MSI-X.)

> There is this Intel board (which I have) where the MCFG is setup
> only via ACPI and in the past we had issues - where we never
> detect that the VF had MSI-X - b/c we could not access the
> configuration registers past 0xff.

The MSI-X capability necessarily lives in the low 256 bytes. Do you
mean the SR-IOV capability?

> I am pretty sure that Linux now uploads the MCFG data during
> bootup from the ACPI AML code, but earlier kernels may not.
> 
> And that would mean the device would try to use MSI-X while
> code would be !pdev->msix.
> 
> Hmm, thought I wonder - with all those improvements of capturing
> the MSI-X and validating it in the hypervisor - would this
> even matter?
> 
> Let me stash an 82576 card in that box and see what happens with
> Xen 4.7.

Thanks.

Jan


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  reply	other threads:[~2016-06-17 16:38 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-08 12:48 [PATCH 0/4] x86/vMSI-X: misc improvements Jan Beulich
2016-06-08 12:52 ` [PATCH 1/4] x86/vMSI-X: defer intercept handler registration Jan Beulich
2016-06-17 16:13   ` Konrad Rzeszutek Wilk
2016-06-17 16:38     ` Jan Beulich [this message]
2016-06-21 17:11   ` Andrew Cooper
2016-06-08 12:53 ` [PATCH 2/4] x86/vMSI-X: drop list lock Jan Beulich
2016-06-21 17:26   ` Andrew Cooper
2016-06-08 12:54 ` [PATCH 3/4] x86/vMSI-X: drop pci_msix_get_table_len() Jan Beulich
2016-06-21 17:27   ` Andrew Cooper
2016-06-08 12:54 ` [PATCH 4/4] x86/vMSI-X: use generic intercept handler in place of MMIO one Jan Beulich
2016-06-13  8:36   ` Paul Durrant
2016-06-21 17:33   ` Andrew Cooper
2016-06-17  8:20 ` Ping: [PATCH 0/4] x86/vMSI-X: misc improvements Jan Beulich

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