hw/pci-host/gpex-acpi: Fix _DSM function 0 support return value

Currently, only function 0 is supported. According to the ACPI
Specification, Revision 6.6, Section 9.1.1 “_DSM (Device Specific
Method)”, bit 0 should be 0 to indicate that no other functions
are supported beyond function 0.

The resulting AML change looks like this:

Method (_DSM, 4, NotSerialized)  // _DSM: Device-Specific Method
{
    If ((Arg0 == ToUUID ("e5c937d0-3553-4d7a-9117-ea4d19c3434d")
    {
        If ((Arg2 == Zero))
        {
            Return (Buffer (One)
            {
-               0x01                                             // .
+               0x00                                             // .
            })
        }
    }
}

Fixes: 5b85eabe68f9 ("acpi: add acpi_dsdt_add_gpex")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20251022080639.243965-3-skolothumtho@nvidia.com>

diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
index 952a0ace19771c5d8a9d06c0bb4dd64af03ef4bb..4587baeb787dfe5d6d053c380201508d6044496c 100644 (file)
--- a/hw/pci-host/gpex-acpi.c
+++ b/hw/pci-host/gpex-acpi.c
@@ -64,7 +64,7 @@ static Aml *build_pci_host_bridge_dsm_method(void)
     UUID = aml_touuid("E5C937D0-3553-4D7A-9117-EA4D19C3434D");
     ifctx = aml_if(aml_equal(aml_arg(0), UUID));
     ifctx1 = aml_if(aml_equal(aml_arg(2), aml_int(0)));
-    uint8_t byte_list[1] = {1};
+    uint8_t byte_list[1] = {0};
     buf = aml_buffer(1, byte_list);
     aml_append(ifctx1, aml_return(buf));
     aml_append(ifctx, ifctx1);