diff options
| -rw-r--r-- | arch/x86/coco/tdx/tdx.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index 50c3b97d6db7..ab10bc73a7c5 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -8,11 +8,17 @@ #include <asm/coco.h> #include <asm/tdx.h> #include <asm/vmx.h> +#include <asm/insn.h> +#include <asm/insn-eval.h> /* TDX module Call Leaf IDs */ #define TDX_GET_INFO 1 #define TDX_GET_VEINFO 3 +/* MMIO direction */ +#define EPT_READ 0 +#define EPT_WRITE 1 + /* * Wrapper for standard use of __tdx_hypercall with no output aside from * return code. @@ -222,6 +228,119 @@ static bool handle_cpuid(struct pt_regs *regs) return true; } +static bool mmio_read(int size, unsigned long addr, unsigned long *val) +{ + struct tdx_hypercall_args args = { + .r10 = TDX_HYPERCALL_STANDARD, + .r11 = hcall_func(EXIT_REASON_EPT_VIOLATION), + .r12 = size, + .r13 = EPT_READ, + .r14 = addr, + .r15 = *val, + }; + + if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT)) + return false; + *val = args.r11; + return true; +} + +static bool mmio_write(int size, unsigned long addr, unsigned long val) +{ + return !_tdx_hypercall(hcall_func(EXIT_REASON_EPT_VIOLATION), size, + EPT_WRITE, addr, val); +} + +static bool handle_mmio(struct pt_regs *regs, struct ve_info *ve) +{ + char buffer[MAX_INSN_SIZE]; + unsigned long *reg, val; + struct insn insn = {}; + enum mmio_type mmio; + int size, extend_size; + u8 extend_val = 0; + + /* Only in-kernel MMIO is supported */ + if (WARN_ON_ONCE(user_mode(regs))) + return false; + + if (copy_from_kernel_nofault(buffer, (void *)regs->ip, MAX_INSN_SIZE)) + return false; + + if (insn_decode(&insn, buffer, MAX_INSN_SIZE, INSN_MODE_64)) + return false; + + mmio = insn_decode_mmio(&insn, &size); + if (WARN_ON_ONCE(mmio == MMIO_DECODE_FAILED)) + return false; + + if (mmio != MMIO_WRITE_IMM && mmio != MMIO_MOVS) { + reg = insn_get_modrm_reg_ptr(&insn, regs); + if (!reg) + return false; + } + + ve->instr_len = insn.length; + + /* Handle writes first */ + switch (mmio) { + case MMIO_WRITE: + memcpy(&val, reg, size); + return mmio_write(size, ve->gpa, val); + case MMIO_WRITE_IMM: + val = insn.immediate.value; + return mmio_write(size, ve->gpa, val); + case MMIO_READ: + case MMIO_READ_ZERO_EXTEND: + case MMIO_READ_SIGN_EXTEND: + /* Reads are handled below */ + break; + case MMIO_MOVS: + case MMIO_DECODE_FAILED: + /* + * MMIO was accessed with an instruction that could not be + * decoded or handled properly. It was likely not using io.h + * helpers or accessed MMIO accidentally. + */ + return false; + default: + WARN_ONCE(1, "Unknown insn_decode_mmio() decode value?"); + return false; + } + + /* Handle reads */ + if (!mmio_read(size, ve->gpa, &val)) + return false; + + switch (mmio) { + case MMIO_READ: + /* Zero-extend for 32-bit operation */ + extend_size = size == 4 ? sizeof(*reg) : 0; + break; + case MMIO_READ_ZERO_EXTEND: + /* Zero extend based on operand size */ + extend_size = insn.opnd_bytes; + break; + case MMIO_READ_SIGN_EXTEND: + /* Sign extend based on operand size */ + extend_size = insn.opnd_bytes; + if (size == 1 && val & BIT(7)) + extend_val = 0xFF; + else if (size > 1 && val & BIT(15)) + extend_val = 0xFF; + break; + default: + /* All other cases has to be covered with the first switch() */ + WARN_ON_ONCE(1); + return false; + } + + if (extend_size) + memset(reg, extend_val, extend_size); + memcpy(reg, &val, size); + return true; +} + void tdx_get_ve_info(struct ve_info *ve) { struct tdx_module_output out; @@ -276,6 +395,8 @@ static bool virt_exception_kernel(struct pt_regs *regs, struct ve_info *ve) return write_msr(regs); case EXIT_REASON_CPUID: return handle_cpuid(regs); + case EXIT_REASON_EPT_VIOLATION: + return handle_mmio(regs, ve); default: pr_warn("Unexpected #VE: %lld\n", ve->exit_reason); return false; |