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Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not
From: |
David Gibson |
Subject: |
Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready |
Date: |
Thu, 22 Oct 2020 23:56:32 +1100 |
On Thu, 22 Oct 2020 08:06:55 -0400
"Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Thu, Oct 22, 2020 at 02:40:26PM +0300, Marcel Apfelbaum wrote:
> > From: Marcel Apfelbaum <marcel@redhat.com>
> >
> > During PCIe Root Port's transition from Power-Off to Power-ON (or
> > vice-versa)
> > the "Slot Control Register" has the "Power Indicator Control"
> > set to "Blinking" expressing a "power transition" mode.
> >
> > Any hotplug operation during the "power transition" mode is not permitted
> > or at least not expected by the Guest OS leading to strange failures.
> >
> > Detect and refuse hotplug operations in such case.
> >
> > Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> > ---
> > hw/pci/pcie.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> > index 5b48bae0f6..2fe5c1473f 100644
> > --- a/hw/pci/pcie.c
> > +++ b/hw/pci/pcie.c
> > @@ -410,6 +410,7 @@ void pcie_cap_slot_pre_plug_cb(HotplugHandler
> > *hotplug_dev, DeviceState *dev,
> > PCIDevice *hotplug_pdev = PCI_DEVICE(hotplug_dev);
> > uint8_t *exp_cap = hotplug_pdev->config + hotplug_pdev->exp.exp_cap;
> > uint32_t sltcap = pci_get_word(exp_cap + PCI_EXP_SLTCAP);
> > + uint32_t sltctl = pci_get_word(exp_cap + PCI_EXP_SLTCTL);
> >
> > /* Check if hot-plug is disabled on the slot */
> > if (dev->hotplugged && (sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
> > @@ -418,6 +419,12 @@ void pcie_cap_slot_pre_plug_cb(HotplugHandler
> > *hotplug_dev, DeviceState *dev,
> > return;
> > }
> >
> > + if ((sltctl & PCI_EXP_SLTCTL_PIC) == PCI_EXP_SLTCTL_PWR_IND_BLINK) {
> > + error_setg(errp, "Hot-plug failed: %s is in Power Transition",
> > + DEVICE(hotplug_pdev)->id);
> > + return;
> > + }
> > +
> > pcie_cap_slot_plug_common(PCI_DEVICE(hotplug_dev), dev, errp);
> > }
>
> Probably the only way to handle for existing machine types.
> For new ones, can't we queue it in host memory somewhere?
I'm not actually convinced we can't do that even for existing machine
types. So I'm a bit hesitant to suggest going ahead with this without
looking a bit closer at whether we can implement a wait-for-ready in
qemu, rather than forcing every user of qemu (human or machine) to do
so.
--
David Gibson <dgibson@redhat.com>
Principal Software Engineer, Virtualization, Red Hat
pgpeSaiFilfdF.pgp
Description: OpenPGP digital signature
- [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Marcel Apfelbaum, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Michael S. Tsirkin, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready,
David Gibson <=
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Marcel Apfelbaum, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Michael S. Tsirkin, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Marcel Apfelbaum, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Michael S. Tsirkin, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Marcel Apfelbaum, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Michael S. Tsirkin, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, David Gibson, 2020/10/22
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Marcel Apfelbaum, 2020/10/23