Merge tag 'kvmarm-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for Linux 5.16

- More progress on the protected VM front, now with the full
  fixed feature set as well as the limitation of some hypercalls
  after initialisation.

- Cleanup of the RAZ/WI sysreg handling, which was pointlessly
  complicated

- Fixes for the vgic placement in the IPA space, together with a
  bunch of selftests

- More memcg accounting of the memory allocated on behalf of a guest

- Timer and vgic selftests

- Workarounds for the Apple M1 broken vgic implementation

- KConfig cleanups

- New kvmarm.mode=none option, for those who really dislike us

15 files changed, 100 insertions, 64 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index dad7f85dcdea..ab83c22d274e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2610,7 +2610,6 @@ config PCI_OLPC
 config PCI_XEN
 	def_bool y
 	depends on PCI && XEN
-	select SWIOTLB_XEN
 
 config MMCONF_FAM10H
 	def_bool y
diff --git a/arch/x86/crypto/sm4-aesni-avx-asm_64.S b/arch/x86/crypto/sm4-aesni-avx-asm_64.S
index fa2c3f50aecb..18d2f5199194 100644
--- a/arch/x86/crypto/sm4-aesni-avx-asm_64.S
+++ b/arch/x86/crypto/sm4-aesni-avx-asm_64.S
@@ -367,10 +367,11 @@ SYM_FUNC_START(sm4_aesni_avx_crypt8)
 	 *	%rdx: src (1..8 blocks)
 	 *	%rcx: num blocks (1..8)
 	 */
-	FRAME_BEGIN
-
 	cmpq $5, %rcx;
 	jb sm4_aesni_avx_crypt4;
+
+	FRAME_BEGIN
+
 	vmovdqu (0 * 16)(%rdx), RA0;
 	vmovdqu (1 * 16)(%rdx), RA1;
 	vmovdqu (2 * 16)(%rdx), RA2;
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 2a57dbed4894..6dfa8ddaa60f 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2465,6 +2465,7 @@ static int x86_pmu_event_init(struct perf_event *event)
 	if (err) {
 		if (event->destroy)
 			event->destroy(event);
+		event->destroy = NULL;
 	}
 
 	if (READ_ONCE(x86_pmu.attr_rdpmc) &&
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 7011e87be6d0..9a044438072b 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -263,6 +263,7 @@ static struct event_constraint intel_icl_event_constraints[] = {
 	INTEL_EVENT_CONSTRAINT_RANGE(0xa8, 0xb0, 0xf),
 	INTEL_EVENT_CONSTRAINT_RANGE(0xb7, 0xbd, 0xf),
 	INTEL_EVENT_CONSTRAINT_RANGE(0xd0, 0xe6, 0xf),
+	INTEL_EVENT_CONSTRAINT(0xef, 0xf),
 	INTEL_EVENT_CONSTRAINT_RANGE(0xf0, 0xf4, 0xf),
 	EVENT_CONSTRAINT_END
 };
diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
index 5c7bcaa79623..1d5f14aff5f6 100644
--- a/arch/x86/include/asm/pkeys.h
+++ b/arch/x86/include/asm/pkeys.h
@@ -2,8 +2,6 @@
 #ifndef _ASM_X86_PKEYS_H
 #define _ASM_X86_PKEYS_H
 
-#define ARCH_DEFAULT_PKEY	0
-
 /*
  * If more than 16 keys are ever supported, a thorough audit
  * will be necessary to ensure that the types that store key
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index f3fbb84ff8a7..68c257a3de0d 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -275,7 +275,7 @@ static inline int enqcmds(void __iomem *dst, const void *src)
 {
 	const struct { char _[64]; } *__src = src;
 	struct { char _[64]; } __iomem *__dst = dst;
-	int zf;
+	bool zf;
 
 	/*
 	 * ENQCMDS %(rdx), rax
diff --git a/arch/x86/include/asm/xen/swiotlb-xen.h b/arch/x86/include/asm/xen/swiotlb-xen.h
index 6b56d0d45d15..66b4ddde7743 100644
--- a/arch/x86/include/asm/xen/swiotlb-xen.h
+++ b/arch/x86/include/asm/xen/swiotlb-xen.h
@@ -3,14 +3,10 @@
 #define _ASM_X86_SWIOTLB_XEN_H
 
 #ifdef CONFIG_SWIOTLB_XEN
-extern int xen_swiotlb;
 extern int __init pci_xen_swiotlb_detect(void);
-extern void __init pci_xen_swiotlb_init(void);
 extern int pci_xen_swiotlb_init_late(void);
 #else
-#define xen_swiotlb (0)
-static inline int __init pci_xen_swiotlb_detect(void) { return 0; }
-static inline void __init pci_xen_swiotlb_init(void) { }
+#define pci_xen_swiotlb_detect NULL
 static inline int pci_xen_swiotlb_init_late(void) { return -ENXIO; }
 #endif
 
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 79f164141116..40ed44ead063 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -830,6 +830,20 @@ void __init setup_arch(char **cmdline_p)
 
 	x86_init.oem.arch_setup();
 
+	/*
+	 * Do some memory reservations *before* memory is added to memblock, so
+	 * memblock allocations won't overwrite it.
+	 *
+	 * After this point, everything still needed from the boot loader or
+	 * firmware or kernel text should be early reserved or marked not RAM in
+	 * e820. All other memory is free game.
+	 *
+	 * This call needs to happen before e820__memory_setup() which calls the
+	 * xen_memory_setup() on Xen dom0 which relies on the fact that those
+	 * early reservations have happened already.
+	 */
+	early_reserve_memory();
+
 	iomem_resource.end = (1ULL << boot_cpu_data.x86_phys_bits) - 1;
 	e820__memory_setup();
 	parse_setup_data();
@@ -876,18 +890,6 @@ void __init setup_arch(char **cmdline_p)
 
 	parse_early_param();
 
-	/*
-	 * Do some memory reservations *before* memory is added to
-	 * memblock, so memblock allocations won't overwrite it.
-	 * Do it after early param, so we could get (unlikely) panic from
-	 * serial.
-	 *
-	 * After this point everything still needed from the boot loader or
-	 * firmware or kernel text should be early reserved or marked not
-	 * RAM in e820. All other memory is free game.
-	 */
-	early_reserve_memory();
-
 #ifdef CONFIG_MEMORY_HOTPLUG
 	/*
 	 * Memory used by the kernel cannot be hot-removed because Linux
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 532791ffcbb9..28b1a4e57827 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -435,7 +435,6 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
 	__FOP_RET(#op)
 
 asm(".pushsection .fixup, \"ax\"\n"
-    ".global kvm_fastop_exception \n"
     "kvm_fastop_exception: xor %esi, %esi; ret\n"
     ".popsection");
 
diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c
index 058f19b20465..c565def611e2 100644
--- a/arch/x86/lib/insn.c
+++ b/arch/x86/lib/insn.c
@@ -37,10 +37,10 @@
 	((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
 
 #define __get_next(t, insn)	\
-	({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
+	({ t r; memcpy(&r, insn->next_byte, sizeof(t)); insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
 
 #define __peek_nbyte_next(t, insn, n)	\
-	({ t r = *(t*)((insn)->next_byte + n); leXX_to_cpu(t, r); })
+	({ t r; memcpy(&r, (insn)->next_byte + n, sizeof(t)); leXX_to_cpu(t, r); })
 
 #define get_next(t, insn)	\
 	({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index b2eefdefc108..84a2c8c4af73 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -710,7 +710,8 @@ oops:
 
 static noinline void
 kernelmode_fixup_or_oops(struct pt_regs *regs, unsigned long error_code,
-			 unsigned long address, int signal, int si_code)
+			 unsigned long address, int signal, int si_code,
+			 u32 pkey)
 {
 	WARN_ON_ONCE(user_mode(regs));
 
@@ -735,8 +736,12 @@ kernelmode_fixup_or_oops(struct pt_regs *regs, unsigned long error_code,
 
 			set_signal_archinfo(address, error_code);
 
-			/* XXX: hwpoison faults will set the wrong code. */
-			force_sig_fault(signal, si_code, (void __user *)address);
+			if (si_code == SEGV_PKUERR) {
+				force_sig_pkuerr((void __user *)address, pkey);
+			} else {
+				/* XXX: hwpoison faults will set the wrong code. */
+				force_sig_fault(signal, si_code, (void __user *)address);
+			}
 		}
 
 		/*
@@ -798,7 +803,8 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
 	struct task_struct *tsk = current;
 
 	if (!user_mode(regs)) {
-		kernelmode_fixup_or_oops(regs, error_code, address, pkey, si_code);
+		kernelmode_fixup_or_oops(regs, error_code, address,
+					 SIGSEGV, si_code, pkey);
 		return;
 	}
 
@@ -930,7 +936,8 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
 {
 	/* Kernel mode? Handle exceptions or die: */
 	if (!user_mode(regs)) {
-		kernelmode_fixup_or_oops(regs, error_code, address, SIGBUS, BUS_ADRERR);
+		kernelmode_fixup_or_oops(regs, error_code, address,
+					 SIGBUS, BUS_ADRERR, ARCH_DEFAULT_PKEY);
 		return;
 	}
 
@@ -1396,7 +1403,8 @@ good_area:
 		 */
 		if (!user_mode(regs))
 			kernelmode_fixup_or_oops(regs, error_code, address,
-						 SIGBUS, BUS_ADRERR);
+						 SIGBUS, BUS_ADRERR,
+						 ARCH_DEFAULT_PKEY);
 		return;
 	}
 
@@ -1416,7 +1424,8 @@ good_area:
 		return;
 
 	if (fatal_signal_pending(current) && !user_mode(regs)) {
-		kernelmode_fixup_or_oops(regs, error_code, address, 0, 0);
+		kernelmode_fixup_or_oops(regs, error_code, address,
+					 0, 0, ARCH_DEFAULT_PKEY);
 		return;
 	}
 
@@ -1424,7 +1433,8 @@ good_area:
 		/* Kernel mode? Handle exceptions or die: */
 		if (!user_mode(regs)) {
 			kernelmode_fixup_or_oops(regs, error_code, address,
-						 SIGSEGV, SEGV_MAPERR);
+						 SIGSEGV, SEGV_MAPERR,
+						 ARCH_DEFAULT_PKEY);
 			return;
 		}
 
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 0fe6aacef3db..9ea57389c554 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1341,9 +1341,10 @@ st:			if (is_imm8(insn->off))
 			if (insn->imm == (BPF_AND | BPF_FETCH) ||
 			    insn->imm == (BPF_OR | BPF_FETCH) ||
 			    insn->imm == (BPF_XOR | BPF_FETCH)) {
-				u8 *branch_target;
 				bool is64 = BPF_SIZE(insn->code) == BPF_DW;
 				u32 real_src_reg = src_reg;
+				u32 real_dst_reg = dst_reg;
+				u8 *branch_target;
 
 				/*
 				 * Can't be implemented with a single x86 insn.
@@ -1354,11 +1355,13 @@ st:			if (is_imm8(insn->off))
 				emit_mov_reg(&prog, true, BPF_REG_AX, BPF_REG_0);
 				if (src_reg == BPF_REG_0)
 					real_src_reg = BPF_REG_AX;
+				if (dst_reg == BPF_REG_0)
+					real_dst_reg = BPF_REG_AX;
 
 				branch_target = prog;
 				/* Load old value */
 				emit_ldx(&prog, BPF_SIZE(insn->code),
-					 BPF_REG_0, dst_reg, insn->off);
+					 BPF_REG_0, real_dst_reg, insn->off);
 				/*
 				 * Perform the (commutative) operation locally,
 				 * put the result in the AUX_REG.
@@ -1369,7 +1372,8 @@ st:			if (is_imm8(insn->off))
 				      add_2reg(0xC0, AUX_REG, real_src_reg));
 				/* Attempt to swap in new value */
 				err = emit_atomic(&prog, BPF_CMPXCHG,
-						  dst_reg, AUX_REG, insn->off,
+						  real_dst_reg, AUX_REG,
+						  insn->off,
 						  BPF_SIZE(insn->code));
 				if (WARN_ON(err))
 					return err;
@@ -1383,11 +1387,10 @@ st:			if (is_imm8(insn->off))
 				/* Restore R0 after clobbering RAX */
 				emit_mov_reg(&prog, true, BPF_REG_0, BPF_REG_AX);
 				break;
-
 			}
 
 			err = emit_atomic(&prog, insn->imm, dst_reg, src_reg,
-						  insn->off, BPF_SIZE(insn->code));
+					  insn->off, BPF_SIZE(insn->code));
 			if (err)
 				return err;
 			break;
@@ -1744,7 +1747,7 @@ static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
 }
 
 static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
-			   struct bpf_prog *p, int stack_size, bool mod_ret)
+			   struct bpf_prog *p, int stack_size, bool save_ret)
 {
 	u8 *prog = *pprog;
 	u8 *jmp_insn;
@@ -1777,11 +1780,15 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
 	if (emit_call(&prog, p->bpf_func, prog))
 		return -EINVAL;
 
-	/* BPF_TRAMP_MODIFY_RETURN trampolines can modify the return
+	/*
+	 * BPF_TRAMP_MODIFY_RETURN trampolines can modify the return
 	 * of the previous call which is then passed on the stack to
 	 * the next BPF program.
+	 *
+	 * BPF_TRAMP_FENTRY trampoline may need to return the return
+	 * value of BPF_PROG_TYPE_STRUCT_OPS prog.
 	 */
-	if (mod_ret)
+	if (save_ret)
 		emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
 
 	/* replace 2 nops with JE insn, since jmp target is known */
@@ -1828,13 +1835,15 @@ static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond)
 }
 
 static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,
-		      struct bpf_tramp_progs *tp, int stack_size)
+		      struct bpf_tramp_progs *tp, int stack_size,
+		      bool save_ret)
 {
 	int i;
 	u8 *prog = *pprog;
 
 	for (i = 0; i < tp->nr_progs; i++) {
-		if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size, false))
+		if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size,
+				    save_ret))
 			return -EINVAL;
 	}
 	*pprog = prog;
@@ -1877,6 +1886,23 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
 	return 0;
 }
 
+static bool is_valid_bpf_tramp_flags(unsigned int flags)
+{
+	if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
+	    (flags & BPF_TRAMP_F_SKIP_FRAME))
+		return false;
+
+	/*
+	 * BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
+	 * and it must be used alone.
+	 */
+	if ((flags & BPF_TRAMP_F_RET_FENTRY_RET) &&
+	    (flags & ~BPF_TRAMP_F_RET_FENTRY_RET))
+		return false;
+
+	return true;
+}
+
 /* Example:
  * __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
  * its 'struct btf_func_model' will be nr_args=2
@@ -1949,17 +1975,19 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 	struct bpf_tramp_progs *fmod_ret = &tprogs[BPF_TRAMP_MODIFY_RETURN];
 	u8 **branches = NULL;
 	u8 *prog;
+	bool save_ret;
 
 	/* x86-64 supports up to 6 arguments. 7+ can be added in the future */
 	if (nr_args > 6)
 		return -ENOTSUPP;
 
-	if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
-	    (flags & BPF_TRAMP_F_SKIP_FRAME))
+	if (!is_valid_bpf_tramp_flags(flags))
 		return -EINVAL;
 
-	if (flags & BPF_TRAMP_F_CALL_ORIG)
-		stack_size += 8; /* room for return value of orig_call */
+	/* room for return value of orig_call or fentry prog */
+	save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
+	if (save_ret)
+		stack_size += 8;
 
 	if (flags & BPF_TRAMP_F_IP_ARG)
 		stack_size += 8; /* room for IP address argument */
@@ -2005,7 +2033,8 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 	}
 
 	if (fentry->nr_progs)
-		if (invoke_bpf(m, &prog, fentry, stack_size))
+		if (invoke_bpf(m, &prog, fentry, stack_size,
+			       flags & BPF_TRAMP_F_RET_FENTRY_RET))
 			return -EINVAL;
 
 	if (fmod_ret->nr_progs) {
@@ -2052,7 +2081,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 	}
 
 	if (fexit->nr_progs)
-		if (invoke_bpf(m, &prog, fexit, stack_size)) {
+		if (invoke_bpf(m, &prog, fexit, stack_size, false)) {
 			ret = -EINVAL;
 			goto cleanup;
 		}
@@ -2072,9 +2101,10 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 			ret = -EINVAL;
 			goto cleanup;
 		}
-		/* restore original return value back into RAX */
-		emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8);
 	}
+	/* restore return value of orig_call or fentry prog back into RAX */
+	if (save_ret)
+		emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8);
 
 	EMIT1(0x5B); /* pop rbx */
 	EMIT1(0xC9); /* leave */
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 349f780a1567..6e0d0754f94f 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -755,8 +755,8 @@ static void xen_write_idt_entry(gate_desc *dt, int entrynum, const gate_desc *g)
 	preempt_enable();
 }
 
-static void xen_convert_trap_info(const struct desc_ptr *desc,
-				  struct trap_info *traps)
+static unsigned xen_convert_trap_info(const struct desc_ptr *desc,
+				      struct trap_info *traps, bool full)
 {
 	unsigned in, out, count;
 
@@ -766,17 +766,18 @@ static void xen_convert_trap_info(const struct desc_ptr *desc,
 	for (in = out = 0; in < count; in++) {
 		gate_desc *entry = (gate_desc *)(desc->address) + in;
 
-		if (cvt_gate_to_trap(in, entry, &traps[out]))
+		if (cvt_gate_to_trap(in, entry, &traps[out]) || full)
 			out++;
 	}
-	traps[out].address = 0;
+
+	return out;
 }
 
 void xen_copy_trap_info(struct trap_info *traps)
 {
 	const struct desc_ptr *desc = this_cpu_ptr(&idt_desc);
 
-	xen_convert_trap_info(desc, traps);
+	xen_convert_trap_info(desc, traps, true);
 }
 
 /* Load a new IDT into Xen.  In principle this can be per-CPU, so we
@@ -786,6 +787,7 @@ static void xen_load_idt(const struct desc_ptr *desc)
 {
 	static DEFINE_SPINLOCK(lock);
 	static struct trap_info traps[257];
+	unsigned out;
 
 	trace_xen_cpu_load_idt(desc);
 
@@ -793,7 +795,8 @@ static void xen_load_idt(const struct desc_ptr *desc)
 
 	memcpy(this_cpu_ptr(&idt_desc), desc, sizeof(idt_desc));
 
-	xen_convert_trap_info(desc, traps);
+	out = xen_convert_trap_info(desc, traps, false);
+	memset(&traps[out], 0, sizeof(traps[0]));
 
 	xen_mc_flush();
 	if (HYPERVISOR_set_trap_table(traps))
diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
index 54f9aa7e8457..46df59aeaa06 100644
--- a/arch/x86/xen/pci-swiotlb-xen.c
+++ b/arch/x86/xen/pci-swiotlb-xen.c
@@ -18,7 +18,7 @@
 #endif
 #include <linux/export.h>
 
-int xen_swiotlb __read_mostly;
+static int xen_swiotlb __read_mostly;
 
 /*
  * pci_xen_swiotlb_detect - set xen_swiotlb to 1 if necessary
@@ -56,7 +56,7 @@ int __init pci_xen_swiotlb_detect(void)
 	return xen_swiotlb;
 }
 
-void __init pci_xen_swiotlb_init(void)
+static void __init pci_xen_swiotlb_init(void)
 {
 	if (xen_swiotlb) {
 		xen_swiotlb_init_early();
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index 96afadf9878e..7ed56c6075b0 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -290,8 +290,6 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 
 	gdt = get_cpu_gdt_rw(cpu);
 
-	memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
-
 	/*
 	 * Bring up the CPU in cpu_bringup_and_idle() with the stack
 	 * pointing just below where pt_regs would be if it were a normal
@@ -308,8 +306,6 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 
 	xen_copy_trap_info(ctxt->trap_ctxt);
 
-	ctxt->ldt_ents = 0;
-
 	BUG_ON((unsigned long)gdt & ~PAGE_MASK);
 
 	gdt_mfn = arbitrary_virt_to_mfn(gdt);