Commit 4c5b9aac authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Dave Hansen
Browse files

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



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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20220405232939.73860-17-kirill.shutemov@linux.intel.com
parent eb4ea1ae

arch/x86/boot/compressed/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/x86/boot/compressed/tdcall.S

0 → 100644
+3 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */



#include "../../coco/tdx/tdcall.S"

arch/x86/boot/compressed/tdx.c

+61 −0
Original line number Diff line number Diff line
@@ -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;

}

arch/x86/include/asm/shared/tdx.h

+32 −0
Original line number Diff line number Diff line
@@ -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 */

arch/x86/include/asm/tdx.h

+0 −27
Original line number Diff line number Diff line
@@ -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);