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Date:   Mon, 11 Dec 2023 08:46:04 +0100
From:   Igor Mammedov <imammedo@redhat.com>
To:     Bjorn Helgaas <helgaas@kernel.org>
Cc:     Fiona Ebner <f.ebner@proxmox.com>, linux-pci@vger.kernel.org,
        linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
        bhelgaas@google.com, lenb@kernel.org, rafael@kernel.org,
        Thomas Lamprecht <t.lamprecht@proxmox.com>
Subject: Re: SCSI hotplug issues with UEFI VM with guest kernel >= 6.5
Message-ID: <20231211084604.25e209af@imammedo.users.ipa.redhat.com>
In-Reply-To: <20231208164723.12828a96@imammedo.users.ipa.redhat.com>
References: <9eb669c0-d8f2-431d-a700-6da13053ae54@proxmox.com>
        <20231207232815.GA771837@bhelgaas>
        <20231208164723.12828a96@imammedo.users.ipa.redhat.com>
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On Fri, 8 Dec 2023 16:47:23 +0100
Igor Mammedov <imammedo@redhat.com> wrote:

> On Thu, 7 Dec 2023 17:28:15 -0600
> Bjorn Helgaas <helgaas@kernel.org> wrote:
> 
> > On Wed, Nov 29, 2023 at 04:22:41PM +0100, Fiona Ebner wrote:  
> > > Hi,
> > > it seems that hot-plugging SCSI disks for QEMU virtual machines booting
> > > with UEFI and with guest kernels >= 6.5 might be broken. It's not
> > > consistently broken, hinting there might be a race somewhere.
> > > 
> > > Reverting the following two commits seems to make it work reliably again:
> > > 
> > > cc22522fd55e2 ("PCI: acpiphp: Use
> > > pci_assign_unassigned_bridge_resources() only for non-root bus")
> > > 40613da52b13f ("PCI: acpiphp: Reassign resources on bridge if necessary"
> > > 
> > > Of course, they might only expose some pre-existing issue, but this is
> > > my best lead. See below for some logs and details about an affected
> > > virtual machine. Happy to provide more information and to debug/test
> > > further.
> > > ...    
> >   
> > > I've attached some logs for guest using kernel 6.7.0-rc3 where hotplug
> > > works rarely and guest using kernel 6.7.0-rc3 with the previously
> > > mentioned commits reverted where hotplug works reliably:
> > > 
> > > 6.7.0-rc3:
> > >     
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:01:02.0: [1af4:1004] type 00 class 0x010000
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:01:02.0: reg 0x10: [io  0x0000-0x003f]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:01:02.0: reg 0x14: [mem 0x00000000-0x00000fff]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:01:02.0: reg 0x20: [mem 0x00000000-0x00003fff 64bit pref]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:01:02.0: BAR 4: assigned [mem 0xc000004000-0xc000007fff 64bit pref]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:01:02.0: BAR 1: assigned [mem 0xc1401000-0xc1401fff]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:01:02.0: BAR 0: assigned [io  0xe040-0xe07f]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:00:05.0: PCI bridge to [bus 01]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:00:05.0:   bridge window [io  0xe000-0xefff]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc1400000-0xc15fffff]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc000000000-0xc01fffffff 64bit pref]
> > > > Nov 29 15:12:02 hotplug kernel: virtio-pci 0000:01:02.0: enabling device (0000 -> 0003)
> > > > Nov 29 15:12:02 hotplug kernel: ACPI: \_SB_.LNKC: Enabled at IRQ 11
> > > > Nov 29 15:12:02 hotplug kernel: scsi host3: Virtio SCSI HBA
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:00:05.0: PCI bridge to [bus 01]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:00:05.0:   bridge window [io  0xe000-0xefff]
> > > > Nov 29 15:12:02 hotplug kernel: scsi 3:0:0:1: Direct-Access     QEMU     QEMU HARDDISK    2.5+ PQ: 0 ANSI: 5
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc1400000-0xc15fffff]
> > > > Nov 29 15:12:02 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc000000000-0xc01fffffff 64bit pref]     
> > 
> > What's the actual symptom that this is broken?  All these log
> > fragments show the exact same assignments for BARs 0, 1, 4 and for the
> > bridge windows.
> > 
> > I assume 0000:01:02.0 is the hot-added SCSI HBA, and 00:05.0 is a
> > bridge leading to it?
> > 
> > Can you put the complete dmesg logs somewhere?  There's a lot of
> > context missing here.
> > 
> > Do you have to revert both cc22522fd55e2 and 40613da52b13f to make it
> > work reliably?  If we have to revert something, reverting one would be
> > better than reverting both.  
> 
> here is simplified reproducer:
> ./qemu-system-x86_64 -enable-kvm -m 4G -smp 4 -cpu host                        \
>     /dev/lvmpool/fedora-rawhide                                                \
>     -device pci-bridge,id=pci.3,chassis_nr=3,bus=pci.0,addr=0x5                \
>     -device virtio-scsi-pci,id=virtioscsi0,bus=pci.3,addr=0x1                  \
>     -blockdev raw,file.driver=file,file.filename=Fedora-Server-dvd-x86_64-Rawhide-20231127.n.0.iso,node-name=drive-scsi1 \
>     -monitor stdio -serial file:/tmp/console_log
> 
> then once booted at monitor prompt:
> 
> (qemu) device_add virtio-scsi-pci,bus=pci.3,addr=2,id=virtioscsi1
> (qemu) device_add scsi-hd,id=scsi1,drive=drive-scsi1,bus=virtioscsi1.0
> 
> with distro shipped 6.7.0-0.rc2.20231125git0f5cc96c367f.26.fc40.x86_64 kernel
> hotplugged HBA is visible but a disk hotplugged into it is not (like Fiona has reported).
> 
> Problem happens when hotpluged virtio-scsi-pci is the 2nd HBA on the same bridge,
> an attempt to rescan HBA (any on the bridge) causes guest hang.
> 
> 
> However with the same 0f5cc96c367f commit, upstream kernel (without initrd and some minimal config):
> 
>  -kernel ./linux-2.6/arch/x86_64/boot/bzImage -append 'root=/dev/sda3 console=ttyS0 console=tty0'
> 
> works as expected (aka disk is visible after hotplug)
> 
> [   75.636170] pci 0000:01:02.0: [1af4:1004] type 00 class 0x010000
> [   75.636178] pci 0000:01:02.0: reg 0x10: [io  0x0000-0x003f]
> [   75.637193] pci 0000:01:02.0: reg 0x14: [mem 0x00000000-0x00000fff]
> [   75.638441] pci 0000:01:02.0: reg 0x20: [mem 0x00000000-0x00003fff 64bit pref]
> [   75.647035] pci 0000:01:02.0: BAR 4: assigned [mem 0x380800004000-0x380800007fff 64bit pref]
> [   75.649461] pci 0000:01:02.0: BAR 1: assigned [mem 0xfe801000-0xfe801fff]
> [   75.650793] pci 0000:01:02.0: BAR 0: assigned [io  0xc040-0xc07f]
> [   75.652109] pci 0000:00:05.0: PCI bridge to [bus 01]
> [   75.653181] pci 0000:00:05.0:   bridge window [io  0xc000-0xcfff]
> [   75.656971] pci 0000:00:05.0:   bridge window [mem 0xfe800000-0xfe9fffff]
> [   75.659970] pci 0000:00:05.0:   bridge window [mem 0x380800000000-0x380fffffffff 64bit pref]
> [   75.664990] virtio-pci 0000:01:02.0: enabling device (0000 -> 0003)
> [   75.695505] scsi host3: Virtio SCSI HBA
> [   75.698099] pci 0000:00:05.0: PCI bridge to [bus 01]
> [   75.735840] pci 0000:00:05.0:   bridge window [io  0xc000-0xcfff]
> [   75.740361] pci 0000:00:05.0:   bridge window [mem 0xfe800000-0xfe9fffff]
> [   75.744088] pci 0000:00:05.0:   bridge window [mem 0x380800000000-0x380fffffffff 64bit pref]
> 
> 
> So, I'm still looking at where/why it goes wrong

I've narrowed it down to ACPI PCI hotpug, (i.e. it works fine with SHPC and Fedora's kernel).
Though I still can't reproduce with upstream kernel (even with Fedora config (mod=yes)).
So far I was testing Seabios variant, next thing to try is UEFI setup (perhaps upstream will fail there)

Fiona,

Does it help if you use q35 machine with '-global ICH9-LPC.acpi-pci-hotplug-with-bridge-support=off' option?

> 
> > Bjorn
> >   
> > > Reboot
> > >     
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:01:02.0: [1af4:1004] type 00 class 0x010000
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:01:02.0: reg 0x10: [io  0x0000-0x003f]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:01:02.0: reg 0x14: [mem 0x00000000-0x00000fff]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:01:02.0: reg 0x20: [mem 0x00000000-0x00003fff 64bit pref]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:01:02.0: BAR 4: assigned [mem 0xc000004000-0xc000007fff 64bit pref]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:01:02.0: BAR 1: assigned [mem 0xc1401000-0xc1401fff]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:01:02.0: BAR 0: assigned [io  0xe040-0xe07f]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:00:05.0: PCI bridge to [bus 01]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:00:05.0:   bridge window [io  0xe000-0xefff]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc1400000-0xc15fffff]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc000000000-0xc01fffffff 64bit pref]
> > > > Nov 29 15:12:52 hotplug kernel: virtio-pci 0000:01:02.0: enabling device (0000 -> 0003)
> > > > Nov 29 15:12:52 hotplug kernel: ACPI: \_SB_.LNKC: Enabled at IRQ 11
> > > > Nov 29 15:12:52 hotplug kernel: scsi host3: Virtio SCSI HBA
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:00:05.0: PCI bridge to [bus 01]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:00:05.0:   bridge window [io  0xe000-0xefff]
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc1400000-0xc15fffff]
> > > > Nov 29 15:12:52 hotplug kernel: scsi 3:0:0:1: Direct-Access     QEMU     QEMU HARDDISK    2.5+ PQ: 0 ANSI: 5
> > > > Nov 29 15:12:52 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc000000000-0xc01fffffff 64bit pref]    
> > > 
> > > RebootThe one time it did work. Note that the line with "QEMU HARDDISK"
> > > comes after all lines with "bridge window":
> > >     
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:01:02.0: [1af4:1004] type 00 class 0x010000
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:01:02.0: reg 0x10: [io  0x0000-0x003f]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:01:02.0: reg 0x14: [mem 0x00000000-0x00000fff]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:01:02.0: reg 0x20: [mem 0x00000000-0x00003fff 64bit pref]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:01:02.0: BAR 4: assigned [mem 0xc000004000-0xc000007fff 64bit pref]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:01:02.0: BAR 1: assigned [mem 0xc1401000-0xc1401fff]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:01:02.0: BAR 0: assigned [io  0xe040-0xe07f]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:00:05.0: PCI bridge to [bus 01]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:00:05.0:   bridge window [io  0xe000-0xefff]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc1400000-0xc15fffff]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc000000000-0xc01fffffff 64bit pref]
> > > > Nov 29 15:13:51 hotplug kernel: virtio-pci 0000:01:02.0: enabling device (0000 -> 0003)
> > > > Nov 29 15:13:51 hotplug kernel: ACPI: \_SB_.LNKC: Enabled at IRQ 11
> > > > Nov 29 15:13:51 hotplug kernel: scsi host3: Virtio SCSI HBA
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:00:05.0: PCI bridge to [bus 01]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:00:05.0:   bridge window [io  0xe000-0xefff]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc1400000-0xc15fffff]
> > > > Nov 29 15:13:51 hotplug kernel: pci 0000:00:05.0:   bridge window [mem 0xc000000000-0xc01fffffff 64bit pref]
> > > > Nov 29 15:13:51 hotplug kernel: scsi 3:0:0:1: Direct-Access     QEMU     QEMU HARDDISK    2.5+ PQ: 0 ANSI: 5
> > > > Nov 29 15:13:51 hotplug kernel: sd 3:0:0:1: Attached scsi generic sg1 type 0
> > > > Nov 29 15:13:51 hotplug kernel: sd 3:0:0:1: Power-on or device reset occurred
> > > > Nov 29 15:13:51 hotplug kernel: sd 3:0:0:1: [sdb] 2048 512-byte logical blocks: (1.05 MB/1.00 MiB)
> > > > Nov 29 15:13:51 hotplug kernel: sd 3:0:0:1: [sdb] Write Protect is off
> > > > Nov 29 15:13:51 hotplug kernel: sd 3:0:0:1: [sdb] Mode Sense: 63 00 00 08
> > > > Nov 29 15:13:51 hotplug kernel: sd 3:0:0:1: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
> > > > Nov 29 15:13:51 hotplug kernel: sd 3:0:0:1: [sdb] Attached SCSI disk
> > > > Nov 29 15:14:08 hotplug systemd[1]: systemd-fsckd.service: Deactivated successfully.    
> > > 
> > > 6.7.0-rc3 with the following reverted:
> > > cc22522fd55e2 ("PCI: acpiphp: Use
> > > pci_assign_unassigned_bridge_resources() only for non-root bus")
> > > 40613da52b13f ("PCI: acpiphp: Reassign resources on bridge if necessary")
> > >     
> > > > Nov 29 15:15:37 hotplug kernel: pci 0000:01:02.0: [1af4:1004] type 00 class 0x010000
> > > > Nov 29 15:15:37 hotplug kernel: pci 0000:01:02.0: reg 0x10: [io  0x0000-0x003f]
> > > > Nov 29 15:15:37 hotplug kernel: pci 0000:01:02.0: reg 0x14: [mem 0x00000000-0x00000fff]
> > > > Nov 29 15:15:37 hotplug kernel: pci 0000:01:02.0: reg 0x20: [mem 0x00000000-0x00003fff 64bit pref]
> > > > Nov 29 15:15:37 hotplug kernel: pci 0000:01:02.0: BAR 4: assigned [mem 0xc000004000-0xc000007fff 64bit pref]
> > > > Nov 29 15:15:37 hotplug kernel: pci 0000:01:02.0: BAR 1: assigned [mem 0xc1401000-0xc1401fff]
> > > > Nov 29 15:15:37 hotplug kernel: pci 0000:01:02.0: BAR 0: assigned [io  0xe040-0xe07f]
> > > > Nov 29 15:15:37 hotplug kernel: virtio-pci 0000:01:02.0: enabling device (0000 -> 0003)
> > > > Nov 29 15:15:37 hotplug kernel: ACPI: \_SB_.LNKC: Enabled at IRQ 11
> > > > Nov 29 15:15:37 hotplug kernel: scsi host3: Virtio SCSI HBA
> > > > Nov 29 15:15:37 hotplug kernel: scsi 3:0:0:1: Direct-Access     QEMU     QEMU HARDDISK    2.5+ PQ: 0 ANSI: 5
> > > > Nov 29 15:15:37 hotplug kernel: sd 3:0:0:1: Attached scsi generic sg1 type 0
> > > > Nov 29 15:15:37 hotplug kernel: sd 3:0:0:1: Power-on or device reset occurred
> > > > Nov 29 15:15:37 hotplug kernel: sd 3:0:0:1: [sdb] 2048 512-byte logical blocks: (1.05 MB/1.00 MiB)
> > > > Nov 29 15:15:37 hotplug kernel: sd 3:0:0:1: [sdb] Write Protect is off
> > > > Nov 29 15:15:37 hotplug kernel: sd 3:0:0:1: [sdb] Mode Sense: 63 00 00 08
> > > > Nov 29 15:15:37 hotplug kernel: sd 3:0:0:1: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
> > > > Nov 29 15:15:37 hotplug kernel: sd 3:0:0:1: [sdb] Attached SCSI disk
> > > > Nov 29 15:15:38 hotplug systemd[1]: systemd-fsckd.service: Deactivated successfully.    
> > >     
> >   
>