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Port I/O instructions trigger #VE in the TDX environment. In response to the exception, kernel emulates these instructions using hypercalls. But during early boot, on the decompression stage, it is cumbersome to deal with #VE. It is cleaner to go to hypercalls directly, bypassing #VE handling. Add a way to hook up alternative port I/O helpers in the boot stub with a new pio_ops structure. For now, set the ops structure to just call the normal I/O operation functions. out*()/in*() macros redefined to use pio_ops callbacks. It eliminates need in changing call sites. io_delay() changed to use port I/O helper instead of inline assembly. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lkml.kernel.org/r/20220405232939.73860-16-kirill.shutemov@linux.intel.com
41 lines
774 B
C
41 lines
774 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef BOOT_IO_H
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#define BOOT_IO_H
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#include <asm/shared/io.h>
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#undef inb
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#undef inw
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#undef inl
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#undef outb
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#undef outw
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#undef outl
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struct port_io_ops {
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u8 (*f_inb)(u16 port);
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void (*f_outb)(u8 v, u16 port);
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void (*f_outw)(u16 v, u16 port);
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};
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extern struct port_io_ops pio_ops;
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/*
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* Use the normal I/O instructions by default.
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* TDX guests override these to use hypercalls.
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*/
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static inline void init_default_io_ops(void)
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{
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pio_ops.f_inb = __inb;
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pio_ops.f_outb = __outb;
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pio_ops.f_outw = __outw;
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}
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/*
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* Redirect port I/O operations via pio_ops callbacks.
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* TDX guests override these callbacks with TDX-specific helpers.
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*/
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#define inb pio_ops.f_inb
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#define outb pio_ops.f_outb
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#define outw pio_ops.f_outw
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#endif
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