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x86/tdx: Make TDX_HYPERCALL asm similar to TDX_MODULE_CALL 

Now the 'struct tdx_hypercall_args' and 'struct tdx_module_args' are
almost the same, and the TDX_HYPERCALL and TDX_MODULE_CALL asm macro
share similar code pattern too.  The __tdx_hypercall() and __tdcall()
should be unified to use the same assembly code.

As a preparation to unify them, simplify the TDX_HYPERCALL to make it
more like the TDX_MODULE_CALL.

The TDX_HYPERCALL takes the pointer of 'struct tdx_hypercall_args' as
function call argument, and does below extra things comparing to the
TDX_MODULE_CALL:

1) It sets RAX to 0 (TDG.VP.VMCALL leaf) internally;
2) It sets RCX to the (fixed) bitmap of shared registers internally;
3) It calls __tdx_hypercall_failed() internally (and panics) when the
   TDCALL instruction itself fails;
4) After TDCALL, it moves R10 to RAX to return the return code of the
   VMCALL leaf, regardless the '\ret' asm macro argument;

Firstly, change the TDX_HYPERCALL to take the same function call
arguments as the TDX_MODULE_CALL does: TDCALL leaf ID, and the pointer
to 'struct tdx_module_args'.  Then 1) and 2) can be moved to the
caller:

 - TDG.VP.VMCALL leaf ID can be passed via the function call argument;
 - 'struct tdx_module_args' is 'struct tdx_hypercall_args' + RCX, thus
   the bitmap of shared registers can be passed via RCX in the
   structure.

Secondly, to move 3) and 4) out of assembly, make the TDX_HYPERCALL
always save output registers to the structure.  The caller then can:

 - Call __tdx_hypercall_failed() when TDX_HYPERCALL returns error;
 - Return R10 in the structure as the return code of the VMCALL leaf;

With above changes, change the asm function from __tdx_hypercall() to
__tdcall_hypercall(), and reimplement __tdx_hypercall() as the C wrapper
of it.  This avoids having to add another wrapper of __tdx_hypercall()
(_tdx_hypercall() is already taken).

The __tdcall_hypercall() will be replaced with a __tdcall() variant
using TDX_MODULE_CALL in a later commit as the final goal is to have one
assembly to handle both TDCALL and TDVMCALL.

Currently, the __tdx_hypercall() asm is in '.noinstr.text'.  To keep
this unchanged, annotate __tdx_hypercall(), which is a C function now,
as 'noinstr'.

Remove the __tdx_hypercall_ret() as __tdx_hypercall() already does so.

Implement __tdx_hypercall() in tdx-shared.c so it can be shared with the
compressed code.

Opportunistically fix a checkpatch error complaining using space around
parenthesis '(' and ')' while moving the bitmap of shared registers to
<asm/shared/tdx.h>.

[ dhansen: quash new calls of __tdx_hypercall_ret() that showed up ]

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/0cbf25e7aee3256288045023a31f65f0cef90af4.1692096753.git.kai.huang%40intel.com
This commit is contained in:
Kai Huang 2023-08-15 23:02:01 +12:00 committed by Dave Hansen
parent 12f34ed862
commit c641cfb5c1
7 changed files with 177 additions and 169 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/boot/compressed/tdx.c
View File

@ -26,7 +26,7 @@ static inline unsigned int tdx_io_in(int size, u16 port)
.r14 = port,
};
if (__tdx_hypercall_ret(&args))
if (__tdx_hypercall(&args))
return UINT_MAX;
return args.r11;

148
arch/x86/coco/tdx/tdcall.S
View File

@ -2,41 +2,12 @@
#include <asm/asm-offsets.h>
#include <asm/asm.h>
#include <asm/frame.h>
#include <asm/unwind_hints.h>
#include <linux/linkage.h>
#include <linux/bits.h>
#include <linux/errno.h>
#include "../../virt/vmx/tdx/tdxcall.S"
/*
* Bitmasks of exposed registers (with VMM).
*/
#define TDX_RDX BIT(2)
#define TDX_RBX BIT(3)
#define TDX_RSI BIT(6)
#define TDX_RDI BIT(7)
#define TDX_R8 BIT(8)
#define TDX_R9 BIT(9)
#define TDX_R10 BIT(10)
#define TDX_R11 BIT(11)
#define TDX_R12 BIT(12)
#define TDX_R13 BIT(13)
#define TDX_R14 BIT(14)
#define TDX_R15 BIT(15)
/*
* These registers are clobbered to hold arguments for each
* TDVMCALL. They are safe to expose to the VMM.
* Each bit in this mask represents a register ID. Bit field
* details can be found in TDX GHCI specification, section
* titled "TDCALL [TDG.VP.VMCALL] leaf".
*/
#define TDVMCALL_EXPOSE_REGS_MASK \
( TDX_RDX | TDX_RBX | TDX_RSI | TDX_RDI | TDX_R8 | TDX_R9 | \
TDX_R10 | TDX_R11 | TDX_R12 | TDX_R13 | TDX_R14 | TDX_R15 )
.section .noinstr.text, "ax"
/*
@ -78,10 +49,13 @@ SYM_FUNC_END(__tdcall_ret)
* TDX_HYPERCALL - Make hypercalls to a TDX VMM using TDVMCALL leaf of TDCALL
* instruction
*
* Transforms values in function call argument struct tdx_hypercall_args @args
* Transforms values in function call argument struct tdx_module_args @args
* into the TDCALL register ABI. After TDCALL operation, VMM output is saved
* back in @args, if \ret is 1.
*
* Depends on the caller to pass TDG.VP.VMCALL as the TDCALL leaf, and set
* @args::rcx to TDVMCALL_EXPOSE_REGS_MASK.
*
*-------------------------------------------------------------------------
* TD VMCALL ABI:
*-------------------------------------------------------------------------
@ -106,7 +80,7 @@ SYM_FUNC_END(__tdcall_ret)
* R8-R15 - Same as above.
*
*/
.macro TDX_HYPERCALL ret:req
.macro TDX_HYPERCALL
FRAME_BEGIN
/* Save callee-saved GPRs as mandated by the x86_64 ABI */
@ -116,63 +90,52 @@ SYM_FUNC_END(__tdcall_ret)
push %r12
push %rbx
/* Free RDI to be used as TDVMCALL arguments */
/* Move Leaf ID to RAX */
movq %rdi, %rax
/* Move bitmap of shared registers to RCX */
movq TDX_MODULE_rcx(%rsi), %rcx
/* Copy hypercall registers from arg struct: */
movq TDX_HYPERCALL_r8(%rax), %r8
movq TDX_HYPERCALL_r9(%rax), %r9
movq TDX_HYPERCALL_r10(%rax), %r10
movq TDX_HYPERCALL_r11(%rax), %r11
movq TDX_HYPERCALL_r12(%rax), %r12
movq TDX_HYPERCALL_r13(%rax), %r13
movq TDX_HYPERCALL_r14(%rax), %r14
movq TDX_HYPERCALL_r15(%rax), %r15
movq TDX_HYPERCALL_rdi(%rax), %rdi
movq TDX_HYPERCALL_rsi(%rax), %rsi
movq TDX_HYPERCALL_rbx(%rax), %rbx
movq TDX_HYPERCALL_rdx(%rax), %rdx
movq TDX_MODULE_r8(%rsi), %r8
movq TDX_MODULE_r9(%rsi), %r9
movq TDX_MODULE_r10(%rsi), %r10
movq TDX_MODULE_r11(%rsi), %r11
movq TDX_MODULE_r12(%rsi), %r12
movq TDX_MODULE_r13(%rsi), %r13
movq TDX_MODULE_r14(%rsi), %r14
movq TDX_MODULE_r15(%rsi), %r15
movq TDX_MODULE_rdi(%rsi), %rdi
movq TDX_MODULE_rbx(%rsi), %rbx
movq TDX_MODULE_rdx(%rsi), %rdx
push %rax
/* Mangle function call ABI into TDCALL ABI: */
/* Set TDCALL leaf ID (TDVMCALL (0)) in RAX */
xor %eax, %eax
movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx
pushq %rsi
movq TDX_MODULE_rsi(%rsi), %rsi
tdcall
/*
* RAX!=0 indicates a failure of the TDVMCALL mechanism itself and that
* something has gone horribly wrong with the TDX module.
* Restore the pointer of the structure to save output registers.
*
* The return status of the hypercall operation is in a separate
* register (in R10). Hypercall errors are a part of normal operation
* and are handled by callers.
* RCX is used as bitmap of shared registers and doesn't hold any
* value provided by the VMM, thus it can be used as spare to
* restore the structure pointer.
*/
testq %rax, %rax
jne .Lpanic\@
popq %rcx
movq %rsi, TDX_MODULE_rsi(%rcx)
movq %rcx, %rsi
pop %rax
.if \ret
movq %r8, TDX_HYPERCALL_r8(%rax)
movq %r9, TDX_HYPERCALL_r9(%rax)
movq %r10, TDX_HYPERCALL_r10(%rax)
movq %r11, TDX_HYPERCALL_r11(%rax)
movq %r12, TDX_HYPERCALL_r12(%rax)
movq %r13, TDX_HYPERCALL_r13(%rax)
movq %r14, TDX_HYPERCALL_r14(%rax)
movq %r15, TDX_HYPERCALL_r15(%rax)
movq %rdi, TDX_HYPERCALL_rdi(%rax)
movq %rsi, TDX_HYPERCALL_rsi(%rax)
movq %rbx, TDX_HYPERCALL_rbx(%rax)
movq %rdx, TDX_HYPERCALL_rdx(%rax)
.endif
/* TDVMCALL leaf return code is in R10 */
movq %r10, %rax
movq %r8, TDX_MODULE_r8(%rsi)
movq %r9, TDX_MODULE_r9(%rsi)
movq %r10, TDX_MODULE_r10(%rsi)
movq %r11, TDX_MODULE_r11(%rsi)
movq %r12, TDX_MODULE_r12(%rsi)
movq %r13, TDX_MODULE_r13(%rsi)
movq %r14, TDX_MODULE_r14(%rsi)
movq %r15, TDX_MODULE_r15(%rsi)
movq %rdi, TDX_MODULE_rdi(%rsi)
movq %rbx, TDX_MODULE_rbx(%rsi)
movq %rdx, TDX_MODULE_rdx(%rsi)
/*
* Zero out registers exposed to the VMM to avoid speculative execution
@ -198,33 +161,20 @@ SYM_FUNC_END(__tdcall_ret)
FRAME_END
RET
.Lpanic\@:
call __tdx_hypercall_failed
/* __tdx_hypercall_failed never returns */
REACHABLE
jmp .Lpanic\@
.endm
/*
*
* __tdx_hypercall() function ABI:
* __tdcall_hypercall() function ABI:
*
* @args (RDI) - struct tdx_hypercall_args for input
* @fn (RDI) - TDCALL leaf ID, moved to RAX
* @args (RSI) - struct tdx_module_args for input/output
*
* @fn and @args::rcx from the caller must be TDG_VP_VMCALL and
* TDVMCALL_EXPOSE_REGS_MASK respectively.
*
* On successful completion, return the hypercall error code.
*/
SYM_FUNC_START(__tdx_hypercall)
TDX_HYPERCALL ret=0
SYM_FUNC_END(__tdx_hypercall)
/*
*
* __tdx_hypercall_ret() function ABI:
*
* @args (RDI) - struct tdx_hypercall_args for input and output
*
* On successful completion, return the hypercall error code.
*/
SYM_FUNC_START(__tdx_hypercall_ret)
TDX_HYPERCALL ret=1
SYM_FUNC_END(__tdx_hypercall_ret)
SYM_FUNC_START(__tdcall_hypercall)
TDX_HYPERCALL
SYM_FUNC_END(__tdcall_hypercall)

43
arch/x86/coco/tdx/tdx-shared.c
View File

@ -69,3 +69,46 @@ bool tdx_accept_memory(phys_addr_t start, phys_addr_t end)
return true;
}
noinstr u64 __tdx_hypercall(struct tdx_hypercall_args *args)
{
struct tdx_module_args margs = {
.rcx = TDVMCALL_EXPOSE_REGS_MASK,
.rdx = args->rdx,
.r8 = args->r8,
.r9 = args->r9,
.r10 = args->r10,
.r11 = args->r11,
.r12 = args->r12,
.r13 = args->r13,
.r14 = args->r14,
.r15 = args->r15,
.rbx = args->rbx,
.rdi = args->rdi,
.rsi = args->rsi,
};
/*
* Failure of __tdcall_hypercall() indicates a failure of the TDVMCALL
* mechanism itself and that something has gone horribly wrong with
* the TDX module. __tdx_hypercall_failed() never returns.
*/
if (__tdcall_hypercall(TDG_VP_VMCALL, &margs))
__tdx_hypercall_failed();
args->r8 = margs.r8;
args->r9 = margs.r9;
args->r10 = margs.r10;
args->r11 = margs.r11;
args->r12 = margs.r12;
args->r13 = margs.r13;
args->r14 = margs.r14;
args->r15 = margs.r15;
args->rdi = margs.rdi;
args->rsi = margs.rsi;
args->rbx = margs.rbx;
args->rdx = margs.rdx;
/* TDVMCALL leaf return code is in R10 */
return args->r10;
}

13
arch/x86/coco/tdx/tdx.c
View File

@ -38,7 +38,7 @@
#define TDREPORT_SUBTYPE_0 0
/* Called from __tdx_hypercall() for unrecoverable failure */
noinstr void __tdx_hypercall_failed(void)
noinstr void __noreturn __tdx_hypercall_failed(void)
{
instrumentation_begin();
panic("TDVMCALL failed. TDX module bug?");
@ -285,7 +285,7 @@ static int read_msr(struct pt_regs *regs, struct ve_info *ve)
* can be found in TDX Guest-Host-Communication Interface
* (GHCI), section titled "TDG.VP.VMCALL<Instruction.RDMSR>".
*/
if (__tdx_hypercall_ret(&args))
if (__tdx_hypercall(&args))
return -EIO;
regs->ax = lower_32_bits(args.r11);
@ -339,7 +339,7 @@ static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve)
* ABI can be found in TDX Guest-Host-Communication Interface
* (GHCI), section titled "VP.VMCALL<Instruction.CPUID>".
*/
if (__tdx_hypercall_ret(&args))
if (__tdx_hypercall(&args))
return -EIO;
/*
@ -366,8 +366,9 @@ static bool mmio_read(int size, unsigned long addr, unsigned long *val)
.r15 = *val,
};
if (__tdx_hypercall_ret(&args))
if (__tdx_hypercall(&args))
return false;
*val = args.r11;
return true;
}
@ -500,7 +501,7 @@ static bool handle_in(struct pt_regs *regs, int size, int port)
* in TDX Guest-Host-Communication Interface (GHCI) section titled
* "TDG.VP.VMCALL<Instruction.IO>".
*/
success = !__tdx_hypercall_ret(&args);
success = !__tdx_hypercall(&args);
/* Update part of the register affected by the emulated instruction */
regs->ax &= ~mask;
@ -729,7 +730,7 @@ static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc)
.r13 = end - start };
u64 map_fail_paddr;
u64 ret = __tdx_hypercall_ret(&args);
u64 ret = __tdx_hypercall(&args);
if (ret != TDVMCALL_STATUS_RETRY)
return !ret;

4
arch/x86/hyperv/ivm.c
View File

@ -404,7 +404,7 @@ static void hv_tdx_msr_read(u64 msr, u64 *val)
.r12 = msr,
};
u64 ret = __tdx_hypercall_ret(&args);
u64 ret = __tdx_hypercall(&args);
if (WARN_ONCE(ret, "Failed to emulate MSR read: %lld\n", ret))
*val = 0;
@ -420,7 +420,7 @@ u64 hv_tdx_hypercall(u64 control, u64 param1, u64 param2)
args.rdx = param1;
args.r8 = param2;
(void)__tdx_hypercall_ret(&args);
(void)__tdx_hypercall(&args);
return args.r11;
}

122
arch/x86/include/asm/shared/tdx.h
View File

@ -11,6 +11,7 @@
#define TDX_IDENT "IntelTDX "
/* TDX module Call Leaf IDs */
#define TDG_VP_VMCALL 0
#define TDG_VP_INFO 1
#define TDG_VP_VEINFO_GET 3
#define TDG_MR_REPORT 4
@ -26,55 +27,35 @@
#define TDVMCALL_STATUS_RETRY 1
/*
* Bitmasks of exposed registers (with VMM).
*/
#define TDX_RDX BIT(2)
#define TDX_RBX BIT(3)
#define TDX_RSI BIT(6)
#define TDX_RDI BIT(7)
#define TDX_R8 BIT(8)
#define TDX_R9 BIT(9)
#define TDX_R10 BIT(10)
#define TDX_R11 BIT(11)
#define TDX_R12 BIT(12)
#define TDX_R13 BIT(13)
#define TDX_R14 BIT(14)
#define TDX_R15 BIT(15)
/*
* These registers are clobbered to hold arguments for each
* TDVMCALL. They are safe to expose to the VMM.
* Each bit in this mask represents a register ID. Bit field
* details can be found in TDX GHCI specification, section
* titled "TDCALL [TDG.VP.VMCALL] leaf".
*/
#define TDVMCALL_EXPOSE_REGS_MASK \
(TDX_RDX | TDX_RBX | TDX_RSI | TDX_RDI | TDX_R8 | TDX_R9 | \
TDX_R10 | TDX_R11 | TDX_R12 | TDX_R13 | TDX_R14 | TDX_R15)
#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 r8;
u64 r9;
u64 r10;
u64 r11;
u64 r12;
u64 r13;
u64 r14;
u64 r15;
u64 rdi;
u64 rsi;
u64 rbx;
u64 rdx;
};
/* Used to request services from the VMM */
u64 __tdx_hypercall(struct tdx_hypercall_args *args);
u64 __tdx_hypercall_ret(struct tdx_hypercall_args *args);
/*
* Wrapper for standard use of __tdx_hypercall with no output aside from
* return code.
*/
static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15)
{
struct tdx_hypercall_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = fn,
.r12 = r12,
.r13 = r13,
.r14 = r14,
.r15 = r15,
};
return __tdx_hypercall(&args);
}
/* Called from __tdx_hypercall() for unrecoverable failure */
void __tdx_hypercall_failed(void);
/*
* Used in __tdcall*() to gather the input/output registers' values of the
* TDCALL instruction when requesting services from the TDX module. This is a
@ -103,6 +84,53 @@ struct tdx_module_args {
u64 __tdcall(u64 fn, struct tdx_module_args *args);
u64 __tdcall_ret(u64 fn, struct tdx_module_args *args);
/*
* 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 r8;
u64 r9;
u64 r10;
u64 r11;
u64 r12;
u64 r13;
u64 r14;
u64 r15;
u64 rdi;
u64 rsi;
u64 rbx;
u64 rdx;
};
/* Used to request services from the VMM */
u64 __tdcall_hypercall(u64 fn, struct tdx_module_args *args);
u64 __tdx_hypercall(struct tdx_hypercall_args *args);
/*
* Wrapper for standard use of __tdx_hypercall with no output aside from
* return code.
*/
static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15)
{
struct tdx_hypercall_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = fn,
.r12 = r12,
.r13 = r13,
.r14 = r14,
.r15 = r15,
};
return __tdx_hypercall(&args);
}
/* Called from __tdx_hypercall() for unrecoverable failure */
void __tdx_hypercall_failed(void);
bool tdx_accept_memory(phys_addr_t start, phys_addr_t end);
/*

14
arch/x86/kernel/asm-offsets.c
View File

@ -82,20 +82,6 @@ static void __used common(void)
OFFSET(TDX_MODULE_rdi, tdx_module_args, rdi);
OFFSET(TDX_MODULE_rsi, tdx_module_args, rsi);
BLANK();
OFFSET(TDX_HYPERCALL_r8, tdx_hypercall_args, r8);
OFFSET(TDX_HYPERCALL_r9, tdx_hypercall_args, r9);
OFFSET(TDX_HYPERCALL_r10, tdx_hypercall_args, r10);
OFFSET(TDX_HYPERCALL_r11, tdx_hypercall_args, r11);
OFFSET(TDX_HYPERCALL_r12, tdx_hypercall_args, r12);
OFFSET(TDX_HYPERCALL_r13, tdx_hypercall_args, r13);
OFFSET(TDX_HYPERCALL_r14, tdx_hypercall_args, r14);
OFFSET(TDX_HYPERCALL_r15, tdx_hypercall_args, r15);
OFFSET(TDX_HYPERCALL_rdi, tdx_hypercall_args, rdi);
OFFSET(TDX_HYPERCALL_rsi, tdx_hypercall_args, rsi);
OFFSET(TDX_HYPERCALL_rbx, tdx_hypercall_args, rbx);
OFFSET(TDX_HYPERCALL_rdx, tdx_hypercall_args, rdx);
BLANK();
OFFSET(BP_scratch, boot_params, scratch);
OFFSET(BP_secure_boot, boot_params, secure_boot);