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x86/boot: Port I/O: Add decompression-time support for TDX

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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.

Hook up TDX-specific port I/O helpers if booting in TDX environment.

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/20220405232939.73860-17-kirill.shutemov@linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2022-04-06 02:29:25 +03:00 committed by Dave Hansen
parent eb4ea1ae8f
commit 4c5b9aac6c
5 changed files with 97 additions and 28 deletions
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2
arch/x86/boot/compressed/Makefile
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@ -101,7 +101,7 @@ ifdef CONFIG_X86_64
endif
vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o
vmlinux-objs-$(CONFIG_INTEL_TDX_GUEST) += $(obj)/tdx.o
vmlinux-objs-$(CONFIG_INTEL_TDX_GUEST) += $(obj)/tdx.o $(obj)/tdcall.o
vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o
efi-obj-$(CONFIG_EFI_STUB) = $(objtree)/drivers/firmware/efi/libstub/lib.a

3
arch/x86/boot/compressed/tdcall.S Normal file
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@ -0,0 +1,3 @@
/* SPDX-License-Identifier: GPL-2.0 */
#include "../../coco/tdx/tdcall.S"

61
arch/x86/boot/compressed/tdx.c
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@ -2,9 +2,65 @@
#include "../cpuflags.h"
#include "../string.h"
#include "../io.h"
#include "error.h"
#include <vdso/limits.h>
#include <uapi/asm/vmx.h>
#include <asm/shared/tdx.h>
/* Called from __tdx_hypercall() for unrecoverable failure */
void __tdx_hypercall_failed(void)
{
error("TDVMCALL failed. TDX module bug?");
}
static inline unsigned int tdx_io_in(int size, u16 port)
{
struct tdx_hypercall_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = EXIT_REASON_IO_INSTRUCTION,
.r12 = size,
.r13 = 0,
.r14 = port,
};
if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT))
return UINT_MAX;
return args.r11;
}
static inline void tdx_io_out(int size, u16 port, u32 value)
{
struct tdx_hypercall_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = EXIT_REASON_IO_INSTRUCTION,
.r12 = size,
.r13 = 1,
.r14 = port,
.r15 = value,
};
__tdx_hypercall(&args, 0);
}
static inline u8 tdx_inb(u16 port)
{
return tdx_io_in(1, port);
}
static inline void tdx_outb(u8 value, u16 port)
{
tdx_io_out(1, port, value);
}
static inline void tdx_outw(u16 value, u16 port)
{
tdx_io_out(2, port, value);
}
void early_tdx_detect(void)
{
u32 eax, sig[3];
@ -13,4 +69,9 @@ void early_tdx_detect(void)
if (memcmp(TDX_IDENT, sig, sizeof(sig)))
return;
/* Use hypercalls instead of I/O instructions */
pio_ops.f_inb = tdx_inb;
pio_ops.f_outb = tdx_outb;
pio_ops.f_outw = tdx_outw;
}

32
arch/x86/include/asm/shared/tdx.h
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@ -2,7 +2,39 @@
#ifndef _ASM_X86_SHARED_TDX_H
#define _ASM_X86_SHARED_TDX_H
#include <linux/bits.h>
#include <linux/types.h>
#define TDX_HYPERCALL_STANDARD 0
#define TDX_HCALL_HAS_OUTPUT BIT(0)
#define TDX_HCALL_ISSUE_STI BIT(1)
#define TDX_CPUID_LEAF_ID 0x21
#define TDX_IDENT "IntelTDX "
#ifndef __ASSEMBLY__
/*
* Used in __tdx_hypercall() to pass down and get back registers' values of
* the TDCALL instruction when requesting services from the VMM.
*
* This is a software only structure and not part of the TDX module/VMM ABI.
*/
struct tdx_hypercall_args {
u64 r10;
u64 r11;
u64 r12;
u64 r13;
u64 r14;
u64 r15;
};
/* Used to request services from the VMM */
u64 __tdx_hypercall(struct tdx_hypercall_args *args, unsigned long flags);
/* Called from __tdx_hypercall() for unrecoverable failure */
void __tdx_hypercall_failed(void);
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_SHARED_TDX_H */

27
arch/x86/include/asm/tdx.h
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@ -3,17 +3,11 @@
#ifndef _ASM_X86_TDX_H
#define _ASM_X86_TDX_H
#include <linux/bits.h>
#include <linux/init.h>
#include <linux/bits.h>
#include <asm/ptrace.h>
#include <asm/shared/tdx.h>
#define TDX_HYPERCALL_STANDARD 0
#define TDX_HCALL_HAS_OUTPUT BIT(0)
#define TDX_HCALL_ISSUE_STI BIT(1)
/*
* SW-defined error codes.
*
@ -41,21 +35,6 @@ struct tdx_module_output {
u64 r11;
};
/*
* Used in __tdx_hypercall() to pass down and get back registers' values of
* the TDCALL instruction when requesting services from the VMM.
*
* This is a software only structure and not part of the TDX module/VMM ABI.
*/
struct tdx_hypercall_args {
u64 r10;
u64 r11;
u64 r12;
u64 r13;
u64 r14;
u64 r15;
};
/*
* Used by the #VE exception handler to gather the #VE exception
* info from the TDX module. This is a software only structure
@ -80,12 +59,6 @@ void __init tdx_early_init(void);
u64 __tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
struct tdx_module_output *out);
/* Used to request services from the VMM */
u64 __tdx_hypercall(struct tdx_hypercall_args *args, unsigned long flags);
/* Called from __tdx_hypercall() for unrecoverable failure */
void __tdx_hypercall_failed(void);
void tdx_get_ve_info(struct ve_info *ve);
bool tdx_handle_virt_exception(struct pt_regs *regs, struct ve_info *ve);