[RFC v2 1/2] hw/pci-host/gpex: Allow to generate preserve boot config DSM #5

[Eric Auger <eric.auger@redhat.com>]

Add a 'preserve_config' field in struct GPEXConfig and
if set generate the DSM #5 for preserving PCI boot configurations.
The DSM presence is needed to expose RMRs.

At the moment the DSM generation is not yet enabled.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 include/hw/pci-host/gpex.h |  1 +
 hw/pci-host/gpex-acpi.c    | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/include/hw/pci-host/gpex.h b/include/hw/pci-host/gpex.h
index fcf8b63820..3f8f8ec38d 100644
--- a/include/hw/pci-host/gpex.h
+++ b/include/hw/pci-host/gpex.h
@@ -64,6 +64,7 @@ struct GPEXConfig {
     MemMapEntry pio;
     int         irq;
     PCIBus      *bus;
+    bool        preserve_config;
 };
 
 int gpex_set_irq_num(GPEXHost *s, int index, int gsi);
diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
index e7e162a00a..7dab259379 100644
--- a/hw/pci-host/gpex-acpi.c
+++ b/hw/pci-host/gpex-acpi.c
@@ -164,6 +164,12 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
                 aml_append(dev, aml_name_decl("_PXM", aml_int(numa_node)));
             }
 
+            if (cfg->preserve_config) {
+                method = aml_method("_DSM", 5, AML_SERIALIZED);
+                aml_append(method, aml_return(aml_int(0)));
+                aml_append(dev, method);
+            }
+
             acpi_dsdt_add_pci_route_table(dev, cfg->irq);
 
             /*
@@ -191,6 +197,12 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
     aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
     aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
 
+    if (cfg->preserve_config) {
+        method = aml_method("_DSM", 5, AML_SERIALIZED);
+        aml_append(method, aml_return(aml_int(0)));
+        aml_append(dev, method);
+    }
+
     acpi_dsdt_add_pci_route_table(dev, cfg->irq);
 
     method = aml_method("_CBA", 0, AML_NOTSERIALIZED);
-- 
2.26.3