[RFC PATCH v3 05/59] KVM: TDX: add a helper function for kvm to call seamcall

isaku.yamahata
2021-11-25T00:21:26Z

From: Isaku Yamahata <isaku.yamahata@intel.com>

Add a helper function for kvm to call seamcall and a helper macro to check
its return value. The later patches will use them.

Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/kvm/vmx/seamcall.h | 113 ++++++++++++++++++++++++++++++++++++
1 file changed, 113 insertions(+)
create mode 100644 arch/x86/kvm/vmx/seamcall.h

diff --git a/arch/x86/kvm/vmx/seamcall.h b/arch/x86/kvm/vmx/seamcall.h
new file mode 100644
index 000000000000..f27e9d27137d
--- /dev/null
+++ b/arch/x86/kvm/vmx/seamcall.h
@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __KVM_VMX_SEAMCALL_H
+#define __KVM_VMX_SEAMCALL_H
+
+#include <asm/asm.h>
+
+#ifdef CONFIG_INTEL_TDX_HOST
+
+#ifdef __ASSEMBLER__
+
+.macro seamcall
+ .byte 0x66, 0x0f, 0x01, 0xcf
+.endm
+
+#else
+
+/*
+ * TDX extended return:
+ * Some of The "TDX module" SEAMCALLs return extended values (which are function
+ * leaf specific) in registers in addition to the completion status code in
+ %rax.
+ */
+struct tdx_ex_ret {
+ union {
+ struct {
+ u64 rcx;
+ u64 rdx;
+ u64 r8;
+ u64 r9;
+ u64 r10;
+ u64 r11;
+ } regs;
+ /* TDH_MNG_INIT returns CPUID info on error. */
+ struct {
+ u32 leaf;
+ u32 subleaf;
+ } mng_init;
+ /* Functions that walk SEPT */
+ struct {
+ u64 septe;
+ struct {
+ u64 level :3;
+ u64 sept_reserved_0 :5;
+ u64 state :8;
+ u64 sept_reserved_1 :48;
+ };
+ } sept_walk;
+ /* TDH_MNG_{RD,WR} return the field value. */
+ struct {
+ u64 field_val;
+ } mng_rdwr;
+ /* TDH_MEM_{RD,WR} return the error info and value. */
+ struct {
+ u64 ext_err_info_1;
+ u64 ext_err_info_2;
+ u64 mem_val;
+ } mem_rdwr;
+ /* TDH_PHYMEM_PAGE_RDMD and TDH_PHYMEM_PAGE_RECLAIM return page metadata. */
+ struct {
+ u64 page_type;
+ u64 owner;
+ u64 page_size;
+ } phymem_page_md;
+ };
+};
+
+static inline u64 seamcall(u64 op, u64 rcx, u64 rdx, u64 r8, u64 r9, u64 r10,
+ struct tdx_ex_ret *ex)
+{
+ register unsigned long r8_in asm("r8");
+ register unsigned long r9_in asm("r9");
+ register unsigned long r10_in asm("r10");
+ register unsigned long r8_out asm("r8");
+ register unsigned long r9_out asm("r9");
+ register unsigned long r10_out asm("r10");
+ register unsigned long r11_out asm("r11");
+ struct tdx_ex_ret dummy;
+ u64 ret;
+
+ if (!ex)
+ /* The following inline assembly requires non-NULL ex. */
+ ex = &dummy;
+
+ /*
+ * Because the TDX module is known to be already initialized, seamcall
+ * instruction should always succeed without exceptions. Don't check
+ * the instruction error with CF=1 for the availability of the TDX
+ * module.
+ */
+ r8_in = r8;
+ r9_in = r9;
+ r10_in = r10;
+ asm volatile (
+ ".byte 0x66, 0x0f, 0x01, 0xcf\n\t" /* seamcall instruction */
+ : ASM_CALL_CONSTRAINT, "=a"(ret),
+ "=c"(ex->regs.rcx), "=d"(ex->regs.rdx),
+ "=r"(r8_out), "=r"(r9_out), "=r"(r10_out), "=r"(r11_out)
+ : "a"(op), "c"(rcx), "d"(rdx),
+ "r"(r8_in), "r"(r9_in), "r"(r10_in)
+ : "cc", "memory");
+ ex->regs.r8 = r8_out;
+ ex->regs.r9 = r9_out;
+ ex->regs.r10 = r10_out;
+ ex->regs.r11 = r11_out;
+
+ return ret;
+}
+
+#endif /* !__ASSEMBLER__ */
+
+#endif /* CONFIG_INTEL_TDX_HOST */
+
+#endif /* __KVM_VMX_SEAMCALL_H */
--
2.25.1