[PATCH v2 12/20] vfio/cxl: Wait for HDM ranges and create memdev

[<mhonap@nvidia.com>]

From: Manish Honap <mhonap@nvidia.com>

After HDM registers are mapped, call cxl_await_range_active() so we
only proceed when DVSEC ranges report active without touching the
memdev register group Type-2 may lack.

Re-snapshot component regs (vfio_cxl_reinit_comp_regs) once
MEM_ACTIVE so firmware final SIZE_HIGH etc. land in comp_reg_virt.

Read committed decoder size from hardware, set capacity via
cxl_set_capacity(), and devm_cxl_add_memdev().

Signed-off-by: Manish Honap <mhonap@nvidia.com>
---
 drivers/vfio/pci/cxl/vfio_cxl_core.c | 56 ++++++++++++++++++++++++++++
 drivers/vfio/pci/cxl/vfio_cxl_emu.c  | 42 +++++++++++++++++++++
 drivers/vfio/pci/cxl/vfio_cxl_priv.h |  4 ++
 3 files changed, 102 insertions(+)

diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c b/drivers/vfio/pci/cxl/vfio_cxl_core.c
index 0b9e4419cd47..02755265d530 100644
--- a/drivers/vfio/pci/cxl/vfio_cxl_core.c
+++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c
@@ -165,6 +165,22 @@ static int vfio_cxl_setup_regs(struct vfio_pci_core_device *vdev,
 	return ret;
 }
 
+static int vfio_cxl_create_memdev(struct vfio_pci_cxl_state *cxl,
+				  resource_size_t capacity)
+{
+	int ret;
+
+	ret = cxl_set_capacity(&cxl->cxlds, capacity);
+	if (ret)
+		return ret;
+
+	cxl->cxlmd = devm_cxl_add_memdev(&cxl->cxlds, NULL);
+	if (IS_ERR(cxl->cxlmd))
+		return PTR_ERR(cxl->cxlmd);
+
+	return 0;
+}
+
 /*
  * Free CXL state early on probe failure.  devm_kfree() on a live devres
  * allocation removes it from the list immediately, so the normal devres
@@ -189,6 +205,7 @@ void vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev)
 {
 	struct pci_dev *pdev = vdev->pdev;
 	struct vfio_pci_cxl_state *cxl;
+	resource_size_t capacity = 0;
 	u16 dvsec;
 	int ret;
 
@@ -234,8 +251,44 @@ void vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev)
 		goto free_cxl;
 	}
 
+	cxl->cxlds.media_ready = !cxl_await_range_active(&cxl->cxlds);
+	if (!cxl->cxlds.media_ready) {
+		pci_warn(pdev, "CXL media not ready\n");
+		pci_disable_device(pdev);
+		goto regs_failed;
+	}
+
+	/*
+	 * Take the single authoritative HDM decoder snapshot now that
+	 * MEM_ACTIVE is confirmed and BAR memory is still enabled.  Using
+	 * readl() per-dword ensures correct MMIO serialisation and captures
+	 * the final firmware-written values for all fields including SIZE_HIGH,
+	 * which firmware commits to the BAR at MEM_ACTIVE time.
+	 */
+	vfio_cxl_reinit_comp_regs(cxl);
+
 	pci_disable_device(pdev);
 
+	capacity = vfio_cxl_read_committed_decoder_size(vdev, cxl);
+	if (capacity == 0) {
+		/*
+		 * TODO: Add handling for devices which do not have
+		 * firmware pre-committed decoders
+		 */
+		pci_info(pdev, "Uncommitted region size must be configured via sysfs before bind\n");
+		goto regs_failed;
+	}
+
+	cxl->dpa_size = capacity;
+
+	pci_dbg(pdev, "Device capacity: %llu MB\n", capacity >> 20);
+
+	ret = vfio_cxl_create_memdev(cxl, capacity);
+	if (ret) {
+		pci_warn(pdev, "Failed to create memdev\n");
+		goto regs_failed;
+	}
+
 	/*
 	 * Register probing succeeded.  Assign vdev->cxl now so that
 	 * all subsequent helpers can access state via vdev->cxl.
@@ -246,6 +299,9 @@ void vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev)
 
 	return;
 
+regs_failed:
+	vfio_cxl_clean_virt_regs(cxl);
+
 free_cxl:
 	vfio_cxl_dev_state_free(pdev, cxl);
 }
diff --git a/drivers/vfio/pci/cxl/vfio_cxl_emu.c b/drivers/vfio/pci/cxl/vfio_cxl_emu.c
index 6fb02253e631..11195e8c21d7 100644
--- a/drivers/vfio/pci/cxl/vfio_cxl_emu.c
+++ b/drivers/vfio/pci/cxl/vfio_cxl_emu.c
@@ -365,6 +365,48 @@ int vfio_cxl_setup_virt_regs(struct vfio_pci_core_device *vdev,
 	return 0;
 }
 
+/*
+ * vfio_cxl_read_committed_decoder_size - Extract committed DPA capacity from
+ *					  comp_reg_virt[].
+ *
+ * Called from probe context after vfio_cxl_reinit_comp_regs() has taken the
+ * post-MEM_ACTIVE readl() snapshot and patched SIZE_HIGH/SIZE_LOW from DVSEC.
+ * comp_reg_virt[] is already correct at this point; no hardware access needed.
+ *
+ * Returns the committed DPA capacity in bytes, or 0 if the decoder is not
+ * committed.
+ */
+resource_size_t
+vfio_cxl_read_committed_decoder_size(struct vfio_pci_core_device *vdev,
+				     struct vfio_pci_cxl_state *cxl)
+{
+	struct pci_dev *pdev = vdev->pdev;
+	resource_size_t capacity;
+	u32 ctrl, sz_hi, sz_lo;
+
+	if (WARN_ON(!cxl || !cxl->comp_reg_virt))
+		return 0;
+
+	ctrl  = le32_to_cpu(*hdm_reg_ptr(cxl, CXL_HDM_DECODER0_CTRL_OFFSET(0)));
+	sz_hi = le32_to_cpu(*hdm_reg_ptr(cxl, CXL_HDM_DECODER0_SIZE_HIGH_OFFSET(0)));
+	sz_lo = le32_to_cpu(*hdm_reg_ptr(cxl, CXL_HDM_DECODER0_SIZE_LOW_OFFSET(0)));
+
+	if (!(ctrl & CXL_HDM_DECODER0_CTRL_COMMITTED)) {
+		pci_dbg(pdev,
+			"vfio_cxl: decoder0 not committed: ctrl=0x%08x\n",
+			ctrl);
+		return 0;
+	}
+
+	capacity = ((resource_size_t)sz_hi << 32) | (sz_lo & GENMASK(31, 28));
+
+	pci_dbg(pdev,
+		"vfio_cxl: decoder0 committed: sz_hi=0x%08x sz_lo=0x%08x capacity=0x%llx\n",
+		sz_hi, sz_lo, (unsigned long long)capacity);
+
+	return capacity;
+}
+
 /*
  * Called with memory_lock write side held (from vfio_cxl_reactivate_region).
  * Uses the pre-established hdm_iobase, no ioremap() under the lock,
diff --git a/drivers/vfio/pci/cxl/vfio_cxl_priv.h b/drivers/vfio/pci/cxl/vfio_cxl_priv.h
index 463a55062144..6359ad260bde 100644
--- a/drivers/vfio/pci/cxl/vfio_cxl_priv.h
+++ b/drivers/vfio/pci/cxl/vfio_cxl_priv.h
@@ -22,6 +22,7 @@ struct vfio_pci_cxl_state {
 	resource_size_t              comp_reg_offset;
 	size_t                       comp_reg_size;
 	__le32                      *comp_reg_virt;
+	size_t                       dpa_size;
 	void __iomem                *hdm_iobase;
 	u16                          dvsec_len;
 	u8                           hdm_count;
@@ -83,5 +84,8 @@ int vfio_cxl_setup_virt_regs(struct vfio_pci_core_device *vdev,
 			     void __iomem *cap_base);
 void vfio_cxl_clean_virt_regs(struct vfio_pci_cxl_state *cxl);
 void vfio_cxl_reinit_comp_regs(struct vfio_pci_cxl_state *cxl);
+resource_size_t
+vfio_cxl_read_committed_decoder_size(struct vfio_pci_core_device *vdev,
+				     struct vfio_pci_cxl_state *cxl);
 
 #endif /* __LINUX_VFIO_CXL_PRIV_H */
-- 
2.25.1