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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/x86/platform/efi/efi_32.c
10820 views
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/*

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 * Extensible Firmware Interface

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 *

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 * Based on Extensible Firmware Interface Specification version 1.0

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 *

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 * Copyright (C) 1999 VA Linux Systems

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 * Copyright (C) 1999 Walt Drummond <[email protected]>

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 * Copyright (C) 1999-2002 Hewlett-Packard Co.

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 *	David Mosberger-Tang <[email protected]>

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 *	Stephane Eranian <[email protected]>

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 *

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 * All EFI Runtime Services are not implemented yet as EFI only

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 * supports physical mode addressing on SoftSDV. This is to be fixed

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 * in a future version.  --drummond 1999-07-20

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 *

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 * Implemented EFI runtime services and virtual mode calls.  --davidm

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 *

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 * Goutham Rao: <[email protected]>

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 *	Skip non-WB memory and ignore empty memory ranges.

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 */

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#include <linux/kernel.h>

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#include <linux/types.h>

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#include <linux/ioport.h>

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#include <linux/efi.h>

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#include <asm/io.h>

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#include <asm/page.h>

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#include <asm/pgtable.h>

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#include <asm/tlbflush.h>

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#include <asm/efi.h>

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/*

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 * To make EFI call EFI runtime service in physical addressing mode we need

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 * prelog/epilog before/after the invocation to disable interrupt, to

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 * claim EFI runtime service handler exclusively and to duplicate a memory in

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 * low memory space say 0 - 3G.

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 */

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static unsigned long efi_rt_eflags;

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static pgd_t efi_bak_pg_dir_pointer[2];

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void efi_call_phys_prelog(void)

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{

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	unsigned long cr4;

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	unsigned long temp;

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	struct desc_ptr gdt_descr;

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	local_irq_save(efi_rt_eflags);

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	/*

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	 * If I don't have PAE, I should just duplicate two entries in page

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	 * directory. If I have PAE, I just need to duplicate one entry in

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	 * page directory.

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	 */

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	cr4 = read_cr4_safe();

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	if (cr4 & X86_CR4_PAE) {

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		efi_bak_pg_dir_pointer[0].pgd =

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		    swapper_pg_dir[pgd_index(0)].pgd;

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		swapper_pg_dir[0].pgd =

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		    swapper_pg_dir[pgd_index(PAGE_OFFSET)].pgd;

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	} else {

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		efi_bak_pg_dir_pointer[0].pgd =

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		    swapper_pg_dir[pgd_index(0)].pgd;

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		efi_bak_pg_dir_pointer[1].pgd =

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		    swapper_pg_dir[pgd_index(0x400000)].pgd;

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		swapper_pg_dir[pgd_index(0)].pgd =

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		    swapper_pg_dir[pgd_index(PAGE_OFFSET)].pgd;

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		temp = PAGE_OFFSET + 0x400000;

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		swapper_pg_dir[pgd_index(0x400000)].pgd =

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		    swapper_pg_dir[pgd_index(temp)].pgd;

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	}

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	/*

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	 * After the lock is released, the original page table is restored.

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	 */

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	__flush_tlb_all();

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	gdt_descr.address = __pa(get_cpu_gdt_table(0));

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	gdt_descr.size = GDT_SIZE - 1;

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	load_gdt(&gdt_descr);

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}

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void efi_call_phys_epilog(void)

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{

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	unsigned long cr4;

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	struct desc_ptr gdt_descr;

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	gdt_descr.address = (unsigned long)get_cpu_gdt_table(0);

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	gdt_descr.size = GDT_SIZE - 1;

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	load_gdt(&gdt_descr);

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	cr4 = read_cr4_safe();

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	if (cr4 & X86_CR4_PAE) {

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		swapper_pg_dir[pgd_index(0)].pgd =

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		    efi_bak_pg_dir_pointer[0].pgd;

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	} else {

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		swapper_pg_dir[pgd_index(0)].pgd =

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		    efi_bak_pg_dir_pointer[0].pgd;

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		swapper_pg_dir[pgd_index(0x400000)].pgd =

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		    efi_bak_pg_dir_pointer[1].pgd;

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	}

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	/*

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	 * After the lock is released, the original page table is restored.

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	 */

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	__flush_tlb_all();

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	local_irq_restore(efi_rt_eflags);

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}

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