diff options
Diffstat (limited to 'arch/x86/coco/tdx/tdx.c')
| -rw-r--r-- | arch/x86/coco/tdx/tdx.c | 260 |
1 files changed, 226 insertions, 34 deletions
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index 327c45c5013f..7b2833705d47 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -14,6 +14,7 @@ #include <asm/ia32.h> #include <asm/insn.h> #include <asm/insn-eval.h> +#include <asm/paravirt_types.h> #include <asm/pgtable.h> #include <asm/set_memory.h> #include <asm/traps.h> @@ -32,12 +33,10 @@ #define VE_GET_PORT_NUM(e) ((e) >> 16) #define VE_IS_IO_STRING(e) ((e) & BIT(4)) -#define ATTR_DEBUG BIT(0) -#define ATTR_SEPT_VE_DISABLE BIT(28) - /* TDX Module call error codes */ #define TDCALL_RETURN_CODE(a) ((a) >> 32) #define TDCALL_INVALID_OPERAND 0xc0000100 +#define TDCALL_OPERAND_BUSY 0x80000200 #define TDREPORT_SUBTYPE_0 0 @@ -78,6 +77,32 @@ static inline void tdcall(u64 fn, struct tdx_module_args *args) panic("TDCALL %lld failed (Buggy TDX module!)\n", fn); } +/* Read TD-scoped metadata */ +static inline u64 tdg_vm_rd(u64 field, u64 *value) +{ + struct tdx_module_args args = { + .rdx = field, + }; + u64 ret; + + ret = __tdcall_ret(TDG_VM_RD, &args); + *value = args.r8; + + return ret; +} + +/* Write TD-scoped metadata */ +static inline u64 tdg_vm_wr(u64 field, u64 value, u64 mask) +{ + struct tdx_module_args args = { + .rdx = field, + .r8 = value, + .r9 = mask, + }; + + return __tdcall(TDG_VM_WR, &args); +} + /** * tdx_mcall_get_report0() - Wrapper to get TDREPORT0 (a.k.a. TDREPORT * subtype 0) using TDG.MR.REPORT TDCALL. @@ -85,12 +110,13 @@ static inline void tdcall(u64 fn, struct tdx_module_args *args) * REPORTDATA to be included into TDREPORT. * @tdreport: Address of the output buffer to store TDREPORT. * - * Refer to section titled "TDG.MR.REPORT leaf" in the TDX Module - * v1.0 specification for more information on TDG.MR.REPORT TDCALL. + * Refer to section titled "TDG.MR.REPORT leaf" in the TDX Module v1.0 + * specification for more information on TDG.MR.REPORT TDCALL. + * * It is used in the TDX guest driver module to get the TDREPORT0. * - * Return 0 on success, -EINVAL for invalid operands, or -EIO on - * other TDCALL failures. + * Return 0 on success, -ENXIO for invalid operands, -EBUSY for busy operation, + * or -EIO on other TDCALL failures. */ int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport) { @@ -104,7 +130,9 @@ int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport) ret = __tdcall(TDG_MR_REPORT, &args); if (ret) { if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND) - return -EINVAL; + return -ENXIO; + else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY) + return -EBUSY; return -EIO; } @@ -113,6 +141,42 @@ int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport) EXPORT_SYMBOL_GPL(tdx_mcall_get_report0); /** + * tdx_mcall_extend_rtmr() - Wrapper to extend RTMR registers using + * TDG.MR.RTMR.EXTEND TDCALL. + * @index: Index of RTMR register to be extended. + * @data: Address of the input buffer with RTMR register extend data. + * + * Refer to section titled "TDG.MR.RTMR.EXTEND leaf" in the TDX Module v1.0 + * specification for more information on TDG.MR.RTMR.EXTEND TDCALL. + * + * It is used in the TDX guest driver module to allow user to extend the RTMR + * registers. + * + * Return 0 on success, -ENXIO for invalid operands, -EBUSY for busy operation, + * or -EIO on other TDCALL failures. + */ +int tdx_mcall_extend_rtmr(u8 index, u8 *data) +{ + struct tdx_module_args args = { + .rcx = virt_to_phys(data), + .rdx = index, + }; + u64 ret; + + ret = __tdcall(TDG_MR_RTMR_EXTEND, &args); + if (ret) { + if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND) + return -ENXIO; + if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY) + return -EBUSY; + return -EIO; + } + + return 0; +} +EXPORT_SYMBOL_GPL(tdx_mcall_extend_rtmr); + +/** * tdx_hcall_get_quote() - Wrapper to request TD Quote using GetQuote * hypercall. * @buf: Address of the directly mapped shared kernel buffer which @@ -144,11 +208,11 @@ static void __noreturn tdx_panic(const char *msg) /* Define register order according to the GHCI */ struct { u64 r14, r15, rbx, rdi, rsi, r8, r9, rdx; }; - char str[64]; + char bytes[64] __nonstring; } message; /* VMM assumes '\0' in byte 65, if the message took all 64 bytes */ - strtomem_pad(message.str, msg, '\0'); + strtomem_pad(message.bytes, msg, '\0'); args.r8 = message.r8; args.r9 = message.r9; @@ -168,7 +232,101 @@ static void __noreturn tdx_panic(const char *msg) __tdx_hypercall(&args); } -static void tdx_parse_tdinfo(u64 *cc_mask) +/* + * The kernel cannot handle #VEs when accessing normal kernel memory. Ensure + * that no #VE will be delivered for accesses to TD-private memory. + * + * TDX 1.0 does not allow the guest to disable SEPT #VE on its own. The VMM + * controls if the guest will receive such #VE with TD attribute + * TDX_ATTR_SEPT_VE_DISABLE. + * + * Newer TDX modules allow the guest to control if it wants to receive SEPT + * violation #VEs. + * + * Check if the feature is available and disable SEPT #VE if possible. + * + * If the TD is allowed to disable/enable SEPT #VEs, the TDX_ATTR_SEPT_VE_DISABLE + * attribute is no longer reliable. It reflects the initial state of the + * control for the TD, but it will not be updated if someone (e.g. bootloader) + * changes it before the kernel starts. Kernel must check TDCS_TD_CTLS bit to + * determine if SEPT #VEs are enabled or disabled. + */ +static void disable_sept_ve(u64 td_attr) +{ + const char *msg = "TD misconfiguration: SEPT #VE has to be disabled"; + bool debug = td_attr & TDX_ATTR_DEBUG; + u64 config, controls; + + /* Is this TD allowed to disable SEPT #VE */ + tdg_vm_rd(TDCS_CONFIG_FLAGS, &config); + if (!(config & TDCS_CONFIG_FLEXIBLE_PENDING_VE)) { + /* No SEPT #VE controls for the guest: check the attribute */ + if (td_attr & TDX_ATTR_SEPT_VE_DISABLE) + return; + + /* Relax SEPT_VE_DISABLE check for debug TD for backtraces */ + if (debug) + pr_warn("%s\n", msg); + else + tdx_panic(msg); + return; + } + + /* Check if SEPT #VE has been disabled before us */ + tdg_vm_rd(TDCS_TD_CTLS, &controls); + if (controls & TD_CTLS_PENDING_VE_DISABLE) + return; + + /* Keep #VEs enabled for splats in debugging environments */ + if (debug) + return; + + /* Disable SEPT #VEs */ + tdg_vm_wr(TDCS_TD_CTLS, TD_CTLS_PENDING_VE_DISABLE, + TD_CTLS_PENDING_VE_DISABLE); +} + +/* + * TDX 1.0 generates a #VE when accessing topology-related CPUID leafs (0xB and + * 0x1F) and the X2APIC_APICID MSR. The kernel returns all zeros on CPUID #VEs. + * In practice, this means that the kernel can only boot with a plain topology. + * Any complications will cause problems. + * + * The ENUM_TOPOLOGY feature allows the VMM to provide topology information. + * Enabling the feature eliminates topology-related #VEs: the TDX module + * virtualizes accesses to the CPUID leafs and the MSR. + * + * Enable ENUM_TOPOLOGY if it is available. + */ +static void enable_cpu_topology_enumeration(void) +{ + u64 configured; + + /* Has the VMM provided a valid topology configuration? */ + tdg_vm_rd(TDCS_TOPOLOGY_ENUM_CONFIGURED, &configured); + if (!configured) { + pr_err("VMM did not configure X2APIC_IDs properly\n"); + return; + } + + tdg_vm_wr(TDCS_TD_CTLS, TD_CTLS_ENUM_TOPOLOGY, TD_CTLS_ENUM_TOPOLOGY); +} + +static void reduce_unnecessary_ve(void) +{ + u64 err = tdg_vm_wr(TDCS_TD_CTLS, TD_CTLS_REDUCE_VE, TD_CTLS_REDUCE_VE); + + if (err == TDX_SUCCESS) + return; + + /* + * Enabling REDUCE_VE includes ENUM_TOPOLOGY. Only try to + * enable ENUM_TOPOLOGY if REDUCE_VE was not successful. + */ + enable_cpu_topology_enumeration(); +} + +static void tdx_setup(u64 *cc_mask) { struct tdx_module_args args = {}; unsigned int gpa_width; @@ -193,21 +351,14 @@ static void tdx_parse_tdinfo(u64 *cc_mask) gpa_width = args.rcx & GENMASK(5, 0); *cc_mask = BIT_ULL(gpa_width - 1); - /* - * The kernel can not handle #VE's when accessing normal kernel - * memory. Ensure that no #VE will be delivered for accesses to - * TD-private memory. Only VMM-shared memory (MMIO) will #VE. - */ td_attr = args.rdx; - if (!(td_attr & ATTR_SEPT_VE_DISABLE)) { - const char *msg = "TD misconfiguration: SEPT_VE_DISABLE attribute must be set."; - /* Relax SEPT_VE_DISABLE check for debug TD. */ - if (td_attr & ATTR_DEBUG) - pr_warn("%s\n", msg); - else - tdx_panic(msg); - } + /* Kernel does not use NOTIFY_ENABLES and does not need random #VEs */ + tdg_vm_wr(TDCS_NOTIFY_ENABLES, 0, -1ULL); + + disable_sept_ve(td_attr); + + reduce_unnecessary_ve(); } /* @@ -282,13 +433,21 @@ static int handle_halt(struct ve_info *ve) { const bool irq_disabled = irqs_disabled(); + /* + * HLT with IRQs enabled is unsafe, as an IRQ that is intended to be a + * wake event may be consumed before requesting HLT emulation, leaving + * the vCPU blocking indefinitely. + */ + if (WARN_ONCE(!irq_disabled, "HLT emulation with IRQs enabled")) + return -EIO; + if (__halt(irq_disabled)) return -EIO; return ve_instr_len(ve); } -void __cpuidle tdx_safe_halt(void) +void __cpuidle tdx_halt(void) { const bool irq_disabled = false; @@ -299,6 +458,16 @@ void __cpuidle tdx_safe_halt(void) WARN_ONCE(1, "HLT instruction emulation failed\n"); } +static void __cpuidle tdx_safe_halt(void) +{ + tdx_halt(); + /* + * "__cpuidle" section doesn't support instrumentation, so stick + * with raw_* variant that avoids tracing hooks. + */ + raw_local_irq_enable(); +} + static int read_msr(struct pt_regs *regs, struct ve_info *ve) { struct tdx_module_args args = { @@ -927,12 +1096,22 @@ static void tdx_kexec_finish(void) } } +static __init void tdx_announce(void) +{ + struct tdx_module_args args = {}; + u64 controls; + + pr_info("Guest detected\n"); + + tdcall(TDG_VP_INFO, &args); + tdx_dump_attributes(args.rdx); + + tdg_vm_rd(TDCS_TD_CTLS, &controls); + tdx_dump_td_ctls(controls); +} + void __init tdx_early_init(void) { - struct tdx_module_args args = { - .rdx = TDCS_NOTIFY_ENABLES, - .r9 = -1ULL, - }; u64 cc_mask; u32 eax, sig[3]; @@ -947,11 +1126,11 @@ void __init tdx_early_init(void) setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); cc_vendor = CC_VENDOR_INTEL; - tdx_parse_tdinfo(&cc_mask); - cc_set_mask(cc_mask); - /* Kernel does not use NOTIFY_ENABLES and does not need random #VEs */ - tdcall(TDG_VM_WR, &args); + /* Configure the TD */ + tdx_setup(&cc_mask); + + cc_set_mask(cc_mask); /* * All bits above GPA width are reserved and kernel treats shared bit @@ -990,6 +1169,19 @@ void __init tdx_early_init(void) x86_platform.guest.enc_kexec_finish = tdx_kexec_finish; /* + * Avoid "sti;hlt" execution in TDX guests as HLT induces a #VE that + * will enable interrupts before HLT TDCALL invocation if executed + * in STI-shadow, possibly resulting in missed wakeup events. + * + * Modify all possible HLT execution paths to use TDX specific routines + * that directly execute TDCALL and toggle the interrupt state as + * needed after TDCALL completion. This also reduces HLT related #VEs + * in addition to having a reliable halt logic execution. + */ + pv_ops.irq.safe_halt = tdx_safe_halt; + pv_ops.irq.halt = tdx_halt; + + /* * TDX intercepts the RDMSR to read the X2APIC ID in the parallel * bringup low level code. That raises #VE which cannot be handled * there. @@ -1000,5 +1192,5 @@ void __init tdx_early_init(void) */ x86_cpuinit.parallel_bringup = false; - pr_info("Guest detected\n"); + tdx_announce(); } |