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

[Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>]

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/pci/fixup.c                          | 10 +++++
 include/linux/platform_data/x86/apple.h       |  5 +++
 security/integrity/platform_certs/load_uefi.c | 38 ++++---------------
 3 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
index b301c6c8df75..fbd204ca4c6d 100644
--- a/arch/x86/pci/fixup.c
+++ b/arch/x86/pci/fixup.c
@@ -7,6 +7,7 @@
 #include <linux/delay.h>
 #include <linux/dmi.h>
 #include <linux/pci.h>
+#include <linux/platform_data/x86/apple.h>
 #include <linux/suspend.h>
 #include <linux/vgaarb.h>
 #include <asm/amd/node.h>
@@ -995,6 +996,15 @@ static void asus_disable_nvme_d3cold(struct pci_dev *pdev)
 }
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x9a09, asus_disable_nvme_d3cold);
 
+bool has_t2_chip;
+EXPORT_SYMBOL(has_t2_chip);
+
+static void apple_has_t2_chip(struct pci_dev *pdev)
+{
+	has_t2_chip = true;
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_APPLE, 0x1801, apple_has_t2_chip);
+
 #ifdef CONFIG_SUSPEND
 /*
  * Root Ports on some AMD SoCs advertise PME_Support for D3hot and D3cold, but
diff --git a/include/linux/platform_data/x86/apple.h b/include/linux/platform_data/x86/apple.h
index 079e816c3c21..a2ab63bd1eac 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_t2_chip - whether the machine has the Apple T2 chip
+ */
+extern bool has_t2_chip;
 #else
 #define x86_apple_machine false
+#define has_t2_chip false
 #endif
 
 #endif
diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index c0d6948446c3..da57ac322e72 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_t2_chip) {
 		pr_err("Reading UEFI Secure Boot Certs is not supported on T2 Macs.\n");
 		return false;
 	}
-- 
2.43.0