From: "Michael S. Tsirkin" <mst@redhat.com>
To: Laszlo Ersek <lersek@redhat.com>
Cc: Marcel Apfelbaum <marcel@redhat.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v6 4/7] hw/pci-bridge: disable hotplug in PXB
Date: Wed, 17 Jun 2015 15:45:28 +0200 [thread overview]
Message-ID: <20150617154222-mutt-send-email-mst@redhat.com> (raw)
In-Reply-To: <1434545105-5811-5-git-send-email-lersek@redhat.com>
On Wed, Jun 17, 2015 at 02:45:02PM +0200, Laszlo Ersek wrote:
> OVMF downloads the ACPI linker/loader script from QEMU when the edk2 PCI
> Bus driver globally signals the firmware that PCI enumeration and resource
> allocation have completed. At this point QEMU regenerates the ACPI payload
> in an fw_cfg read callback, and this is when the PXB's _CRS gets
> populated.
>
> Unfortunately, when this happens, the PCI_COMMAND_MEMORY bit is clear in
> the root bus's command register, *unlike* under SeaBIOS. The consequences
> unfold as follows:
>
> - When build_crs() fetches dev->io_regions[i].addr, it is all-bits-one,
> because pci_update_mappings() --> pci_bar_address() calculated it as
> PCI_BAR_UNMAPPED, due to the PCI_COMMAND_MEMORY bit being clear.
>
> - Consequently, the SHPC MMIO BAR (bar 0) of the bridge is not added to
> the _CRS, *despite* having been programmed in PCI config space.
>
> - Similarly, the SHPC MMIO BAR of the PXB is not removed from the main
> root bus's DWordMemory descriptor.
>
> - Guest OSes (Linux and Windows alike) notice the pre-programmed SHPC BAR
> within the PXB's config space, and notice that it conflicts with the
> main root bus's memory resource descriptors. Linux reports
>
> pci 0000:04:00.0: BAR 0: can't assign mem (size 0x100)
> pci 0000:04:00.0: BAR 0: trying firmware assignment [mem
> 0x88200000-0x882000ff 64bit]
> pci 0000:04:00.0: BAR 0: [mem 0x88200000-0x882000ff 64bit] conflicts
> with PCI Bus 0000:00 [mem
> 0x88200000-0xfebfffff]
>
> While Windows Server 2012 R2 reports
>
> https://technet.microsoft.com/en-us/library/cc732199%28v=ws.10%29.aspx
>
> This device cannot find enough free resources that it can use. If you
> want to use this device, you will need to disable one of the other
> devices on this system. (Code 12)
>
> This issue was apparently encountered earlier, see the "hack" in:
>
> https://lists.nongnu.org/archive/html/qemu-devel/2015-01/msg02983.html
>
> and the current hole-punching logic in build_crs() and build_ssdt() is
> probably supposed to remedy exactly that problem -- however, for OVMF they
> don't work, because at the end of the PCI enumeration and resource
> allocation, which cues the ACPI linker/loader client, the command register
> is clear.
>
> The "hotplug" property of "pci-bridge", introduced in the previous
> patches, enables us to disable the standard hotplug controller cleanly,
> eliminating the SHPC bar and the conflict.
>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Marcel Apfelbaum <marcel@redhat.com>
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
>
> Notes:
> v6:
> - new in v6 (replaces "hw/pci-bridge: create interrupt-less,
> hotplug-less bridge for PXB" from v5) [Michael]
>
> hw/pci-bridge/pci_expander_bridge.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/hw/pci-bridge/pci_expander_bridge.c b/hw/pci-bridge/pci_expander_bridge.c
> index ec2bb45..4398d98 100644
> --- a/hw/pci-bridge/pci_expander_bridge.c
> +++ b/hw/pci-bridge/pci_expander_bridge.c
> @@ -176,6 +176,7 @@ static int pxb_dev_initfn(PCIDevice *dev)
> bds = qdev_create(BUS(bus), "pci-bridge");
> bds->id = dev_name;
> qdev_prop_set_uint8(bds, "chassis_nr", pxb->bus_nr);
BTW this is a bug: it will conflict with chassis_nr
on another bridge if user set it. Not related to this
patch of course.
> + qdev_prop_set_bit(bds, "hotplug", false);
>
> PCI_HOST_BRIDGE(ds)->bus = bus;
>
> --
> 1.8.3.1
>
next prev parent reply other threads:[~2015-06-17 13:45 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-17 12:44 [Qemu-devel] [PATCH v6 0/7] PXB changes Laszlo Ersek
2015-06-17 12:44 ` [Qemu-devel] [PATCH v6 1/7] migration: introduce VMSTATE_BUFFER_UNSAFE_INFO_TEST() Laszlo Ersek
2015-06-17 12:45 ` [Qemu-devel] [PATCH v6 2/7] hw/pci-bridge: expose _test parameter in SHPC_VMSTATE() Laszlo Ersek
2015-06-17 12:45 ` [Qemu-devel] [PATCH v6 3/7] hw/pci-bridge: introduce "hotplug" property Laszlo Ersek
2015-06-17 13:42 ` Michael S. Tsirkin
2015-06-17 13:55 ` Laszlo Ersek
2015-06-17 14:02 ` Michael S. Tsirkin
2015-06-17 14:15 ` Laszlo Ersek
2015-06-17 19:54 ` Marcel Apfelbaum
2015-06-18 13:47 ` Paolo Bonzini
2015-06-18 14:44 ` Michael S. Tsirkin
2015-06-17 12:45 ` [Qemu-devel] [PATCH v6 4/7] hw/pci-bridge: disable hotplug in PXB Laszlo Ersek
2015-06-17 13:45 ` Michael S. Tsirkin [this message]
2015-06-17 19:52 ` Marcel Apfelbaum
2015-06-17 12:45 ` [Qemu-devel] [PATCH v6 5/7] hw/core: rebase sysbus_get_fw_dev_path() to g_strdup_printf() Laszlo Ersek
2015-06-17 13:46 ` Michael S. Tsirkin
2015-06-17 13:56 ` Laszlo Ersek
2015-06-17 12:45 ` [Qemu-devel] [PATCH v6 6/7] hw/core: explicit OFW unit address callback for SysBusDeviceClass Laszlo Ersek
2015-06-17 12:45 ` [Qemu-devel] [PATCH v6 7/7] hw/pci-bridge: format SeaBIOS-compliant OFW device node for PXB Laszlo Ersek
2015-06-17 13:57 ` Michael S. Tsirkin
2015-06-17 14:00 ` Laszlo Ersek
2015-06-17 14:03 ` Michael S. Tsirkin
2015-06-17 14:18 ` Kevin O'Connor
2015-06-17 14:45 ` Laszlo Ersek
2015-06-17 15:05 ` Michael S. Tsirkin
2015-06-17 18:16 ` Laszlo Ersek
2015-06-17 18:54 ` Michael S. Tsirkin
2015-06-17 19:15 ` Laszlo Ersek
2015-06-17 19:28 ` Kevin O'Connor
2015-06-17 19:32 ` Michael S. Tsirkin
2015-06-17 19:44 ` Laszlo Ersek
2015-06-17 21:50 ` Michael S. Tsirkin
2015-06-18 13:22 ` Laszlo Ersek
2015-06-18 13:40 ` Michael S. Tsirkin
2015-06-18 15:42 ` Laszlo Ersek
2015-06-17 19:09 ` Kevin O'Connor
2015-06-17 19:21 ` Michael S. Tsirkin
2015-06-17 19:35 ` Laszlo Ersek
2015-06-17 21:49 ` Michael S. Tsirkin
2015-06-18 13:18 ` Laszlo Ersek
2015-06-17 19:38 ` Kevin O'Connor
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