[PATCH v4 11/27] vfio/cxl: Own the whole component register BAR

[mhonap]

From: Manish Honap <mhonap@xxxxxxxxxx>

devm_cxl_probe_mem() maps the component registers through the CXL core.
By default the core claims each HDM/RAS sub-block, which then collides
with the full-BAR request that vfio-pci makes when the guest opens the
device.

Discover the component registers into the device reg_map and pass
bar_owned to cxl_pci_setup_regs(), so the core maps the sub-blocks
without claiming them and vfio-pci owns the whole BAR.

Signed-off-by: Manish Honap <mhonap@xxxxxxxxxx>
---
 drivers/vfio/pci/cxl/vfio_cxl_core.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c b/drivers/vfio/pci/cxl/vfio_cxl_core.c
index 7edc53b25576..966b7c22a6ac 100644
--- a/drivers/vfio/pci/cxl/vfio_cxl_core.c
+++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c
@@ -10,6 +10,7 @@
 #include <linux/range.h>
 #include <linux/vfio_pci_core.h>
 #include <cxl/cxl.h>
+#include <cxl/pci.h>
 
 /**
  * struct vfio_cxl_state - per-device state for a vfio-cxl device
@@ -70,6 +71,16 @@ static int vfio_cxl_init_device(struct vfio_pci_core_device *vdev)
 	if (!cxl)
 		return -ENOMEM;
 
+	/*
+	 * vfio-pci requests the whole component BAR when the guest opens the
+	 * device. Declare the BAR owned so the CXL core maps the HDM/RAS
+	 * sub-blocks without claiming them and that request does not collide.
+	 */
+	ret = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_COMPONENT,
+				 &cxl->cxlds.reg_map, true);
+	if (ret)
+		return ret;
+
 	ret = cxl_set_capacity(&cxl->cxlds, hdm_size);
 	if (ret)
 		return ret;
-- 
2.25.1