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ae7e1238e6
Xen PVH guests receive the address of the RSDP table from Xen. In order to support booting a Xen PVH guest via Grub2 using the standard x86 boot entry we need a way for Grub2 to pass the RSDP address to the kernel. For this purpose expand the struct setup_header to hold the physical address of the RSDP address. Being zero means it isn't specified and has to be located the legacy way (searching through low memory or EBDA). While documenting the new setup_header layout and protocol version 2.14 add the missing documentation of protocol version 2.13. There are Grub2 versions in several distros with a downstream patch violating the boot protocol by writing past the end of setup_header. This requires another update of the boot protocol to enable the kernel to distinguish between a specified RSDP address and one filled with garbage by such a broken Grub2. From protocol 2.14 on Grub2 will write the version it is supporting (but never a higher value than found to be supported by the kernel) ored with 0x8000 to the version field of setup_header. This enables the kernel to know up to which field Grub2 has written information to. All fields after that are supposed to be clobbered. Signed-off-by: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boris.ostrovsky@oracle.com Cc: bp@alien8.de Cc: corbet@lwn.net Cc: linux-doc@vger.kernel.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/20181010061456.22238-3-jgross@suse.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
121 lines
3.2 KiB
C
121 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/arch/i386/kernel/head32.c -- prepare to run common code
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*
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* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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* Copyright (C) 2007 Eric Biederman <ebiederm@xmission.com>
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*/
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#include <linux/init.h>
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#include <linux/start_kernel.h>
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#include <linux/mm.h>
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#include <linux/memblock.h>
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#include <asm/desc.h>
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#include <asm/setup.h>
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#include <asm/sections.h>
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#include <asm/e820/api.h>
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#include <asm/page.h>
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#include <asm/apic.h>
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#include <asm/io_apic.h>
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#include <asm/bios_ebda.h>
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#include <asm/tlbflush.h>
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#include <asm/bootparam_utils.h>
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static void __init i386_default_early_setup(void)
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{
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/* Initialize 32bit specific setup functions */
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x86_init.resources.reserve_resources = i386_reserve_resources;
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x86_init.mpparse.setup_ioapic_ids = setup_ioapic_ids_from_mpc;
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}
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asmlinkage __visible void __init i386_start_kernel(void)
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{
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/* Make sure IDT is set up before any exception happens */
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idt_setup_early_handler();
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cr4_init_shadow();
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sanitize_boot_params(&boot_params);
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x86_verify_bootdata_version();
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x86_early_init_platform_quirks();
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/* Call the subarch specific early setup function */
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switch (boot_params.hdr.hardware_subarch) {
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case X86_SUBARCH_INTEL_MID:
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x86_intel_mid_early_setup();
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break;
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case X86_SUBARCH_CE4100:
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x86_ce4100_early_setup();
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break;
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default:
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i386_default_early_setup();
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break;
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}
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start_kernel();
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}
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/*
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* Initialize page tables. This creates a PDE and a set of page
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* tables, which are located immediately beyond __brk_base. The variable
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* _brk_end is set up to point to the first "safe" location.
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* Mappings are created both at virtual address 0 (identity mapping)
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* and PAGE_OFFSET for up to _end.
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*
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* In PAE mode initial_page_table is statically defined to contain
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* enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
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* entries). The identity mapping is handled by pointing two PGD entries
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* to the first kernel PMD. Note the upper half of each PMD or PTE are
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* always zero at this stage.
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*/
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void __init mk_early_pgtbl_32(void)
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{
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#ifdef __pa
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#undef __pa
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#endif
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#define __pa(x) ((unsigned long)(x) - PAGE_OFFSET)
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pte_t pte, *ptep;
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int i;
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unsigned long *ptr;
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/* Enough space to fit pagetables for the low memory linear map */
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const unsigned long limit = __pa(_end) +
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(PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);
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#ifdef CONFIG_X86_PAE
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pmd_t pl2, *pl2p = (pmd_t *)__pa(initial_pg_pmd);
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#define SET_PL2(pl2, val) { (pl2).pmd = (val); }
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#else
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pgd_t pl2, *pl2p = (pgd_t *)__pa(initial_page_table);
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#define SET_PL2(pl2, val) { (pl2).pgd = (val); }
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#endif
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ptep = (pte_t *)__pa(__brk_base);
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pte.pte = PTE_IDENT_ATTR;
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while ((pte.pte & PTE_PFN_MASK) < limit) {
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SET_PL2(pl2, (unsigned long)ptep | PDE_IDENT_ATTR);
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*pl2p = pl2;
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#ifndef CONFIG_X86_PAE
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/* Kernel PDE entry */
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*(pl2p + ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;
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#endif
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for (i = 0; i < PTRS_PER_PTE; i++) {
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*ptep = pte;
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pte.pte += PAGE_SIZE;
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ptep++;
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}
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pl2p++;
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}
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ptr = (unsigned long *)__pa(&max_pfn_mapped);
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/* Can't use pte_pfn() since it's a call with CONFIG_PARAVIRT */
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*ptr = (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
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ptr = (unsigned long *)__pa(&_brk_end);
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*ptr = (unsigned long)ptep + PAGE_OFFSET;
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}
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