[PATCH v5 0/2] Add Apple T2 NHI device links

[PATCH v5 0/2] Add Apple T2 NHI device links

[Atharva Tiwari]

This series adds a cached flag to detect Apple T2 systems, then uses it
to create device links for the Thunderbolt NHI.

Changes in v5:
- Used Icelake root PCI IDs for detection of root ports instead of TRP

Changes in v4:
- Limited TRP check to T2 Icelake systems only
- Optimized has_apple_t2_chip check
- Included pci.h to drivers/thunderbolt/tb.c
- Used __free(pci_dev_put) to avoid label

Changes in v3:
- Fix build errors with non-x86 machines
- Used __initconst for apple_t2_devices
- Removed UEFI_QUIRK_SKIP_CERT as its unused now
- Used IS_ENABLED(CONFIG_ACPI) in tb_apple_add_links for the T2 part
- Removed !bid check to remove warning with -Waddress

Changes in v2:
- Used a less generic name for has_t2_chip
- Used DMI instead of PCI for has_apple_t2_chip to avoid PCI problems
- Initialized ret in tb_apple_add_links

Link to v4:
https://lore.kernel.org/all/20260724164641.2239-1-atharvatiwarilinuxdev@gmail.com/

Link to v3:
https://lore.kernel.org/all/20260721063412.11588-1-atharvatiwarilinuxdev@gmail.com/

Link to v2:
https://lore.kernel.org/all/20260721054506.11871-1-atharvatiwarilinuxdev@gmail.com/

Link to v1:
https://lore.kernel.org/all/20260719180308.1398-1-atharvatiwarilinuxdev@gmail.com/

Atharva Tiwari (2):
  treewide: Add a flag to detect the Apple T2 chip
  thunderbolt: Add device links for Apple T2 NHI

 arch/x86/kernel/quirks.c                      | 37 +++++++++++++
 drivers/thunderbolt/tb.c                      | 54 ++++++++++++++++++-
 include/linux/platform_data/x86/apple.h       |  5 ++
 .../platform_certs/keyring_handler.h          |  8 ---
 security/integrity/platform_certs/load_uefi.c | 38 +++----------
 5 files changed, 102 insertions(+), 40 deletions(-)

-- 
2.43.0

[PATCH v5 1/2] treewide: Add a flag to detect the Apple T2 chip

[Atharva Tiwari]

Add a flag to detect Apple T2 chips on Intel Macs.
Cache the result to avoid repeated checks. That will
be used in upcoming patches.

Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>
---
 arch/x86/kernel/quirks.c                      | 37 ++++++++++++++++++
 include/linux/platform_data/x86/apple.h       |  5 +++
 .../platform_certs/keyring_handler.h          |  8 ----
 security/integrity/platform_certs/load_uefi.c | 38 ++++---------------
 4 files changed, 50 insertions(+), 38 deletions(-)

diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c
index a92f18db9610..6651e5d4d106 100644
--- a/arch/x86/kernel/quirks.c
+++ b/arch/x86/kernel/quirks.c
@@ -664,8 +664,45 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2083, quirk_intel_purley_xeon_ras
 bool x86_apple_machine;
 EXPORT_SYMBOL(x86_apple_machine);
 
+bool has_apple_t2_chip;
+EXPORT_SYMBOL(has_apple_t2_chip);
+
+static const char * const __initconst apple_t2_models[] = {
+	"MacBookPro15,1",
+	"MacBookPro15,2",
+	"MacBookPro15,3",
+	"MacBookPro15,4",
+	"MacBookPro16,1",
+	"MacBookPro16,2",
+	"MacBookPro16,3",
+	"MacBookPro16,4",
+	"MacBookAir8,1",
+	"MacBookAir8,2",
+	"MacBookAir9,1",
+	"Macmini8,1",
+	"MacPro7,1",
+	"iMac20,1",
+	"iMac20,2",
+	"iMacPro1,1",
+};
+
 void __init early_platform_quirks(void)
 {
 	x86_apple_machine = dmi_match(DMI_SYS_VENDOR, "Apple Inc.") ||
 			    dmi_match(DMI_SYS_VENDOR, "Apple Computer, Inc.");
+
+	if (x86_apple_machine) {
+		const char *product_name = dmi_get_system_info(DMI_PRODUCT_NAME);
+		int i;
+
+		if (!product_name)
+			return;
+
+		for (i = 0; i < ARRAY_SIZE(apple_t2_models); i++) {
+			if (!strcmp(product_name, apple_t2_models[i])) {
+				has_apple_t2_chip = true;
+				break;
+			}
+		}
+	}
 }
diff --git a/include/linux/platform_data/x86/apple.h b/include/linux/platform_data/x86/apple.h
index 079e816c3c21..47b27dceab18 100644
--- a/include/linux/platform_data/x86/apple.h
+++ b/include/linux/platform_data/x86/apple.h
@@ -6,8 +6,13 @@
  * x86_apple_machine - whether the machine is an x86 Apple Macintosh
  */
 extern bool x86_apple_machine;
+/**
+ * has_apple_t2_chip - whether the machine has the Apple T2 chip
+ */
+extern bool has_apple_t2_chip;
 #else
 #define x86_apple_machine false
+#define has_apple_t2_chip false
 #endif
 
 #endif
diff --git a/security/integrity/platform_certs/keyring_handler.h b/security/integrity/platform_certs/keyring_handler.h
index f92895cc50f6..a355f4400179 100644
--- a/security/integrity/platform_certs/keyring_handler.h
+++ b/security/integrity/platform_certs/keyring_handler.h
@@ -45,11 +45,3 @@ efi_element_handler_t get_handler_for_code_signing_keys(const efi_guid_t *sig_ty
 efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type);
 
 #endif
-
-#ifndef UEFI_QUIRK_SKIP_CERT
-#define UEFI_QUIRK_SKIP_CERT(vendor, product) \
-		 .matches = { \
-			DMI_MATCH(DMI_BOARD_VENDOR, vendor), \
-			DMI_MATCH(DMI_PRODUCT_NAME, product), \
-		},
-#endif
diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index c0d6948446c3..b4096d4c828d 100644
--- a/security/integrity/platform_certs/load_uefi.c
+++ b/security/integrity/platform_certs/load_uefi.c
@@ -3,42 +3,16 @@
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/cred.h>
-#include <linux/dmi.h>
 #include <linux/err.h>
 #include <linux/efi.h>
 #include <linux/slab.h>
 #include <linux/ima.h>
+#include <linux/platform_data/x86/apple.h>
 #include <keys/asymmetric-type.h>
 #include <keys/system_keyring.h>
 #include "../integrity.h"
 #include "keyring_handler.h"
 
-/*
- * On T2 Macs reading the db and dbx efi variables to load UEFI Secure Boot
- * certificates causes occurrence of a page fault in Apple's firmware and
- * a crash disabling EFI runtime services. The following quirk skips reading
- * these variables.
- */
-static const struct dmi_system_id uefi_skip_cert[] = {
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,2") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,3") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,4") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,2") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,3") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,4") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,2") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir9,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "Macmini8,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacPro7,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,1") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,2") },
-	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMacPro1,1") },
-	{ }
-};
-
 /*
  * Look to see if a UEFI variable called MokIgnoreDB exists and return true if
  * it does.
@@ -165,10 +139,14 @@ static int __init load_uefi_certs(void)
 	unsigned long dbsize = 0, dbxsize = 0, mokxsize = 0;
 	efi_status_t status;
 	int rc = 0;
-	const struct dmi_system_id *dmi_id;
 
-	dmi_id = dmi_first_match(uefi_skip_cert);
-	if (dmi_id) {
+	/*
+	 * On T2 Macs reading the db and dbx efi variables to load UEFI Secure Boot
+	 * certificates causes occurrence of a page fault in Apple's firmware and
+	 * a crash disabling EFI runtime services. The following quirk skips reading
+	 * these variables.
+	 */
+	if (has_apple_t2_chip) {
 		pr_err("Reading UEFI Secure Boot Certs is not supported on T2 Macs.\n");
 		return false;
 	}
-- 
2.43.0

Re: [PATCH v5 1/2] treewide: Add a flag to detect the Apple T2 chip

[sashiko-bot]

> Add a flag to detect Apple T2 chips on Intel Macs.
> Cache the result to avoid repeated checks. That will
> be used in upcoming patches.
> 
> Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260727211807.1223-1-atharvatiwarilinuxdev@gmail.com?part=1

Re: [PATCH v5 1/2] treewide: Add a flag to detect the Apple T2 chip

[Borislav Petkov]

On Mon, Jul 27, 2026 at 05:18:02PM -0400, Atharva Tiwari wrote:
> Add a flag to detect Apple T2 chips on Intel Macs.
> Cache the result to avoid repeated checks. That will
> be used in upcoming patches.
> 
> Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>
> ---
>  arch/x86/kernel/quirks.c                      | 37 ++++++++++++++++++
>  include/linux/platform_data/x86/apple.h       |  5 +++
>  .../platform_certs/keyring_handler.h          |  8 ----
>  security/integrity/platform_certs/load_uefi.c | 38 ++++---------------
>  4 files changed, 50 insertions(+), 38 deletions(-)
> 
> diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c
> index a92f18db9610..6651e5d4d106 100644
> --- a/arch/x86/kernel/quirks.c
> +++ b/arch/x86/kernel/quirks.c
> @@ -664,8 +664,45 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x2083, quirk_intel_purley_xeon_ras
>  bool x86_apple_machine;
>  EXPORT_SYMBOL(x86_apple_machine);
>  
> +bool has_apple_t2_chip;
> +EXPORT_SYMBOL(has_apple_t2_chip);

I'm guessing this is parrotting the non-GPL export of x86_apple_machine from

  630b3aff8a51 ("treewide: Consolidate Apple DMI checks")

Lemme add those folks and ask why aren't those exports GPL only?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

[PATCH v5 2/2] thunderbolt: Add device links for Apple T2 NHI

[Atharva Tiwari]

Ice Lake Thunderbolt NHI on T2 Macs (2018–2020). The NHI and its
associated PCIe Root Ports all sit directly on the Root Complex
with no upstream port. Identify the tunneled PCIe Root Ports by
their PCI IDs and create device links back to the NHI so that
PCIe tunnels can be re-established after sleep.

And on other T2 Thunderbolt NHI's, like Titan Ridge, the default method
is used to add device links.

Co-developed-by: Andre Eikmeyer <dev@deq.rocks>
Signed-off-by: Andre Eikmeyer <dev@deq.rocks>

Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>
---
 drivers/thunderbolt/tb.c | 54 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index c69c323e6952..9b80e9339728 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -9,6 +9,7 @@
 #include <linux/slab.h>
 #include <linux/errno.h>
 #include <linux/delay.h>
+#include <linux/pci.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_data/x86/apple.h>
 
@@ -3305,21 +3306,70 @@ static const struct tb_cm_ops tb_cm_ops = {
 static bool tb_apple_add_links(struct tb_nhi *nhi)
 {
 	struct pci_dev *upstream, *pdev;
-	bool ret;
+	bool ret = false;
 
 	if (!x86_apple_machine)
 		return false;
 
+	/* On T2 Macs with Ice Lake Thunderbolt NHIs,
+	 * identify the tunneled PCIe Root Ports by their PCI IDs
+	 * and create device links so that
+	 * PCIe tunnels can be re-established after sleep.
+	 */
+	if (has_apple_t2_chip && (nhi->pdev->device == PCI_DEVICE_ID_INTEL_ICL_NHI0 ||
+				nhi->pdev->device == PCI_DEVICE_ID_INTEL_ICL_NHI1)) {
+		unsigned int slot, func;
+		const struct device_link *link;
+
+		for (slot = 0; slot < 32; slot++) {
+			for (func = 0; func < 8; func++) {
+				struct pci_dev *current_pdev __free(pci_dev_put) =
+					pci_get_slot(nhi->pdev->bus, PCI_DEVFN(slot, func));
+				if (!current_pdev)
+					continue;
+
+				if (!pci_is_pcie(current_pdev) || pci_pcie_type(current_pdev) !=
+						PCI_EXP_TYPE_ROOT_PORT)
+					continue;
+
+				switch (current_pdev->device) {
+				case 0x8a1d:
+				case 0x8a1f:
+				case 0x8a21:
+				case 0x8a23:
+					break;
+				default:
+					continue;
+				}
+
+				link = device_link_add(&current_pdev->dev, &nhi->pdev->dev,
+						DL_FLAG_AUTOREMOVE_SUPPLIER |
+						DL_FLAG_PM_RUNTIME);
+				if (link) {
+					dev_dbg(&nhi->pdev->dev, "created link from %s\n",
+						dev_name(&current_pdev->dev));
+					ret = true;
+				} else {
+					dev_warn(&nhi->pdev->dev,
+						"device link creation from %s failed\n",
+						dev_name(&current_pdev->dev));
+				}
+			}
+		}
+		return ret;
+	}
+
 	switch (nhi->pdev->device) {
 	case PCI_DEVICE_ID_INTEL_LIGHT_RIDGE:
 	case PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C:
 	case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_2C_NHI:
 	case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_4C_NHI:
+	case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_2C_NHI:
+	case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_4C_NHI:
 		break;
 	default:
 		return false;
 	}
-
 	upstream = pci_upstream_bridge(nhi->pdev);
 	while (upstream) {
 		if (!pci_is_pcie(upstream))
-- 
2.43.0

Re: [PATCH v5 2/2] thunderbolt: Add device links for Apple T2 NHI

[sashiko-bot]

> Ice Lake Thunderbolt NHI on T2 Macs (2018–2020). The NHI and its
> associated PCIe Root Ports all sit directly on the Root Complex
> with no upstream port. Identify the tunneled PCIe Root Ports by
> their PCI IDs and create device links back to the NHI so that
> PCIe tunnels can be re-established after sleep.
> 
> And on other T2 Thunderbolt NHI's, like Titan Ridge, the default method
> is used to add device links.
> 
> Co-developed-by: Andre Eikmeyer <dev@deq.rocks>
> Signed-off-by: Andre Eikmeyer <dev@deq.rocks>
> 
> Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260727211807.1223-1-atharvatiwarilinuxdev@gmail.com?part=2

Re: [PATCH v5 2/2] thunderbolt: Add device links for Apple T2 NHI

[Mika Westerberg]

On Mon, Jul 27, 2026 at 05:18:03PM -0400, Atharva Tiwari wrote:
> Ice Lake Thunderbolt NHI on T2 Macs (2018–2020). The NHI and its
> associated PCIe Root Ports all sit directly on the Root Complex
> with no upstream port. Identify the tunneled PCIe Root Ports by
> their PCI IDs and create device links back to the NHI so that
> PCIe tunnels can be re-established after sleep.
> 
> And on other T2 Thunderbolt NHI's, like Titan Ridge, the default method
> is used to add device links.
> 
> Co-developed-by: Andre Eikmeyer <dev@deq.rocks>
> Signed-off-by: Andre Eikmeyer <dev@deq.rocks>
> 
> Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>
> ---
>  drivers/thunderbolt/tb.c | 54 ++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 52 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
> index c69c323e6952..9b80e9339728 100644
> --- a/drivers/thunderbolt/tb.c
> +++ b/drivers/thunderbolt/tb.c
> @@ -9,6 +9,7 @@
>  #include <linux/slab.h>
>  #include <linux/errno.h>
>  #include <linux/delay.h>
> +#include <linux/pci.h>

We should not be calling PCI functions anymore from the SW CM core. We have
pci.c for that.

>  #include <linux/pm_runtime.h>
>  #include <linux/platform_data/x86/apple.h>
>  
> @@ -3305,21 +3306,70 @@ static const struct tb_cm_ops tb_cm_ops = {
>  static bool tb_apple_add_links(struct tb_nhi *nhi)

I wonder if we can put this to pci.c, rename it to tb_pci_add_links()
instead.

>  {
>  	struct pci_dev *upstream, *pdev;
> -	bool ret;
> +	bool ret = false;
>  
>  	if (!x86_apple_machine)
>  		return false;

BTW, why you need to differentiate T2 vs. the rest of Apple x86? Don't this
variable do?

>  
> +	/* On T2 Macs with Ice Lake Thunderbolt NHIs,
> +	 * identify the tunneled PCIe Root Ports by their PCI IDs
> +	 * and create device links so that
> +	 * PCIe tunnels can be re-established after sleep.
> +	 */
> +	if (has_apple_t2_chip && (nhi->pdev->device == PCI_DEVICE_ID_INTEL_ICL_NHI0 ||
> +				nhi->pdev->device == PCI_DEVICE_ID_INTEL_ICL_NHI1)) {
> +		unsigned int slot, func;
> +		const struct device_link *link;
> +
> +		for (slot = 0; slot < 32; slot++) {
> +			for (func = 0; func < 8; func++) {
> +				struct pci_dev *current_pdev __free(pci_dev_put) =
> +					pci_get_slot(nhi->pdev->bus, PCI_DEVFN(slot, func));

I'm not fan of __free() and the like so let's not use it here.

Also you don't need to scan all the slots. Just look for the tunneled
downstream ports based on their PCI IDs like we do already.

> +				if (!current_pdev)
> +					continue;
> +
> +				if (!pci_is_pcie(current_pdev) || pci_pcie_type(current_pdev) !=
> +						PCI_EXP_TYPE_ROOT_PORT)
> +					continue;
> +
> +				switch (current_pdev->device) {
> +				case 0x8a1d:
> +				case 0x8a1f:
> +				case 0x8a21:
> +				case 0x8a23:
> +					break;
> +				default:
> +					continue;
> +				}
> +
> +				link = device_link_add(&current_pdev->dev, &nhi->pdev->dev,
> +						DL_FLAG_AUTOREMOVE_SUPPLIER |
> +						DL_FLAG_PM_RUNTIME);
> +				if (link) {
> +					dev_dbg(&nhi->pdev->dev, "created link from %s\n",
> +						dev_name(&current_pdev->dev));
> +					ret = true;
> +				} else {
> +					dev_warn(&nhi->pdev->dev,
> +						"device link creation from %s failed\n",
> +						dev_name(&current_pdev->dev));
> +				}
> +			}
> +		}
> +		return ret;
> +	}
> +
>  	switch (nhi->pdev->device) {
>  	case PCI_DEVICE_ID_INTEL_LIGHT_RIDGE:
>  	case PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C:
>  	case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_2C_NHI:
>  	case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_4C_NHI:
> +	case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_2C_NHI:
> +	case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_4C_NHI:
>  		break;
>  	default:
>  		return false;
>  	}
> -

This is unrelated change.

>  	upstream = pci_upstream_bridge(nhi->pdev);
>  	while (upstream) {
>  		if (!pci_is_pcie(upstream))
> -- 
> 2.43.0