linux-kernel - [PATCH v5 1/6] PCI/IOV: Restore VF resizable BAR state after reset

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Message-ID: <20250312225949.969716-2-michal.winiarski@intel.com>
Date: Wed, 12 Mar 2025 23:59:44 +0100
From: Michał Winiarski <michal.winiarski@...el.com>
To: <linux-pci@...r.kernel.org>, <intel-xe@...ts.freedesktop.org>,
	<dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>, "Bjorn
 Helgaas" <bhelgaas@...gle.com>, Christian König
	<christian.koenig@....com>, Krzysztof Wilczyński
	<kw@...ux.com>, Ilpo Järvinen
	<ilpo.jarvinen@...ux.intel.com>
CC: Rodrigo Vivi <rodrigo.vivi@...el.com>, Michal Wajdeczko
	<michal.wajdeczko@...el.com>, Lucas De Marchi <lucas.demarchi@...el.com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
	<mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
	<airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Matt Roper
	<matthew.d.roper@...el.com>, Michał Winiarski
	<michal.winiarski@...el.com>
Subject: [PATCH v5 1/6] PCI/IOV: Restore VF resizable BAR state after reset

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@...el.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Reviewed-by: Christian König <christian.koenig@....com>
---
 drivers/pci/iov.c             | 29 ++++++++++++++++++++++++++++-
 include/uapi/linux/pci_regs.h |  1 +
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 121540f57d4bf..eb4d33eacacb8 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -7,6 +7,7 @@
  * Copyright (C) 2009 Intel Corporation, Yu Zhao <yu.zhao@...el.com>
  */
 
+#include <linux/bitfield.h>
 #include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/export.h>
@@ -868,6 +869,30 @@ 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 = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_VF_REBAR);
+	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 +1052,10 @@ 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/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index 3c2558b98d225..aadd483c47d6f 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -744,6 +744,7 @@
 #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 */
-- 
2.48.1