Merge tag 'x86-cleanups-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cleanups from Thomas Gleixner:
 "A set of cleanups across x86:

   - Use memremap() for the EISA probe instead of ioremap(). EISA is
     strictly memory and not MMIO

   - Cleanups and enhancement all over the place"

* tag 'x86-cleanups-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/EISA: Dereference memory directly instead of using readl()
  x86/extable: Remove unused declaration fixup_bug()
  x86/boot/64: Strip percpu address space when setting up GDT descriptors
  x86/cpu: Clarify the error message when BIOS does not support SGX
  x86/kexec: Add comments around swap_pages() assembly to improve readability
  x86/kexec: Fix a comment of swap_pages() assembly
  x86/sgx: Fix a W=1 build warning in function comment
  x86/EISA: Use memremap() to probe for the EISA BIOS signature
  x86/mtrr: Remove obsolete declaration for mtrr_bp_restore()
  x86/cpu_entry_area: Annotate percpu_setup_exception_stacks() as __init

arch/x86/include/asm/extable.h

@@ -37,7 +37,6 @@ struct pt_regs;
 
 extern int fixup_exception(struct pt_regs *regs, int trapnr,
 			   unsigned long error_code, unsigned long fault_addr);
-extern int fixup_bug(struct pt_regs *regs, int trapnr);
 extern int ex_get_fixup_type(unsigned long ip);
 extern void early_fixup_exception(struct pt_regs *regs, int trapnr);
 

arch/x86/include/asm/mtrr.h

@@ -69,7 +69,6 @@ extern int mtrr_add_page(unsigned long base, unsigned long size,
 			 unsigned int type, bool increment);
 extern int mtrr_del(int reg, unsigned long base, unsigned long size);
 extern int mtrr_del_page(int reg, unsigned long base, unsigned long size);
-extern void mtrr_bp_restore(void);
 extern int mtrr_trim_uncached_memory(unsigned long end_pfn);
 extern int amd_special_default_mtrr(void);
 void mtrr_disable(void);
@@ -117,7 +116,6 @@ static inline int mtrr_trim_uncached_memory(unsigned long end_pfn)
 	return 0;
 }
 #define mtrr_bp_init() do {} while (0)
-#define mtrr_bp_restore() do {} while (0)
 #define mtrr_disable() do {} while (0)
 #define mtrr_enable() do {} while (0)
 #define mtrr_generic_set_state() do {} while (0)

arch/x86/kernel/cpu/feat_ctl.c

@@ -188,7 +188,7 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
 update_sgx:
 	if (!(msr & FEAT_CTL_SGX_ENABLED)) {
 		if (enable_sgx_kvm || enable_sgx_driver)
-			pr_err_once("SGX disabled by BIOS.\n");
+			pr_err_once("SGX disabled or unsupported by BIOS.\n");
 		clear_cpu_cap(c, X86_FEATURE_SGX);
 		return;
 	}

arch/x86/kernel/cpu/sgx/main.c

@@ -733,7 +733,7 @@ int arch_memory_failure(unsigned long pfn, int flags)
 	return 0;
 }
 
-/**
+/*
  * A section metric is concatenated in a way that @low bits 12-31 define the
  * bits 12-31 of the metric and @high bits 0-19 define the bits 32-51 of the
  * metric.

arch/x86/kernel/eisa.c

@@ -11,15 +11,15 @@
 
 static __init int eisa_bus_probe(void)
 {
-	void __iomem *p;
+	u32 *p;
 
 	if ((xen_pv_domain() && !xen_initial_domain()) || cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
 		return 0;
 
-	p = ioremap(0x0FFFD9, 4);
-	if (p && readl(p) == 'E' + ('I' << 8) + ('S' << 16) + ('A' << 24))
+	p = memremap(0x0FFFD9, 4, MEMREMAP_WB);
+	if (p && *p == 'E' + ('I' << 8) + ('S' << 16) + ('A' << 24))
 		EISA_bus = 1;
-	iounmap(p);
+	memunmap(p);
 	return 0;
 }
 subsys_initcall(eisa_bus_probe);

arch/x86/kernel/head64.c

@@ -559,10 +559,11 @@ void early_setup_idt(void)
  */
 void __head startup_64_setup_gdt_idt(void)
 {
+	struct desc_struct *gdt = (void *)(__force unsigned long)init_per_cpu_var(gdt_page.gdt);
 	void *handler = NULL;
 
 	struct desc_ptr startup_gdt_descr = {
-		.address = (unsigned long)&RIP_REL_REF(init_per_cpu_var(gdt_page.gdt)),
+		.address = (unsigned long)&RIP_REL_REF(*gdt),
 		.size    = GDT_SIZE - 1,
 	};
 

arch/x86/kernel/relocate_kernel_64.S

@@ -170,6 +170,7 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
 	wbinvd
 .Lsme_off:
 
+	/* Save the preserve_context to %r11 as swap_pages clobbers %rcx. */
 	movq	%rcx, %r11
 	call	swap_pages
 
@@ -258,7 +259,7 @@ SYM_CODE_END(virtual_mapped)
 	/* Do the copies */
 SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
 	UNWIND_HINT_END_OF_STACK
-	movq	%rdi, %rcx	/* Put the page_list in %rcx */
+	movq	%rdi, %rcx	/* Put the indirection_page in %rcx */
 	xorl	%edi, %edi
 	xorl	%esi, %esi
 	jmp	1f
@@ -289,18 +290,21 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
 	movq	%rcx,   %rsi  /* For ever source page do a copy */
 	andq	$0xfffffffffffff000, %rsi
 
-	movq	%rdi, %rdx
-	movq	%rsi, %rax
+	movq	%rdi, %rdx    /* Save destination page to %rdx */
+	movq	%rsi, %rax    /* Save source page to %rax */
 
+	/* copy source page to swap page */
 	movq	%r10, %rdi
 	movl	$512, %ecx
 	rep ; movsq
 
+	/* copy destination page to source page */
 	movq	%rax, %rdi
 	movq	%rdx, %rsi
 	movl	$512, %ecx
 	rep ; movsq
 
+	/* copy swap page to destination page */
 	movq	%rdx, %rdi
 	movq	%r10, %rsi
 	movl	$512, %ecx

arch/x86/mm/cpu_entry_area.c

@@ -164,7 +164,7 @@ static void __init percpu_setup_exception_stacks(unsigned int cpu)
 	}
 }
 #else
-static inline void percpu_setup_exception_stacks(unsigned int cpu)
+static void __init percpu_setup_exception_stacks(unsigned int cpu)
 {
 	struct cpu_entry_area *cea = get_cpu_entry_area(cpu);