[RFC PATCH v2 3/4] hw/i386/acpi-build: Turn off support of PCIe native hot-plug and SHPC in _OSC

[Julia Suvorova <jusual@redhat.com>]

Other methods may be used if the system is capable of this and the _OSC bit
is set. Disable them explicitly to force ACPI PCI hot-plug use. The older
versions will still use PCIe native.

Signed-off-by: Julia Suvorova <jusual@redhat.com>
---
 hw/i386/acpi-build.h | 11 +++++++++++
 hw/i386/acpi-build.c | 21 +++++++++++++++------
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/hw/i386/acpi-build.h b/hw/i386/acpi-build.h
index 74df5fc612..6f94312c39 100644
--- a/hw/i386/acpi-build.h
+++ b/hw/i386/acpi-build.h
@@ -5,6 +5,17 @@
 
 extern const struct AcpiGenericAddress x86_nvdimm_acpi_dsmio;
 
+/* PCI Firmware Specification 3.2, Table 4-5 */
+typedef enum {
+    ACPI_OSC_NATIVE_HP_EN = 0,
+    ACPI_OSC_SHPC_EN = 1,
+    ACPI_OSC_PME_EN = 2,
+    ACPI_OSC_AER_EN = 3,
+    ACPI_OSC_PCIE_CAP_EN = 4,
+    ACPI_OSC_LTR_EN = 5,
+    ACPI_OSC_ALLONES_INVALID = 6,
+} AcpiOSCField;
+
 void acpi_setup(void);
 
 #endif
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index f3cd52bd06..c5f4802b8c 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1411,7 +1411,7 @@ static void build_i386_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(AcpiPmInfo *pm)
 {
     Aml *if_ctx;
     Aml *if_ctx2;
@@ -1419,6 +1419,7 @@ static Aml *build_q35_osc_method(void)
     Aml *method;
     Aml *a_cwd1 = aml_name("CDW1");
     Aml *a_ctrl = aml_local(0);
+    unsigned osc_ctrl;
 
     method = aml_method("_OSC", 4, AML_NOTSERIALIZED);
     aml_append(method, aml_create_dword_field(aml_arg(3), aml_int(0), "CDW1"));
@@ -1430,11 +1431,19 @@ static Aml *build_q35_osc_method(void)
 
     aml_append(if_ctx, aml_store(aml_name("CDW3"), a_ctrl));
 
+    /* Always allow native PME, AER (depend on PCIE Capability Control) */
+    osc_ctrl = BIT(ACPI_OSC_PME_EN) | BIT(ACPI_OSC_AER_EN) |
+               BIT(ACPI_OSC_PCIE_CAP_EN);
+
     /*
-     * Always allow native PME, AER (no dependencies)
-     * Allow SHPC (PCI bridges can have SHPC controller)
+     * Guests seem to generally prefer native hot-plug control.
+     * Enable it only when we do not use ACPI hot-plug.
      */
-    aml_append(if_ctx, aml_and(a_ctrl, aml_int(0x1F), a_ctrl));
+    if (!pm->pcihp_bridge_en) {
+        osc_ctrl |= BIT(ACPI_OSC_NATIVE_HP_EN) | BIT(ACPI_OSC_SHPC_EN);
+    }
+
+    aml_append(if_ctx, aml_and(a_ctrl, aml_int(osc_ctrl), a_ctrl));
 
     if_ctx2 = aml_if(aml_lnot(aml_equal(aml_arg(1), aml_int(1))));
     /* Unknown revision */
@@ -1514,7 +1523,7 @@ 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(1)));
-        aml_append(dev, build_q35_osc_method());
+        aml_append(dev, build_q35_osc_method(pm));
         aml_append(sb_scope, dev);
         aml_append(dsdt, sb_scope);
 
@@ -1590,7 +1599,7 @@ 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());
+                aml_append(dev, build_q35_osc_method(pm));
             } else {
                 aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
             }
-- 
2.25.4