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Bug 2224472 - [RFE] Request to expose pcie-root-port's mem-reserve option
Summary: [RFE] Request to expose pcie-root-port's mem-reserve option
Keywords:
Status: CLOSED MIGRATED
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: libvirt
Version: 9.3
Hardware: All
OS: Linux
unspecified
medium
Target Milestone: rc
: ---
Assignee: Virtualization Maintenance
QA Contact: Meina Li
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2023-07-21 03:53 UTC by Yanghang Liu
Modified: 2024-01-21 04:26 UTC (History)
11 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2023-09-22 17:20:37 UTC
Type: Story
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker   RHEL-7461 0 None Migrated None 2023-09-22 17:20:31 UTC
Red Hat Issue Tracker RHELPLAN-162932 0 None None None 2023-07-21 03:53:36 UTC

Description Yanghang Liu 2023-07-21 03:53:10 UTC 
Description of problem:
Currently we need to setup pcie root port's mem-reserve property if we want to hot-plug the non-prefetchable PF/VF whose memory bar > 2MP into the domain 

Considering that hot-plugging a PF/VF into domain is a basic use case, we expect to expose pcie-root-port's mem-reserve property in upper-layer products.

How reproducible:
100%

Steps to Reproduce:
(1) Choose a non-prefetchable + memory bar size> 2M PF for testing

# lspci -v -s 0000:1a:00.1
1a:00.1 Ethernet controller: Solarflare Communications SFC9220 10/40G Ethernet Controller (rev 02)
        Subsystem: Solarflare Communications SFN8522-R2 8000 Series 10G Adapter
        Flags: bus master, fast devsel, latency 0, IRQ 363, NUMA node 0, IOMMU group 34
        I/O ports at 4000 [size=256]
        Memory at 9d800000 (64-bit, non-prefetchable) [size=8M]
        Memory at a6800000 (64-bit, non-prefetchable) [size=16K]
        Expansion ROM at a6a80000 [disabled] [size=256K]
        Capabilities: [40] Power Management version 3
        Capabilities: [70] Express Endpoint, MSI 00
        Capabilities: [b0] MSI-X: Enable+ Count=32 Masked-
        Capabilities: [d0] Vital Product Data
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [148] Device Serial Number 00-0f-53-ff-ff-4d-8c-30
        Capabilities: [158] Alternative Routing-ID Interpretation (ARI)
        Capabilities: [198] Single Root I/O Virtualization (SR-IOV)
        Capabilities: [1d8] Transaction Processing Hints
        Kernel driver in use: sfc
        Kernel modules: sfc

(2) start a Q35 + OVMF domain

# virt-install --machine=q35 --noreboot --name=rhel93 --memory=4096 --vcpus=4 --graphics type=vnc,port=5993,listen=0.0.0.0 --boot=uefi --network bridge=switch,model=virtio,mac=52:54:00:00:93:93 --import --noautoconsole --disk path=/home/images/RHEL93.qcow2,bus=virtio,cache=none,format=qcow2,io=threads,size=20 --osinfo detect=on,require=off

(3) hot-plug a XL710 PF into domain
# /bin/virsh attach-device rhel93 /tmp/device/0000:1a:00.1.xml

(4) check if the SFC9220 PF can be hot-plug into the domain

# ifconfig  <--- There is not any output about SFC9220 PF info 

# dmesg 
[   38.986998] pci 0000:04:00.0: [1924:0a03] type 00 class 0x020000
[   38.988300] pci 0000:04:00.0: reg 0x10: [io  0x0000-0x00ff]
[   38.989381] pci 0000:04:00.0: reg 0x18: [mem 0x00000000-0x007fffff 64bit]
[   38.990229] pci 0000:04:00.0: reg 0x20: [mem 0x00000000-0x00003fff 64bit]
[   38.990523] pci 0000:04:00.0: reg 0x30: [mem 0x00000000-0x0003ffff pref]
[   38.991142] pci 0000:04:00.0: Max Payload Size set to 128 (was 256, max 1024)
[   38.994702] pci 0000:04:00.0: supports D1 D2
[   39.001323] pci 0000:04:00.0: BAR 2: no space for [mem size 0x00800000 64bit]
[   39.001330] pci 0000:04:00.0: BAR 2: failed to assign [mem size 0x00800000 64bit]
[   39.001335] pci 0000:04:00.0: BAR 6: assigned [mem 0xc2400000-0xc243ffff pref]
[   39.001340] pci 0000:04:00.0: BAR 4: assigned [mem 0xc2440000-0xc2443fff 64bit]
[   39.001808] pci 0000:04:00.0: BAR 0: assigned [io  0x4000-0x40ff]
[   39.073706] Solarflare NET driver
[   39.074273] sfc 0000:04:00.0: Solarflare NIC detected
[   39.081769] sfc 0000:04:00.0: Part Number : SFN8522
[   39.081804] sfc 0000:04:00.0: enabling device (0000 -> 0003)
[   39.084283] sfc 0000:04:00.0: ERROR: No BAR2 mapping from the BIOS. Try pci=realloc on the kernel command line

（5）If we can setup pcie-root-port's mem-reserve value to 16M, the SFC9220 PF can be hot-plugged into the domain successfully.

The detailed test step is in https://bugzilla.redhat.com/show_bug.cgi?id=2055123#c31



Actual results:
Failed to setup pcie-root-port's mem-reserve option via libvirt domain xml

Expected results:
We can setup pcie-root-port's mem-reserve option via libvirt domain xml



Additional info:
(1) This bug is opened based on https://bugzilla.redhat.com/show_bug.cgi?id=2055123#c32


(2) The related qemu-kvm cmd line is like:
-device '{"driver":"pcie-root-port","port":16,"chassis":1,"id":"pci.1","bus":"pcie.0","multifunction":true,"addr":"0x2"}' \
...
-device '{"driver":"pcie-root-port","port":20,"chassis":5,"id":"pci.5","mem-reserve":16777216,"bus":"pcie.0","addr":"0x2.0x4"}' \
-device '{"driver":"pcie-root-port","port":21,"chassis":6,"id":"pci.6","mem-reserve":16777216,"bus":"pcie.0","addr":"0x2.0x5"}' \
Comment 2 Michal Privoznik 2023-07-25 08:05:21 UTC 
Adding the knob should be fairly trivial. But what I am wondering about is how users know the value to pass, or - whether there is an automated way for libvirt to select the correct value automagically, without user intervention (which then might create a problem on its own, e.g. during migration because I bet this knob is part of guest ABI). Gerd? Igor?
Comment 3 Gerd Hoffmann 2023-08-23 09:22:24 UTC 
(In reply to Michal Privoznik from comment #2)
> Adding the knob should be fairly trivial. But what I am wondering about is
> how users know the value to pass, or - whether there is an automated way for
> libvirt to select the correct value automagically, without user intervention
> (which then might create a problem on its own, e.g. during migration because
> I bet this knob is part of guest ABI). Gerd? Igor?

I don't think there is an easy way to do this automatically.  This is needed
for hotplugging devices with large mmio bars (large memory bars are essentially
solved with the dynamic mmio window changes).  So you have to look at the device
you want eventually hotplug into the guest to figure the size needed.

Coldplugged devices are no problem, for those the firmware can adjust the bridge
windows as needed automatically.
Comment 4 RHEL Program Management 2023-09-22 17:18:56 UTC 
Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.
Comment 5 RHEL Program Management 2023-09-22 17:20:37 UTC 
This BZ has been automatically migrated to the issues.redhat.com Red Hat Issue Tracker. All future work related to this report will be managed there.

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Comment 6 Red Hat Bugzilla 2024-01-21 04:26:00 UTC 
The needinfo request[s] on this closed bug have been removed as they have been unresolved for 120 days
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