avoid EFIv2 runtime services on Apple x86 machines

While booting a MacBookPro15,2 (the last Intel model, 2019), shim 15.8
gets stuck in RT->QueryVariableInfo().  Previously, these devices
shipped with EFI firmware version 1.10, and we had a quirk in place for
this (#364).  However, Apple updated the firmware to version 2.40, but
it still doesn't implement runtime services.

This patch adds a test for Apple as the vendor, and treats that as
equivalent to having an older major UEFI version.

Signed-off-by: Eduard Acatrinei <[email protected]>

mok.c

@@ -217,6 +217,22 @@ typedef UINTN SIZE_T;
 #define EFI_MAJOR_VERSION(tablep) ((UINT16)((((tablep)->Hdr.Revision) >> 16) & 0xfffful))
 #define EFI_MINOR_VERSION(tablep) ((UINT16)(((tablep)->Hdr.Revision) & 0xfffful))
 
+static BOOLEAN is_apple_firmware_vendor(void)
+{
+	CHAR16 vendorbuf[100] = L"";
+	CHAR16 *vendor = ST->FirmwareVendor;
+	if (!vendor)
+		return FALSE;
+
+	CopyMem(vendorbuf, vendor, sizeof(vendorbuf) - sizeof(vendorbuf[0]));
+	dprint(L"FirmwareVendor: \"%s\"\n", vendorbuf);
+
+	if (StrnCmp(vendorbuf, L"Apple", 5) == 0)
+		return TRUE;
+
+	return FALSE;
+}
+
 static EFI_STATUS
 get_max_var_sz(UINT32 attrs, SIZE_T *max_var_szp)
 {
@@ -226,7 +242,7 @@ get_max_var_sz(UINT32 attrs, SIZE_T *max_var_szp)
 	uint64_t max_var_sz = 0;
 
 	*max_var_szp = 0;
-	if (EFI_MAJOR_VERSION(RT) < 2) {
+	if (EFI_MAJOR_VERSION(RT) < 2 || is_apple_firmware_vendor()) {
 		dprint(L"EFI %d.%d; no RT->QueryVariableInfo().  Using 1024!\n",
 		       EFI_MAJOR_VERSION(RT), EFI_MINOR_VERSION(RT));
 		max_var_sz = remaining_sz = max_storage_sz = 1024;