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Re: [PATCH for 6.2 v2 4/5] hw/i386/acpi-build: Deny control on PCIe Nati
From: |
Igor Mammedov |
Subject: |
Re: [PATCH for 6.2 v2 4/5] hw/i386/acpi-build: Deny control on PCIe Native Hot-plug in _OSC |
Date: |
Fri, 12 Nov 2021 11:51:28 +0100 |
On Thu, 11 Nov 2021 11:19:30 +0530 (IST)
Ani Sinha <ani@anisinha.ca> wrote:
> On Wed, 10 Nov 2021, Igor Mammedov wrote:
>
> > From: Julia Suvorova <jusual@redhat.com>
> >
> > 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 <jusual@redhat.com>
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> > 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.
> > */
>
> Based on v2, I think its more useful to have this comment where the
> function is called.
I'd leave it as is, which is consistent with other bits described here
>
> > - 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));
>
> See above. I think it helps to add a comment here saying native hotplug is
> enabled when acpi hotplug is disabled for cold plugged bridges.
>
>
> > aml_append(sb_scope, dev);
> > if (mcfg_valid) {
> > aml_append(sb_scope, build_q35_dram_controller(&mcfg));
> > @@ -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
> >
> >
>