[PATCH v6 1/6] PCI/IOV: Restore VF resizable BAR state after reset

[Michał Winiarski]

Similar to regular resizable BAR, VF BAR can also be resized, e.g. by
the system firmware or the PCI subsystem itself.

Add the capability ID and restore it as a part of IOV state.

See PCIe r4.0, sec 9.3.7.4.

Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Reviewed-by: Christian König <christian.koenig@xxxxxxx>
---
 drivers/pci/iov.c             | 30 +++++++++++++++++++++++++++++-
 drivers/pci/pci.h             |  1 +
 include/uapi/linux/pci_regs.h |  1 +
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 121540f57d4bf..bf95387993cd5 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -7,6 +7,7 @@
  * Copyright (C) 2009 Intel Corporation, Yu Zhao <yu.zhao@xxxxxxxxx>
  */
 
+#include <linux/bitfield.h>
 #include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/export.h>
@@ -830,6 +831,7 @@ static int sriov_init(struct pci_dev *dev, int pos)
 	pci_read_config_byte(dev, pos + PCI_SRIOV_FUNC_LINK, &iov->link);
 	if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END)
 		iov->link = PCI_DEVFN(PCI_SLOT(dev->devfn), iov->link);
+	iov->vf_rebar_cap = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_VF_REBAR);
 
 	if (pdev)
 		iov->dev = pci_dev_get(pdev);
@@ -868,6 +870,30 @@ static void sriov_release(struct pci_dev *dev)
 	dev->sriov = NULL;
 }
 
+static void sriov_restore_vf_rebar_state(struct pci_dev *dev)
+{
+	unsigned int pos, nbars, i;
+	u32 ctrl;
+
+	pos = dev->sriov->vf_rebar_cap;
+	if (!pos)
+		return;
+
+	pci_read_config_dword(dev, pos + PCI_REBAR_CTRL, &ctrl);
+	nbars = FIELD_GET(PCI_REBAR_CTRL_NBAR_MASK, ctrl);
+
+	for (i = 0; i < nbars; i++, pos += 8) {
+		int bar_idx, size;
+
+		pci_read_config_dword(dev, pos + PCI_REBAR_CTRL, &ctrl);
+		bar_idx = FIELD_GET(PCI_REBAR_CTRL_BAR_IDX, ctrl);
+		size = pci_rebar_bytes_to_size(dev->sriov->barsz[bar_idx]);
+		ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
+		ctrl |= FIELD_PREP(PCI_REBAR_CTRL_BAR_SIZE, size);
+		pci_write_config_dword(dev, pos + PCI_REBAR_CTRL, ctrl);
+	}
+}
+
 static void sriov_restore_state(struct pci_dev *dev)
 {
 	int i;
@@ -1027,8 +1053,10 @@ resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno)
  */
 void pci_restore_iov_state(struct pci_dev *dev)
 {
-	if (dev->is_physfn)
+	if (dev->is_physfn) {
+		sriov_restore_vf_rebar_state(dev);
 		sriov_restore_state(dev);
+	}
 }
 
 /**
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index b81e99cd4b62a..adc54bb2c8b34 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -482,6 +482,7 @@ struct pci_sriov {
 	u16		subsystem_vendor; /* VF subsystem vendor */
 	u16		subsystem_device; /* VF subsystem device */
 	resource_size_t	barsz[PCI_SRIOV_NUM_BARS];	/* VF BAR size */
+	u16		vf_rebar_cap;	/* VF Resizable BAR capability offset */
 	bool		drivers_autoprobe; /* Auto probing of VFs by driver */
 };
 
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index ba326710f9c8b..bb2a334e50386 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -745,6 +745,7 @@
 #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_NPEM	0x29	/* Native PCIe Enclosure Management */
-- 
2.49.0