- Ignore invalid x2APIC entries in order to not waste per-CPU data

- Fix a back-to-back signals handling scenario when shadow stack is in
   use
 
 - A documentation fix
 
 - Add Kirill as TDX maintainer
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Merge tag 'x86_urgent_for_v6.7_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Borislav Petkov:

 - Ignore invalid x2APIC entries in order to not waste per-CPU data

 - Fix a back-to-back signals handling scenario when shadow stack is in
   use

 - A documentation fix

 - Add Kirill as TDX maintainer

* tag 'x86_urgent_for_v6.7_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/acpi: Ignore invalid x2APIC entries
  x86/shstk: Delay signal entry SSP write until after user accesses
  x86/Documentation: Indent 'note::' directive for protocol version number note
  MAINTAINERS: Add Intel TDX entry

Documentation/arch/x86/boot.rst

@@ -77,7 +77,7 @@ Protocol 2.14	BURNT BY INCORRECT COMMIT
 Protocol 2.15	(Kernel 5.5) Added the kernel_info and kernel_info.setup_type_max.
 =============	============================================================
 
-.. note::
+  .. note::
      The protocol version number should be changed only if the setup header
      is changed. There is no need to update the version number if boot_params
      or kernel_info are changed. Additionally, it is recommended to use

MAINTAINERS

@@ -23702,6 +23702,20 @@ F:	arch/x86/kernel/dumpstack.c
 F:	arch/x86/kernel/stacktrace.c
 F:	arch/x86/kernel/unwind_*.c
 
+X86 TRUST DOMAIN EXTENSIONS (TDX)
+M:	Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+R:	Dave Hansen <dave.hansen@linux.intel.com>
+L:	x86@kernel.org
+L:	linux-coco@lists.linux.dev
+S:	Supported
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/tdx
+F:	arch/x86/boot/compressed/tdx*
+F:	arch/x86/coco/tdx/
+F:	arch/x86/include/asm/shared/tdx.h
+F:	arch/x86/include/asm/tdx.h
+F:	arch/x86/virt/vmx/tdx/
+F:	drivers/virt/coco/tdx-guest
+
 X86 VDSO
 M:	Andy Lutomirski <luto@kernel.org>
 L:	linux-kernel@vger.kernel.org

arch/x86/kernel/acpi/boot.c

@@ -63,6 +63,7 @@ int acpi_fix_pin2_polarity __initdata;
 
 #ifdef CONFIG_X86_LOCAL_APIC
 static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
+static bool has_lapic_cpus __initdata;
 static bool acpi_support_online_capable;
 #endif
 
@@ -232,6 +233,14 @@ acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end)
 	if (!acpi_is_processor_usable(processor->lapic_flags))
 		return 0;
 
+	/*
+	 * According to https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#processor-local-x2apic-structure
+	 * when MADT provides both valid LAPIC and x2APIC entries, the APIC ID
+	 * in x2APIC must be equal or greater than 0xff.
+	 */
+	if (has_lapic_cpus && apic_id < 0xff)
+		return 0;
+
 	/*
 	 * We need to register disabled CPU as well to permit
 	 * counting disabled CPUs. This allows us to size
@@ -1114,10 +1123,7 @@ static int __init early_acpi_parse_madt_lapic_addr_ovr(void)
 
 static int __init acpi_parse_madt_lapic_entries(void)
 {
-	int count;
+	int count, x2count = 0;
-	int x2count = 0;
-	int ret;
-	struct acpi_subtable_proc madt_proc[2];
 
 	if (!boot_cpu_has(X86_FEATURE_APIC))
 		return -ENODEV;
@@ -1126,21 +1132,11 @@ static int __init acpi_parse_madt_lapic_entries(void)
 				      acpi_parse_sapic, MAX_LOCAL_APIC);
 
 	if (!count) {
-		memset(madt_proc, 0, sizeof(madt_proc));
+		count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC,
-		madt_proc[0].id = ACPI_MADT_TYPE_LOCAL_APIC;
+					acpi_parse_lapic, MAX_LOCAL_APIC);
-		madt_proc[0].handler = acpi_parse_lapic;
+		has_lapic_cpus = count > 0;
-		madt_proc[1].id = ACPI_MADT_TYPE_LOCAL_X2APIC;
+		x2count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_X2APIC,
-		madt_proc[1].handler = acpi_parse_x2apic;
+					acpi_parse_x2apic, MAX_LOCAL_APIC);
-		ret = acpi_table_parse_entries_array(ACPI_SIG_MADT,
-				sizeof(struct acpi_table_madt),
-				madt_proc, ARRAY_SIZE(madt_proc), MAX_LOCAL_APIC);
-		if (ret < 0) {
-			pr_err("Error parsing LAPIC/X2APIC entries\n");
-			return ret;
-		}
-
-		count = madt_proc[0].count;
-		x2count = madt_proc[1].count;
 	}
 	if (!count && !x2count) {
 		pr_err("No LAPIC entries present\n");

arch/x86/kernel/signal_64.c

@@ -175,9 +175,6 @@ int x64_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 	frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe), &fp);
 	uc_flags = frame_uc_flags(regs);
 
-	if (setup_signal_shadow_stack(ksig))
-		return -EFAULT;
-
 	if (!user_access_begin(frame, sizeof(*frame)))
 		return -EFAULT;
 
@@ -198,6 +195,9 @@ int x64_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 			return -EFAULT;
 	}
 
+	if (setup_signal_shadow_stack(ksig))
+		return -EFAULT;
+
 	/* Set up registers for signal handler */
 	regs->di = ksig->sig;
 	/* In case the signal handler was declared without prototypes */