Merge tag 'x86_seves_fixes_for_v5.10_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 SEV-ES fixes from Borislav Petkov:
 "Three fixes to SEV-ES to correct setting up the new early pagetable on
  5-level paging machines, to always map boot_params and the kernel
  cmdline, and disable stack protector for ../compressed/head{32,64}.c.
  (Arvind Sankar)"

* tag 'x86_seves_fixes_for_v5.10_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot/64: Explicitly map boot_params and command line
  x86/head/64: Disable stack protection for head$(BITS).o
  x86/boot/64: Initialize 5-level paging variables earlier

Author: torvalds

arch/x86/boot/compressed/head_64.S

@@ -544,6 +544,9 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
 	pushq	%rsi
 	call	set_sev_encryption_mask
 	call	load_stage2_idt
+
+	/* Pass boot_params to initialize_identity_maps() */
+	movq	(%rsp), %rdi
 	call	initialize_identity_maps
 	popq	%rsi
 

arch/x86/boot/compressed/ident_map_64.c

@@ -33,11 +33,11 @@
 #define __PAGE_OFFSET __PAGE_OFFSET_BASE
 #include "../../mm/ident_map.c"
 
-#ifdef CONFIG_X86_5LEVEL
-unsigned int __pgtable_l5_enabled;
-unsigned int pgdir_shift = 39;
-unsigned int ptrs_per_p4d = 1;
-#endif
+#define _SETUP
+#include <asm/setup.h>	/* For COMMAND_LINE_SIZE */
+#undef _SETUP
+
+extern unsigned long get_cmd_line_ptr(void);
 
 /* Used by PAGE_KERN* macros: */
 pteval_t __default_kernel_pte_mask __read_mostly = ~0;
@@ -107,8 +107,10 @@ static void add_identity_map(unsigned long start, unsigned long end)
 }
 
 /* Locates and clears a region for a new top level page table. */
-void initialize_identity_maps(void)
+void initialize_identity_maps(void *rmode)
 {
+	unsigned long cmdline;
+
 	/* Exclude the encryption mask from __PHYSICAL_MASK */
 	physical_mask &= ~sme_me_mask;
 
@@ -149,10 +151,19 @@ void initialize_identity_maps(void)
 	}
 
 	/*
-	 * New page-table is set up - map the kernel image and load it
-	 * into cr3.
+	 * New page-table is set up - map the kernel image, boot_params and the
+	 * command line. The uncompressed kernel requires boot_params and the
+	 * command line to be mapped in the identity mapping. Map them
+	 * explicitly here in case the compressed kernel does not touch them,
+	 * or does not touch all the pages covering them.
 	 */
 	add_identity_map((unsigned long)_head, (unsigned long)_end);
+	boot_params = rmode;
+	add_identity_map((unsigned long)boot_params, (unsigned long)(boot_params + 1));
+	cmdline = get_cmd_line_ptr();
+	add_identity_map(cmdline, cmdline + COMMAND_LINE_SIZE);
+
+	/* Load the new page-table. */
 	write_cr3(top_level_pgt);
 }
 

arch/x86/boot/compressed/kaslr.c

@@ -840,14 +840,6 @@ void choose_random_location(unsigned long input,
 		return;
 	}
 
-#ifdef CONFIG_X86_5LEVEL
-	if (__read_cr4() & X86_CR4_LA57) {
-		__pgtable_l5_enabled = 1;
-		pgdir_shift = 48;
-		ptrs_per_p4d = 512;
-	}
-#endif
-
 	boot_params->hdr.loadflags |= KASLR_FLAG;
 
 	if (IS_ENABLED(CONFIG_X86_32))

arch/x86/boot/compressed/pgtable_64.c

@@ -8,6 +8,13 @@
 #define BIOS_START_MIN		0x20000U	/* 128K, less than this is insane */
 #define BIOS_START_MAX		0x9f000U	/* 640K, absolute maximum */
 
+#ifdef CONFIG_X86_5LEVEL
+/* __pgtable_l5_enabled needs to be in .data to avoid being cleared along with .bss */
+unsigned int __section(.data) __pgtable_l5_enabled;
+unsigned int __section(.data) pgdir_shift = 39;
+unsigned int __section(.data) ptrs_per_p4d = 1;
+#endif
+
 struct paging_config {
 	unsigned long trampoline_start;
 	unsigned long l5_required;
@@ -198,4 +205,13 @@ void cleanup_trampoline(void *pgtable)
 
 	/* Restore trampoline memory */
 	memcpy(trampoline_32bit, trampoline_save, TRAMPOLINE_32BIT_SIZE);
+
+	/* Initialize variables for 5-level paging */
+#ifdef CONFIG_X86_5LEVEL
+	if (__read_cr4() & X86_CR4_LA57) {
+		__pgtable_l5_enabled = 1;
+		pgdir_shift = 48;
+		ptrs_per_p4d = 512;
+	}
+#endif
 }

arch/x86/kernel/Makefile

@@ -47,6 +47,8 @@ endif
 # non-deterministic coverage.
 KCOV_INSTRUMENT		:= n
 
+CFLAGS_head$(BITS).o	+= -fno-stack-protector
+
 CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
 
 obj-y			:= process_$(BITS).o signal.o