Bug 503818

Created attachment 346317 [details]
Give Dom0 access to machine e820 map

In order for a Physical Function driver to create Virtual Function devices
the PCI subsystem needs to access the extended capabilities for the PF.   
The exteneded capabilities are only accessible through the MMCONFIG PCI
access method.  Although the RHEL 5.4 kernel tries to use MMCONFIG this
access method fails for the Dom0 kernel because the Dom0 kernel is using
a PV E820 map that only maps RAM.  When the PCI subsystem tries to verify
that the MMCONFIG address is reserved in the E820 map it fails (the      
MMCONFI address space is not in the PV map).  This patch solves this problem
by giving Dom0 access to the real E820 map.                                 
                                           
Upstream status: Accepted (CS 26 of the Xen Dom0 kernel)
                                                        
Signed-off-by: Don Dugger <donald.d.dugger>

Fixed the summary to be a little more descriptive.

I'm a bit concerned about putting this into 5.4 at this stage.  I'm not against the patch per-se, just against the timing.  It changes a pretty fundamental thing in the way that dom0 works, and since it is going to miss beta, it's going to miss out partner testing on a variety of different hardware, which I consider a pre-requisite to having this in 5.4.

Chris Lalancette

Don't we also need similar changes to the 32-bit arch/i386/kernel/setup-xen.c code?

And agreed with Chris, this would seem to be very risky going in post-beta, since e820 changes are something that we really want to see get the broadest possible hardware testing on.

Release note added. If any revisions are required, please set the 
"requires_release_notes" flag to "?" and edit the "Release Notes" field accordingly.
All revisions will be proofread by the Engineering Content Services team.

New Contents:
The release note that gets generated for this needs to be highlighted, per RHEL meeting discussion.

in kernel-2.6.18-154.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Please do NOT transition this bugzilla state to VERIFIED until our QE team
has sent specific instructions indicating when to do so.  However feel free
to provide a comment indicating that this fix has been verified.

~~ Attention - RHEL 5.4 Beta Released! ~~

RHEL 5.4 Beta has been released! There should be a fix present in the Beta release that addresses this particular request. Please test and report back results here, at your earliest convenience. RHEL 5.4 General Availability release is just around the corner!

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~~ Attention Partners - RHEL 5.4 Snapshot 1 Released! ~~

RHEL 5.4 Snapshot 1 has been released on partners.redhat.com. If you have already reported your test results, you can safely ignore this request. Otherwise, please notice that there should be a fix available now that addresses this particular request. Please test and report back your results here, at your earliest convenience. The RHEL 5.4 exception freeze is quickly approaching.

If you encounter any issues while testing Beta, please describe the issues you have encountered and set the bug into NEED_INFO. If you encounter new issues, please clone this bug to open a new issue and request it be reviewed for inclusion in RHEL 5.4 or a later update, if it is not of urgent severity.

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The proposed release notes in comment 1 for BZ 480376 actually apply to this BZ but I've added a release note that addresses the specific issue in this BZ.

Release note updated. If any revisions are required, please set the 
"requires_release_notes"  flag to "?" and edit the "Release Notes" field accordingly.
All revisions will be proofread by the Engineering Content Services team.

Diffed Contents:
@@ -1 +1,11 @@
-The release note that gets generated for this needs to be highlighted, per RHEL meeting discussion.+Boot parameter required to enable Virtual Function devices.
+
+Virtual Function devices can only be access if the parameter `pci_pt_e820_access=on' is added to the boot stanza in the `/boot/grub/grub.conf' file, e.g.:
+
+title Red Hat Enterprise Linux Server (2.6.18-152.el5xen)
+        root (hd0,1)
+        kernel /xen.gz-2.6.18-152.el5 com1=115200,8n1 console=com1 iommu=1
+        module /vmlinuz-2.6.18-152.el5xen ro root=LABEL=/ console=ttyS0,115200
+pci_pt_e820_access=on
+
+This will enable the MMCONF access methode to the PCI configuration space, a requirement for VF device support

Excellent, thanks Don!

Should the release note contain "SRIOV" somewhere?

Good point, I've updated the release not to include SR/IOV.

Release note updated. If any revisions are required, please set the 
"requires_release_notes"  flag to "?" and edit the "Release Notes" field accordingly.
All revisions will be proofread by the Engineering Content Services team.

Diffed Contents:
@@ -1,6 +1,6 @@
-Boot parameter required to enable Virtual Function devices.
+Boot parameter required to enable SR/IOV Virtual Function devices.
 
-Virtual Function devices can only be access if the parameter `pci_pt_e820_access=on' is added to the boot stanza in the `/boot/grub/grub.conf' file, e.g.:
+SR/IOV Virtual Function devices can only be access if the parameter `pci_pt_e820_access=on' is added to the boot stanza in the `/boot/grub/grub.conf' file, e.g.:
 
 title Red Hat Enterprise Linux Server (2.6.18-152.el5xen)
         root (hd0,1)

Release note updated. If any revisions are required, please set the 
"requires_release_notes"  flag to "?" and edit the "Release Notes" field accordingly.
All revisions will be proofread by the Engineering Content Services team.

Diffed Contents:
@@ -1,11 +1,9 @@
-Boot parameter required to enable SR/IOV Virtual Function devices.
+Boot parameters are required to enable SR/IOV Virtual Function devices. SR/IOV Virtual Function devices can only be accessed if the parameter pci_pt_e820_access=on is added to the boot stanza in the /boot/grub/grub.conf file. For example:
 
-SR/IOV Virtual Function devices can only be access if the parameter `pci_pt_e820_access=on' is added to the boot stanza in the `/boot/grub/grub.conf' file, e.g.:
-
 title Red Hat Enterprise Linux Server (2.6.18-152.el5xen)
         root (hd0,1)
         kernel /xen.gz-2.6.18-152.el5 com1=115200,8n1 console=com1 iommu=1
         module /vmlinuz-2.6.18-152.el5xen ro root=LABEL=/ console=ttyS0,115200
 pci_pt_e820_access=on
 
-This will enable the MMCONF access methode to the PCI configuration space, a requirement for VF device support+This enables the MMCONF access method for the PCI configuration space, a requirement for VF device support.

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2009-1243.html