On Fri, Nov 12, 2021 at 4:41 PM Igor Mammedov wrote:
>
> From: Julia Suvorova
>
> There are two ways to enable ACPI PCI Hot-plug:
>
> * Disable the Hot-plug Capable bit on PCIe slots.
>
> This was the first approach which led to regression [1-2], as
> I/O space for a port is allocated only when it is hot-pluggable,
> which is determined by HPC bit.
>
> * Leave the HPC bit on and disable PCIe Native Hot-plug in _OSC
> method.
>
> This removes the (future) ability of hot-plugging switches with PCIe
> Native hotplug since ACPI PCI Hot-plug only works with cold-plugged
> bridges. If the user wants to explicitely use this feature, they can
> disable ACPI PCI Hot-plug with:
> --global ICH9-LPC.acpi-pci-hotplug-with-bridge-support=off
>
> Change the bit in _OSC method so that the OS selects ACPI PCI Hot-plug
> instead of PCIe Native.
>
> [1] https://gitlab.com/qemu-project/qemu/-/issues/641
> [2] https://bugzilla.redhat.com/show_bug.cgi?id=2006409
>
> Signed-off-by: Julia Suvorova
> Signed-off-by: Igor Mammedov
Reviewed-by: Ani Sinha
> ---
> v2:
> - (mst)
> * drop local hotplug var and opencode it
> * rename acpi_pcihp parameter to enable_native_pcie_hotplug
> to reflect what it actually does
>
> tested:
> with hotplugging nic into 1 root port with seabios/ovmf/Fedora34
> Windows tested only with seabios (using exiting images)
> (installer fails to install regardless on bios)
> ---
> hw/i386/acpi-build.c | 12
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index a3ad6abd33..a99c6e4fe3 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1337,7 +1337,7 @@ static void build_x86_acpi_pci_hotplug(Aml *table,
> uint64_t pcihp_addr)
> aml_append(table, scope);
> }
>
> -static Aml *build_q35_osc_method(void)
> +static Aml *build_q35_osc_method(bool enable_native_pcie_hotplug)
> {
> Aml *if_ctx;
> Aml *if_ctx2;
> @@ -1359,8 +1359,10 @@ static Aml *build_q35_osc_method(void)
> /*
> * Always allow native PME, AER (no dependencies)
> * Allow SHPC (PCI bridges can have SHPC controller)
> + * Disable PCIe Native Hot-plug if ACPI PCI Hot-plug is enabled.
> */
> -aml_append(if_ctx, aml_and(a_ctrl, aml_int(0x1F), a_ctrl));
> +aml_append(if_ctx, aml_and(a_ctrl,
> +aml_int(0x1E | (enable_native_pcie_hotplug ? 0x1 : 0x0)), a_ctrl));
>
> if_ctx2 = aml_if(aml_lnot(aml_equal(aml_arg(1), aml_int(1;
> /* Unknown revision */
> @@ -1449,7 +1451,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> aml_append(dev, aml_name_decl("_CID", aml_eisaid("PNP0A03")));
> aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
> aml_append(dev, aml_name_decl("_UID", aml_int(pcmc->pci_root_uid)));
> -aml_append(dev, build_q35_osc_method());
> +aml_append(dev, build_q35_osc_method(!pm->pcihp_bridge_en));
> aml_append(sb_scope, dev);
> if (mcfg_valid) {
> aml_append(sb_scope, build_q35_dram_controller());
> @@ -1565,7 +1567,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> if (pci_bus_is_express(bus)) {
> aml_append(dev, aml_name_decl("_HID",
> aml_eisaid("PNP0A08")));
> aml_append(dev, aml_name_decl("_CID",
> aml_eisaid("PNP0A03")));
> -aml_append(dev, build_q35_osc_method());
> +
> +/* Expander bridges do not have ACPI PCI Hot-plug enabled */
> +aml_append(dev, build_q35_osc_method(true));
> } else {
> aml_append(dev, aml_name_decl("_HID",
> aml_eisaid("PNP0A03")));
> }
> --
> 2.27.0
>