[PATCH v7 0/8] PCI: vmd: Add support for second rootbus under VMD

[PATCH v7 0/8] PCI: vmd: Add support for second rootbus under VMD

[Szymon Durawa]

This patch series implements second rootbus support inside Intel VMD
module. Current implementation allows VMD to take ownership of devices
only on first bus (Rootbus0). Starting from Intel Arrow Lake, VMD exposes
second bus (Rootbus1) to allow VMD to own devices on this bus as well.
VMD MMIO BARs (CFGBAR. MEMBAR1 and MEMBAR2) are now shared between
Rootbus0 and Rootbus1. Reconfiguration of 3 MMIO BARs is required by
resizing current MMIO BARs ranges. It allows to find/register VMD Rootbus1
and discovers devices or root ports under it.

Patches 1 to 6 introduce code refactoring without functional changes.
Patch 7 implements VMD Rootbus1 support and patch 8 provides workaround
for rootbus number hardwired to fixed non-zero value. Patch 8 is necessary
for correct enumeration attached devices under VMD Rootbus1. Without it
user cannot access those devices as they are not visible in the system,
only drives under VMD Rootbus0 are available to the user.

Changes from v1:
- splitting series into more commits, requested by Bjorn
- adding helper functions, suggested by Bjorn
- minor typos and unclear wording updated, suggested by Bjorn

Changes from v2:
- wording update in commit logs, suggested by Bjorn

Changes from v3:
- using GENMASK() instead of manual bits shifting, suggested by Bjorn
- converting decimal number to hex representation, suggested by Bjorn
- wording update in commit logs, suggested by Bjorn

Changes from v4:
- Update Dan's email address
- Resending the whole series to the correct mailing list

Changes from v5:
- Addressed review feedback from Sashiko AI:
 * Critical correctness in bus/resource layout in patches 7 and 8
 * Lifetime and Use-After-Free risks in patches 3 and 7
 * Resource tree integrity issues in patch 7
 * Memory leak issues on error paths across patches 3, 4 and 5
 * Allocation failure handling in patch 3
- Note on Sashiko feedback: Pre-existing warnings (unrelated to
  this feature series) were left untouched.

Changes from v6:
- Refactoring the series to align with recent changes in link below:
 https://patchwork.kernel.org/project/linux-pci/patch/20260629165025.268836-1-nirmal.patel@linux.intel.com/
- Fixing Sashiko's suggestions regarding:
 * double free of the IRQ domain and emulated domain number
 * race with concurrent reader when modifying the sibling pointers
 * the MEMBAR2 split equations in vmd_configure_membar1_membar2()
 * hardcoded resource indices in vmd_configure_membar()

Szymon Durawa (8):
  PCI: vmd: Add vmd_bus_enumeration() helper function
  PCI: vmd: Add vmd_configure_cfgbar() helper function
  PCI: vmd: Add vmd_configure_membar() and
    vmd_configure_membar1_membar2()
  PCI: vmd: Add vmd_create_bus()
  PCI: vmd: Replace hardcoded values with enum and defines
  PCI: vmd: Convert bus and busn_start to an array
  PCI: vmd: Add support for second rootbus under VMD
  PCI: vmd: Add workaround for bus number hardwired to fixed non-zero
    value

 drivers/pci/controller/vmd.c | 621 ++++++++++++++++++++++++++++-------
 1 file changed, 502 insertions(+), 119 deletions(-)

-- 
2.43.0

[PATCH v7 1/8] PCI: vmd: Add vmd_bus_enumeration() helper function

[Szymon Durawa]

Move the vmd bus enumeration code to a new helper vmd_bus_enumeration().
No functional changes.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 89 ++++++++++++++++++++----------------
 1 file changed, 49 insertions(+), 40 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index f3b0e45232ef..c7d705fe2530 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -902,6 +902,54 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
 	return 0;
 }
 
+static void vmd_bus_enumeration(struct pci_bus *bus, unsigned long features)
+{
+	struct pci_bus *child;
+	struct pci_dev *dev;
+	int ret;
+
+	vmd_acpi_begin();
+
+	pci_scan_child_bus(bus);
+	vmd_domain_reset(vmd_from_bus(bus));
+
+	/*
+	 * When Intel VMD is enabled, the OS does not discover the Root Ports
+	 * owned by Intel VMD within the MMCFG space. pci_reset_bus() applies
+	 * a reset to the parent of the PCI device supplied as argument. This
+	 * is why we pass a child device, so the reset can be triggered at
+	 * the Intel bridge level and propagated to all the children in the
+	 * hierarchy.
+	 */
+	list_for_each_entry(child, &bus->children, node) {
+		if (!list_empty(&child->devices)) {
+			dev = list_first_entry(&child->devices, struct pci_dev,
+					       bus_list);
+			ret = pci_reset_bus(dev);
+			if (ret)
+				pci_warn(dev, "can't reset device: %d\n", ret);
+
+			break;
+		}
+	}
+
+	pci_assign_unassigned_bus_resources(bus);
+
+	pci_walk_bus(bus, vmd_pm_enable_quirk, &features);
+
+	/*
+	 * VMD root buses are virtual and don't return true on pci_is_pcie()
+	 * and will fail pcie_bus_configure_settings() early. It can instead be
+	 * run on each of the real root ports.
+	 */
+	list_for_each_entry(child, &bus->children, node)
+		pcie_bus_configure_settings(child);
+
+	pci_bus_add_devices(bus);
+
+	vmd_acpi_end();
+}
+
 static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 {
 	struct pci_sysdata *sd = &vmd->sysdata;
@@ -912,8 +960,6 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	resource_size_t offset[2] = {0};
 	resource_size_t membar2_offset = 0x2000;
 	resource_size_t busn_end;
-	struct pci_bus *child;
-	struct pci_dev *dev;
 	int ret;
 
 	ret = vmd_prepare_offsets_and_bus(vmd, features, &membar2_offset,
@@ -1038,45 +1084,8 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj,
 			       "domain"), "Can't create symlink to domain\n");
 
-	vmd_acpi_begin();
-
-	pci_scan_child_bus(vmd->bus);
-	vmd_domain_reset(vmd);
+	vmd_bus_enumeration(vmd->bus, features);
 
-	/* When Intel VMD is enabled, the OS does not discover the Root Ports
-	 * owned by Intel VMD within the MMCFG space. pci_reset_bus() applies
-	 * a reset to the parent of the PCI device supplied as argument. This
-	 * is why we pass a child device, so the reset can be triggered at
-	 * the Intel bridge level and propagated to all the children in the
-	 * hierarchy.
-	 */
-	list_for_each_entry(child, &vmd->bus->children, node) {
-		if (!list_empty(&child->devices)) {
-			dev = list_first_entry(&child->devices,
-					       struct pci_dev, bus_list);
-			ret = pci_reset_bus(dev);
-			if (ret)
-				pci_warn(dev, "can't reset device: %d\n", ret);
-
-			break;
-		}
-	}
-
-	pci_assign_unassigned_bus_resources(vmd->bus);
-
-	pci_walk_bus(vmd->bus, vmd_pm_enable_quirk, &features);
-
-	/*
-	 * VMD root buses are virtual and don't return true on pci_is_pcie()
-	 * and will fail pcie_bus_configure_settings() early. It can instead be
-	 * run on each of the real root ports.
-	 */
-	list_for_each_entry(child, &vmd->bus->children, node)
-		pcie_bus_configure_settings(child);
-
-	pci_bus_add_devices(vmd->bus);
-
-	vmd_acpi_end();
 	return 0;
 }
 
-- 
2.43.0

[PATCH v7 2/8] PCI: vmd: Add vmd_configure_cfgbar() helper function

[Szymon Durawa]

Move the VMD CFGBAR initialization code to a new helper
vmd_configure_cfgbar(). No functional changes.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index c7d705fe2530..08636e2ba010 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -902,6 +902,22 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
 	return 0;
 }
 
+static void vmd_configure_cfgbar(struct vmd_dev *vmd)
+{
+	struct resource *res = &vmd->dev->resource[VMD_CFGBAR];
+	resource_size_t busn_end;
+
+	/* Do not let resource[0] end go out of bound.*/
+	busn_end = vmd->busn_start + (resource_size(res) >> 20) - 1;
+	busn_end = min_t(resource_size_t, busn_end, 0xff);
+	vmd->resources[0] = (struct resource) {
+		.name  = "VMD CFGBAR",
+		.start = vmd->busn_start,
+		.end   = busn_end,
+		.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED,
+	};
+}
+
 static void vmd_bus_enumeration(struct pci_bus *bus, unsigned long features)
 {
 	struct pci_bus *child;
@@ -959,7 +975,6 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	LIST_HEAD(resources);
 	resource_size_t offset[2] = {0};
 	resource_size_t membar2_offset = 0x2000;
-	resource_size_t busn_end;
 	int ret;
 
 	ret = vmd_prepare_offsets_and_bus(vmd, features, &membar2_offset,
@@ -967,16 +982,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	if (ret)
 		return ret;
 
-	/* Do not let resource[0] end go out of bound.*/
-	res = &vmd->dev->resource[VMD_CFGBAR];
-	busn_end = vmd->busn_start + (resource_size(res) >> 20) - 1;
-	busn_end = min_t(resource_size_t, busn_end, 0xff);
-	vmd->resources[0] = (struct resource) {
-		.name  = "VMD CFGBAR",
-		.start = vmd->busn_start,
-		.end   = busn_end,
-		.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED,
-	};
+	vmd_configure_cfgbar(vmd);
 
 	/*
 	 * If the window is below 4GB, clear IORESOURCE_MEM_64 so we can
-- 
2.43.0

[PATCH v7 3/8] PCI: vmd: Add vmd_configure_membar() and vmd_configure_membar1_membar2()

[Szymon Durawa]

Move the MEMBAR1 and MEMBAR2 registry initialization code to new helpers
vmd_configure_membar() and vmd_configure_membar1_membar2().
The refactor preserves MEMBAR address/offset/flags programming, but
resource name construction is now generated in the helper ("VMD MEMBAR%d")
instead of using two separate string literals.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 98 +++++++++++++++++++++++++-----------
 1 file changed, 68 insertions(+), 30 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 08636e2ba010..213aba6fc9bb 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -918,6 +918,69 @@ static void vmd_configure_cfgbar(struct vmd_dev *vmd)
 	};
 }
 
+/*
+ * vmd_configure_membar - Configure VMD MemBAR register, which points
+ * to MMIO address assigned by the OS or BIOS.
+ * @vmd: the VMD device
+ * @resource_number: resource buffer number to be filled in
+ * @membar_number: number of the MemBAR
+ * @start_offset: 4K aligned offset applied to start of VMD’s MEMBAR MMIO space
+ * @end_offset: 4K aligned offset applied to end of VMD’s MEMBAR MMIO space
+ *
+ * Function fills resource buffer inside the VMD structure.
+ *
+ * Return: 0 on success, -ENOMEM on allocation failure.
+ */
+static int vmd_configure_membar(struct vmd_dev *vmd, u8 resource_number,
+				u8 membar_number, resource_size_t start_offset,
+				resource_size_t end_offset)
+{
+	char *name;
+	u32 upper_bits;
+	unsigned long flags;
+
+	struct resource *res = &vmd->dev->resource[membar_number];
+
+	upper_bits = upper_32_bits(res->end);
+	flags = res->flags & ~IORESOURCE_SIZEALIGN;
+	if (!upper_bits)
+		flags &= ~IORESOURCE_MEM_64;
+
+	name = devm_kasprintf(&vmd->dev->dev, GFP_KERNEL, "VMD MEMBAR%d",
+			      resource_number);
+	if (!name)
+		return -ENOMEM;
+
+	vmd->resources[resource_number] = (struct resource){
+		.name = name,
+		.start = res->start + start_offset,
+		.end = res->end - end_offset,
+		.flags = flags,
+		.parent = res,
+	};
+
+	return 0;
+}
+
+static int vmd_configure_membar1_membar2(struct vmd_dev *vmd,
+					 resource_size_t mbar2_ofs)
+{
+	int ret;
+
+	ret = vmd_configure_membar(vmd, 1, VMD_MEMBAR1, 0, 0);
+	if (ret)
+		return ret;
+
+	ret = vmd_configure_membar(vmd, 2, VMD_MEMBAR2, mbar2_ofs, 0);
+	if (ret) {
+		devm_kfree(&vmd->dev->dev, (void *)vmd->resources[1].name);
+		memset(&vmd->resources[1], 0, sizeof(vmd->resources[1]));
+		return ret;
+	}
+
+	return 0;
+}
+
 static void vmd_bus_enumeration(struct pci_bus *bus, unsigned long features)
 {
 	struct pci_bus *child;
@@ -969,9 +1032,6 @@ static void vmd_bus_enumeration(struct pci_bus *bus, unsigned long features)
 static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 {
 	struct pci_sysdata *sd = &vmd->sysdata;
-	struct resource *res;
-	u32 upper_bits;
-	unsigned long flags;
 	LIST_HEAD(resources);
 	resource_size_t offset[2] = {0};
 	resource_size_t membar2_offset = 0x2000;
@@ -996,36 +1056,14 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	 *
 	 * The only way we could use a 64-bit non-prefetchable MEMBAR is
 	 * if its address is <4GB so that we can convert it to a 32-bit
-	 * resource.  To be visible to the host OS, all VMD endpoints must
+	 * resource. To be visible to the host OS, all VMD endpoints must
 	 * be initially configured by platform BIOS, which includes setting
-	 * up these resources.  We can assume the device is configured
+	 * up these resources. We can assume the device is configured
 	 * according to the platform needs.
 	 */
-	res = &vmd->dev->resource[VMD_MEMBAR1];
-	upper_bits = upper_32_bits(res->end);
-	flags = res->flags & ~IORESOURCE_SIZEALIGN;
-	if (!upper_bits)
-		flags &= ~IORESOURCE_MEM_64;
-	vmd->resources[1] = (struct resource) {
-		.name  = "VMD MEMBAR1",
-		.start = res->start,
-		.end   = res->end,
-		.flags = flags,
-		.parent = res,
-	};
-
-	res = &vmd->dev->resource[VMD_MEMBAR2];
-	upper_bits = upper_32_bits(res->end);
-	flags = res->flags & ~IORESOURCE_SIZEALIGN;
-	if (!upper_bits)
-		flags &= ~IORESOURCE_MEM_64;
-	vmd->resources[2] = (struct resource) {
-		.name  = "VMD MEMBAR2",
-		.start = res->start + membar2_offset,
-		.end   = res->end,
-		.flags = flags,
-		.parent = res,
-	};
+	ret = vmd_configure_membar1_membar2(vmd, membar2_offset);
+	if (ret)
+		return ret;
 
 	/*
 	 * Currently MSI remapping must be enabled in guest passthrough mode
-- 
2.43.0

[PATCH v7 4/8] PCI: vmd: Add vmd_create_bus()

[Szymon Durawa]

Move the VMD bus initialization code to a new helper vmd_create_bus().
No functional changes.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 57 ++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 22 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 213aba6fc9bb..e19b7fcb2025 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -981,6 +981,37 @@ static int vmd_configure_membar1_membar2(struct vmd_dev *vmd,
 	return 0;
 }
 
+static int vmd_create_bus(struct vmd_dev *vmd, struct pci_sysdata *sd,
+			  resource_size_t *offset)
+{
+	LIST_HEAD(resources);
+
+	pci_add_resource(&resources, &vmd->resources[0]);
+	pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
+	pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);
+
+	vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
+				       &vmd_ops, sd, &resources);
+	if (!vmd->bus) {
+		pci_free_resource_list(&resources);
+		return -ENODEV;
+	}
+
+	/* Don't copy _OSC control flags in VM, it disables features.*/
+	if (!offset[0] || !offset[1])
+		vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
+					   to_pci_host_bridge(vmd->bus->bridge));
+
+	vmd_attach_resources(vmd);
+	if (vmd->irq_domain)
+		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
+	else
+		dev_set_msi_domain(&vmd->bus->dev,
+				   dev_get_msi_domain(&vmd->dev->dev));
+
+	return 0;
+}
+
 static void vmd_bus_enumeration(struct pci_bus *bus, unsigned long features)
 {
 	struct pci_bus *child;
@@ -1032,7 +1063,6 @@ static void vmd_bus_enumeration(struct pci_bus *bus, unsigned long features)
 static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 {
 	struct pci_sysdata *sd = &vmd->sysdata;
-	LIST_HEAD(resources);
 	resource_size_t offset[2] = {0};
 	resource_size_t membar2_offset = 0x2000;
 	int ret;
@@ -1086,10 +1116,6 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 		vmd_set_msi_remapping(vmd, false);
 	}
 
-	pci_add_resource(&resources, &vmd->resources[0]);
-	pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
-	pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);
-
 	sd->vmd_dev = vmd->dev;
 
 	/*
@@ -1104,27 +1130,14 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 
 	sd->node = pcibus_to_node(vmd->dev->bus);
 
-	vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
-				       &vmd_ops, sd, &resources);
-	if (!vmd->bus) {
+	ret = vmd_create_bus(vmd, sd, offset);
+	if (ret) {
+		pci_err(vmd->dev, "Can't create bus: %d\n", ret);
 		pci_bus_release_emul_domain_nr(sd->domain);
-		pci_free_resource_list(&resources);
 		vmd_remove_irq_domain(vmd);
-		return -ENODEV;
+		return ret;
 	}
 
-	/* Don't copy _OSC control flags in VM, it disables features.*/
-	if (!offset[0] || !offset[1])
-		vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
-					 to_pci_host_bridge(vmd->bus->bridge));
-
-	vmd_attach_resources(vmd);
-	if (vmd->irq_domain)
-		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
-	else
-		dev_set_msi_domain(&vmd->bus->dev,
-				   dev_get_msi_domain(&vmd->dev->dev));
-
 	WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj,
 			       "domain"), "Can't create symlink to domain\n");
 
-- 
2.43.0

[PATCH v7 5/8] PCI: vmd: Replace hardcoded values with enum and defines

[Szymon Durawa]

Add enum vmd_resource type to replace hardcoded values. Add defines for
vmd bus start number based on VMD restriction value. No functional
changes.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 45 ++++++++++++++++++++++++------------
 1 file changed, 30 insertions(+), 15 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index e19b7fcb2025..79ae4a62e29e 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -26,6 +26,11 @@
 #define VMD_MEMBAR1	2
 #define VMD_MEMBAR2	4
 
+/* VMD restriction value determines secondary start bus number */
+#define VMD_RESTRICT_0_BUS_START 0x0
+#define VMD_RESTRICT_1_BUS_START 0x80
+#define VMD_RESTRICT_2_BUS_START 0xE0
+
 #define PCI_REG_VMCAP		0x40
 #define BUS_RESTRICT_CAP(vmcap)	(vmcap & 0x1)
 #define PCI_REG_VMCONFIG	0x44
@@ -43,6 +48,13 @@
 #define BASE_ID_REG_28C1		0x2840
 #define MEMBAR2_OFFSET_28C1		0x30d0
 
+enum vmd_resource {
+	VMD_RES_CFGBAR = 0, /* VMD Bus0 Config BAR */
+	VMD_RES_MBAR_1, /* VMD Bus0 Resource MemBAR 1 */
+	VMD_RES_MBAR_2, /* VMD Bus0 Resource MemBAR 2 */
+	VMD_RES_COUNT
+};
+
 enum vmd_features {
 	/*
 	 * Device may contain registers which hint the physical location of the
@@ -150,7 +162,7 @@ struct vmd_dev {
 	struct vmd_irq_list	*irqs;
 
 	struct pci_sysdata	sysdata;
-	struct resource		resources[3];
+	struct resource		resources[VMD_RES_COUNT];
 	struct irq_domain	*irq_domain;
 	struct pci_bus		*bus;
 	u8			busn_start;
@@ -562,7 +574,7 @@ static resource_size_t vmd_cfgbar_ecam_space(struct vmd_dev *vmd)
 }
 static void vmd_domain_reset(struct vmd_dev *vmd)
 {
-	u16 bus, max_buses = resource_size(&vmd->resources[0]);
+	u16 bus, max_buses = resource_size(&vmd->resources[VMD_RES_CFGBAR]);
 	u8 dev, functions, fn, hdr_type;
 	unsigned int ecam_bus;
 	char __iomem *base;
@@ -613,8 +625,8 @@ static void vmd_domain_reset(struct vmd_dev *vmd)
 
 static void vmd_attach_resources(struct vmd_dev *vmd)
 {
-	vmd->dev->resource[VMD_MEMBAR1].child = &vmd->resources[1];
-	vmd->dev->resource[VMD_MEMBAR2].child = &vmd->resources[2];
+	vmd->dev->resource[VMD_MEMBAR1].child = &vmd->resources[VMD_RES_MBAR_1];
+	vmd->dev->resource[VMD_MEMBAR2].child = &vmd->resources[VMD_RES_MBAR_2];
 }
 
 static void vmd_detach_resources(struct vmd_dev *vmd)
@@ -688,13 +700,13 @@ static int vmd_get_bus_number_start(struct vmd_dev *vmd)
 
 		switch (BUS_RESTRICT_CFG(reg)) {
 		case 0:
-			vmd->busn_start = 0;
+			vmd->busn_start = VMD_RESTRICT_0_BUS_START;
 			break;
 		case 1:
-			vmd->busn_start = 128;
+			vmd->busn_start = VMD_RESTRICT_1_BUS_START;
 			break;
 		case 2:
-			vmd->busn_start = 224;
+			vmd->busn_start = VMD_RESTRICT_2_BUS_START;
 			break;
 		default:
 			pci_err(dev, "Unknown Bus Offset Setting (%d)\n",
@@ -910,7 +922,7 @@ static void vmd_configure_cfgbar(struct vmd_dev *vmd)
 	/* Do not let resource[0] end go out of bound.*/
 	busn_end = vmd->busn_start + (resource_size(res) >> 20) - 1;
 	busn_end = min_t(resource_size_t, busn_end, 0xff);
-	vmd->resources[0] = (struct resource) {
+	vmd->resources[VMD_RES_CFGBAR] = (struct resource) {
 		.name  = "VMD CFGBAR",
 		.start = vmd->busn_start,
 		.end   = busn_end,
@@ -967,14 +979,15 @@ static int vmd_configure_membar1_membar2(struct vmd_dev *vmd,
 {
 	int ret;
 
-	ret = vmd_configure_membar(vmd, 1, VMD_MEMBAR1, 0, 0);
+	ret = vmd_configure_membar(vmd, VMD_RES_MBAR_1, VMD_MEMBAR1, 0, 0);
 	if (ret)
 		return ret;
 
-	ret = vmd_configure_membar(vmd, 2, VMD_MEMBAR2, mbar2_ofs, 0);
+	ret = vmd_configure_membar(vmd, VMD_RES_MBAR_2, VMD_MEMBAR2, mbar2_ofs, 0);
 	if (ret) {
-		devm_kfree(&vmd->dev->dev, (void *)vmd->resources[1].name);
-		memset(&vmd->resources[1], 0, sizeof(vmd->resources[1]));
+		devm_kfree(&vmd->dev->dev, (void *)vmd->resources[VMD_RES_MBAR_1].name);
+		memset(&vmd->resources[VMD_RES_MBAR_1], 0,
+		       sizeof(vmd->resources[VMD_RES_MBAR_1]));
 		return ret;
 	}
 
@@ -986,9 +999,11 @@ static int vmd_create_bus(struct vmd_dev *vmd, struct pci_sysdata *sd,
 {
 	LIST_HEAD(resources);
 
-	pci_add_resource(&resources, &vmd->resources[0]);
-	pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
-	pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);
+	pci_add_resource(&resources, &vmd->resources[VMD_RES_CFGBAR]);
+	pci_add_resource_offset(&resources, &vmd->resources[VMD_RES_MBAR_1],
+				offset[0]);
+	pci_add_resource_offset(&resources, &vmd->resources[VMD_RES_MBAR_2],
+				offset[1]);
 
 	vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
 				       &vmd_ops, sd, &resources);
-- 
2.43.0

[PATCH v7 6/8] PCI: vmd: Convert bus and busn_start to an array

[Szymon Durawa]

Convert bus and busn_start from scalar to an array to support
multiple VMD buses in the future. No functional changes.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 47 +++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 20 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 79ae4a62e29e..681bdd54f050 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -55,6 +55,11 @@ enum vmd_resource {
 	VMD_RES_COUNT
 };
 
+enum vmd_rootbus {
+	VMD_BUS_0 = 0,
+	VMD_BUS_COUNT
+};
+
 enum vmd_features {
 	/*
 	 * Device may contain registers which hint the physical location of the
@@ -164,8 +169,8 @@ struct vmd_dev {
 	struct pci_sysdata	sysdata;
 	struct resource		resources[VMD_RES_COUNT];
 	struct irq_domain	*irq_domain;
-	struct pci_bus		*bus;
-	u8			busn_start;
+	struct pci_bus		*bus[VMD_BUS_COUNT];
+	u8			busn_start[VMD_BUS_COUNT];
 	u8			first_vec;
 	char			*name;
 	int			instance;
@@ -425,7 +430,7 @@ static unsigned int vmd_bus_to_ecam(struct vmd_dev *vmd, unsigned int busnr)
 	if (!!(vmd->features & VMD_FEAT_USE_BIOS_INFO))
 		return busnr;
 
-	return busnr - vmd->busn_start;
+	return busnr - vmd->busn_start[VMD_BUS_0];
 }
 
 static void __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
@@ -700,13 +705,13 @@ static int vmd_get_bus_number_start(struct vmd_dev *vmd)
 
 		switch (BUS_RESTRICT_CFG(reg)) {
 		case 0:
-			vmd->busn_start = VMD_RESTRICT_0_BUS_START;
+			vmd->busn_start[VMD_BUS_0] = VMD_RESTRICT_0_BUS_START;
 			break;
 		case 1:
-			vmd->busn_start = VMD_RESTRICT_1_BUS_START;
+			vmd->busn_start[VMD_BUS_0] = VMD_RESTRICT_1_BUS_START;
 			break;
 		case 2:
-			vmd->busn_start = VMD_RESTRICT_2_BUS_START;
+			vmd->busn_start[VMD_BUS_0] = VMD_RESTRICT_2_BUS_START;
 			break;
 		default:
 			pci_err(dev, "Unknown Bus Offset Setting (%d)\n",
@@ -743,7 +748,7 @@ static int vmd_get_bus_info_from_bar4(struct vmd_dev *vmd,
 	bar4_2840 = readq(bar4 + BASE_ID_REG_28C1);
 	base_id = bar4_2840 & 0xFFFFFF;
 	base_bus = base_id >> 8;
-	vmd->busn_start = base_bus;
+	vmd->busn_start[VMD_BUS_0] = base_bus;
 
 	/* Calculate offsets like vmd_get_phys_offsets() does. */
 	if (phys1)
@@ -920,11 +925,11 @@ static void vmd_configure_cfgbar(struct vmd_dev *vmd)
 	resource_size_t busn_end;
 
 	/* Do not let resource[0] end go out of bound.*/
-	busn_end = vmd->busn_start + (resource_size(res) >> 20) - 1;
+	busn_end = vmd->busn_start[VMD_BUS_0] + (resource_size(res) >> 20) - 1;
 	busn_end = min_t(resource_size_t, busn_end, 0xff);
 	vmd->resources[VMD_RES_CFGBAR] = (struct resource) {
 		.name  = "VMD CFGBAR",
-		.start = vmd->busn_start,
+		.start = vmd->busn_start[VMD_BUS_0],
 		.end   = busn_end,
 		.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED,
 	};
@@ -1005,9 +1010,10 @@ static int vmd_create_bus(struct vmd_dev *vmd, struct pci_sysdata *sd,
 	pci_add_resource_offset(&resources, &vmd->resources[VMD_RES_MBAR_2],
 				offset[1]);
 
-	vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
-				       &vmd_ops, sd, &resources);
-	if (!vmd->bus) {
+	vmd->bus[VMD_BUS_0] = pci_create_root_bus(&vmd->dev->dev,
+						  vmd->busn_start[VMD_BUS_0],
+						  &vmd_ops, sd, &resources);
+	if (!vmd->bus[VMD_BUS_0]) {
 		pci_free_resource_list(&resources);
 		return -ENODEV;
 	}
@@ -1015,13 +1021,13 @@ static int vmd_create_bus(struct vmd_dev *vmd, struct pci_sysdata *sd,
 	/* Don't copy _OSC control flags in VM, it disables features.*/
 	if (!offset[0] || !offset[1])
 		vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
-					   to_pci_host_bridge(vmd->bus->bridge));
+					   to_pci_host_bridge(vmd->bus[VMD_BUS_0]->bridge));
 
 	vmd_attach_resources(vmd);
 	if (vmd->irq_domain)
-		dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
+		dev_set_msi_domain(&vmd->bus[VMD_BUS_0]->dev, vmd->irq_domain);
 	else
-		dev_set_msi_domain(&vmd->bus->dev,
+		dev_set_msi_domain(&vmd->bus[VMD_BUS_0]->dev,
 				   dev_get_msi_domain(&vmd->dev->dev));
 
 	return 0;
@@ -1153,10 +1159,11 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 		return ret;
 	}
 
-	WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj,
-			       "domain"), "Can't create symlink to domain\n");
+	WARN(sysfs_create_link(&vmd->dev->dev.kobj,
+			       &vmd->bus[VMD_BUS_0]->dev.kobj, "domain"),
+	     "Can't create symlink to domain\n");
 
-	vmd_bus_enumeration(vmd->bus, features);
+	vmd_bus_enumeration(vmd->bus[VMD_BUS_0], features);
 
 	return 0;
 }
@@ -1253,9 +1260,9 @@ static void vmd_remove(struct pci_dev *dev)
 {
 	struct vmd_dev *vmd = pci_get_drvdata(dev);
 
-	pci_stop_root_bus(vmd->bus);
+	pci_stop_root_bus(vmd->bus[VMD_BUS_0]);
 	sysfs_remove_link(&vmd->dev->dev.kobj, "domain");
-	pci_remove_root_bus(vmd->bus);
+	pci_remove_root_bus(vmd->bus[VMD_BUS_0]);
 	vmd_cleanup_srcu(vmd);
 	vmd_detach_resources(vmd);
 	vmd_remove_irq_domain(vmd);
-- 
2.43.0

[PATCH v7 7/8] PCI: vmd: Add support for second rootbus under VMD

[Szymon Durawa]

Starting from Intel Arrow Lake VMD enhancement introduces second root bus
support with fixed root bus number (0x80). It means that all 3 MMIO BARs
exposed by VMD are shared now between both buses (current BUS0 and
new BUS1).

Add new BUS1 enumeration and divide MMIO space to be shared between
both root buses. Due to enumeration issues with root bus hardwired to a
fixed non-zero value, this patch will work with a workaround proposed
in next patch. Without workaround user won't see attached devices for BUS1
root bus.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 311 +++++++++++++++++++++++++++++++----
 1 file changed, 276 insertions(+), 35 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 681bdd54f050..7e76ef3d7ec8 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -4,6 +4,7 @@
  * Copyright (c) 2015, Intel Corporation.
  */
 
+#include <linux/bitfield.h>
 #include <linux/device.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
@@ -30,6 +31,7 @@
 #define VMD_RESTRICT_0_BUS_START 0x0
 #define VMD_RESTRICT_1_BUS_START 0x80
 #define VMD_RESTRICT_2_BUS_START 0xE0
+#define VMD_RESTRICT_3_BUS_START 0xE1
 
 #define PCI_REG_VMCAP		0x40
 #define BUS_RESTRICT_CAP(vmcap)	(vmcap & 0x1)
@@ -48,15 +50,36 @@
 #define BASE_ID_REG_28C1		0x2840
 #define MEMBAR2_OFFSET_28C1		0x30d0
 
+/* Primary Bus Number for VMD devices on root bus 0 */
+#define VMD_PRIMARY_BUS0    0x00
+/* Primary Bus Number for VMD devices on root bus 1 */
+#define VMD_PRIMARY_BUS1    0x80
+
+#define VMD_BUSRANGE0       0xc8
+#define VMD_BUSRANGE1       0xcc
+#define VMD_MEMBAR1_OFFSET  0xd0
+#define VMD_MEMBAR2_OFFSET1 0xd8
+#define VMD_MEMBAR2_OFFSET2 0xdc
+#define VMD_BUS_END(busr) FIELD_GET(GENMASK(15, 8), busr)
+#define VMD_BUS_START(busr) FIELD_GET(GENMASK(7, 0), busr)
+
+/*
+ * Add VMD resources for BUS1, it will share the same MMIO space with
+ * previous VMD resources.
+ */
 enum vmd_resource {
-	VMD_RES_CFGBAR = 0, /* VMD Bus0 Config BAR */
-	VMD_RES_MBAR_1, /* VMD Bus0 Resource MemBAR 1 */
-	VMD_RES_MBAR_2, /* VMD Bus0 Resource MemBAR 2 */
+	VMD_RES_CFGBAR = 0,  /* VMD Bus0 Config BAR */
+	VMD_RES_MBAR_1,      /* VMD Bus0 Resource MemBAR 1 */
+	VMD_RES_MBAR_2,      /* VMD Bus0 Resource MemBAR 2 */
+	VMD_RES_BUS1_CFGBAR, /* VMD Bus1 Config BAR */
+	VMD_RES_BUS1_MBAR_1, /* VMD Bus1 Resource MemBAR 1 */
+	VMD_RES_BUS1_MBAR_2, /* VMD Bus1 Resource MemBAR 2 */
 	VMD_RES_COUNT
 };
 
 enum vmd_rootbus {
 	VMD_BUS_0 = 0,
+	VMD_BUS_1,
 	VMD_BUS_COUNT
 };
 
@@ -109,6 +132,12 @@ enum vmd_features {
 	 * to as MEMBAR2 or MSI-X bar.
 	 */
 	VMD_FEAT_USE_BIOS_INFO		= (1 << 6),
+
+	/*
+	 * Starting from Intel Arrow Lake, VMD devices have their VMD root ports
+	 * on the additional BUS1 root bus.
+	 */
+	VMD_FEAT_HAS_BUS1_ROOTBUS	= (1 << 7)
 };
 
 #define VMD_BIOS_PM_QUIRK_LTR	0x1003	/* 3145728 ns */
@@ -116,7 +145,8 @@ enum vmd_features {
 #define VMD_FEATS_CLIENT	(VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |	\
 				 VMD_FEAT_HAS_BUS_RESTRICTIONS |	\
 				 VMD_FEAT_OFFSET_FIRST_VECTOR |		\
-				 VMD_FEAT_BIOS_PM_QUIRK)
+				 VMD_FEAT_BIOS_PM_QUIRK |		\
+				 VMD_FEAT_HAS_BUS1_ROOTBUS)
 
 static DEFINE_IDA(vmd_instance_ida);
 
@@ -175,6 +205,7 @@ struct vmd_dev {
 	char			*name;
 	int			instance;
 	unsigned long		features;
+	bool			bus1_rootbus;
 };
 
 static inline struct vmd_dev *vmd_from_bus(struct pci_bus *bus)
@@ -579,7 +610,8 @@ static resource_size_t vmd_cfgbar_ecam_space(struct vmd_dev *vmd)
 }
 static void vmd_domain_reset(struct vmd_dev *vmd)
 {
-	u16 bus, max_buses = resource_size(&vmd->resources[VMD_RES_CFGBAR]);
+	/* One ECAM bus consumes 1MB of CFGBAR space. */
+	u16 bus, max_buses = resource_size(&vmd->dev->resource[VMD_CFGBAR]) >> 20;
 	u8 dev, functions, fn, hdr_type;
 	unsigned int ecam_bus;
 	char __iomem *base;
@@ -632,12 +664,24 @@ static void vmd_attach_resources(struct vmd_dev *vmd)
 {
 	vmd->dev->resource[VMD_MEMBAR1].child = &vmd->resources[VMD_RES_MBAR_1];
 	vmd->dev->resource[VMD_MEMBAR2].child = &vmd->resources[VMD_RES_MBAR_2];
+
+	if (vmd->bus1_rootbus) {
+		vmd->resources[VMD_RES_MBAR_1].sibling =
+			&vmd->resources[VMD_RES_BUS1_MBAR_1];
+		vmd->resources[VMD_RES_MBAR_2].sibling =
+			&vmd->resources[VMD_RES_BUS1_MBAR_2];
+	}
 }
 
 static void vmd_detach_resources(struct vmd_dev *vmd)
 {
 	vmd->dev->resource[VMD_MEMBAR1].child = NULL;
 	vmd->dev->resource[VMD_MEMBAR2].child = NULL;
+
+	if (vmd->bus1_rootbus) {
+		vmd->resources[VMD_RES_MBAR_1].sibling = NULL;
+		vmd->resources[VMD_RES_MBAR_2].sibling = NULL;
+	}
 }
 
 static int vmd_get_phys_offsets(struct vmd_dev *vmd, bool native_hint,
@@ -694,7 +738,7 @@ static int vmd_get_phys_offsets(struct vmd_dev *vmd, bool native_hint,
 	return 0;
 }
 
-static int vmd_get_bus_number_start(struct vmd_dev *vmd)
+static int vmd_get_bus_number_start(struct vmd_dev *vmd, unsigned long features)
 {
 	struct pci_dev *dev = vmd->dev;
 	u16 reg;
@@ -713,6 +757,24 @@ static int vmd_get_bus_number_start(struct vmd_dev *vmd)
 		case 2:
 			vmd->busn_start[VMD_BUS_0] = VMD_RESTRICT_2_BUS_START;
 			break;
+		case 3:
+			if (!(features & VMD_FEAT_HAS_BUS1_ROOTBUS)) {
+				pci_err(dev, "VMD Bus Restriction detected type %d, but BUS1 root bus is not supported, aborting.\n",
+					BUS_RESTRICT_CFG(reg));
+				return -ENODEV;
+			}
+
+			/*
+			 * Per Intel VMD specification (e.g., Arrow Lake-S):
+			 * - VMD (on root bus 0) secondary bus start number: 0xE0
+			 *	(devices span 0xE2..0xF0 via VMD_BUSRANGE0).
+			 * - VMD (on root bus 1) secondary bus start number: 0xE1
+			 *	(devices span 0xF1..0xFF via VMD_BUSRANGE1).
+			 */
+			vmd->busn_start[VMD_BUS_0] = VMD_RESTRICT_2_BUS_START;
+			vmd->busn_start[VMD_BUS_1] = VMD_RESTRICT_3_BUS_START;
+			vmd->bus1_rootbus = true;
+			break;
 		default:
 			pci_err(dev, "Unknown Bus Offset Setting (%d)\n",
 				BUS_RESTRICT_CFG(reg));
@@ -852,7 +914,7 @@ static int vmd_prepare_offsets_and_bus(struct vmd_dev *vmd,
 	 * limits the bus range to between 0-127, 128-255, or 224-255.
 	 */
 	if (features & VMD_FEAT_HAS_BUS_RESTRICTIONS) {
-		ret = vmd_get_bus_number_start(vmd);
+		ret = vmd_get_bus_number_start(vmd, features);
 		if (ret)
 			return ret;
 	}
@@ -919,7 +981,7 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
 	return 0;
 }
 
-static void vmd_configure_cfgbar(struct vmd_dev *vmd)
+static int vmd_configure_cfgbar(struct vmd_dev *vmd)
 {
 	struct resource *res = &vmd->dev->resource[VMD_CFGBAR];
 	resource_size_t busn_end;
@@ -933,6 +995,62 @@ static void vmd_configure_cfgbar(struct vmd_dev *vmd)
 		.end   = busn_end,
 		.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED,
 	};
+
+	if (vmd->bus1_rootbus) {
+		int ret;
+		u16 bus0_range = 0;
+		u16 bus1_range = 0;
+		u8 bus0_start, bus0_end;
+		u8 bus1_start, bus1_end;
+
+		ret = pci_read_config_word(vmd->dev, VMD_BUSRANGE0, &bus0_range);
+		if (ret) {
+			pci_err(vmd->dev, "Failed to read VMD_BUSRANGE0: %d\n", ret);
+			return -EIO;
+		}
+
+		ret = pci_read_config_word(vmd->dev, VMD_BUSRANGE1, &bus1_range);
+		if (ret) {
+			pci_err(vmd->dev, "Failed to read VMD_BUSRANGE1: %d\n", ret);
+			return -EIO;
+		}
+
+		bus0_start = VMD_BUS_START(bus0_range);
+		bus0_end = VMD_BUS_END(bus0_range);
+		bus1_start = VMD_BUS_START(bus1_range);
+		bus1_end = VMD_BUS_END(bus1_range);
+
+		if (bus0_start > bus0_end || bus1_start > bus1_end) {
+			pci_err(vmd->dev,
+				"Invalid bus range(s): BUS0 [%02x-%02x], BUS1 [%02x-%02x]\n",
+				bus0_start, bus0_end, bus1_start, bus1_end);
+			return -EINVAL;
+		}
+
+		if (!(bus0_end < bus1_start || bus1_end < bus0_start)) {
+			pci_err(vmd->dev,
+				"Overlapping bus ranges: BUS0 [%02x-%02x], BUS1 [%02x-%02x]\n",
+				bus0_start, bus0_end, bus1_start, bus1_end);
+			return -EINVAL;
+		}
+
+		/*
+		 * Resize BUS0 CFGBAR range to make space for BUS1
+		 * owned devices by adjusting range end with value stored in
+		 * VMD_BUSRANGE0 register.
+		 */
+		vmd->resources[VMD_RES_CFGBAR].start = bus0_start;
+		vmd->resources[VMD_RES_CFGBAR].end = bus0_end;
+
+		vmd->resources[VMD_RES_BUS1_CFGBAR] = (struct resource){
+			.name = "VMD CFGBAR BUS1",
+			.start = bus1_start,
+			.end = bus1_end,
+			.flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED,
+		};
+	}
+
+	return 0;
 }
 
 /*
@@ -963,8 +1081,9 @@ static int vmd_configure_membar(struct vmd_dev *vmd, u8 resource_number,
 	if (!upper_bits)
 		flags &= ~IORESOURCE_MEM_64;
 
-	name = devm_kasprintf(&vmd->dev->dev, GFP_KERNEL, "VMD MEMBAR%d",
-			      resource_number);
+	name = devm_kasprintf(&vmd->dev->dev, GFP_KERNEL, "VMD MEMBAR%d %s",
+			      membar_number / 2,
+			      resource_number > VMD_RES_MBAR_2 ? "BUS1" : "");
 	if (!name)
 		return -ENOMEM;
 
@@ -984,52 +1103,131 @@ static int vmd_configure_membar1_membar2(struct vmd_dev *vmd,
 {
 	int ret;
 
-	ret = vmd_configure_membar(vmd, VMD_RES_MBAR_1, VMD_MEMBAR1, 0, 0);
-	if (ret)
-		return ret;
+	if (vmd->bus1_rootbus) {
+		u32 reg = 0;
+		u32 bus1_mbar1_ofs = 0;
+		u64 bus1_mbar2_ofs = 0;
+		resource_size_t mbar1_sz, mbar2_sz;
 
-	ret = vmd_configure_membar(vmd, VMD_RES_MBAR_2, VMD_MEMBAR2, mbar2_ofs, 0);
-	if (ret) {
-		devm_kfree(&vmd->dev->dev, (void *)vmd->resources[VMD_RES_MBAR_1].name);
-		memset(&vmd->resources[VMD_RES_MBAR_1], 0,
-		       sizeof(vmd->resources[VMD_RES_MBAR_1]));
-		return ret;
+		mbar1_sz = resource_size(&vmd->dev->resource[VMD_MEMBAR1]);
+		mbar2_sz = resource_size(&vmd->dev->resource[VMD_MEMBAR2]);
+
+		ret = pci_read_config_dword(vmd->dev, VMD_MEMBAR1_OFFSET,
+					    &bus1_mbar1_ofs);
+		if (ret)
+			return -EIO;
+
+		ret = pci_read_config_dword(vmd->dev, VMD_MEMBAR2_OFFSET1, &reg);
+		if (ret)
+			return -EIO;
+		bus1_mbar2_ofs = reg;
+
+		ret = pci_read_config_dword(vmd->dev, VMD_MEMBAR2_OFFSET2, &reg);
+		if (ret)
+			return -EIO;
+		bus1_mbar2_ofs |= (u64)reg << 32;
+
+		if (!bus1_mbar1_ofs || bus1_mbar1_ofs >= mbar1_sz) {
+			pci_err(vmd->dev, "Invalid MEMBAR1 offset %#llx (BAR size %#llx)\n",
+				(unsigned long long)bus1_mbar1_ofs,
+				(unsigned long long)mbar1_sz);
+			return -EINVAL;
+		}
+
+		if (!bus1_mbar2_ofs || mbar2_ofs >= mbar2_sz ||
+		    bus1_mbar2_ofs <= mbar2_ofs || bus1_mbar2_ofs >= mbar2_sz) {
+			pci_err(vmd->dev,
+				"Invalid MEMBAR2 split %#llx (shadow offset %#llx, BAR size %#llx)\n",
+				(unsigned long long)bus1_mbar2_ofs,
+				(unsigned long long)mbar2_ofs,
+				(unsigned long long)mbar2_sz);
+			return -EINVAL;
+		}
+
+		/*
+		 * Resize BUS MEMBAR1 and MEMBAR2 ranges to make space
+		 * for BUS1 owned devices by adjusting range end with values
+		 * stored in VMD_MEMBAR1_OFFSET and VMD_MEMBAR2_OFFSET registers
+		 */
+		ret = vmd_configure_membar(vmd, VMD_RES_MBAR_1, VMD_MEMBAR1, 0,
+					   mbar1_sz - bus1_mbar1_ofs);
+		if (ret)
+			return ret;
+
+		ret = vmd_configure_membar(vmd, VMD_RES_MBAR_2, VMD_MEMBAR2,
+					   mbar2_ofs, mbar2_sz - bus1_mbar2_ofs);
+		if (ret)
+			return ret;
+
+		ret = vmd_configure_membar(vmd, VMD_RES_BUS1_MBAR_1, VMD_MEMBAR1,
+					   bus1_mbar1_ofs, 0);
+		if (ret)
+			return ret;
+
+		ret = vmd_configure_membar(vmd, VMD_RES_BUS1_MBAR_2, VMD_MEMBAR2,
+					   bus1_mbar2_ofs, 0);
+		if (ret)
+			return ret;
+	} else {
+		ret = vmd_configure_membar(vmd, VMD_RES_MBAR_1, VMD_MEMBAR1, 0, 0);
+		if (ret)
+			return ret;
+
+		ret = vmd_configure_membar(vmd, VMD_RES_MBAR_2, VMD_MEMBAR2,
+					   mbar2_ofs, 0);
+		if (ret)
+			return ret;
 	}
 
 	return 0;
 }
 
-static int vmd_create_bus(struct vmd_dev *vmd, struct pci_sysdata *sd,
-			  resource_size_t *offset)
+static int vmd_create_bus(struct vmd_dev *vmd, enum vmd_rootbus bus_number,
+			  struct pci_sysdata *sd, resource_size_t *offset,
+			  u8 primary)
 {
+	u8 cfgbar = bus_number * 3;
+	u8 membar1 = cfgbar + 1;
+	u8 membar2 = cfgbar + 2;
+	struct pci_bus *vmd_bus;
 	LIST_HEAD(resources);
 
-	pci_add_resource(&resources, &vmd->resources[VMD_RES_CFGBAR]);
-	pci_add_resource_offset(&resources, &vmd->resources[VMD_RES_MBAR_1],
+	pci_add_resource(&resources, &vmd->resources[cfgbar]);
+	pci_add_resource_offset(&resources, &vmd->resources[membar1],
 				offset[0]);
-	pci_add_resource_offset(&resources, &vmd->resources[VMD_RES_MBAR_2],
+	pci_add_resource_offset(&resources, &vmd->resources[membar2],
 				offset[1]);
 
-	vmd->bus[VMD_BUS_0] = pci_create_root_bus(&vmd->dev->dev,
-						  vmd->busn_start[VMD_BUS_0],
-						  &vmd_ops, sd, &resources);
-	if (!vmd->bus[VMD_BUS_0]) {
+	vmd_bus = pci_create_root_bus(&vmd->dev->dev,
+				      vmd->busn_start[bus_number], &vmd_ops, sd,
+				      &resources);
+
+	if (!vmd_bus) {
 		pci_free_resource_list(&resources);
 		return -ENODEV;
 	}
 
+	/*
+	 * pci_create_root_bus() does not initialise bus->primary.
+	 * Set it here before any scanning so bridge traversal logic
+	 * sees the correct upstream bus number from the start.
+	 */
+	vmd_bus->primary = primary;
+
 	/* Don't copy _OSC control flags in VM, it disables features.*/
 	if (!offset[0] || !offset[1])
 		vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
-					   to_pci_host_bridge(vmd->bus[VMD_BUS_0]->bridge));
+					   to_pci_host_bridge(vmd_bus->bridge));
 
 	vmd_attach_resources(vmd);
 	if (vmd->irq_domain)
-		dev_set_msi_domain(&vmd->bus[VMD_BUS_0]->dev, vmd->irq_domain);
+		dev_set_msi_domain(&vmd_bus->dev, vmd->irq_domain);
 	else
-		dev_set_msi_domain(&vmd->bus[VMD_BUS_0]->dev,
+		dev_set_msi_domain(&vmd_bus->dev,
 				   dev_get_msi_domain(&vmd->dev->dev));
 
+	vmd->bus[bus_number] = vmd_bus;
+
 	return 0;
 }
 
@@ -1042,7 +1240,15 @@ static void vmd_bus_enumeration(struct pci_bus *bus, unsigned long features)
 	vmd_acpi_begin();
 
 	pci_scan_child_bus(bus);
-	vmd_domain_reset(vmd_from_bus(bus));
+
+	/*
+	 * vmd_domain_reset() walks the full VMD CFGBAR aperture, so a single
+	 * invocation from BUS0 resets bridge windows for the whole VMD domain,
+	 * including BUS1. Running it again during BUS1 enumeration would
+	 * re-clobber windows already assigned for BUS0.
+	 */
+	if (bus->primary == VMD_PRIMARY_BUS0)
+		vmd_domain_reset(vmd_from_bus(bus));
 
 	/*
 	 * When Intel VMD is enabled, the OS does not discover the Root Ports
@@ -1093,7 +1299,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	if (ret)
 		return ret;
 
-	vmd_configure_cfgbar(vmd);
+	ret = vmd_configure_cfgbar(vmd);
+	if (ret)
+		return ret;
 
 	/*
 	 * If the window is below 4GB, clear IORESOURCE_MEM_64 so we can
@@ -1151,7 +1359,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 
 	sd->node = pcibus_to_node(vmd->dev->bus);
 
-	ret = vmd_create_bus(vmd, sd, offset);
+	ret = vmd_create_bus(vmd, VMD_BUS_0, sd, offset, VMD_PRIMARY_BUS0);
 	if (ret) {
 		pci_err(vmd->dev, "Can't create bus: %d\n", ret);
 		pci_bus_release_emul_domain_nr(sd->domain);
@@ -1163,8 +1371,34 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 			       &vmd->bus[VMD_BUS_0]->dev.kobj, "domain"),
 	     "Can't create symlink to domain\n");
 
+	if (vmd->bus1_rootbus) {
+		ret = vmd_create_bus(vmd, VMD_BUS_1, sd, offset, VMD_PRIMARY_BUS1);
+		if (ret) {
+			pci_warn(vmd->dev,
+				 "Can't create BUS1: %d, continuing with BUS0 only\n",
+				 ret);
+
+			vmd->resources[VMD_RES_MBAR_1].sibling = NULL;
+			vmd->resources[VMD_RES_MBAR_2].sibling = NULL;
+			vmd->resources[VMD_RES_BUS1_CFGBAR] = (struct resource){};
+			vmd->resources[VMD_RES_BUS1_MBAR_1] = (struct resource){};
+			vmd->resources[VMD_RES_BUS1_MBAR_2] = (struct resource){};
+			vmd->bus1_rootbus = false;
+			vmd->bus[VMD_BUS_1] = NULL;
+		}
+
+		if (vmd->bus1_rootbus)
+			WARN(sysfs_create_link(&vmd->dev->dev.kobj,
+					       &vmd->bus[VMD_BUS_1]->dev.kobj,
+					       "domain1"),
+			     "Can't create symlink to domain1\n");
+	}
+
 	vmd_bus_enumeration(vmd->bus[VMD_BUS_0], features);
 
+	if (vmd->bus1_rootbus)
+		vmd_bus_enumeration(vmd->bus[VMD_BUS_1], features);
+
 	return 0;
 }
 
@@ -1263,6 +1497,13 @@ static void vmd_remove(struct pci_dev *dev)
 	pci_stop_root_bus(vmd->bus[VMD_BUS_0]);
 	sysfs_remove_link(&vmd->dev->dev.kobj, "domain");
 	pci_remove_root_bus(vmd->bus[VMD_BUS_0]);
+
+	if (vmd->bus1_rootbus && vmd->bus[VMD_BUS_1]) {
+		pci_stop_root_bus(vmd->bus[VMD_BUS_1]);
+		sysfs_remove_link(&vmd->dev->dev.kobj, "domain1");
+		pci_remove_root_bus(vmd->bus[VMD_BUS_1]);
+	}
+
 	vmd_cleanup_srcu(vmd);
 	vmd_detach_resources(vmd);
 	vmd_remove_irq_domain(vmd);
@@ -1359,4 +1600,4 @@ module_pci_driver(vmd_drv);
 MODULE_AUTHOR("Intel Corporation");
 MODULE_DESCRIPTION("Volume Management Device driver");
 MODULE_LICENSE("GPL v2");
-MODULE_VERSION("0.6");
+MODULE_VERSION("0.7");
-- 
2.43.0

[PATCH v7 8/8] PCI: vmd: Add workaround for bus number hardwired to fixed non-zero value

[Szymon Durawa]

The VMD BUS1 root bus number is fixed in hardware to 0x80. It marks bridge
invalid configuration when detecting a non-zero (0x80) the VMD BUS1 root
bus number.
Thus root bus number is deconfigured in the first pass of pci_scan_bridge()
to be re-assigned to 0x0 in the second pass. As a result no subordinate bus
number behind VMD BUS1 is found.

To avoid bus number reconfiguration, BUS1 number has to be the same
as BUS1 primary number.

Log snippet without workaround:

[    3.752507] vmd 0000:00:0e.0: PCI host bridge to bus 10000:e1
[    3.752510] pci_bus 10000:e1: busn_res: can not insert [bus e1-ff] under domain [bus 00-ff] (conflicts with (null) [bus e0-f0])
[    3.752515] pci_bus 10000:e1: root bus resource [bus f1-ff]
[    3.752517] pci_bus 10000:e1: root bus resource [mem 0x8c800000-0x8cffffff]
[    3.752519] pci_bus 10000:e1: root bus resource [mem 0x701b802000-0x701bffffff 64bit]
[    3.752523] pci_bus 10000:e1: scanning bus
[    3.752732] pci (null): Looking for ACPI companion (address 0x80e0ffff)
[    3.752745] pci 10000:e1:1c.0: [8086:7f38] type 01 class 0x060400 PCIe Root Port
[    3.752779] pci 10000:e1:1c.0: PCI bridge to [bus f1]
[    3.752861] pci 10000:e1:1c.0: PME# supported from D0 D3hot D3cold
[    3.752864] pci 10000:e1:1c.0: PME# disabled
[    3.752909] pci 10000:e1:1c.0: PTM enabled (root), 4ns granularity
[    3.752981] pci 10000:e1:1c.0: vgaarb: pci_notify
[    3.752987] pci_bus 10000:e1: fixups for bus
[    3.752992] pci 10000:e1:1c.0: scanning [bus f1-f1] behind bridge, pass 0
[    3.752993] pci 10000:e1:1c.0: primary 80, bus->number e1.
[    3.752994] pci 10000:e1:1c.0: bridge configuration invalid ([bus f1-f1]), reconfiguring
[    3.753003] pci 10000:e1:1c.0: scanning [bus 00-00] behind bridge, pass 1
[    3.753004] pci 10000:e1:1c.0: primary 00, bus->number e1.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 66 ++++++++++++++++++++++++++++++++----
 1 file changed, 60 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 7e76ef3d7ec8..f4c6a16e8473 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -467,10 +467,23 @@ static unsigned int vmd_bus_to_ecam(struct vmd_dev *vmd, unsigned int busnr)
 static void __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
 				  unsigned int devfn, int reg, int len)
 {
+	unsigned char bus_number;
 	unsigned int busnr_ecam;
 	u32 offset;
 
-	busnr_ecam = vmd_bus_to_ecam(vmd, bus->number);
+	/*
+	 * Remap ONLY the virtual BUS1 root bus number (0x80) to its physical
+	 * CFGBAR start aperture (0xE1). Downstream subordinate buses behind
+	 * the root port are assigned physical numbers (0xF1..0xFF per
+	 * VMD_BUSRANGE1) and must NOT be remapped, otherwise child endpoint
+	 * accesses would target the root port rather than their own ECAM space.
+	 */
+	if (vmd->bus1_rootbus && bus->number == VMD_PRIMARY_BUS1)
+		bus_number = vmd->busn_start[VMD_BUS_1];
+	else
+		bus_number = bus->number;
+
+	busnr_ecam = vmd_bus_to_ecam(vmd, bus_number);
 	offset = PCIE_ECAM_OFFSET(busnr_ecam, devfn, reg);
 
 	if (offset + len >= resource_size(&vmd->dev->resource[VMD_CFGBAR]))
@@ -550,18 +563,39 @@ static struct pci_ops vmd_ops = {
 static struct acpi_device *vmd_acpi_find_companion(struct pci_dev *pci_dev)
 {
 	struct pci_host_bridge *bridge;
-	u32 busnr, addr;
+	struct vmd_dev *vmd;
+	u32 addr;
+	int busnr;
+	u8 pci_bus_number;
+	u8 bridge_bus_number;
 
 	if (pci_dev->bus->ops != &vmd_ops)
 		return NULL;
 
+	vmd = vmd_from_bus(pci_dev->bus);
 	bridge = pci_find_host_bridge(pci_dev->bus);
-	busnr = pci_dev->bus->number - bridge->bus->number;
+	pci_bus_number = pci_dev->bus->number;
+	bridge_bus_number = bridge->bus->number;
+
+	/*
+	 * BUS1 is registered with logical root number 0x80. For ACPI companion
+	 * matching, map only the logical root bus (0x80) to the physical
+	 * BUS1 start base (0xE1). Downstream child buses (0xF1..0xFF) already
+	 * reflect their physical bus numbers and must remain untranslated to
+	 * produce the correct relative depth against bridge_bus_number.
+	 */
+	if (vmd->bus1_rootbus && bridge->bus == vmd->bus[VMD_BUS_1]) {
+		bridge_bus_number = vmd->busn_start[VMD_BUS_1];
+		if (pci_bus_number == VMD_PRIMARY_BUS1)
+			pci_bus_number = vmd->busn_start[VMD_BUS_1];
+	}
+
+	busnr = pci_bus_number - bridge_bus_number;
 	/*
 	 * The address computation below is only applicable to relative bus
 	 * numbers below 32.
 	 */
-	if (busnr > 31)
+	if (busnr < 0 || busnr > 31)
 		return NULL;
 
 	addr = (busnr << 24) | ((u32)pci_dev->devfn << 16) | 0x8000FFFFU;
@@ -1186,6 +1220,7 @@ static int vmd_create_bus(struct vmd_dev *vmd, enum vmd_rootbus bus_number,
 			  struct pci_sysdata *sd, resource_size_t *offset,
 			  u8 primary)
 {
+	u8 root_busnr;
 	u8 cfgbar = bus_number * 3;
 	u8 membar1 = cfgbar + 1;
 	u8 membar2 = cfgbar + 2;
@@ -1198,8 +1233,27 @@ static int vmd_create_bus(struct vmd_dev *vmd, enum vmd_rootbus bus_number,
 	pci_add_resource_offset(&resources, &vmd->resources[membar2],
 				offset[1]);
 
-	vmd_bus = pci_create_root_bus(&vmd->dev->dev,
-				      vmd->busn_start[bus_number], &vmd_ops, sd,
+	/*
+	 * Register BUS1 with its logical root number (0x80) up front so PCI core
+	 * bridge scanning does not see a post-registration bus-number mutation.
+	 *
+	 * This is a workaround for pci_scan_bridge_extend() code.
+	 * It marks bridge invalid configuration when detecting a
+	 * non-zero (0x80) the VMD BUS1 root bus number. Thus Primary Bus Number
+	 * of Root Ports on BUS1 is deconfigured in the first pass of
+	 * pci_scan_bridge() to be re-assigned to 0x0 in the second pass.
+	 * As a result no subordinate bus number behind VMD BUS1 is found.
+	 * Workaround: VMD_BUS_1 bus number shall be set to VMD_PRIMARY_BUS1 so it has
+	 * the same value as vmd->bus[VMD_BUS_1]->primary, it will bypass bus number
+	 * reconfiguration.
+	 */
+
+	if (bus_number == VMD_BUS_1 && vmd->bus1_rootbus)
+		root_busnr = VMD_PRIMARY_BUS1;
+	else
+		root_busnr = vmd->busn_start[bus_number];
+
+	vmd_bus = pci_create_root_bus(&vmd->dev->dev, root_busnr, &vmd_ops, sd,
 				      &resources);
 
 	if (!vmd_bus) {
-- 
2.43.0

Re: [PATCH v7 8/8] PCI: vmd: Add workaround for bus number hardwired to fixed non-zero value

[Bjorn Helgaas]

On Wed, Sep 02, 2026 at 05:58:44PM +0000, Szymon Durawa wrote:
> The VMD BUS1 root bus number is fixed in hardware to 0x80. It marks bridge
> invalid configuration when detecting a non-zero (0x80) the VMD BUS1 root
> bus number.

Add blank line between paragraphs.  I can't quite parse that second
sentence.  I don't know who is marking bridge configuration as
invalid.

> Thus root bus number is deconfigured in the first pass of pci_scan_bridge()
> to be re-assigned to 0x0 in the second pass. As a result no subordinate bus
> number behind VMD BUS1 is found.
> 
> To avoid bus number reconfiguration, BUS1 number has to be the same
> as BUS1 primary number.
> 
> Log snippet without workaround:
> 
> [    3.752507] vmd 0000:00:0e.0: PCI host bridge to bus 10000:e1

You're adding support for a second root bus.  So I assume there are
two "PCI host bridge to bus 10000:XX" lines, and it would help
understand this if you included both.

> [    3.752510] pci_bus 10000:e1: busn_res: can not insert [bus e1-ff] under domain [bus 00-ff] (conflicts with (null) [bus e0-f0])

We should fix whatever results in the "(null)" part here so the
message is more meaningful.

> [    3.752515] pci_bus 10000:e1: root bus resource [bus f1-ff]
> [    3.752517] pci_bus 10000:e1: root bus resource [mem 0x8c800000-0x8cffffff]
> [    3.752519] pci_bus 10000:e1: root bus resource [mem 0x701b802000-0x701bffffff 64bit]
> [    3.752523] pci_bus 10000:e1: scanning bus
> [    3.752732] pci (null): Looking for ACPI companion (address 0x80e0ffff)
> [    3.752745] pci 10000:e1:1c.0: [8086:7f38] type 01 class 0x060400 PCIe Root Port
> [    3.752779] pci 10000:e1:1c.0: PCI bridge to [bus f1]
> [    3.752861] pci 10000:e1:1c.0: PME# supported from D0 D3hot D3cold
> [    3.752864] pci 10000:e1:1c.0: PME# disabled
> [    3.752909] pci 10000:e1:1c.0: PTM enabled (root), 4ns granularity
> [    3.752981] pci 10000:e1:1c.0: vgaarb: pci_notify
> [    3.752987] pci_bus 10000:e1: fixups for bus
> [    3.752992] pci 10000:e1:1c.0: scanning [bus f1-f1] behind bridge, pass 0
> [    3.752993] pci 10000:e1:1c.0: primary 80, bus->number e1.
> [    3.752994] pci 10000:e1:1c.0: bridge configuration invalid ([bus f1-f1]), reconfiguring
> [    3.753003] pci 10000:e1:1c.0: scanning [bus 00-00] behind bridge, pass 1
> [    3.753004] pci 10000:e1:1c.0: primary 00, bus->number e1.

Remove timestamps (unless they are telling us something useful) and
indent the quoted log two spaces.

Also remove the unrelated log messages.  I don't think the mem
windows, scanning, ACPI companion, Root Port, PME#, PTM, vgaarb stuff
is relevant.

A few nits below.

> Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
> Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
> ---
>  drivers/pci/controller/vmd.c | 66 ++++++++++++++++++++++++++++++++----
>  1 file changed, 60 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index 7e76ef3d7ec8..f4c6a16e8473 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -467,10 +467,23 @@ static unsigned int vmd_bus_to_ecam(struct vmd_dev *vmd, unsigned int busnr)
>  static void __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
>  				  unsigned int devfn, int reg, int len)
>  {
> +	unsigned char bus_number;
>  	unsigned int busnr_ecam;
>  	u32 offset;
>  
> -	busnr_ecam = vmd_bus_to_ecam(vmd, bus->number);
> +	/*
> +	 * Remap ONLY the virtual BUS1 root bus number (0x80) to its physical
> +	 * CFGBAR start aperture (0xE1). Downstream subordinate buses behind
> +	 * the root port are assigned physical numbers (0xF1..0xFF per
> +	 * VMD_BUSRANGE1) and must NOT be remapped, otherwise child endpoint
> +	 * accesses would target the root port rather than their own ECAM space.
> +	 */
> +	if (vmd->bus1_rootbus && bus->number == VMD_PRIMARY_BUS1)
> +		bus_number = vmd->busn_start[VMD_BUS_1];
> +	else
> +		bus_number = bus->number;
> +
> +	busnr_ecam = vmd_bus_to_ecam(vmd, bus_number);
>  	offset = PCIE_ECAM_OFFSET(busnr_ecam, devfn, reg);
>  
>  	if (offset + len >= resource_size(&vmd->dev->resource[VMD_CFGBAR]))
> @@ -550,18 +563,39 @@ static struct pci_ops vmd_ops = {
>  static struct acpi_device *vmd_acpi_find_companion(struct pci_dev *pci_dev)
>  {
>  	struct pci_host_bridge *bridge;
> -	u32 busnr, addr;
> +	struct vmd_dev *vmd;
> +	u32 addr;
> +	int busnr;
> +	u8 pci_bus_number;
> +	u8 bridge_bus_number;
>  
>  	if (pci_dev->bus->ops != &vmd_ops)
>  		return NULL;
>  
> +	vmd = vmd_from_bus(pci_dev->bus);
>  	bridge = pci_find_host_bridge(pci_dev->bus);
> -	busnr = pci_dev->bus->number - bridge->bus->number;
> +	pci_bus_number = pci_dev->bus->number;
> +	bridge_bus_number = bridge->bus->number;
> +
> +	/*
> +	 * BUS1 is registered with logical root number 0x80. For ACPI companion
> +	 * matching, map only the logical root bus (0x80) to the physical
> +	 * BUS1 start base (0xE1). Downstream child buses (0xF1..0xFF) already
> +	 * reflect their physical bus numbers and must remain untranslated to
> +	 * produce the correct relative depth against bridge_bus_number.
> +	 */
> +	if (vmd->bus1_rootbus && bridge->bus == vmd->bus[VMD_BUS_1]) {
> +		bridge_bus_number = vmd->busn_start[VMD_BUS_1];
> +		if (pci_bus_number == VMD_PRIMARY_BUS1)
> +			pci_bus_number = vmd->busn_start[VMD_BUS_1];
> +	}
> +
> +	busnr = pci_bus_number - bridge_bus_number;

Need a blank line here to follow existing style.

>  	/*
>  	 * The address computation below is only applicable to relative bus
>  	 * numbers below 32.
>  	 */
> -	if (busnr > 31)
> +	if (busnr < 0 || busnr > 31)
>  		return NULL;
>  
>  	addr = (busnr << 24) | ((u32)pci_dev->devfn << 16) | 0x8000FFFFU;
> @@ -1186,6 +1220,7 @@ static int vmd_create_bus(struct vmd_dev *vmd, enum vmd_rootbus bus_number,
>  			  struct pci_sysdata *sd, resource_size_t *offset,
>  			  u8 primary)
>  {
> +	u8 root_busnr;
>  	u8 cfgbar = bus_number * 3;
>  	u8 membar1 = cfgbar + 1;
>  	u8 membar2 = cfgbar + 2;
> @@ -1198,8 +1233,27 @@ static int vmd_create_bus(struct vmd_dev *vmd, enum vmd_rootbus bus_number,
>  	pci_add_resource_offset(&resources, &vmd->resources[membar2],
>  				offset[1]);
>  
> -	vmd_bus = pci_create_root_bus(&vmd->dev->dev,
> -				      vmd->busn_start[bus_number], &vmd_ops, sd,
> +	/*
> +	 * Register BUS1 with its logical root number (0x80) up front so PCI core
> +	 * bridge scanning does not see a post-registration bus-number mutation.
> +	 *
> +	 * This is a workaround for pci_scan_bridge_extend() code.
> +	 * It marks bridge invalid configuration when detecting a
> +	 * non-zero (0x80) the VMD BUS1 root bus number. Thus Primary Bus Number
> +	 * of Root Ports on BUS1 is deconfigured in the first pass of
> +	 * pci_scan_bridge() to be re-assigned to 0x0 in the second pass.
> +	 * As a result no subordinate bus number behind VMD BUS1 is found.
> +	 * Workaround: VMD_BUS_1 bus number shall be set to VMD_PRIMARY_BUS1 so it has
> +	 * the same value as vmd->bus[VMD_BUS_1]->primary, it will bypass bus number
> +	 * reconfiguration.

Make sure your comments all fit in 80 columns.

Add blank lines between paragraphs.

> +	 */
> +

Don't need a blank line here.

> +	if (bus_number == VMD_BUS_1 && vmd->bus1_rootbus)
> +		root_busnr = VMD_PRIMARY_BUS1;
> +	else
> +		root_busnr = vmd->busn_start[bus_number];
> +
> +	vmd_bus = pci_create_root_bus(&vmd->dev->dev, root_busnr, &vmd_ops, sd,
>  				      &resources);
>  
>  	if (!vmd_bus) {
> -- 
> 2.43.0
>