Merge tag 'x86_tdx_for_6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 TDX updates from Dave Hansen:
 "The majority of this is a rework of the assembly and C wrappers that
  are used to talk to the TDX module and VMM. This is a nice cleanup in
  general but is also clearing the way for using this code when Linux is
  the TDX VMM.

  There are also some tidbits to make TDX guests play nicer with Hyper-V
  and to take advantage the hardware TSC.

  Summary:

   - Refactor and clean up TDX hypercall/module call infrastructure

   - Handle retrying/resuming page conversion hypercalls

   - Make sure to use the (shockingly) reliable TSC in TDX guests"

[ TLA reminder: TDX is "Trust Domain Extensions", Intel's guest VM
  confidentiality technology ]

* tag 'x86_tdx_for_6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/tdx: Mark TSC reliable
  x86/tdx: Fix __noreturn build warning around __tdx_hypercall_failed()
  x86/virt/tdx: Make TDX_MODULE_CALL handle SEAMCALL #UD and #GP
  x86/virt/tdx: Wire up basic SEAMCALL functions
  x86/tdx: Remove 'struct tdx_hypercall_args'
  x86/tdx: Reimplement __tdx_hypercall() using TDX_MODULE_CALL asm
  x86/tdx: Make TDX_HYPERCALL asm similar to TDX_MODULE_CALL
  x86/tdx: Extend TDX_MODULE_CALL to support more TDCALL/SEAMCALL leafs
  x86/tdx: Pass TDCALL/SEAMCALL input/output registers via a structure
  x86/tdx: Rename __tdx_module_call() to __tdcall()
  x86/tdx: Make macros of TDCALLs consistent with the spec
  x86/tdx: Skip saving output regs when SEAMCALL fails with VMFailInvalid
  x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro
  x86/tdx: Retry partially-completed page conversion hypercalls

2 files changed, 66 insertions, 34 deletions

diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index 7513b3bb69b7..f74695dea217 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -11,11 +11,12 @@
 #define TDX_IDENT		"IntelTDX    "
 
 /* TDX module Call Leaf IDs */
-#define TDX_GET_INFO			1
-#define TDX_GET_VEINFO			3
-#define TDX_GET_REPORT			4
-#define TDX_ACCEPT_PAGE			6
-#define TDX_WR				8
+#define TDG_VP_VMCALL			0
+#define TDG_VP_INFO			1
+#define TDG_VP_VEINFO_GET		3
+#define TDG_MR_REPORT			4
+#define TDG_MEM_PAGE_ACCEPT		6
+#define TDG_VM_WR			8
 
 /* TDCS fields. To be used by TDG.VM.WR and TDG.VM.RD module calls */
 #define TDCS_NOTIFY_ENABLES		0x9100000000000010
@@ -24,32 +25,70 @@
 #define TDVMCALL_MAP_GPA		0x10001
 #define TDVMCALL_REPORT_FATAL_ERROR	0x10003
 
+#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__
 
+#include <linux/compiler_attributes.h>
+
 /*
- * 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.
+ * Used in __tdcall*() to gather the input/output registers' values of the
+ * TDCALL instruction when requesting services from the TDX module. This is a
+ * software only structure and not part of the TDX module/VMM ABI
  */
-struct tdx_hypercall_args {
+struct tdx_module_args {
+	/* callee-clobbered */
+	u64 rcx;
+	u64 rdx;
 	u64 r8;
 	u64 r9;
+	/* extra callee-clobbered */
 	u64 r10;
 	u64 r11;
+	/* callee-saved + rdi/rsi */
 	u64 r12;
 	u64 r13;
 	u64 r14;
 	u64 r15;
+	u64 rbx;
 	u64 rdi;
 	u64 rsi;
-	u64 rbx;
-	u64 rdx;
 };
 
+/* Used to communicate with the TDX module */
+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 to request services from the VMM */
-u64 __tdx_hypercall(struct tdx_hypercall_args *args);
-u64 __tdx_hypercall_ret(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
@@ -57,7 +96,7 @@ u64 __tdx_hypercall_ret(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,
@@ -71,25 +110,7 @@ static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15)
 
 
 /* Called from __tdx_hypercall() for unrecoverable failure */
-void __tdx_hypercall_failed(void);
-
-/*
- * Used in __tdx_module_call() to gather the output registers' values of the
- * TDCALL instruction when requesting services from the TDX module. This is a
- * software only structure and not part of the TDX module/VMM ABI
- */
-struct tdx_module_output {
-	u64 rcx;
-	u64 rdx;
-	u64 r8;
-	u64 r9;
-	u64 r10;
-	u64 r11;
-};
-
-/* Used to communicate with the TDX module */
-u64 __tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
-		      struct tdx_module_output *out);
+void __noreturn __tdx_hypercall_failed(void);
 
 bool tdx_accept_memory(phys_addr_t start, phys_addr_t end);
 
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 603e6d1e9d4a..adcbe3f1de30 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -8,6 +8,7 @@
 
 #include <asm/errno.h>
 #include <asm/ptrace.h>
+#include <asm/trapnr.h>
 #include <asm/shared/tdx.h>
 
 /*
@@ -20,6 +21,9 @@
 #define TDX_SW_ERROR			(TDX_ERROR | GENMASK_ULL(47, 40))
 #define TDX_SEAMCALL_VMFAILINVALID	(TDX_SW_ERROR | _UL(0xFFFF0000))
 
+#define TDX_SEAMCALL_GP			(TDX_SW_ERROR | X86_TRAP_GP)
+#define TDX_SEAMCALL_UD			(TDX_SW_ERROR | X86_TRAP_UD)
+
 #ifndef __ASSEMBLY__
 
 /*
@@ -72,5 +76,12 @@ static inline long tdx_kvm_hypercall(unsigned int nr, unsigned long p1,
 	return -ENODEV;
 }
 #endif /* CONFIG_INTEL_TDX_GUEST && CONFIG_KVM_GUEST */
+
+#ifdef CONFIG_INTEL_TDX_HOST
+u64 __seamcall(u64 fn, struct tdx_module_args *args);
+u64 __seamcall_ret(u64 fn, struct tdx_module_args *args);
+u64 __seamcall_saved_ret(u64 fn, struct tdx_module_args *args);
+#endif	/* CONFIG_INTEL_TDX_HOST */
+
 #endif /* !__ASSEMBLY__ */
 #endif /* _ASM_X86_TDX_H */