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From: Gerd Hoffmann <kraxel@redhat.com>
To: Annie Li <annie.li@oracle.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [PATCH 1/1] pcie: Do not set power state for some hot-plugged devices
Date: Wed, 15 Dec 2021 07:05:13 +0100	[thread overview]
Message-ID: <20211215060513.kugy3y32nj2te7ui@sirius.home.kraxel.org> (raw)
In-Reply-To: <20211214215312.944-1-annie.li@oracle.com>

On Tue, Dec 14, 2021 at 09:53:12PM +0000, Annie Li wrote:
> After the PCIe device is hot-plugged, the device's power state is
> initialized as ON. However, the device isn't powered on yet, i.e.
> the PCI_EXP_SYSCTL_PCC bit isn't set to PCI_EXP_SLTCTL_PWR_ON.
> Later on, its power state will set back to OFF due to the non
> PCI_EXP_SLTCTL_PWR_ON state. The device is invisible until
> PCI_EXP_SLTCTL_PWR_ON is set.
> 
> This may be appropriate for general PCIe hot-plug cases. However,
> if the device is hot-plugged when the VM is in VM_STATE_PRELAUNCH
> state, especially the system disk device, the firmware will fail
> to find the system disk. As a result, the guest fails to boot.

Maybe we should just not set DeviceState->hotplugged = true for devices
added in VM_STATE_PRELAUNCH?  It's not actual hotplug (i.e. device added
while the system is running) after all ...

There are lots of places checking DeviceState->hotplugged, and I suspect
we have similar issues elsewhere.

take care,
  Gerd



  reply	other threads:[~2021-12-15  6:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-14 21:53 [PATCH 1/1] pcie: Do not set power state for some hot-plugged devices Annie Li
2021-12-15  6:05 ` Gerd Hoffmann [this message]
2021-12-15 19:20   ` Annie.li
2021-12-16  6:11     ` Gerd Hoffmann
2021-12-16 23:10       ` Annie.li
2021-12-17  6:47         ` Gerd Hoffmann

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