From: Igor Mammedov <imammedo@redhat.com>

it's a helper method for acpi-index support on PCI buses
that do no support or have disabled ACPI PCI hotplug
or for non-hotpluggble endpoint devices.
(like non-hotpluggble NICs, integrated endpoints and
later for machines that do not support ACPI PCI hotplug)

no functional change, commit adds only EDSM method in DSDT
without any users. (the follow up patches will use it)

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20230302161543.286002-18-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/acpi-build.c | 54 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index d8ec91b8e3..6f5501fb74 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -399,6 +399,58 @@ static void build_append_pci_dsm_func0_common(Aml *ctx, Aml *retvar)
     aml_append(ctx, ifctx1);
 }
 
+static Aml *aml_pci_edsm(void)
+{
+    Aml *method, *ifctx;
+    Aml *zero = aml_int(0);
+    Aml *func = aml_arg(2);
+    Aml *ret = aml_local(0);
+    Aml *aidx = aml_local(1);
+    Aml *params = aml_arg(4);
+
+    method = aml_method("EDSM", 5, AML_SERIALIZED);
+
+    /* get supported functions */
+    ifctx = aml_if(aml_equal(func, zero));
+    {
+        /* 1: have supported functions */
+        /* 7: support for function 7 */
+        const uint8_t caps = 1 | BIT(7);
+        build_append_pci_dsm_func0_common(ifctx, ret);
+        aml_append(ifctx, aml_store(aml_int(caps), aml_index(ret, zero)));
+        aml_append(ifctx, aml_return(ret));
+    }
+    aml_append(method, ifctx);
+
+    /* handle specific functions requests */
+    /*
+     * PCI Firmware Specification 3.1
+     * 4.6.7. _DSM for Naming a PCI or PCI Express Device Under
+     *        Operating Systems
+     */
+    ifctx = aml_if(aml_equal(func, aml_int(7)));
+    {
+       Aml *pkg = aml_package(2);
+       aml_append(pkg, zero);
+       /* optional, if not impl. should return null string */
+       aml_append(pkg, aml_string("%s", ""));
+       aml_append(ifctx, aml_store(pkg, ret));
+
+       /*
+        * IASL is fine when initializing Package with computational data,
+        * however it makes guest unhappy /it fails to process such AML/.
+        * So use runtime assignment to set acpi-index after initializer
+        * to make OSPM happy.
+        */
+       aml_append(ifctx,
+           aml_store(aml_derefof(aml_index(params, aml_int(0))), aidx));
+       aml_append(ifctx, aml_store(aidx, aml_index(ret, zero)));
+       aml_append(ifctx, aml_return(ret));
+    }
+    aml_append(method, ifctx);
+
+    return method;
+}
 
 static void build_append_pcihp_notify_entry(Aml *method, int slot)
 {
@@ -1398,6 +1450,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         aml_append(dev, aml_name_decl("_HID", 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, aml_pci_edsm());
         aml_append(sb_scope, dev);
         aml_append(dsdt, sb_scope);
 
@@ -1413,6 +1466,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         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(!pm->pcihp_bridge_en));
+        aml_append(dev, aml_pci_edsm());
         aml_append(sb_scope, dev);
         if (mcfg_valid) {
             aml_append(sb_scope, build_q35_dram_controller(&mcfg));
-- 
MST