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From: Lianjie Shi <Lianjie.Shi@amd.com>
To: <linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>, Bjorn Helgaas
	<bhelgaas@google.com>
CC: Lianjie Shi <Lianjie.Shi@amd.com>
Subject: [PATCH 1/1] PCI: Support VF resizable BAR
Date: Thu, 16 May 2024 17:33:34 +0800
Message-ID: <20240516093334.2266599-2-Lianjie.Shi@amd.com>
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Add support for VF resizable BAR PCI extended cap.
Similar to regular BAR, drivers can use pci_resize_resource() to
resize an IOV BAR. For each VF, dev->sriov->barsz of the IOV BAR is
resized, but the total resource size of the IOV resource should not
exceed its original size upon init.

Based on following patch series:
Link: https://lore.kernel.org/lkml/YbqGplTKl5i%2F1%2FkY@rocinante/T/

Signed-off-by: Lianjie Shi <Lianjie.Shi@amd.com>
---
 drivers/pci/pci.c             | 44 +++++++++++++++++++++++++++++++++-
 drivers/pci/setup-res.c       | 45 +++++++++++++++++++++++++++++------
 include/uapi/linux/pci_regs.h |  1 +
 3 files changed, 82 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e5f243dd4..bb9a2f322 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1867,6 +1867,39 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
 	}
 }
 
+static void pci_restore_vf_rebar_state(struct pci_dev *pdev)
+{
+#ifdef CONFIG_PCI_IOV
+	unsigned int pos, nbars, i;
+	u32 ctrl;
+	u16 total;
+
+	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_VF_REBAR);
+	if (!pos)
+		return;
+
+	pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
+	nbars = FIELD_GET(PCI_REBAR_CTRL_NBAR_MASK, ctrl);
+
+	for (i = 0; i < nbars; i++, pos += 8) {
+		struct resource *res;
+		int bar_idx, size;
+
+		pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
+		bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
+		total = pdev->sriov->total_VFs;
+		if (!total)
+			return;
+
+		res = pdev->resource + bar_idx + PCI_IOV_RESOURCES;
+		size = pci_rebar_bytes_to_size(resource_size(res) / total);
+		ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
+		ctrl |= FIELD_PREP(PCI_REBAR_CTRL_BAR_SIZE, size);
+		pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
+	}
+#endif
+}
+
 /**
  * pci_restore_state - Restore the saved state of a PCI device
  * @dev: PCI device that we're dealing with
@@ -1882,6 +1915,7 @@ void pci_restore_state(struct pci_dev *dev)
 	pci_restore_ats_state(dev);
 	pci_restore_vc_state(dev);
 	pci_restore_rebar_state(dev);
+	pci_restore_vf_rebar_state(dev);
 	pci_restore_dpc_state(dev);
 	pci_restore_ptm_state(dev);
 
@@ -3677,10 +3711,18 @@ void pci_acs_init(struct pci_dev *dev)
  */
 static int pci_rebar_find_pos(struct pci_dev *pdev, int bar)
 {
+	int cap = PCI_EXT_CAP_ID_REBAR;
 	unsigned int pos, nbars, i;
 	u32 ctrl;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_REBAR);
+#ifdef CONFIG_PCI_IOV
+	if (bar >= PCI_IOV_RESOURCES) {
+		cap = PCI_EXT_CAP_ID_VF_REBAR;
+		bar -= PCI_IOV_RESOURCES;
+	}
+#endif
+
+	pos = pci_find_ext_capability(pdev, cap);
 	if (!pos)
 		return -ENOTSUPP;
 
diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
index c6d933ddf..d978a2ccf 100644
--- a/drivers/pci/setup-res.c
+++ b/drivers/pci/setup-res.c
@@ -427,13 +427,32 @@ void pci_release_resource(struct pci_dev *dev, int resno)
 }
 EXPORT_SYMBOL(pci_release_resource);
 
+static int pci_memory_decoding(struct pci_dev *dev, int resno)
+{
+	u16 cmd;
+
+#ifdef CONFIG_PCI_IOV
+	if (resno >= PCI_IOV_RESOURCES) {
+		pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_CTRL, &cmd);
+		if (cmd & PCI_SRIOV_CTRL_MSE)
+			return -EBUSY;
+		else
+			return 0;
+	}
+#endif
+	pci_read_config_word(dev, PCI_COMMAND, &cmd);
+	if (cmd & PCI_COMMAND_MEMORY)
+		return -EBUSY;
+
+	return 0;
+}
+
 int pci_resize_resource(struct pci_dev *dev, int resno, int size)
 {
 	struct resource *res = dev->resource + resno;
 	struct pci_host_bridge *host;
 	int old, ret;
 	u32 sizes;
-	u16 cmd;
 
 	/* Check if we must preserve the firmware's resource assignment */
 	host = pci_find_host_bridge(dev->bus);
@@ -444,9 +463,9 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
 	if (!(res->flags & IORESOURCE_UNSET))
 		return -EBUSY;
 
-	pci_read_config_word(dev, PCI_COMMAND, &cmd);
-	if (cmd & PCI_COMMAND_MEMORY)
-		return -EBUSY;
+	ret = pci_memory_decoding(dev, resno);
+	if (ret)
+		return ret;
 
 	sizes = pci_rebar_get_possible_sizes(dev, resno);
 	if (!sizes)
@@ -463,19 +482,31 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
 	if (ret)
 		return ret;
 
-	res->end = res->start + pci_rebar_size_to_bytes(size) - 1;
+#ifdef CONFIG_PCI_IOV
+	if (resno >= PCI_IOV_RESOURCES)
+		dev->sriov->barsz[resno - PCI_IOV_RESOURCES] = pci_rebar_size_to_bytes(size);
+	else
+#endif
+		res->end = res->start + pci_rebar_size_to_bytes(size) - 1;
 
 	/* Check if the new config works by trying to assign everything. */
 	if (dev->bus->self) {
 		ret = pci_reassign_bridge_resources(dev->bus->self, res->flags);
-		if (ret)
+		if (ret && ret != -ENOENT)
 			goto error_resize;
 	}
 	return 0;
 
 error_resize:
 	pci_rebar_set_size(dev, resno, old);
-	res->end = res->start + pci_rebar_size_to_bytes(old) - 1;
+
+#ifdef CONFIG_PCI_IOV
+	if (resno >= PCI_IOV_RESOURCES)
+		dev->sriov->barsz[resno - PCI_IOV_RESOURCES] = pci_rebar_size_to_bytes(old);
+	else
+#endif
+		res->end = res->start + pci_rebar_size_to_bytes(old) - 1;
+
 	return ret;
 }
 EXPORT_SYMBOL(pci_resize_resource);
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index a39193213..a66b90982 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -738,6 +738,7 @@
 #define PCI_EXT_CAP_ID_L1SS	0x1E	/* L1 PM Substates */
 #define PCI_EXT_CAP_ID_PTM	0x1F	/* Precision Time Measurement */
 #define PCI_EXT_CAP_ID_DVSEC	0x23	/* Designated Vendor-Specific */
+#define PCI_EXT_CAP_ID_VF_REBAR	0x24	/* VF Resizable BAR */
 #define PCI_EXT_CAP_ID_DLF	0x25	/* Data Link Feature */
 #define PCI_EXT_CAP_ID_PL_16GT	0x26	/* Physical Layer 16.0 GT/s */
 #define PCI_EXT_CAP_ID_PL_32GT  0x2A    /* Physical Layer 32.0 GT/s */
-- 
2.34.1