Re: [PULL v3 05/19] hw/acpi/ich9: Set ACPI PCI hot-plug as default on Q35

[Igor Mammedov]

On Tue, 20 Jul 2021 14:56:06 +0200
Laurent Vivier <lvivier@redhat.com> wrote:

> On 20/07/2021 13:38, Laurent Vivier wrote:
> > On 16/07/2021 17:15, Michael S. Tsirkin wrote:  
> >> From: Julia Suvorova <jusual@redhat.com>
> >>
> >> Q35 has three different types of PCI devices hot-plug: PCIe Native,
> >> SHPC Native and ACPI hot-plug. This patch changes the default choice
> >> for cold-plugged bridges from PCIe Native to ACPI Hot-plug with
> >> ability to use SHPC and PCIe Native for hot-plugged bridges.
> >>
> >> This is a list of the PCIe Native hot-plug issues that led to this
> >> change:
> >>     * no racy behavior during boot (see 110c477c2ed)
> >>     * no delay during deleting - after the actual power off software
> >>       must wait at least 1 second before indicating about it. This case
> >>       is quite important for users, it even has its own bug:
> >>           https://bugzilla.redhat.com/show_bug.cgi?id=1594168
> >>     * no timer-based behavior - in addition to the previous example,
> >>       the attention button has a 5-second waiting period, during which
> >>       the operation can be canceled with a second press. While this
> >>       looks fine for manual button control, automation will result in
> >>       the need to queue or drop events, and the software receiving
> >>       events in all sort of unspecified combinations of attention/power
> >>       indicator states, which is racy and uppredictable.
> >>     * fixes:
> >>         * https://bugzilla.redhat.com/show_bug.cgi?id=1752465
> >>         * https://bugzilla.redhat.com/show_bug.cgi?id=1690256
> >>
> >> To return to PCIe Native hot-plug:
> >>     -global ICH9-LPC.acpi-pci-hotplug-with-bridge-support=off
> >>
> >> Known issue: older linux guests need the following flag
> >> to allow hotplugged pci express devices to use io:
> >>         -device pcie-root-port,io-reserve=4096.
> >> io is unusual for pci express so this seems minor.
> >> We'll fix this by a follow up patch.
> >>
> >> Signed-off-by: Julia Suvorova <jusual@redhat.com>
> >> Reviewed-by: Igor Mammedov <imammedo@redhat.com>
> >> Message-Id: <20210713004205.775386-6-jusual@redhat.com>
> >> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> >> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> >> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> >> ---
> >>  hw/acpi/ich9.c | 2 +-
> >>  hw/i386/pc.c   | 1 +
> >>  2 files changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
> >> index 2f4eb453ac..778e27b659 100644
> >> --- a/hw/acpi/ich9.c
> >> +++ b/hw/acpi/ich9.c
> >> @@ -427,7 +427,7 @@ void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs 
> >> *pm)
> >>      pm->disable_s3 = 0;
> >>      pm->disable_s4 = 0;
> >>      pm->s4_val = 2;
> >> -    pm->use_acpi_hotplug_bridge = false;
> >> +    pm->use_acpi_hotplug_bridge = true;
> >>  
> >>      object_property_add_uint32_ptr(obj, ACPI_PM_PROP_PM_IO_BASE,
> >>                                     &pm->pm_io_base, OBJ_PROP_FLAG_READ);
> >> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> >> index aa79c5e0e6..f4c7a78362 100644
> >> --- a/hw/i386/pc.c
> >> +++ b/hw/i386/pc.c
> >> @@ -99,6 +99,7 @@ GlobalProperty pc_compat_6_0[] = {
> >>      { "qemu64" "-" TYPE_X86_CPU, "model", "6" },
> >>      { "qemu64" "-" TYPE_X86_CPU, "stepping", "3" },
> >>      { TYPE_X86_CPU, "x-vendor-cpuid-only", "off" },
> >> +    { "ICH9-LPC", "acpi-pci-hotplug-with-bridge-support", "off" },
> >>  };
> >>  const size_t pc_compat_6_0_len = G_N_ELEMENTS(pc_compat_6_0);
> >>  
> >>  
> > 
> > There is an issue with this patch.
> > 
> > When I try to unplug a VFIO device I have the following error and the 
> > device is not unplugged:
> > 
> > (qemu) device_del hostdev0
> > 
> > [   34.116714] ACPI BIOS Error (bug): Could not resolve symbol [^S0B.PCNT], 
> > AE_NOT_FOUND
> > (20201113/psargs-330)
> > [   34.117987] ACPI Error: Aborting method \_SB.PCI0.PCNT due to previous 
> > error
> > (AE_NOT_FOUND) (20201113/psparse-531)
> > [   34.119318] ACPI Error: Aborting method \_GPE._E01 due to previous error 
> > (AE_NOT_FOUND)
> > (20201113/psparse-531)
> > [   34.120600] ACPI Error: AE_NOT_FOUND, while evaluating GPE method [_E01]
> > (20201113/evgpe-515)
> > 
> > We can see device is not unplugged (03:00.0)
> > 
> > # lspci -v -s 03:00.0
> > 03:00.0 Ethernet controller: Intel Corporation Ethernet Virtual Function 
> > 700 Series (rev 02)
> >     Subsystem: Intel Corporation Device 0000
> >     Flags: bus master, fast devsel, latency 0
> >     Memory at fe800000 (64-bit, prefetchable) [size=64K]
> >     Memory at fe810000 (64-bit, prefetchable) [size=16K]
> >     Capabilities: [70] MSI-X: Enable+ Count=5 Masked-
> >     Capabilities: [a0] Express Endpoint, MSI 00
> >     Capabilities: [100] Advanced Error Reporting
> >     Capabilities: [1a0] Transaction Processing Hints
> >     Capabilities: [1d0] Access Control Services
> >     Kernel driver in use: iavf
> >     Kernel modules: iavf
> > 
> > My guest kernel is from RHEL 8.5 (4.18.0-310.el8.x86_64) and my command 
> > line is:
> > 
> > $QEMU \
> > -L .../pc-bios \
> > -nodefaults \
> > -nographic \
> > -machine q35 \
> > -device 
> > pcie-root-port,id=pcie-root-port-0,multifunction=on,bus=pcie.0,addr=0x1,chassis=1
> >  \
> > -device pcie-pci-bridge,id=pcie-pci-bridge-0,addr=0x0,bus=pcie-root-port-0  
> > \
> > -device 
> > pcie-root-port,id=pcie-root-port-1,port=0x1,addr=0x1.0x1,bus=pcie.0,chassis=2
> >  \
> > -device 
> > pcie-root-port,id=pcie-root-port-2,port=0x2,addr=0x1.0x2,bus=pcie.0,chassis=3
> >  \
> > -device 
> > pcie-root-port,id=pcie-root-port-3,port=0x3,addr=0x1.0x3,bus=pcie.0,chassis=4
> >  \
> > -device
> > pcie-root-port,id=pcie_extra_root_port_0,multifunction=on,bus=pcie.0,addr=0x3,chassis=5
> >  \
> > -nodefaults \
> > -m 4066  \
> > -smp 4 \
> > -device virtio-scsi-pci,id=virtio_scsi_pci0,bus=pcie-root-port-2,addr=0x0 \
> > -blockdev
> > node-name=file_image1,driver=file,auto-read-only=on,discard=unmap,aio=threads,filename=$IMAGE,cache.direct=on,cache.no-fl\
> > -blockdev
> > node-name=drive_image1,driver=qcow2,read-only=off,cache.direct=on,cache.no-flush=off,file=file_image1
> > \
> > -device scsi-hd,id=image1,drive=drive_image1,write-cache=on \
> > -enable-kvm \
> > -serial mon:stdio \
> > -device vfio-pci,host=04:02.0,bus=pcie-root-port-1,addr=0x0,id=hostdev0
> > 
> > PCI 04:02.0 is:
> > 
> > $ lspci -v -s 04:02.0
> > 04:02.0 Ethernet controller: Intel Corporation Ethernet Virtual Function 
> > 700 Series (rev 02)
> >     Subsystem: Intel Corporation Device 0000
> >     Flags: fast devsel, NUMA node 0, IOMMU group 53
> >     Memory at 92400000 (64-bit, prefetchable) [virtual] [size=64K]
> >     Memory at 92910000 (64-bit, prefetchable) [virtual] [size=16K]
> >     Capabilities: <access denied>
> >     Kernel driver in use: vfio-pci
> >     Kernel modules: iavf
> > 
> > Any idea?  
> 
> It also happens with non-VFIO device like e1000e:
> 
> ...
> -device e1000e,bus=pcie-root-port-1,addr=0x0,id=hostdev0 \
                     ^^^^^^^^^^^^^
ACPI hotplug operates on slot level, so functions greater than 0 are not 
considered,
hence unexpected ACPI error. For above CLI, setting 'addr' on root-ports to 
dedicated slots
should fix issue.

The same will happen on PC machine if you assign bridge to any function other 
than 0.

Following should fix ACPI error:

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 17836149fe..e2345bd7d0 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -527,7 +527,7 @@ static void build_append_pci_bus_devices(Aml *parent_scope, 
PCIBus *bus,
             QLIST_FOREACH(sec, &bus->child, sibling) {
                 int32_t devfn = sec->parent_dev->devfn;
 
-                if (pci_bus_is_root(sec)) {
+                if (pci_bus_is_root(sec) || PCI_FUNC(devfn)) {
                     continue;
                 }

but unplug request will stay ignored if root port/bridge is not on function 0.

> ...
> device_del hostdev0
> 
> [   40.275904] ACPI BIOS Error (bug): Could not resolve symbol [^S0B.PCNT], 
> AE_NOT_FOUND
> (20201113/psargs-330)
> [   40.277189] ACPI Error: Aborting method \_SB.PCI0.PCNT due to previous 
> error
> (AE_NOT_FOUND) (20201113/psparse-531)
> [   40.278529] ACPI Error: Aborting method \_GPE._E01 due to previous error 
> (AE_NOT_FOUND)
> (20201113/psparse-531)
> [   40.279819] ACPI Error: AE_NOT_FOUND, while evaluating GPE method [_E01]
> (20201113/evgpe-515)
> 
> # lspci -v -s 03:00.0
> 03:00.0 Ethernet controller: Intel Corporation 82574L Gigabit Network 
> Connection
>       Subsystem: Intel Corporation Device 0000
>       Flags: bus master, fast devsel, latency 0, IRQ 21
>       Memory at fdc40000 (32-bit, non-prefetchable) [size=128K]
>       Memory at fdc60000 (32-bit, non-prefetchable) [size=128K]
>       I/O ports at c000 [size=32]
>       Memory at fdc80000 (32-bit, non-prefetchable) [size=16K]
>       Expansion ROM at fdc00000 [disabled] [size=256K]
>       Capabilities: [c8] Power Management version 2
>       Capabilities: [d0] MSI: Enable- Count=1/1 Maskable- 64bit+
>       Capabilities: [e0] Express Endpoint, MSI 00
>       Capabilities: [a0] MSI-X: Enable+ Count=5 Masked-
>       Capabilities: [100] Advanced Error Reporting
>       Capabilities: [140] Device Serial Number 52-54-00-ff-ff-12-34-56
>       Kernel driver in use: e1000e
>       Kernel modules: e1000e
> 
> Thanks,
> Laurent
>