linux-kernel - [PATCH v1 5/6] vfio/nvgrace-gpu: split the code to wait for GPU ready

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Message-ID: <20251117124159.3560-6-ankita@nvidia.com>
Date: Mon, 17 Nov 2025 12:41:58 +0000
From: <ankita@...dia.com>
To: <ankita@...dia.com>, <jgg@...pe.ca>, <yishaih@...dia.com>,
	<skolothumtho@...dia.com>, <kevin.tian@...el.com>, <alex@...zbot.org>,
	<aniketa@...dia.com>, <vsethi@...dia.com>, <mochs@...dia.com>
CC: <Yunxiang.Li@....com>, <yi.l.liu@...el.com>,
	<zhangdongdong@...incomputing.com>, <avihaih@...dia.com>,
	<bhelgaas@...gle.com>, <peterx@...hat.com>, <pstanner@...hat.com>,
	<apopple@...dia.com>, <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<cjia@...dia.com>, <kwankhede@...dia.com>, <targupta@...dia.com>,
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Subject: [PATCH v1 5/6] vfio/nvgrace-gpu: split the code to wait for GPU ready

From: Ankit Agrawal <ankita@...dia.com>

Split the function that check for the GPU device being ready on
the probe.

Move the code to wait for the GPU to be ready through BAR0 register
reads to a separate function. This would help reuse the code.

Signed-off-by: Ankit Agrawal <ankita@...dia.com>
---
 drivers/vfio/pci/nvgrace-gpu/main.c | 33 ++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/vfio/pci/nvgrace-gpu/main.c b/drivers/vfio/pci/nvgrace-gpu/main.c
index 25b0663f350d..fc89c381151a 100644
--- a/drivers/vfio/pci/nvgrace-gpu/main.c
+++ b/drivers/vfio/pci/nvgrace-gpu/main.c
@@ -130,6 +130,24 @@ static void nvgrace_gpu_close_device(struct vfio_device *core_vdev)
 	vfio_pci_core_close_device(core_vdev);
 }
 
+static int nvgrace_gpu_wait_device_ready(void __iomem *io)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(POLL_TIMEOUT_MS);
+	int ret = -ETIME;
+
+	do {
+		if ((ioread32(io + C2C_LINK_BAR0_OFFSET) == STATUS_READY) &&
+		    (ioread32(io + HBM_TRAINING_BAR0_OFFSET) == STATUS_READY)) {
+			ret = 0;
+			goto ready_check_exit;
+		}
+		msleep(POLL_QUANTUM_MS);
+	} while (!time_after(jiffies, timeout));
+
+ready_check_exit:
+	return ret;
+}
+
 static vm_fault_t nvgrace_gpu_vfio_pci_huge_fault(struct vm_fault *vmf,
 						  unsigned int order)
 {
@@ -930,9 +948,8 @@ static bool nvgrace_gpu_has_mig_hw_bug(struct pci_dev *pdev)
  * Ensure that the BAR0 region is enabled before accessing the
  * registers.
  */
-static int nvgrace_gpu_wait_device_ready(struct pci_dev *pdev)
+static int nvgrace_gpu_check_device_ready(struct pci_dev *pdev)
 {
-	unsigned long timeout = jiffies + msecs_to_jiffies(POLL_TIMEOUT_MS);
 	void __iomem *io;
 	int ret = -ETIME;
 
@@ -950,16 +967,8 @@ static int nvgrace_gpu_wait_device_ready(struct pci_dev *pdev)
 		goto iomap_exit;
 	}
 
-	do {
-		if ((ioread32(io + C2C_LINK_BAR0_OFFSET) == STATUS_READY) &&
-		    (ioread32(io + HBM_TRAINING_BAR0_OFFSET) == STATUS_READY)) {
-			ret = 0;
-			goto reg_check_exit;
-		}
-		msleep(POLL_QUANTUM_MS);
-	} while (!time_after(jiffies, timeout));
+	ret = nvgrace_gpu_wait_device_ready(io);
 
-reg_check_exit:
 	pci_iounmap(pdev, io);
 iomap_exit:
 	pci_release_selected_regions(pdev, 1 << 0);
@@ -976,7 +985,7 @@ static int nvgrace_gpu_probe(struct pci_dev *pdev,
 	u64 memphys, memlength;
 	int ret;
 
-	ret = nvgrace_gpu_wait_device_ready(pdev);
+	ret = nvgrace_gpu_check_device_ready(pdev);
 	if (ret)
 		return ret;
 
-- 
2.34.1