Merge tag 'x86_cc_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 confidential computing updates from Borislav Petkov:
 "Unrelated x86/cc changes queued here to avoid ugly cross-merges and
  conflicts:

   - Carve out CPU hotplug function declarations into a separate header
     with the goal to be able to use the lockdep assertions in a more
     flexible manner

   - As a result, refactor cacheinfo code after carving out a function
     to return the cache ID associated with a given cache level

   - Cleanups

  Add support to be able to kexec TDX guests:

   - Expand ACPI MADT CPU offlining support

   - Add machinery to prepare CoCo guests memory before kexec-ing into a
     new kernel

   - Cleanup, readjust and massage related code"

* tag 'x86_cc_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  ACPI: tables: Print MULTIPROC_WAKEUP when MADT is parsed
  x86/acpi: Add support for CPU offlining for ACPI MADT wakeup method
  x86/mm: Introduce kernel_ident_mapping_free()
  x86/smp: Add smp_ops.stop_this_cpu() callback
  x86/acpi: Do not attempt to bring up secondary CPUs in the kexec case
  x86/acpi: Rename fields in the acpi_madt_multiproc_wakeup structure
  x86/mm: Do not zap page table entries mapping unaccepted memory table during kdump
  x86/mm: Make e820__end_ram_pfn() cover E820_TYPE_ACPI ranges
  x86/tdx: Convert shared memory back to private on kexec
  x86/mm: Add callbacks to prepare encrypted memory for kexec
  x86/tdx: Account shared memory
  x86/mm: Return correct level from lookup_address() if pte is none
  x86/mm: Make x86_platform.guest.enc_status_change_*() return an error
  x86/kexec: Keep CR4.MCE set during kexec for TDX guest
  x86/relocate_kernel: Use named labels for less confusion
  cpu/hotplug, x86/acpi: Disable CPU offlining for ACPI MADT wakeup
  cpu/hotplug: Add support for declaring CPU offlining not supported
  x86/apic: Mark acpi_mp_wake_* variables as __ro_after_init
  x86/acpi: Extract ACPI MADT wakeup code into a separate file
  x86/kexec: Remove spurious unconditional JMP from from identity_mapped()
  ...

4 files changed, 322 insertions, 85 deletions

diff --git a/arch/x86/kernel/acpi/Makefile b/arch/x86/kernel/acpi/Makefile
index fc17b3f136fe..842a5f449404 100644
--- a/arch/x86/kernel/acpi/Makefile
+++ b/arch/x86/kernel/acpi/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_ACPI)		+= boot.o
 obj-$(CONFIG_ACPI_SLEEP)	+= sleep.o wakeup_$(BITS).o
 obj-$(CONFIG_ACPI_APEI)		+= apei.o
 obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc.o
+obj-$(CONFIG_ACPI_MADT_WAKEUP)	+= madt_wakeup.o madt_playdead.o
 
 ifneq ($(CONFIG_ACPI_PROCESSOR),)
 obj-y				+= cstate.o
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 4bf82dbd2a6b..9f4618dcd704 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -67,13 +67,6 @@ static bool has_lapic_cpus __initdata;
 static bool acpi_support_online_capable;
 #endif
 
-#ifdef CONFIG_X86_64
-/* Physical address of the Multiprocessor Wakeup Structure mailbox */
-static u64 acpi_mp_wake_mailbox_paddr;
-/* Virtual address of the Multiprocessor Wakeup Structure mailbox */
-static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox;
-#endif
-
 #ifdef CONFIG_X86_IO_APIC
 /*
  * Locks related to IOAPIC hotplug
@@ -341,60 +334,6 @@ acpi_parse_lapic_nmi(union acpi_subtable_headers * header, const unsigned long e
 
 	return 0;
 }
-
-#ifdef CONFIG_X86_64
-static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip)
-{
-	/*
-	 * Remap mailbox memory only for the first call to acpi_wakeup_cpu().
-	 *
-	 * Wakeup of secondary CPUs is fully serialized in the core code.
-	 * No need to protect acpi_mp_wake_mailbox from concurrent accesses.
-	 */
-	if (!acpi_mp_wake_mailbox) {
-		acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr,
-						sizeof(*acpi_mp_wake_mailbox),
-						MEMREMAP_WB);
-	}
-
-	/*
-	 * Mailbox memory is shared between the firmware and OS. Firmware will
-	 * listen on mailbox command address, and once it receives the wakeup
-	 * command, the CPU associated with the given apicid will be booted.
-	 *
-	 * The value of 'apic_id' and 'wakeup_vector' must be visible to the
-	 * firmware before the wakeup command is visible.  smp_store_release()
-	 * ensures ordering and visibility.
-	 */
-	acpi_mp_wake_mailbox->apic_id	    = apicid;
-	acpi_mp_wake_mailbox->wakeup_vector = start_ip;
-	smp_store_release(&acpi_mp_wake_mailbox->command,
-			  ACPI_MP_WAKE_COMMAND_WAKEUP);
-
-	/*
-	 * Wait for the CPU to wake up.
-	 *
-	 * The CPU being woken up is essentially in a spin loop waiting to be
-	 * woken up. It should not take long for it wake up and acknowledge by
-	 * zeroing out ->command.
-	 *
-	 * ACPI specification doesn't provide any guidance on how long kernel
-	 * has to wait for a wake up acknowledgement. It also doesn't provide
-	 * a way to cancel a wake up request if it takes too long.
-	 *
-	 * In TDX environment, the VMM has control over how long it takes to
-	 * wake up secondary. It can postpone scheduling secondary vCPU
-	 * indefinitely. Giving up on wake up request and reporting error opens
-	 * possible attack vector for VMM: it can wake up a secondary CPU when
-	 * kernel doesn't expect it. Wait until positive result of the wake up
-	 * request.
-	 */
-	while (READ_ONCE(acpi_mp_wake_mailbox->command))
-		cpu_relax();
-
-	return 0;
-}
-#endif /* CONFIG_X86_64 */
 #endif /* CONFIG_X86_LOCAL_APIC */
 
 #ifdef CONFIG_X86_IO_APIC
@@ -1124,29 +1063,6 @@ static int __init acpi_parse_madt_lapic_entries(void)
 	}
 	return 0;
 }
-
-#ifdef CONFIG_X86_64
-static int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,
-				     const unsigned long end)
-{
-	struct acpi_madt_multiproc_wakeup *mp_wake;
-
-	if (!IS_ENABLED(CONFIG_SMP))
-		return -ENODEV;
-
-	mp_wake = (struct acpi_madt_multiproc_wakeup *)header;
-	if (BAD_MADT_ENTRY(mp_wake, end))
-		return -EINVAL;
-
-	acpi_table_print_madt_entry(&header->common);
-
-	acpi_mp_wake_mailbox_paddr = mp_wake->base_address;
-
-	apic_update_callback(wakeup_secondary_cpu_64, acpi_wakeup_cpu);
-
-	return 0;
-}
-#endif				/* CONFIG_X86_64 */
 #endif				/* CONFIG_X86_LOCAL_APIC */
 
 #ifdef	CONFIG_X86_IO_APIC
@@ -1343,7 +1259,7 @@ static void __init acpi_process_madt(void)
 				smp_found_config = 1;
 			}
 
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_ACPI_MADT_WAKEUP
 			/*
 			 * Parse MADT MP Wake entry.
 			 */
diff --git a/arch/x86/kernel/acpi/madt_playdead.S b/arch/x86/kernel/acpi/madt_playdead.S
new file mode 100644
index 000000000000..4e498d28cdc8
--- /dev/null
+++ b/arch/x86/kernel/acpi/madt_playdead.S
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/linkage.h>
+#include <asm/nospec-branch.h>
+#include <asm/page_types.h>
+#include <asm/processor-flags.h>
+
+	.text
+	.align PAGE_SIZE
+
+/*
+ * asm_acpi_mp_play_dead() - Hand over control of the CPU to the BIOS
+ *
+ * rdi: Address of the ACPI MADT MPWK ResetVector
+ * rsi: PGD of the identity mapping
+ */
+SYM_FUNC_START(asm_acpi_mp_play_dead)
+	/* Turn off global entries. Following CR3 write will flush them. */
+	movq	%cr4, %rdx
+	andq	$~(X86_CR4_PGE), %rdx
+	movq	%rdx, %cr4
+
+	/* Switch to identity mapping */
+	movq	%rsi, %cr3
+
+	/* Jump to reset vector */
+	ANNOTATE_RETPOLINE_SAFE
+	jmp	*%rdi
+SYM_FUNC_END(asm_acpi_mp_play_dead)
diff --git a/arch/x86/kernel/acpi/madt_wakeup.c b/arch/x86/kernel/acpi/madt_wakeup.c
new file mode 100644
index 000000000000..6cfe762be28b
--- /dev/null
+++ b/arch/x86/kernel/acpi/madt_wakeup.c
@@ -0,0 +1,292 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <linux/acpi.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kexec.h>
+#include <linux/memblock.h>
+#include <linux/pgtable.h>
+#include <linux/sched/hotplug.h>
+#include <asm/apic.h>
+#include <asm/barrier.h>
+#include <asm/init.h>
+#include <asm/intel_pt.h>
+#include <asm/nmi.h>
+#include <asm/processor.h>
+#include <asm/reboot.h>
+
+/* Physical address of the Multiprocessor Wakeup Structure mailbox */
+static u64 acpi_mp_wake_mailbox_paddr __ro_after_init;
+
+/* Virtual address of the Multiprocessor Wakeup Structure mailbox */
+static struct acpi_madt_multiproc_wakeup_mailbox *acpi_mp_wake_mailbox __ro_after_init;
+
+static u64 acpi_mp_pgd __ro_after_init;
+static u64 acpi_mp_reset_vector_paddr __ro_after_init;
+
+static void acpi_mp_stop_this_cpu(void)
+{
+	asm_acpi_mp_play_dead(acpi_mp_reset_vector_paddr, acpi_mp_pgd);
+}
+
+static void acpi_mp_play_dead(void)
+{
+	play_dead_common();
+	asm_acpi_mp_play_dead(acpi_mp_reset_vector_paddr, acpi_mp_pgd);
+}
+
+static void acpi_mp_cpu_die(unsigned int cpu)
+{
+	u32 apicid = per_cpu(x86_cpu_to_apicid, cpu);
+	unsigned long timeout;
+
+	/*
+	 * Use TEST mailbox command to prove that BIOS got control over
+	 * the CPU before declaring it dead.
+	 *
+	 * BIOS has to clear 'command' field of the mailbox.
+	 */
+	acpi_mp_wake_mailbox->apic_id = apicid;
+	smp_store_release(&acpi_mp_wake_mailbox->command,
+			  ACPI_MP_WAKE_COMMAND_TEST);
+
+	/* Don't wait longer than a second. */
+	timeout = USEC_PER_SEC;
+	while (READ_ONCE(acpi_mp_wake_mailbox->command) && --timeout)
+		udelay(1);
+
+	if (!timeout)
+		pr_err("Failed to hand over CPU %d to BIOS\n", cpu);
+}
+
+/* The argument is required to match type of x86_mapping_info::alloc_pgt_page */
+static void __init *alloc_pgt_page(void *dummy)
+{
+	return memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+}
+
+static void __init free_pgt_page(void *pgt, void *dummy)
+{
+	return memblock_free(pgt, PAGE_SIZE);
+}
+
+/*
+ * Make sure asm_acpi_mp_play_dead() is present in the identity mapping at
+ * the same place as in the kernel page tables. asm_acpi_mp_play_dead() switches
+ * to the identity mapping and the function has be present at the same spot in
+ * the virtual address space before and after switching page tables.
+ */
+static int __init init_transition_pgtable(pgd_t *pgd)
+{
+	pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
+	unsigned long vaddr, paddr;
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	vaddr = (unsigned long)asm_acpi_mp_play_dead;
+	pgd += pgd_index(vaddr);
+	if (!pgd_present(*pgd)) {
+		p4d = (p4d_t *)alloc_pgt_page(NULL);
+		if (!p4d)
+			return -ENOMEM;
+		set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
+	}
+	p4d = p4d_offset(pgd, vaddr);
+	if (!p4d_present(*p4d)) {
+		pud = (pud_t *)alloc_pgt_page(NULL);
+		if (!pud)
+			return -ENOMEM;
+		set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
+	}
+	pud = pud_offset(p4d, vaddr);
+	if (!pud_present(*pud)) {
+		pmd = (pmd_t *)alloc_pgt_page(NULL);
+		if (!pmd)
+			return -ENOMEM;
+		set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
+	}
+	pmd = pmd_offset(pud, vaddr);
+	if (!pmd_present(*pmd)) {
+		pte = (pte_t *)alloc_pgt_page(NULL);
+		if (!pte)
+			return -ENOMEM;
+		set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
+	}
+	pte = pte_offset_kernel(pmd, vaddr);
+
+	paddr = __pa(vaddr);
+	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
+
+	return 0;
+}
+
+static int __init acpi_mp_setup_reset(u64 reset_vector)
+{
+	struct x86_mapping_info info = {
+		.alloc_pgt_page = alloc_pgt_page,
+		.free_pgt_page	= free_pgt_page,
+		.page_flag      = __PAGE_KERNEL_LARGE_EXEC,
+		.kernpg_flag    = _KERNPG_TABLE_NOENC,
+	};
+	pgd_t *pgd;
+
+	pgd = alloc_pgt_page(NULL);
+	if (!pgd)
+		return -ENOMEM;
+
+	for (int i = 0; i < nr_pfn_mapped; i++) {
+		unsigned long mstart, mend;
+
+		mstart = pfn_mapped[i].start << PAGE_SHIFT;
+		mend   = pfn_mapped[i].end << PAGE_SHIFT;
+		if (kernel_ident_mapping_init(&info, pgd, mstart, mend)) {
+			kernel_ident_mapping_free(&info, pgd);
+			return -ENOMEM;
+		}
+	}
+
+	if (kernel_ident_mapping_init(&info, pgd,
+				      PAGE_ALIGN_DOWN(reset_vector),
+				      PAGE_ALIGN(reset_vector + 1))) {
+		kernel_ident_mapping_free(&info, pgd);
+		return -ENOMEM;
+	}
+
+	if (init_transition_pgtable(pgd)) {
+		kernel_ident_mapping_free(&info, pgd);
+		return -ENOMEM;
+	}
+
+	smp_ops.play_dead = acpi_mp_play_dead;
+	smp_ops.stop_this_cpu = acpi_mp_stop_this_cpu;
+	smp_ops.cpu_die = acpi_mp_cpu_die;
+
+	acpi_mp_reset_vector_paddr = reset_vector;
+	acpi_mp_pgd = __pa(pgd);
+
+	return 0;
+}
+
+static int acpi_wakeup_cpu(u32 apicid, unsigned long start_ip)
+{
+	if (!acpi_mp_wake_mailbox_paddr) {
+		pr_warn_once("No MADT mailbox: cannot bringup secondary CPUs. Booting with kexec?\n");
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * Remap mailbox memory only for the first call to acpi_wakeup_cpu().
+	 *
+	 * Wakeup of secondary CPUs is fully serialized in the core code.
+	 * No need to protect acpi_mp_wake_mailbox from concurrent accesses.
+	 */
+	if (!acpi_mp_wake_mailbox) {
+		acpi_mp_wake_mailbox = memremap(acpi_mp_wake_mailbox_paddr,
+						sizeof(*acpi_mp_wake_mailbox),
+						MEMREMAP_WB);
+	}
+
+	/*
+	 * Mailbox memory is shared between the firmware and OS. Firmware will
+	 * listen on mailbox command address, and once it receives the wakeup
+	 * command, the CPU associated with the given apicid will be booted.
+	 *
+	 * The value of 'apic_id' and 'wakeup_vector' must be visible to the
+	 * firmware before the wakeup command is visible.  smp_store_release()
+	 * ensures ordering and visibility.
+	 */
+	acpi_mp_wake_mailbox->apic_id	    = apicid;
+	acpi_mp_wake_mailbox->wakeup_vector = start_ip;
+	smp_store_release(&acpi_mp_wake_mailbox->command,
+			  ACPI_MP_WAKE_COMMAND_WAKEUP);
+
+	/*
+	 * Wait for the CPU to wake up.
+	 *
+	 * The CPU being woken up is essentially in a spin loop waiting to be
+	 * woken up. It should not take long for it wake up and acknowledge by
+	 * zeroing out ->command.
+	 *
+	 * ACPI specification doesn't provide any guidance on how long kernel
+	 * has to wait for a wake up acknowledgment. It also doesn't provide
+	 * a way to cancel a wake up request if it takes too long.
+	 *
+	 * In TDX environment, the VMM has control over how long it takes to
+	 * wake up secondary. It can postpone scheduling secondary vCPU
+	 * indefinitely. Giving up on wake up request and reporting error opens
+	 * possible attack vector for VMM: it can wake up a secondary CPU when
+	 * kernel doesn't expect it. Wait until positive result of the wake up
+	 * request.
+	 */
+	while (READ_ONCE(acpi_mp_wake_mailbox->command))
+		cpu_relax();
+
+	return 0;
+}
+
+static void acpi_mp_disable_offlining(struct acpi_madt_multiproc_wakeup *mp_wake)
+{
+	cpu_hotplug_disable_offlining();
+
+	/*
+	 * ACPI MADT doesn't allow to offline a CPU after it was onlined. This
+	 * limits kexec: the second kernel won't be able to use more than one CPU.
+	 *
+	 * To prevent a kexec kernel from onlining secondary CPUs invalidate the
+	 * mailbox address in the ACPI MADT wakeup structure which prevents a
+	 * kexec kernel to use it.
+	 *
+	 * This is safe as the booting kernel has the mailbox address cached
+	 * already and acpi_wakeup_cpu() uses the cached value to bring up the
+	 * secondary CPUs.
+	 *
+	 * Note: This is a Linux specific convention and not covered by the
+	 *       ACPI specification.
+	 */
+	mp_wake->mailbox_address = 0;
+}
+
+int __init acpi_parse_mp_wake(union acpi_subtable_headers *header,
+			      const unsigned long end)
+{
+	struct acpi_madt_multiproc_wakeup *mp_wake;
+
+	mp_wake = (struct acpi_madt_multiproc_wakeup *)header;
+
+	/*
+	 * Cannot use the standard BAD_MADT_ENTRY() to sanity check the @mp_wake
+	 * entry.  'sizeof (struct acpi_madt_multiproc_wakeup)' can be larger
+	 * than the actual size of the MP wakeup entry in ACPI table because the
+	 * 'reset_vector' is only available in the V1 MP wakeup structure.
+	 */
+	if (!mp_wake)
+		return -EINVAL;
+	if (end - (unsigned long)mp_wake < ACPI_MADT_MP_WAKEUP_SIZE_V0)
+		return -EINVAL;
+	if (mp_wake->header.length < ACPI_MADT_MP_WAKEUP_SIZE_V0)
+		return -EINVAL;
+
+	acpi_table_print_madt_entry(&header->common);
+
+	acpi_mp_wake_mailbox_paddr = mp_wake->mailbox_address;
+
+	if (mp_wake->version >= ACPI_MADT_MP_WAKEUP_VERSION_V1 &&
+	    mp_wake->header.length >= ACPI_MADT_MP_WAKEUP_SIZE_V1) {
+		if (acpi_mp_setup_reset(mp_wake->reset_vector)) {
+			pr_warn("Failed to setup MADT reset vector\n");
+			acpi_mp_disable_offlining(mp_wake);
+		}
+	} else {
+		/*
+		 * CPU offlining requires version 1 of the ACPI MADT wakeup
+		 * structure.
+		 */
+		acpi_mp_disable_offlining(mp_wake);
+	}
+
+	apic_update_callback(wakeup_secondary_cpu_64, acpi_wakeup_cpu);
+
+	return 0;
+}