| Message ID | 20210617190739.3673064-7-jusual@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Use ACPI PCI hot-plug for Q35 | expand |
On Thu, Jun 17, 2021 at 10:08 PM Julia Suvorova <jusual@redhat.com> wrote: > 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. > > I personally think the best of all worlds is to have as default: - Native PCIe hotplug for pcie-root-ports - ACPI hotplug for devices behind PCI bridges (pcie-pci bridge or pci-pci bridge). Having ACPI hotplug *as default* for pcie-root-ports seems weird even if it solves existing bugs (we should solve them...). I am not against having a property to force ACPI hotplug even for pcie root-ports, just not being the default. It doesn't have to be part of this series, it can be a patch on top. I would leave APCI hotplug as an option and not as the default, giving us time to test it, come up with a fix for the pcie-hotplug race and a patch for allowing ACPI hotplug only for the bridges. Thanks, Marcel > 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 > > Signed-off-by: Julia Suvorova <jusual@redhat.com> > Reviewed-by: Igor Mammedov <imammedo@redhat.com> > --- > 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 bcbd567cb0..daa3cd44b1 100644 > --- a/hw/acpi/ich9.c > +++ b/hw/acpi/ich9.c > @@ -424,7 +424,7 @@ 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 c6d8d0d84d..cc10589552 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -98,6 +98,7 @@ GlobalProperty pc_compat_6_0[] = { > { "qemu64" "-" TYPE_X86_CPU, "family", "6" }, > { "qemu64" "-" TYPE_X86_CPU, "model", "6" }, > { "qemu64" "-" TYPE_X86_CPU, "stepping", "3" }, > + { "ICH9-LPC", "acpi-pci-hotplug-with-bridge-support", "off" }, > }; > const size_t pc_compat_6_0_len = G_N_ELEMENTS(pc_compat_6_0); > > -- > 2.30.2 > >
diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c index bcbd567cb0..daa3cd44b1 100644 --- a/hw/acpi/ich9.c +++ b/hw/acpi/ich9.c @@ -424,7 +424,7 @@ 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 c6d8d0d84d..cc10589552 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -98,6 +98,7 @@ GlobalProperty pc_compat_6_0[] = { { "qemu64" "-" TYPE_X86_CPU, "family", "6" }, { "qemu64" "-" TYPE_X86_CPU, "model", "6" }, { "qemu64" "-" TYPE_X86_CPU, "stepping", "3" }, + { "ICH9-LPC", "acpi-pci-hotplug-with-bridge-support", "off" }, }; const size_t pc_compat_6_0_len = G_N_ELEMENTS(pc_compat_6_0);
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 Signed-off-by: Julia Suvorova <jusual@redhat.com> Reviewed-by: Igor Mammedov <imammedo@redhat.com> --- hw/acpi/ich9.c | 2 +- hw/i386/pc.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-)