Re: [PATCH v2 1/2] treewide: Add a flag to detect the Apple T2 chip

On Tue, Jul 21, 2026 at 01:45:01AM -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 <[email protected]>
> ---
>  arch/x86/kernel/quirks.c                      | 105 ++++++++++++++++++
>  include/linux/platform_data/x86/apple.h       |   5 +
>  security/integrity/platform_certs/load_uefi.c |  38 ++-----
>  3 files changed, 118 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c
> index a92f18db9610..74b29738d404 100644
> --- a/arch/x86/kernel/quirks.c
> +++ b/arch/x86/kernel/quirks.c
> @@ -664,8 +664,113 @@ 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 struct dmi_system_id apple_t2_devices[] = {
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro15,1"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro15,2"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro15,3"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro15,4"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,1"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,2"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,3"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,4"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookAir8,1"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookAir8,2"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookAir9,1"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "Macmini8,1"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "MacPro7,1"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "iMac20,1"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "iMac20,2"),
> +		},
> +	},
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "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.");
> +
> +	has_apple_t2_chip = dmi_check_system(apple_t2_devices);
>  }
> diff --git a/include/linux/platform_data/x86/apple.h b/include/linux/platform_data/x86/apple.h
> index 079e816c3c21..50bbcc5134fc 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_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..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
> 

Reviewed-by: Jarkko Sakkinen <[email protected]>

BR, Jarkko