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Re: [PATCH v7 12/12] hw/acpi: Make the PCI hot-plug aware of SR-IOV
From: |
Igor Mammedov |
Subject: |
Re: [PATCH v7 12/12] hw/acpi: Make the PCI hot-plug aware of SR-IOV |
Date: |
Thu, 31 Mar 2022 14:38:41 +0200 |
On Fri, 18 Mar 2022 20:18:19 +0100
Lukasz Maniak <lukasz.maniak@linux.intel.com> wrote:
> From: Łukasz Gieryk <lukasz.gieryk@linux.intel.com>
>
> PCI device capable of SR-IOV support is a new, still-experimental
> feature with only a single working example of the Nvme device.
>
> This patch in an attempt to fix a double-free problem when a
> SR-IOV-capable Nvme device is hot-unplugged. The problem and the
> reproduction steps can be found in this thread:
>
> https://patchew.org/QEMU/20220217174504.1051716-1-lukasz.maniak@linux.intel.com/20220217174504.1051716-14-lukasz.maniak@linux.intel.com/
pls include that in patch description.
> Details of the proposed solution are, for convenience, included below.
>
> 1) The current SR-IOV implementation assumes it’s the PhysicalFunction
> that creates and deletes VirtualFunctions.
> 2) It’s a design decision (the Nvme device at least) for the VFs to be
> of the same class as PF. Effectively, they share the dc->hotpluggable
> value.
> 3) When a VF is created, it’s added as a child node to PF’s PCI bus
> slot.
> 4) Monitor/device_del triggers the ACPI mechanism. The implementation is
> not aware of SR/IOV and ejects PF’s PCI slot, directly unrealizing all
> hot-pluggable (!acpi_pcihp_pc_no_hotplug) children nodes.
> 5) VFs are unrealized directly, and it doesn’t work well with (1).
> SR/IOV structures are not updated, so when it’s PF’s turn to be
> unrealized, it works on stale pointers to already-deleted VFs.
it's unclear what's bing hotpluged and unplugged, it would be better if
you included QEMU CLI and relevan qmp/monito commands to reproduce it.
>
> Signed-off-by: Łukasz Gieryk <lukasz.gieryk@linux.intel.com>
> ---
> hw/acpi/pcihp.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
> index 6351bd3424d..248839e1110 100644
> --- a/hw/acpi/pcihp.c
> +++ b/hw/acpi/pcihp.c
> @@ -192,8 +192,12 @@ static bool acpi_pcihp_pc_no_hotplug(AcpiPciHpState *s,
> PCIDevice *dev)
> * ACPI doesn't allow hotplug of bridge devices. Don't allow
> * hot-unplug of bridge devices unless they were added by hotplug
> * (and so, not described by acpi).
> + *
> + * Don't allow hot-unplug of SR-IOV Virtual Functions, as they
> + * will be removed implicitly, when Physical Function is unplugged.
> */
> - return (pc->is_bridge && !dev->qdev.hotplugged) || !dc->hotpluggable;
> + return (pc->is_bridge && !dev->qdev.hotplugged) || !dc->hotpluggable ||
> + pci_is_vf(dev);
> }
>
> static void acpi_pcihp_eject_slot(AcpiPciHpState *s, unsigned bsel, unsigned
> slots)
- [PATCH v7 05/12] hw/nvme: Make max_ioqpairs and msix_qsize configurable in runtime, (continued)
- [PATCH v7 05/12] hw/nvme: Make max_ioqpairs and msix_qsize configurable in runtime, Lukasz Maniak, 2022/03/18
- [PATCH v7 04/12] hw/nvme: Implement the Function Level Reset, Lukasz Maniak, 2022/03/18
- [PATCH v7 02/12] hw/nvme: Add support for Primary Controller Capabilities, Lukasz Maniak, 2022/03/18
- [PATCH v7 06/12] hw/nvme: Remove reg_size variable and update BAR0 size calculation, Lukasz Maniak, 2022/03/18
- [PATCH v7 07/12] hw/nvme: Calculate BAR attributes in a function, Lukasz Maniak, 2022/03/18
- [PATCH v7 08/12] hw/nvme: Initialize capability structures for primary/secondary controllers, Lukasz Maniak, 2022/03/18
- [PATCH v7 09/12] hw/nvme: Add support for the Virtualization Management command, Lukasz Maniak, 2022/03/18
- [PATCH v7 10/12] docs: Add documentation for SR-IOV and Virtualization Enhancements, Lukasz Maniak, 2022/03/18
- [PATCH v7 11/12] hw/nvme: Update the initalization place for the AER queue, Lukasz Maniak, 2022/03/18
- [PATCH v7 12/12] hw/acpi: Make the PCI hot-plug aware of SR-IOV, Lukasz Maniak, 2022/03/18
- Re: [PATCH v7 12/12] hw/acpi: Make the PCI hot-plug aware of SR-IOV,
Igor Mammedov <=