x86/tdx: Drop flags from __tdx_hypercall()

After TDX_HCALL_ISSUE_STI got dropped, the only flag left is
TDX_HCALL_HAS_OUTPUT. The flag indicates if the caller wants to see
tdx_hypercall_args updated based on the hypercall output.

Drop the flags and provide __tdx_hypercall_ret() that matches
TDX_HCALL_HAS_OUTPUT semantics.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230321003511.9469-1-kirill.shutemov%40linux.intel.com

diff --git a/arch/x86/boot/compressed/tdx.c b/arch/x86/boot/compressed/tdx.c
index 918a760..2d81d3c 100644 (file)
--- a/arch/x86/boot/compressed/tdx.c
+++ b/arch/x86/boot/compressed/tdx.c
@@ -26,7 +26,7 @@ static inline unsigned int tdx_io_in(int size, u16 port)
                .r14 = port,
        };
 
-       if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT))
+       if (__tdx_hypercall_ret(&args))
                return UINT_MAX;
 
        return args.r11;
@@ -43,7 +43,7 @@ static inline void tdx_io_out(int size, u16 port, u32 value)
                .r15 = value,
        };
 
-       __tdx_hypercall(&args, 0);
+       __tdx_hypercall(&args);
 }
 
 static inline u8 tdx_inb(u16 port)

diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S
index 6a255e6..b193c0a 100644 (file)
--- a/arch/x86/coco/tdx/tdcall.S
+++ b/arch/x86/coco/tdx/tdcall.S
@@ -85,12 +85,12 @@ SYM_FUNC_START(__tdx_module_call)
 SYM_FUNC_END(__tdx_module_call)
 
 /*
- * __tdx_hypercall() - Make hypercalls to a TDX VMM using TDVMCALL leaf
- * of TDCALL instruction
+ * 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
  * into the TDCALL register ABI. After TDCALL operation, VMM output is saved
- * back in @args.
+ * back in @args, if \ret is 1.
  *
  *-------------------------------------------------------------------------
  * TD VMCALL ABI:
@@ -105,26 +105,18 @@ SYM_FUNC_END(__tdx_module_call)
  *                       specification. Non zero value indicates vendor
  *                       specific ABI.
  * R11                 - VMCALL sub function number
- * RBX, RBP, RDI, RSI  - Used to pass VMCALL sub function specific arguments.
+ * RBX, RDX, RDI, RSI  - Used to pass VMCALL sub function specific arguments.
  * R8-R9, R12-R15      - Same as above.
  *
  * Output Registers:
  *
  * RAX                 - TDCALL instruction status (Not related to hypercall
  *                        output).
- * R10                 - Hypercall output error code.
- * R11-R15             - Hypercall sub function specific output values.
+ * RBX, RDX, RDI, RSI  - Hypercall sub function specific output values.
+ * R8-R15              - Same as above.
  *
- *-------------------------------------------------------------------------
- *
- * __tdx_hypercall() function ABI:
- *
- * @args  (RDI)        - struct tdx_hypercall_args for input and output
- * @flags (RSI)        - TDX_HCALL_* flags
- *
- * On successful completion, return the hypercall error code.
  */
-SYM_FUNC_START(__tdx_hypercall)
+.macro TDX_HYPERCALL ret:req
        FRAME_BEGIN
 
        /* Save callee-saved GPRs as mandated by the x86_64 ABI */
@@ -134,9 +126,8 @@ SYM_FUNC_START(__tdx_hypercall)
        push %r12
        push %rbx
 
-       /* Free RDI and RSI to be used as TDVMCALL arguments */
+       /* Free RDI to be used as TDVMCALL arguments */
        movq %rdi, %rax
-       push %rsi
 
        /* Copy hypercall registers from arg struct: */
        movq TDX_HYPERCALL_r8(%rax),  %r8
@@ -171,14 +162,11 @@ SYM_FUNC_START(__tdx_hypercall)
         * and are handled by callers.
         */
        testq %rax, %rax
-       jne .Lpanic
+       jne .Lpanic\@
 
        pop %rax
 
-       /* Copy hypercall result registers to arg struct if needed */
-       testq $TDX_HCALL_HAS_OUTPUT, (%rsp)
-       jz .Lout
-
+       .if \ret
        movq %r8,  TDX_HYPERCALL_r8(%rax)
        movq %r9,  TDX_HYPERCALL_r9(%rax)
        movq %r10, TDX_HYPERCALL_r10(%rax)
@@ -191,7 +179,8 @@ SYM_FUNC_START(__tdx_hypercall)
        movq %rsi, TDX_HYPERCALL_rsi(%rax)
        movq %rbx, TDX_HYPERCALL_rbx(%rax)
        movq %rdx, TDX_HYPERCALL_rdx(%rax)
-.Lout:
+       .endif
+
        /* TDVMCALL leaf return code is in R10 */
        movq %r10, %rax
 
@@ -208,9 +197,6 @@ SYM_FUNC_START(__tdx_hypercall)
        xor %rdi,  %rdi
        xor %rdx,  %rdx
 
-       /* Remove TDX_HCALL_* flags from the stack */
-       pop %rsi
-
        /* Restore callee-saved GPRs as mandated by the x86_64 ABI */
        pop %rbx
        pop %r12
@@ -221,9 +207,33 @@ SYM_FUNC_START(__tdx_hypercall)
        FRAME_END
 
        RET
-.Lpanic:
+.Lpanic\@:
        call __tdx_hypercall_failed
        /* __tdx_hypercall_failed never returns */
        REACHABLE
-       jmp .Lpanic
+       jmp .Lpanic\@
+.endm
+
+/*
+ *
+ * __tdx_hypercall() function ABI:
+ *
+ * @args  (RDI)        - struct tdx_hypercall_args for input
+ *
+ * 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)

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 055300e..e146b59 100644 (file)
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -66,7 +66,7 @@ static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15)
                .r15 = r15,
        };
 
-       return __tdx_hypercall(&args, 0);
+       return __tdx_hypercall(&args);
 }
 
 /* Called from __tdx_hypercall() for unrecoverable failure */
@@ -99,7 +99,7 @@ long tdx_kvm_hypercall(unsigned int nr, unsigned long p1, unsigned long p2,
                .r14 = p4,
        };
 
-       return __tdx_hypercall(&args, 0);
+       return __tdx_hypercall(&args);
 }
 EXPORT_SYMBOL_GPL(tdx_kvm_hypercall);
 #endif
@@ -179,7 +179,7 @@ static void __noreturn tdx_panic(const char *msg)
         * happens to return.
         */
        while (1)
-               __tdx_hypercall(&args, 0);
+               __tdx_hypercall(&args);
 }
 
 static void tdx_parse_tdinfo(u64 *cc_mask)
@@ -289,7 +289,7 @@ static u64 __cpuidle __halt(const bool irq_disabled)
         * can keep the vCPU in virtual HLT, even if an IRQ is
         * pending, without hanging/breaking the guest.
         */
-       return __tdx_hypercall(&args, 0);
+       return __tdx_hypercall(&args);
 }
 
 static int handle_halt(struct ve_info *ve)
@@ -326,7 +326,7 @@ 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(&args, TDX_HCALL_HAS_OUTPUT))
+       if (__tdx_hypercall_ret(&args))
                return -EIO;
 
        regs->ax = lower_32_bits(args.r11);
@@ -348,7 +348,7 @@ static int write_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.WRMSR>".
         */
-       if (__tdx_hypercall(&args, 0))
+       if (__tdx_hypercall(&args))
                return -EIO;
 
        return ve_instr_len(ve);
@@ -380,7 +380,7 @@ 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(&args, TDX_HCALL_HAS_OUTPUT))
+       if (__tdx_hypercall_ret(&args))
                return -EIO;
 
        /*
@@ -407,7 +407,7 @@ static bool mmio_read(int size, unsigned long addr, unsigned long *val)
                .r15 = *val,
        };
 
-       if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT))
+       if (__tdx_hypercall_ret(&args))
                return false;
        *val = args.r11;
        return true;
@@ -541,7 +541,7 @@ 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(&args, TDX_HCALL_HAS_OUTPUT);
+       success = !__tdx_hypercall_ret(&args);
 
        /* Update part of the register affected by the emulated instruction */
        regs->ax &= ~mask;

diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 4a03993..2631e01 100644 (file)
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -7,8 +7,6 @@
 
 #define TDX_HYPERCALL_STANDARD  0
 
-#define TDX_HCALL_HAS_OUTPUT   BIT(0)
-
 #define TDX_CPUID_LEAF_ID      0x21
 #define TDX_IDENT              "IntelTDX    "
 
@@ -36,7 +34,8 @@ struct tdx_hypercall_args {
 };
 
 /* Used to request services from the VMM */
-u64 __tdx_hypercall(struct tdx_hypercall_args *args, unsigned long flags);
+u64 __tdx_hypercall(struct tdx_hypercall_args *args);
+u64 __tdx_hypercall_ret(struct tdx_hypercall_args *args);
 
 /* Called from __tdx_hypercall() for unrecoverable failure */
 void __tdx_hypercall_failed(void);