[PATCH qemu v5 4/7] hw/cxl: Update CXL Fixed Memory Window ACPI description to include Back Invalidate support.

Jonathan Cameron via posted 7 patches 1 month ago
Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Ani Sinha <anisinha@redhat.com>, Jonathan Cameron <jonathan.cameron@huawei.com>, Fan Ni <fan.ni@samsung.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
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[PATCH qemu v5 4/7] hw/cxl: Update CXL Fixed Memory Window ACPI description to include Back Invalidate support.
Posted by Jonathan Cameron via 1 month ago
Defaults for these windows has always been to enable anything QEMU supports.
With the addition of back invalidate support it is necessary to specify that
host windows support this.

CXL emulation is currently only suitable for software stack verification.
The relaxation of the restrictions on this window to include BI have no
affect on the OS until BI capable devices are added and until now these
have not existed. As such no backwards compatibility impacts are expected
from this change.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
v5: Equivalent of the default change in the window restrictions patch.
    That patch isn't ready for upstream just yet, so for now just
    change the value for everyone.
---
 hw/acpi/cxl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/acpi/cxl.c b/hw/acpi/cxl.c
index 75edb2c0a652..f92f7fa3d558 100644
--- a/hw/acpi/cxl.c
+++ b/hw/acpi/cxl.c
@@ -172,7 +172,7 @@ static void cedt_build_cfmws(CXLFixedWindow *fw, Aml *cedt)
     build_append_int_noprefix(table_data, fw->enc_int_gran, 4);
 
     /* Window Restrictions */
-    build_append_int_noprefix(table_data, 0x0f, 2);
+    build_append_int_noprefix(table_data, 0x2f, 2);
 
     /* QTG ID */
     build_append_int_noprefix(table_data, 0, 2);
-- 
2.48.1
Re: [PATCH qemu v5 4/7] hw/cxl: Update CXL Fixed Memory Window ACPI description to include Back Invalidate support.
Posted by Davidlohr Bueso 1 month ago
On Fri, 09 Jan 2026, Jonathan Cameron wrote:

>Defaults for these windows has always been to enable anything QEMU supports.
>With the addition of back invalidate support it is necessary to specify that
>host windows support this.
>
>CXL emulation is currently only suitable for software stack verification.
>The relaxation of the restrictions on this window to include BI have no
>affect on the OS until BI capable devices are added and until now these
>have not existed. As such no backwards compatibility impacts are expected
>from this change.
>
>Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>