0001-PCI-add-a-reset-quirk-for-Intel-I219LM-ethernet-adap.patch

From 59dfd8ce5ae0680da665746194ca7f76bcc83f71 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
 <marmarek@invisiblethingslab.com>
Date: Mon, 15 Jul 2024 16:55:56 +0200
Subject: [PATCH] PCI: add a reset quirk for Intel I219LM ethernet adapter
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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The device does support FLR, has the relevant registers in the config
space, but fails to link them to the pci caps list. Fix it by linking
them manually, so the standard pci_af_flr() will find it. The fixup
needs to be repeated after reset.

The fixup will be visible via sysfs, which is intended side effect so
that libvirt can see FLR as supported too.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
---
 drivers/pci/pci.c    |  2 +-
 drivers/pci/pci.h    |  1 +
 drivers/pci/quirks.c | 66 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 35fb1f17a589..ba3e4732f125 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4491,7 +4491,7 @@ int pcie_reset_flr(struct pci_dev *dev, bool probe)
 }
 EXPORT_SYMBOL_GPL(pcie_reset_flr);
 
-static int pci_af_flr(struct pci_dev *dev, bool probe)
+int pci_af_flr(struct pci_dev *dev, bool probe)
 {
 	int pos;
 	u8 cap;
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index fd44565c4756..9dfc05e3d0b3 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -600,6 +600,7 @@ void pcie_ecrc_get_policy(char *str);
 static inline void pcie_set_ecrc_checking(struct pci_dev *dev) { }
 static inline void pcie_ecrc_get_policy(char *str) { }
 #endif
+int pci_af_flr(struct pci_dev *dev, bool probe);
 
 struct pci_dev_reset_methods {
 	u16 vendor;
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 568410e64ce6..9b77e6182500 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4194,6 +4194,74 @@ static int reset_hinic_vf_dev(struct pci_dev *pdev, bool probe)
 	return 0;
 }
 
+#define PCI_DEVICE_ID_INTEL_I219LM 0x550A
+#define I219_PCI_MSI_POS 0xd0
+#define I219_PCI_AF_POS 0xe0
+
+/* FLR fixup for Intel I219LM Ethernet controller.
+ * The device does support FLR, has the relevant registers in the config space,
+ * but fails to link them to the pci caps list. Fix it by linking them
+ * manually, so the standard pci_af_flr() will find it. The fixup needs to be
+ * repeated after reset, so do that in probe stage.
+ * The fixup will be visible via sysfs, which is intended side effect so that
+ * libvirt can see FLR as supported too.
+ */
+static void fixup_intel_i219lm_flr(struct pci_dev *dev)
+{
+	int pos;
+	u8 cap;
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_AF);
+	if (pos)
+		return;
+
+	/*
+	 * If not found, check if we can find it - the last listed cap should
+	 * be MSI at 0xd0 (I219_PCI_MSI_POS), and AF should be at 0xe0
+	 * (I219_PCI_AF_POS).
+	 */
+
+	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
+	if (pos != I219_PCI_MSI_POS)
+		return;
+
+	pci_read_config_byte(dev, pos + PCI_CAP_LIST_NEXT, &cap);
+	/*
+	 * Linked to something else already? Already linked to PCI_AF was
+	 * handled earlier.
+	 */
+	if (cap)
+		return;
+	/* Check if PCI_AF indeed is at I219_PCI_AF_POS. */
+	pci_read_config_byte(dev, I219_PCI_AF_POS, &cap);
+	if (cap != PCI_CAP_ID_AF)
+		return;
+
+	/* All sanity checks done, link the cap */
+	pci_write_config_byte(dev, pos + PCI_CAP_LIST_NEXT, I219_PCI_AF_POS);
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_I219LM,
+			 fixup_intel_i219lm_flr);
+
+static int reset_i219lm_dev(struct pci_dev *dev, bool probe)
+{
+	int ret;
+
+	/* Ensure AF FLR is visible before using it */
+	if (!probe)
+		fixup_intel_i219lm_flr(dev);
+
+	/* Call normal FLR, but re-apply fixup_intel_i219lm_flr() afterwards. */
+	ret = pci_af_flr(dev, probe);
+	if (ret)
+		return ret;
+
+	if (!probe)
+		fixup_intel_i219lm_flr(dev);
+
+	return 0;
+}
+
 static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
 	{ PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82599_SFP_VF,
 		 reset_intel_82599_sfp_virtfn },
@@ -4209,6 +4273,8 @@ static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
 		reset_chelsio_generic_dev },
 	{ PCI_VENDOR_ID_HUAWEI, PCI_DEVICE_ID_HINIC_VF,
 		reset_hinic_vf_dev },
+	{ PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_I219LM,
+		reset_i219lm_dev },
 	{ 0 }
 };
 
-- 
2.45.2