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    Subject[PATCHv2 11/29] x86/boot: Allow to hook up alternative port I/O helpers
    Date
    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.
    All port I/O operations are routed via 'pio_ops'. By default 'pio_ops'
    initialized with native port I/O implementations.

    This is a preparation patch. The next patch will override 'pio_ops' if
    the kernel booted in the TDX environment.

    Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    ---
    arch/x86/boot/a20.c | 14 +++++++-------
    arch/x86/boot/boot.h | 2 +-
    arch/x86/boot/compressed/misc.c | 18 ++++++++++++------
    arch/x86/boot/compressed/misc.h | 2 +-
    arch/x86/boot/early_serial_console.c | 28 ++++++++++++++--------------
    arch/x86/boot/io.h | 28 ++++++++++++++++++++++++++++
    arch/x86/boot/main.c | 4 ++++
    arch/x86/boot/pm.c | 10 +++++-----
    arch/x86/boot/tty.c | 4 ++--
    arch/x86/boot/video-vga.c | 6 +++---
    arch/x86/boot/video.h | 8 +++++---
    arch/x86/realmode/rm/wakemain.c | 14 +++++++++-----
    12 files changed, 91 insertions(+), 47 deletions(-)
    create mode 100644 arch/x86/boot/io.h

    diff --git a/arch/x86/boot/a20.c b/arch/x86/boot/a20.c
    index a2b6b428922a..7f6dd5cc4670 100644
    --- a/arch/x86/boot/a20.c
    +++ b/arch/x86/boot/a20.c
    @@ -25,7 +25,7 @@ static int empty_8042(void)
    while (loops--) {
    io_delay();

    - status = inb(0x64);
    + status = pio_ops.inb(0x64);
    if (status == 0xff) {
    /* FF is a plausible, but very unlikely status */
    if (!--ffs)
    @@ -34,7 +34,7 @@ static int empty_8042(void)
    if (status & 1) {
    /* Read and discard input data */
    io_delay();
    - (void)inb(0x60);
    + (void)pio_ops.inb(0x60);
    } else if (!(status & 2)) {
    /* Buffers empty, finished! */
    return 0;
    @@ -99,13 +99,13 @@ static void enable_a20_kbc(void)
    {
    empty_8042();

    - outb(0xd1, 0x64); /* Command write */
    + pio_ops.outb(0xd1, 0x64); /* Command write */
    empty_8042();

    - outb(0xdf, 0x60); /* A20 on */
    + pio_ops.outb(0xdf, 0x60); /* A20 on */
    empty_8042();

    - outb(0xff, 0x64); /* Null command, but UHCI wants it */
    + pio_ops.outb(0xff, 0x64); /* Null command, but UHCI wants it */
    empty_8042();
    }

    @@ -113,10 +113,10 @@ static void enable_a20_fast(void)
    {
    u8 port_a;

    - port_a = inb(0x92); /* Configuration port A */
    + port_a = pio_ops.inb(0x92); /* Configuration port A */
    port_a |= 0x02; /* Enable A20 */
    port_a &= ~0x01; /* Do not reset machine */
    - outb(port_a, 0x92);
    + pio_ops.outb(port_a, 0x92);
    }

    /*
    diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
    index 22a474c5b3e8..bd8f640ca15f 100644
    --- a/arch/x86/boot/boot.h
    +++ b/arch/x86/boot/boot.h
    @@ -23,10 +23,10 @@
    #include <linux/edd.h>
    #include <asm/setup.h>
    #include <asm/asm.h>
    -#include <asm/shared/io.h>
    #include "bitops.h"
    #include "ctype.h"
    #include "cpuflags.h"
    +#include "io.h"

    /* Useful macros */
    #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
    diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
    index d8373d766672..cc47cf239c67 100644
    --- a/arch/x86/boot/compressed/misc.c
    +++ b/arch/x86/boot/compressed/misc.c
    @@ -47,6 +47,8 @@ void *memmove(void *dest, const void *src, size_t n);
    */
    struct boot_params *boot_params;

    +struct port_io_ops pio_ops;
    +
    memptr free_mem_ptr;
    memptr free_mem_end_ptr;

    @@ -103,10 +105,12 @@ static void serial_putchar(int ch)
    {
    unsigned timeout = 0xffff;

    - while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
    + while ((pio_ops.inb(early_serial_base + LSR) & XMTRDY) == 0 &&
    + --timeout) {
    cpu_relax();
    + }

    - outb(ch, early_serial_base + TXR);
    + pio_ops.outb(ch, early_serial_base + TXR);
    }

    void __putstr(const char *s)
    @@ -152,10 +156,10 @@ void __putstr(const char *s)
    boot_params->screen_info.orig_y = y;

    pos = (x + cols * y) * 2; /* Update cursor position */
    - outb(14, vidport);
    - outb(0xff & (pos >> 9), vidport+1);
    - outb(15, vidport);
    - outb(0xff & (pos >> 1), vidport+1);
    + pio_ops.outb(14, vidport);
    + pio_ops.outb(0xff & (pos >> 9), vidport+1);
    + pio_ops.outb(15, vidport);
    + pio_ops.outb(0xff & (pos >> 1), vidport+1);
    }

    void __puthex(unsigned long value)
    @@ -370,6 +374,8 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
    lines = boot_params->screen_info.orig_video_lines;
    cols = boot_params->screen_info.orig_video_cols;

    + init_io_ops();
    +
    /*
    * Detect TDX guest environment.
    *
    diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
    index 8a253e85f990..ea71cf3d64e1 100644
    --- a/arch/x86/boot/compressed/misc.h
    +++ b/arch/x86/boot/compressed/misc.h
    @@ -26,7 +26,6 @@
    #include <asm/boot.h>
    #include <asm/bootparam.h>
    #include <asm/desc_defs.h>
    -#include <asm/shared/io.h>

    #include "tdx.h"

    @@ -35,6 +34,7 @@

    #define BOOT_BOOT_H
    #include "../ctype.h"
    +#include "../io.h"

    #ifdef CONFIG_X86_64
    #define memptr long
    diff --git a/arch/x86/boot/early_serial_console.c b/arch/x86/boot/early_serial_console.c
    index 023bf1c3de8b..03e43d770571 100644
    --- a/arch/x86/boot/early_serial_console.c
    +++ b/arch/x86/boot/early_serial_console.c
    @@ -28,17 +28,17 @@ static void early_serial_init(int port, int baud)
    unsigned char c;
    unsigned divisor;

    - outb(0x3, port + LCR); /* 8n1 */
    - outb(0, port + IER); /* no interrupt */
    - outb(0, port + FCR); /* no fifo */
    - outb(0x3, port + MCR); /* DTR + RTS */
    + pio_ops.outb(0x3, port + LCR); /* 8n1 */
    + pio_ops.outb(0, port + IER); /* no interrupt */
    + pio_ops.outb(0, port + FCR); /* no fifo */
    + pio_ops.outb(0x3, port + MCR); /* DTR + RTS */

    divisor = 115200 / baud;
    - c = inb(port + LCR);
    - outb(c | DLAB, port + LCR);
    - outb(divisor & 0xff, port + DLL);
    - outb((divisor >> 8) & 0xff, port + DLH);
    - outb(c & ~DLAB, port + LCR);
    + c = pio_ops.inb(port + LCR);
    + pio_ops.outb(c | DLAB, port + LCR);
    + pio_ops.outb(divisor & 0xff, port + DLL);
    + pio_ops.outb((divisor >> 8) & 0xff, port + DLH);
    + pio_ops.outb(c & ~DLAB, port + LCR);

    early_serial_base = port;
    }
    @@ -104,11 +104,11 @@ static unsigned int probe_baud(int port)
    unsigned char lcr, dll, dlh;
    unsigned int quot;

    - lcr = inb(port + LCR);
    - outb(lcr | DLAB, port + LCR);
    - dll = inb(port + DLL);
    - dlh = inb(port + DLH);
    - outb(lcr, port + LCR);
    + lcr = pio_ops.inb(port + LCR);
    + pio_ops.outb(lcr | DLAB, port + LCR);
    + dll = pio_ops.inb(port + DLL);
    + dlh = pio_ops.inb(port + DLH);
    + pio_ops.outb(lcr, port + LCR);
    quot = (dlh << 8) | dll;

    return BASE_BAUD / quot;
    diff --git a/arch/x86/boot/io.h b/arch/x86/boot/io.h
    new file mode 100644
    index 000000000000..2659180e3210
    --- /dev/null
    +++ b/arch/x86/boot/io.h
    @@ -0,0 +1,28 @@
    +/* SPDX-License-Identifier: GPL-2.0 */
    +#ifndef BOOT_IO_H
    +#define BOOT_IO_H
    +
    +#include <asm/shared/io.h>
    +
    +struct port_io_ops {
    + unsigned char (*inb)(int port);
    + unsigned short (*inw)(int port);
    + unsigned int (*inl)(int port);
    + void (*outb)(unsigned char v, int port);
    + void (*outw)(unsigned short v, int port);
    + void (*outl)(unsigned int v, int port);
    +};
    +
    +extern struct port_io_ops pio_ops;
    +
    +static inline void init_io_ops(void)
    +{
    + pio_ops.inb = inb;
    + pio_ops.inw = inw;
    + pio_ops.inl = inl;
    + pio_ops.outb = outb;
    + pio_ops.outw = outw;
    + pio_ops.outl = outl;
    +}
    +
    +#endif
    diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
    index e3add857c2c9..447a797891be 100644
    --- a/arch/x86/boot/main.c
    +++ b/arch/x86/boot/main.c
    @@ -17,6 +17,8 @@

    struct boot_params boot_params __attribute__((aligned(16)));

    +struct port_io_ops pio_ops;
    +
    char *HEAP = _end;
    char *heap_end = _end; /* Default end of heap = no heap */

    @@ -133,6 +135,8 @@ static void init_heap(void)

    void main(void)
    {
    + init_io_ops();
    +
    /* First, copy the boot header into the "zeropage" */
    copy_boot_params();

    diff --git a/arch/x86/boot/pm.c b/arch/x86/boot/pm.c
    index 40031a614712..4180b6a264c9 100644
    --- a/arch/x86/boot/pm.c
    +++ b/arch/x86/boot/pm.c
    @@ -25,7 +25,7 @@ static void realmode_switch_hook(void)
    : "eax", "ebx", "ecx", "edx");
    } else {
    asm volatile("cli");
    - outb(0x80, 0x70); /* Disable NMI */
    + pio_ops.outb(0x80, 0x70); /* Disable NMI */
    io_delay();
    }
    }
    @@ -35,9 +35,9 @@ static void realmode_switch_hook(void)
    */
    static void mask_all_interrupts(void)
    {
    - outb(0xff, 0xa1); /* Mask all interrupts on the secondary PIC */
    + pio_ops.outb(0xff, 0xa1); /* Mask all interrupts on the secondary PIC */
    io_delay();
    - outb(0xfb, 0x21); /* Mask all but cascade on the primary PIC */
    + pio_ops.outb(0xfb, 0x21); /* Mask all but cascade on the primary PIC */
    io_delay();
    }

    @@ -46,9 +46,9 @@ static void mask_all_interrupts(void)
    */
    static void reset_coprocessor(void)
    {
    - outb(0, 0xf0);
    + pio_ops.outb(0, 0xf0);
    io_delay();
    - outb(0, 0xf1);
    + pio_ops.outb(0, 0xf1);
    io_delay();
    }

    diff --git a/arch/x86/boot/tty.c b/arch/x86/boot/tty.c
    index f7eb976b0a4b..ee8700682801 100644
    --- a/arch/x86/boot/tty.c
    +++ b/arch/x86/boot/tty.c
    @@ -29,10 +29,10 @@ static void __section(".inittext") serial_putchar(int ch)
    {
    unsigned timeout = 0xffff;

    - while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
    + while ((pio_ops.inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
    cpu_relax();

    - outb(ch, early_serial_base + TXR);
    + pio_ops.outb(ch, early_serial_base + TXR);
    }

    static void __section(".inittext") bios_putchar(int ch)
    diff --git a/arch/x86/boot/video-vga.c b/arch/x86/boot/video-vga.c
    index 4816cb9cf996..17baac542ee7 100644
    --- a/arch/x86/boot/video-vga.c
    +++ b/arch/x86/boot/video-vga.c
    @@ -131,7 +131,7 @@ static void vga_set_80x43(void)
    /* I/O address of the VGA CRTC */
    u16 vga_crtc(void)
    {
    - return (inb(0x3cc) & 1) ? 0x3d4 : 0x3b4;
    + return (pio_ops.inb(0x3cc) & 1) ? 0x3d4 : 0x3b4;
    }

    static void vga_set_480_scanlines(void)
    @@ -148,10 +148,10 @@ static void vga_set_480_scanlines(void)
    out_idx(0xdf, crtc, 0x12); /* Vertical display end */
    out_idx(0xe7, crtc, 0x15); /* Vertical blank start */
    out_idx(0x04, crtc, 0x16); /* Vertical blank end */
    - csel = inb(0x3cc);
    + csel = pio_ops.inb(0x3cc);
    csel &= 0x0d;
    csel |= 0xe2;
    - outb(csel, 0x3c2);
    + pio_ops.outb(csel, 0x3c2);
    }

    static void vga_set_vertical_end(int lines)
    diff --git a/arch/x86/boot/video.h b/arch/x86/boot/video.h
    index 04bde0bb2003..87a5f726e731 100644
    --- a/arch/x86/boot/video.h
    +++ b/arch/x86/boot/video.h
    @@ -15,6 +15,8 @@

    #include <linux/types.h>

    +#include "boot.h"
    +
    /*
    * This code uses an extended set of video mode numbers. These include:
    * Aliases for standard modes
    @@ -96,13 +98,13 @@ extern int graphic_mode; /* Graphics mode with linear frame buffer */
    /* Accessing VGA indexed registers */
    static inline u8 in_idx(u16 port, u8 index)
    {
    - outb(index, port);
    - return inb(port+1);
    + pio_ops.outb(index, port);
    + return pio_ops.inb(port+1);
    }

    static inline void out_idx(u8 v, u16 port, u8 index)
    {
    - outw(index+(v << 8), port);
    + pio_ops.outw(index+(v << 8), port);
    }

    /* Writes a value to an indexed port and then reads the port again */
    diff --git a/arch/x86/realmode/rm/wakemain.c b/arch/x86/realmode/rm/wakemain.c
    index 1d6437e6d2ba..b49404d0d63c 100644
    --- a/arch/x86/realmode/rm/wakemain.c
    +++ b/arch/x86/realmode/rm/wakemain.c
    @@ -17,18 +17,18 @@ static void beep(unsigned int hz)
    } else {
    u16 div = 1193181/hz;

    - outb(0xb6, 0x43); /* Ctr 2, squarewave, load, binary */
    + pio_ops.outb(0xb6, 0x43); /* Ctr 2, squarewave, load, binary */
    io_delay();
    - outb(div, 0x42); /* LSB of counter */
    + pio_ops.outb(div, 0x42); /* LSB of counter */
    io_delay();
    - outb(div >> 8, 0x42); /* MSB of counter */
    + pio_ops.outb(div >> 8, 0x42); /* MSB of counter */
    io_delay();

    enable = 0x03; /* Turn on speaker */
    }
    - inb(0x61); /* Dummy read of System Control Port B */
    + pio_ops.inb(0x61); /* Dummy read of System Control Port B */
    io_delay();
    - outb(enable, 0x61); /* Enable timer 2 output to speaker */
    + pio_ops.outb(enable, 0x61); /* Enable timer 2 output to speaker */
    io_delay();
    }

    @@ -62,8 +62,12 @@ static void send_morse(const char *pattern)
    }
    }

    +struct port_io_ops pio_ops;
    +
    void main(void)
    {
    + init_io_ops();
    +
    /* Kill machine if structures are wrong */
    if (wakeup_header.real_magic != 0x12345678)
    while (1)
    --
    2.34.1
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