arch/x86/tdx.rst

1 .. SPDX-License-Identifier: GPL-2.0
18 CPU-attested software module called 'the TDX module' runs inside the new
22 TDX also leverages Intel Multi-Key Total Memory Encryption (MKTME) to
23 provide crypto-protection to the VMs.  TDX reserves part of MKTME KeyIDs
32 TDX boot-time detection
33 -----------------------
41 ---------------------------------------
59 Besides initializing the TDX module, a per-cpu initialization SEAMCALL
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110 of memory regions (out of CMRs) as "TDX-usable" memory and pass those
111 regions to the TDX module.  Once this is done, those "TDX-usable" memory
116 system memory in the core-mm "at the time of TDX module initialization"
117 as TDX memory, and in the meantime, refuses to online any non-TDX-memory
124 machine's runtime.  A non-buggy BIOS should never support hot-removal of
131 TDX module requires the per-cpu initialization SEAMCALL must be done on
137 TDX verifies all boot-time present logical CPUs are TDX compatible before
138 enabling TDX.  A non-buggy BIOS should never support hot-add/removal of
162 non-temporal write instructions (like MOVNTI), or through UC/WC memory
168 software-triggered issue.  But in the end, this issue is hard to trigger.
181 The kernel uses S3 for suspend-to-ram, and use S4 and deeper states for
204 TDX includes new hypercall-like mechanisms for communicating from the
208 ------------------
210 TDX guests behave differently from bare-metal and traditional VMX guests.
217 Instruction-based #VE
220 - Port I/O (INS, OUTS, IN, OUT)
221 - HLT
222 - MONITOR, MWAIT
223 - WBINVD, INVD
224 - VMCALL
225 - RDMSR*,WRMSR*
226 - CPUID*
228 Instruction-based #GP
231 - All VMX instructions: INVEPT, INVVPID, VMCLEAR, VMFUNC, VMLAUNCH,
233 - ENCLS, ENCLU
234 - GETSEC
235 - RSM
236 - ENQCMD
237 - RDMSR*,WRMSR*
244 - #GP generated
245 - #VE generated
246 - "Just works"
263 For some CPUID leaves and sub-leaves, the virtualized bit fields of CPUID
268 - Bit fields for which the hypervisor controls the value seen by the guest
271 - Bit fields for which the hypervisor configures the value such that the
276 A #VE is generated for CPUID leaves and sub-leaves that the TDX module does
281 ----------------------
306 stacks.  A good rule of thumb is that hypervisor-shared memory should be
323 A modest amount of memory (typically 512M) is pre-accepted by the firmware
333 -----------------
350 #VE-triggering actions (discussed above) while this block is in place.
355 -------------
357 In non-TDX VMs, MMIO is usually implemented by giving a guest access to a
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422 from the TDX module. TDREPORT is a fixed-size data structure generated by
423 the TDX module which contains guest-specific information (such as build
425 the integrity of the TDREPORT. A user-provided 64-Byte REPORTDATA is used
427 provided by attestation service so the TDREPORT can be verified uniquely.
433 by design can only be verified on the local platform as the MAC key is
446 https://www.intel.com/content/www/us/en/developer/articles/technical/intel-trust-domain-extensions.…