[PATCH v4 09/12] x86/tdx: Remove 'struct tdx_hypercall_args'

Kai Huang
2023-08-15T11:03:59Z

Now 'struct tdx_hypercall_args' is basically 'struct tdx_module_args'
minus RCX. Although from __tdx_hypercall()'s perspective RCX isn't
used as shared register thus not part of input/output registers, it's
not worth to have a separate structure just due to one register.

Remove the 'struct tdx_hypercall_args' and use 'struct tdx_module_args'
instead in __tdx_hypercall() related code. This also saves the memory
copy between the two structures within __tdx_hypercall().

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/boot/compressed/tdx.c | 4 ++--
arch/x86/coco/tdx/tdx-shared.c | 37 ++++++-------------------------
arch/x86/coco/tdx/tdx.c | 16 ++++++-------
arch/x86/include/asm/shared/tdx.h | 25 ++-------------------
4 files changed, 19 insertions(+), 63 deletions(-)

diff --git a/arch/x86/boot/compressed/tdx.c b/arch/x86/boot/compressed/tdx.c
index bc03eae2c560..8451d6a1030c 100644
--- a/arch/x86/boot/compressed/tdx.c
+++ b/arch/x86/boot/compressed/tdx.c
@@ -18,7 +18,7 @@ void __tdx_hypercall_failed(void)

static inline unsigned int tdx_io_in(int size, u16 port)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
.r12 = size,
@@ -34,7 +34,7 @@ static inline unsigned int tdx_io_in(int size, u16 port)

static inline void tdx_io_out(int size, u16 port, u32 value)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
.r12 = size,
diff --git a/arch/x86/coco/tdx/tdx-shared.c b/arch/x86/coco/tdx/tdx-shared.c
index 344b3818f4c3..78e413269791 100644
--- a/arch/x86/coco/tdx/tdx-shared.c
+++ b/arch/x86/coco/tdx/tdx-shared.c
@@ -70,45 +70,22 @@ bool tdx_accept_memory(phys_addr_t start, phys_addr_t end)
return true;
}

-noinstr u64 __tdx_hypercall(struct tdx_hypercall_args *args)
+noinstr u64 __tdx_hypercall(struct tdx_module_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,
- };
+ /*
+ * For TDVMCALL explicitly set RCX to the bitmap of shared registers.
+ * The caller isn't expected to set @args->rcx anyway.
+ */
+ args->rcx = TDVMCALL_EXPOSE_REGS_MASK;

/*
* Failure of __tdcall_saved_ret() 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_saved_ret(TDG_VP_VMCALL, &margs))
+ if (__tdcall_saved_ret(TDG_VP_VMCALL, args))
__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;
}
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 731d164e2421..6311d843cbc5 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -48,7 +48,7 @@ noinstr void __noreturn __tdx_hypercall_failed(void)
long tdx_kvm_hypercall(unsigned int nr, unsigned long p1, unsigned long p2,
unsigned long p3, unsigned long p4)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = nr,
.r11 = p1,
.r12 = p2,
@@ -108,7 +108,7 @@ EXPORT_SYMBOL_GPL(tdx_mcall_get_report0);

static void __noreturn tdx_panic(const char *msg)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = TDVMCALL_REPORT_FATAL_ERROR,
.r12 = 0, /* Error code: 0 is Panic */
@@ -230,7 +230,7 @@ static int ve_instr_len(struct ve_info *ve)

static u64 __cpuidle __halt(const bool irq_disabled)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_HLT),
.r12 = irq_disabled,
@@ -274,7 +274,7 @@ void __cpuidle tdx_safe_halt(void)

static int read_msr(struct pt_regs *regs, struct ve_info *ve)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_MSR_READ),
.r12 = regs->cx,
@@ -295,7 +295,7 @@ static int read_msr(struct pt_regs *regs, struct ve_info *ve)

static int write_msr(struct pt_regs *regs, struct ve_info *ve)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_MSR_WRITE),
.r12 = regs->cx,
@@ -315,7 +315,7 @@ static int write_msr(struct pt_regs *regs, struct ve_info *ve)

static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_CPUID),
.r12 = regs->ax,
@@ -357,7 +357,7 @@ static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve)

static bool mmio_read(int size, unsigned long addr, unsigned long *val)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_EPT_VIOLATION),
.r12 = size,
@@ -486,7 +486,7 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve)

static bool handle_in(struct pt_regs *regs, int size, int port)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
.r12 = size,
diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 188e8bf3332c..74fc466dfdcd 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -83,29 +83,8 @@ u64 __tdcall(u64 fn, struct tdx_module_args *args);
u64 __tdcall_ret(u64 fn, struct tdx_module_args *args);
u64 __tdcall_saved_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 __tdx_hypercall(struct tdx_hypercall_args *args);
+u64 __tdx_hypercall(struct tdx_module_args *args);

/*
* Wrapper for standard use of __tdx_hypercall with no output aside from
@@ -113,7 +92,7 @@ u64 __tdx_hypercall(struct tdx_hypercall_args *args);
*/
static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15)
{
- struct tdx_hypercall_args args = {
+ struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = fn,
.r12 = r12,
--
2.41.0