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Date:   Wed, 1 Jun 2022 13:53:41 -0700
From:   Isaku Yamahata <isaku.yamahata@gmail.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     isaku.yamahata@intel.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com,
        erdemaktas@google.com, Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>
Subject: Re: [RFC PATCH v6 000/104] KVM TDX basic feature support
Message-ID: <20220601205341.GC3778155@ls.amr.corp.intel.com>
References: <cover.1651774250.git.isaku.yamahata@intel.com>
 <7366c21e-6f70-91cb-ddda-d9a277622c31@redhat.com>
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On Tue, May 31, 2022 at 04:46:02PM +0200,
Paolo Bonzini <pbonzini@redhat.com> wrote:

> On 5/5/22 20:13, isaku.yamahata@intel.com wrote:
> > From: Isaku Yamahata <isaku.yamahata@intel.com>
> > 
> > Hello.  This is v6 the patch series vof KVM TDX support.
> > This is based on v5.18-rc3 + kvm/queue branch + TDX HOST patch series.
> > The tree can be found at https://github.com/intel/tdx/tree/kvm-upstream
> > 
> > Major changes from v5:
> > - initialize TDX module on loading kvm_intel.ko
> >    This requires changes to other arch. I compile-tested only other arch.
> >    Needs review by each KVM arch maintainer.
> > - introduced protected apic suggested by Sean Christopherson <seanjc@google.com>
> > - use constants for non-present SPTE value
> >    I tested on VMX, but complie test only for SVM.
> > - introduced debug mode to enable #VE suppressbit for VMX and warn on #VE exit
> > 
> > TODO:
> > - 2M large page support. It's work-in-progress.
> 
> So the only important conflicts are with the PRIVATE mapping series
> (see reply to patch 47) and with commit ba3a6120a4e7:
> 
>     Author: Sean Christopherson <seanjc@google.com>
>     Date:   Sat Apr 23 03:47:43 2022 +0000
> 
>     KVM: x86/mmu: Use atomic XCHG to write TDP MMU SPTEs with volatile bits
> 
> which are a bit boring but not hard.  If you can post a v7 relatively
> soon I'd be grateful.

Ok, I'll do. Do you want v7 to be on top of memfd notifier patch series?
or without the patches?  I'm fine with either way because it's already integrated
in github repo. https://github.com/intel/tdx/tree/kvm-upstream-workaround
It's a matter of tedious patch reordering.

Thanks,

> 
> Paolo
> 
> > How to run/test:
> > It's describe at
> > https://github.com/intel/tdx/blob/kvm-upstream-workaround/KVM-TDX.README.md
> > 
> > Trello:
> > I've created to track details. If you want to update items, please let me know.
> > https://trello.com/b/B1cLGCcA/kvm-tdx
> > 
> > Thanks,
> > Isaku Yamahata
> > 
> > Changes from v5:
> > - export __seamcall and use it
> > - move mutex lock from callee function of smp_call_on_cpu to the caller.
> > - rename mmu_prezap => flush_shadow_all_private() and tdx_mmu_release_hkid
> > - updated comment
> > - drop the use of tdh_mng_key.reclaimid(): as the function is for backward
> >    compatibility to only return success
> > - struct kvm_tdx_cmd: metadata => flags, added __u64 error.
> > - make this ioctl systemwide ioctl
> > - ABI change to struct kvm_init_vm
> > - guest_tsc_khz: use kvm->arch.default_tsc_khz
> > - rename BUILD_BUG_ON_MEMCPY to MEMCPY_SAME_SIZE
> > - drop exporting kvm_set_tsc_khz().
> > - fix kvm_tdp_page_fault() for mtrr emulation
> > - rename it to kvm_gfn_shared_mask(), dropped kvm_gpa_shared_mask()
> > - drop kvm_is_private_gfn(), kept kvm_is_private_gpa()
> >    keep kvm_{gfn, gpa}_private(), kvm_gpa_private()
> > - update commit message
> > - rename shadow_init_value => shadow_nonprsent_value
> > - added ept_violation_ve_test mode
> > - shadow_nonpresent_value => SHADOW_NONPRESENT_VALUE in tdp_mmu.c
> > - legacy MMU case
> >    => - mmu_topup_shadow_page_cache(), kvm_mmu_create()
> >       - FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
> > - #VE warning:
> > - rename: REMOVED_SPTE => __REMOVED_SPTE, SHADOW_REMOVED_SPTE => REMOVED_SPTE
> > - merge into Like we discussed, this patch should be merged with patch
> >    "KVM: x86/mmu: Allow non-zero init value for shadow PTE".
> > - fix pointed by Sagi. check !is_private check => (kvm_gfn_shared_mask && !is_private)
> > - introduce kvm_gfn_for_root(kvm, root, gfn)
> > - add only_shared argument to kvm_tdp_mmu_handle_gfn()
> > - use kvm_arch_dirty_log_supported()
> > - rename SPTE_PRIVATE_PROHIBIT to SPTE_SHARED_MASK.
> > - rename: is_private_prohibit_spte() => spte_shared_mask()
> > - fix: shadow_nonpresent_value => SHADOW_NONPRESENT_VALUE in comment
> > - dropped this patch as the change was merged into kvm/queue
> > - update vt_apicv_post_state_restore()
> > - use is_64_bit_hypercall()
> > - comment: expand MSMI -> Machine Check System Management Interrupt
> > - fixed TDX_SEPT_PFERR
> > - tdvmcall_p[1234]_{write, read}() => tdvmcall_a[0123]_{read,write}()
> > - rename tdmvcall_exit_readon() => tdvmcall_leaf()
> > - remove optional zero check of argument.
> > - do a check for static_call(kvm_x86_has_emulated_msr)(kvm, MSR_IA32_SMBASE)
> >     in kvm_vcpu_ioctl_smi and __apic_accept_irq.
> > - WARN_ON_ONCE in tdx_smi_allowed and tdx_enable_smi_window.
> > - introduce vcpu_deliver_init to x86_ops
> > - sprinkeled KVM_BUG_ON()
> > 
> > Changes from v4:
> > - rebased to TDX host kernel patch series.
> > - include all the patches to make this patch series working.
> > - add [MARKER] patches to mark the patch layer clear.
> > 
> > ---
> > * What's TDX?
> > TDX stands for Trust Domain Extensions, which extends Intel Virtual Machines
> > Extensions (VMX) to introduce a kind of virtual machine guest called a Trust
> > Domain (TD) for confidential computing.
> > 
> > A TD runs in a CPU mode that is designed to protect the confidentiality of its
> > memory contents and its CPU state from any other software, including the hosting
> > Virtual Machine Monitor (VMM), unless explicitly shared by the TD itself.
> > 
> > We have more detailed explanations below (***).
> > We have the high-level design of TDX KVM below (****).
> > 
> > In this patch series, we use "TD" or "guest TD" to differentiate it from the
> > current "VM" (Virtual Machine), which is supported by KVM today.
> > 
> > 
> > * The organization of this patch series
> > This patch series is on top of the patches series "TDX host kernel support":
> > https://lore.kernel.org/lkml/cover.1646007267.git.kai.huang@intel.com/
> > 
> > this patch series is available at
> > https://github.com/intel/tdx/releases/tag/kvm-upstream
> > The corresponding patches to qemu are available at
> > https://github.com/intel/qemu-tdx/commits/tdx-upstream
> > 
> > The relations of the layers are depicted as follows.
> > The arrows below show the order of patch reviews we would like to have.
> > 
> > The below layers are chosen so that the device model, for example, qemu can
> > exercise each layering step by step.  Check if TDX is supported, create TD VM,
> > create TD vcpu, allow vcpu running, populate TD guest private memory, and handle
> > vcpu exits/hypercalls/interrupts to run TD fully.
> > 
> >    TDX vcpu
> >    interrupt/exits/hypercall<------------\
> >          ^                               |
> >          |                               |
> >    TD finalization                       |
> >          ^                               |
> >          |                               |
> >    TDX EPT violation<------------\       |
> >          ^                       |       |
> >          |                       |       |
> >    TD vcpu enter/exit            |       |
> >          ^                       |       |
> >          |                       |       |
> >    TD vcpu creation/destruction  |       \-------KVM TDP MMU MapGPA
> >          ^                       |                       ^
> >          |                       |                       |
> >    TD VM creation/destruction    \---------------KVM TDP MMU hooks
> >          ^                                               ^
> >          |                                               |
> >    TDX architectural definitions                 KVM TDP refactoring for TDX
> >          ^                                               ^
> >          |                                               |
> >     TDX, VMX    <--------TDX host kernel         KVM MMU GPA share mask
> >     coexistence          support
> > 
> > 
> > The followings are explanations of each layer.  Each layer has a dummy commit
> > that starts with [MARKER] in subject.  It is intended to help to identify where
> > each layer starts.
> > 
> > TDX host kernel support:
> >          https://lore.kernel.org/lkml/cover.1646007267.git.kai.huang@intel.com/
> >          The guts of system-wide initialization of TDX module.  There is an
> >          independent patch series for host x86.  TDX KVM patches call functions
> >          this patch series provides to initialize the TDX module.
> > 
> > TDX, VMX coexistence:
> >          Infrastructure to allow TDX to coexist with VMX and trigger the
> >          initialization of the TDX module.
> >          This layer starts with
> >          "KVM: VMX: Move out vmx_x86_ops to 'main.c' to wrap VMX and TDX"
> > TDX architectural definitions:
> >          Add TDX architectural definitions and helper functions
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: TDX architectural definitions".
> > TD VM creation/destruction:
> >          Guest TD creation/destroy allocation and releasing of TDX specific vm
> >          and vcpu structure.  Create an initial guest memory image with TDX
> >          measurement.
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: TD VM creation/destruction".
> > TD vcpu creation/destruction:
> >          guest TD creation/destroy Allocation and releasing of TDX specific vm
> >          and vcpu structure.  Create an initial guest memory image with TDX
> >          measurement.
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: TD vcpu creation/destruction"
> > TDX EPT violation:
> >          Create an initial guest memory image with TDX measurement.  Handle
> >          secure EPT violations to populate guest pages with TDX SEAMCALLs.
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: TDX EPT violation"
> > TD vcpu enter/exit:
> >          Allow TDX vcpu to enter into TD and exit from TD.  Save CPU state before
> >          entering into TD.  Restore CPU state after exiting from TD.
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: TD vcpu enter/exit"
> > TD vcpu interrupts/exit/hypercall:
> >          Handle various exits/hypercalls and allow interrupts to be injected so
> >          that TD vcpu can continue running.
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: TD vcpu exits/interrupts/hypercalls"
> > 
> > KVM MMU GPA shared bit:
> >          Introduce framework to handle shared bit repurposed bit of GPA TDX
> >          repurposed a bit of GPA to indicate shared or private. If it's shared,
> >          it's the same as the conventional VMX EPT case.  VMM can access shared
> >          guest pages.  If it's private, it's handled by Secure-EPT and the guest
> >          page is encrypted.
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: KVM MMU GPA stolen bits"
> > KVM TDP refactoring for TDX:
> >          TDX Secure EPT requires different constants. e.g. initial value EPT
> >          entry value etc. Various refactoring for those differences.
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: KVM TDP refactoring for TDX"
> > KVM TDP MMU hooks:
> >          Introduce framework to TDP MMU to add hooks in addition to direct EPT
> >          access TDX added Secure EPT which is an enhancement to VMX EPT.  Unlike
> >          conventional VMX EPT, CPU can't directly read/write Secure EPT. Instead,
> >          use TDX SEAMCALLs to operate on Secure EPT.
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: KVM TDP MMU hooks"
> > KVM TDP MMU MapGPA:
> >          Introduce framework to handle switching guest pages from private/shared
> >          to shared/private.  For a given GPA, a guest page can be assigned to a
> >          private GPA or a shared GPA exclusively.  With TDX MapGPA hypercall,
> >          guest TD converts GPA assignments from private (or shared) to shared (or
> >          private).
> >          This layer starts with
> >          "[MARKER] The start of TDX KVM patch series: KVM TDP MMU MapGPA "
> > 
> > KVM guest private memory: (not shown in the above diagram)
> > [PATCH v4 00/12] KVM: mm: fd-based approach for supporting KVM guest private
> > memory: https://lkml.org/lkml/2022/1/18/395
> >          Guest private memory requires different memory management in KVM.  The
> >          patch proposes a way for it.  Integration with TDX KVM.
> > 
> > (***)
> > * TDX module
> > A CPU-attested software module called the "TDX module" is designed to implement
> > the TDX architecture, and it is loaded by the UEFI firmware today. It can be
> > loaded by the kernel or driver at runtime, but in this patch series we assume
> > that the TDX module is already loaded and initialized.
> > 
> > The TDX module provides two main new logical modes of operation built upon the
> > new SEAM (Secure Arbitration Mode) root and non-root CPU modes added to the VMX
> > architecture. TDX root mode is mostly identical to the VMX root operation mode,
> > and the TDX functions (described later) are triggered by the new SEAMCALL
> > instruction with the desired interface function selected by an input operand
> > (leaf number, in RAX). TDX non-root mode is used for TD guest operation.  TDX
> > non-root operation (i.e. "guest TD" mode) is similar to the VMX non-root
> > operation (i.e. guest VM), with changes and restrictions to better assure that
> > no other software or hardware has direct visibility of the TD memory and state.
> > 
> > TDX transitions between TDX root operation and TDX non-root operation include TD
> > Entries, from TDX root to TDX non-root mode, and TD Exits from TDX non-root to
> > TDX root mode.  A TD Exit might be asynchronous, triggered by some external
> > event (e.g., external interrupt or SMI) or an exception, or it might be
> > synchronous, triggered by a TDCALL (TDG.VP.VMCALL) function.
> > 
> > TD VCPUs can be entered using SEAMCALL(TDH.VP.ENTER) by KVM. TDH.VP.ENTER is one
> > of the TDX interface functions as mentioned above, and "TDH" stands for Trust
> > Domain Host. Those host-side TDX interface functions are categorized into
> > various areas just for better organization, such as SYS (TDX module management),
> > MNG (TD management), VP (VCPU), PHYSMEM (physical memory), MEM (private memory),
> > etc. For example, SEAMCALL(TDH.SYS.INFO) returns the TDX module information.
> > 
> > TDCS (Trust Domain Control Structure) is the main control structure of a guest
> > TD, and encrypted (using the guest TD's ephemeral private key).  At a high
> > level, TDCS holds information for controlling TD operation as a whole,
> > execution, EPTP, MSR bitmaps, etc that KVM needs to set it up.  Note that MSR
> > bitmaps are held as part of TDCS (unlike VMX) because they are meant to have the
> > same value for all VCPUs of the same TD.
> > 
> > Trust Domain Virtual Processor State (TDVPS) is the root control structure of a
> > TD VCPU.  It helps the TDX module control the operation of the VCPU, and holds
> > the VCPU state while the VCPU is not running. TDVPS is opaque to software and
> > DMA access, accessible only by using the TDX module interface functions (such as
> > TDH.VP.RD, TDH.VP.WR). TDVPS includes TD VMCS, and TD VMCS auxiliary structures,
> > such as virtual APIC page, virtualization exception information, etc.
> > 
> > Several VMX control structures (such as Shared EPT and Posted interrupt
> > descriptor) are directly managed and accessed by the host VMM.  These control
> > structures are pointed to by fields in the TD VMCS.
> > 
> > The above means that 1) KVM needs to allocate different data structures for TDs,
> > 2) KVM can reuse the existing code for TDs for some operations, 3) it needs to
> > define TD-specific handling for others.  3) Redirect operations to .  3)
> > Redirect operations to the TDX specific callbacks, like "if (is_td_vcpu(vcpu))
> > tdx_callback() else vmx_callback();".
> > 
> > *TD Private Memory
> > TD private memory is designed to hold TD private content, encrypted by the CPU
> > using the TD ephemeral key. An encryption engine holds a table of encryption
> > keys, and an encryption key is selected for each memory transaction based on a
> > Host Key Identifier (HKID). By design, the host VMM does not have access to the
> > encryption keys.
> > 
> > In the first generation of MKTME, HKID is "stolen" from the physical address by
> > allocating a configurable number of bits from the top of the physical
> > address. The HKID space is partitioned into shared HKIDs for legacy MKTME
> > accesses and private HKIDs for SEAM-mode-only accesses. We use 0 for the shared
> > HKID on the host so that MKTME can be opaque or bypassed on the host.
> > 
> > During TDX non-root operation (i.e. guest TD), memory accesses can be qualified
> > as either shared or private, based on the value of a new SHARED bit in the Guest
> > Physical Address (GPA).  The CPU translates shared GPAs using the usual VMX EPT
> > (Extended Page Table) or "Shared EPT" (in this document), which resides in host
> > VMM memory. The Shared EPT is directly managed by the host VMM - the same as
> > with the current VMX. Since guest TDs usually require I/O, and the data exchange
> > needs to be done via shared memory, thus KVM needs to use the current EPT
> > functionality even for TDs.
> > 
> > * Secure EPT and Minoring using the TDP code
> > The CPU translates private GPAs using a separate Secure EPT.  The Secure EPT
> > pages are encrypted and integrity-protected with the TD's ephemeral private
> > key.  Secure EPT can be managed _indirectly_ by the host VMM, using the TDX
> > interface functions, and thus conceptually Secure EPT is a subset of EPT (why
> > "subset"). Since execution of such interface functions takes much longer time
> > than accessing memory directly, in KVM we use the existing TDP code to minor the
> > Secure EPT for the TD.
> > 
> > This way, we can effectively walk Secure EPT without using the TDX interface
> > functions.
> > 
> > * VM life cycle and TDX specific operations
> > The userspace VMM, such as QEMU, needs to build and treat TDs differently.  For
> > example, a TD needs to boot in private memory, and the host software cannot copy
> > the initial image to private memory.
> > 
> > * TSC Virtualization
> > The TDX module helps TDs maintain reliable TSC (Time Stamp Counter) values
> > (e.g. consistent among the TD VCPUs) and the virtual TSC frequency is determined
> > by TD configuration, i.e. when the TD is created, not per VCPU.  The current KVM
> > owns TSC virtualization for VMs, but the TDX module does for TDs.
> > 
> > * MCE support for TDs
> > The TDX module doesn't allow VMM to inject MCE.  Instead PV way is needed for TD
> > to communicate with VMM.  For now, KVM silently ignores MCE request by VMM.  MSRs
> > related to MCE (e.g, MCE bank registers) can be naturally emulated by
> > paravirtualizing MSR access.
> > 
> > [1] For details, the specifications, [2], [3], [4], [5], [6], [7], are
> > available.
> > 
> > * Restrictions or future work
> > Some features are not included to reduce patch size.  Those features are
> > addressed as future independent patch series.
> > - large page (2M, 1G)
> > - qemu gdb stub
> > - guest PMU
> > - and more
> > 
> > * Prerequisites
> > It's required to load the TDX module and initialize it.  It's out of the scope
> > of this patch series.  Another independent patch for the common x86 code is
> > planned.  It defines CONFIG_INTEL_TDX_HOST and this patch series uses
> > CONFIG_INTEL_TDX_HOST.  It's assumed that With CONFIG_INTEL_TDX_HOST=y, the TDX
> > module is initialized and ready for KVM to use the TDX module APIs for TDX guest
> > life cycle like tdh.mng.init are ready to use.
> > 
> > Concretely Global initialization, LP (Logical Processor) initialization, global
> > configuration, the key configuration, and TDMR and PAMT initialization are done.
> > The state of the TDX module is SYS_READY.  Please refer to the TDX module
> > specification, the chapter Intel TDX Module Lifecycle State Machine
> > 
> > ** Detecting the TDX module readiness.
> > TDX host patch series implements the detection of the TDX module availability
> > and its initialization so that KVM can use it.  Also it manages Host KeyID
> > (HKID) assigned to guest TD.
> > The assumed APIs the TDX host patch series provides are
> > - int seamrr_enabled()
> >    Check if required cpu feature (SEAM mode) is available. This only check CPU
> >    feature availability.  At this point, the TDX module may not be ready for KVM
> >    to use.
> > - int init_tdx(void);
> >    Initialization of TDX module so that the TDX module is ready for KVM to use.
> > - const struct tdsysinfo_struct *tdx_get_sysinfo(void);
> >    Return the system wide information about the TDX module.  NULL if the TDX
> >    isn't initialized.
> > - u32 tdx_get_global_keyid(void);
> >    Return global key id that is used for the TDX module itself.
> > - int tdx_keyid_alloc(void);
> >    Allocate HKID for guest TD.
> > - void tdx_keyid_free(int keyid);
> >    Free HKID for guest TD.
> > 
> > (****)
> > * TDX KVM high-level design
> > - Host key ID management
> > Host Key ID (HKID) needs to be assigned to each TDX guest for memory encryption.
> > It is assumed The TDX host patch series implements necessary functions,
> > u32 tdx_get_global_keyid(void), int tdx_keyid_alloc(void) and,
> > void tdx_keyid_free(int keyid).
> > 
> > - Data structures and VM type
> > Because TDX is different from VMX, define its own VM/VCPU structures, struct
> > kvm_tdx and struct vcpu_tdx instead of struct kvm_vmx and struct vcpu_vmx.  To
> > identify the VM, introduce VM-type to specify which VM type, VMX (default) or
> > TDX, is used.
> > 
> > - VM life cycle and TDX specific operations
> > Re-purpose the existing KVM_MEMORY_ENCRYPT_OP to add TDX specific operations.
> > New commands are used to get the TDX system parameters, set TDX specific VM/VCPU
> > parameters, set initial guest memory and measurement.
> > 
> > The creation of TDX VM requires five additional operations in addition to the
> > conventional VM creation.
> >    - Get KVM system capability to check if TDX VM type is supported
> >    - VM creation (KVM_CREATE_VM)
> >    - New: Get the TDX specific system parameters.  KVM_TDX_GET_CAPABILITY.
> >    - New: Set TDX specific VM parameters.  KVM_TDX_INIT_VM.
> >    - VCPU creation (KVM_CREATE_VCPU)
> >    - New: Set TDX specific VCPU parameters.  KVM_TDX_INIT_VCPU.
> >    - New: Initialize guest memory as boot state and extend the measurement with
> >      the memory.  KVM_TDX_INIT_MEM_REGION.
> >    - New: Finalize VM. KVM_TDX_FINALIZE. Complete measurement of the initial
> >      TDX VM contents.
> >    - VCPU RUN (KVM_VCPU_RUN)
> > 
> > - Protected guest state
> > Because the guest state (CPU state and guest memory) is protected, the KVM VMM
> > can't operate on them.  For example, accessing CPU registers, injecting
> > exceptions, and accessing guest memory.  Those operations are handled as
> > silently ignored, returning zero or initial reset value when it's requested via
> > KVM API ioctls.
> > 
> >      VM/VCPU state and callbacks for TDX specific operations.
> >      Define tdx specific VM state and VCPU state instead of VMX ones.  Redirect
> >      operations to TDX specific callbacks.  "if (tdx) tdx_op() else vmx_op()".
> > 
> >      Operations on the CPU state
> >      silently ignore operations on the guest state.  For example, the write to
> >      CPU registers is ignored and the read from CPU registers returns 0.
> > 
> >      . ignore access to CPU registers except for allowed ones.
> >      . TSC: add a check if tsc is immutable and return an error.  Because the KVM
> >        implementation updates the internal tsc state and it's difficult to back
> >        out those changes.  Instead, skip the logic.
> >      . dirty logging: add check if dirty logging is supported.
> >      . exceptions/SMI/MCE/SIPI/INIT: silently ignore
> > 
> >      Note: virtual external interrupt and NMI can be injected into TDX guests.
> > 
> > - KVM MMU integration
> > One bit of the guest physical address (bit 51 or 47) is repurposed to indicate if
> > the guest physical address is private (the bit is cleared) or shared (the bit is
> > set).  The bits are called stolen bits.
> > 
> >    - Stolen bits framework
> >      systematically tracks which guest physical address, shared or private, is
> >      used.
> > 
> >    - Shared EPT and secure EPT
> >      There are two EPTs. Shared EPT (the conventional one) and Secure
> >      EPT(the new one). Shared EPT is handled the same for the stolen
> >      bit set.  Secure EPT points to private guest pages.  To resolve
> >      EPT violation, KVM walks one of two EPTs based on faulted GPA.
> >      Because it's costly to access secure EPT during walking EPTs with
> >      SEAMCALLs for the private guest physical address, another private
> >      EPT is used as a shadow of Secure-EPT with the existing logic at
> >      the cost of extra memory.
> > 
> > The following depicts the relationship.
> > 
> >                      KVM                             |       TDX module
> >                       |                              |           |
> >          -------------+----------                    |           |
> >          |                      |                    |           |
> >          V                      V                    |           |
> >       shared GPA           private GPA               |           |
> >    CPU shared EPT pointer  KVM private EPT pointer   |  CPU secure EPT pointer
> >          |                      |                    |           |
> >          |                      |                    |           |
> >          V                      V                    |           V
> >    shared EPT                private EPT--------mirror----->Secure EPT
> >          |                      |                    |           |
> >          |                      \--------------------+------\    |
> >          |                                           |      |    |
> >          V                                           |      V    V
> >    shared guest page                                 |    private guest page
> >                                                      |
> >                                                      |
> >                                non-encrypted memory  |    encrypted memory
> >                                                      |
> > 
> >    - Operating on Secure EPT
> >      Use the TDX module APIs to operate on Secure EPT.  To call the TDX API
> >      during resolving EPT violation, add hooks to additional operation and wiring
> >      it to TDX backend.
> > 
> > * References
> > 
> > [1] TDX specification
> >     https://www.intel.com/content/www/us/en/developer/articles/technical/intel-trust-domain-extensions.html
> > [2] Intel Trust Domain Extensions (Intel TDX)
> >     https://cdrdv2.intel.com/v1/dl/getContent/726790
> > [3] Intel CPU Architectural Extensions Specification
> >     https://www.intel.com/content/dam/develop/external/us/en/documents-tps/intel-tdx-cpu-architectural-specification.pdf
> > [4] Intel TDX Module 1.0 Specification
> >     https://www.intel.com/content/dam/develop/external/us/en/documents/tdx-module-1.0-public-spec-v0.931.pdf
> > [5] Intel TDX Loader Interface Specification
> >    https://www.intel.com/content/dam/develop/external/us/en/documents-tps/intel-tdx-seamldr-interface-specification.pdf
> > [6] Intel TDX Guest-Hypervisor Communication Interface
> >     https://cdrdv2.intel.com/v1/dl/getContent/726790
> > [7] Intel TDX Virtual Firmware Design Guide
> >     https://www.intel.com/content/dam/develop/external/us/en/documents/tdx-virtual-firmware-design-guide-rev-1.01.pdf
> > [8] intel public github
> >     kvm TDX branch: https://github.com/intel/tdx/tree/kvm
> >     TDX guest branch: https://github.com/intel/tdx/tree/guest
> >     qemu TDX https://github.com/intel/qemu-tdx
> > [9] TDVF
> >      https://github.com/tianocore/edk2-staging/tree/TDVF
> >      This was merged into EDK2 main branch. https://github.com/tianocore/edk2
> > 
> > Chao Gao (3):
> >    KVM: x86: Move check_processor_compatibility from init ops to runtime
> >      ops
> >    Partially revert "KVM: Pass kvm_init()'s opaque param to additional
> >      arch funcs"
> >    KVM: x86: Allow to update cached values in kvm_user_return_msrs w/o
> >      wrmsr
> > 
> > Isaku Yamahata (74):
> >    KVM: Refactor CPU compatibility check on module initialiization
> >    x86/virt/vmx/tdx: export platform_has_tdx
> >    KVM: TDX: Detect CPU feature on kernel module initialization
> >    KVM: x86: Refactor KVM VMX module init/exit functions
> >    KVM: TDX: Add placeholders for TDX VM/vcpu structure
> >    x86/virt/tdx: Add a helper function to return system wide info about
> >      TDX module
> >    KVM: TDX: Initialize TDX module when loading kvm_intel.ko
> >    KVM: TDX: Make TDX VM type supported
> >    [MARKER] The start of TDX KVM patch series: TDX architectural
> >      definitions
> >    KVM: TDX: Define TDX architectural definitions
> >    KVM: TDX: Add C wrapper functions for SEAMCALLs to the TDX module
> >    KVM: TDX: Add helper functions to print TDX SEAMCALL error
> >    [MARKER] The start of TDX KVM patch series: TD VM creation/destruction
> >    x86/cpu: Add helper functions to allocate/free TDX private host key id
> >    KVM: TDX: Add place holder for TDX VM specific mem_enc_op ioctl
> >    KVM: TDX: Make KVM_CAP_SET_IDENTITY_MAP_ADDR unsupported for TDX
> >    KVM: TDX: Make pmu_intel.c ignore guest TD case
> >    [MARKER] The start of TDX KVM patch series: TD vcpu
> >      creation/destruction
> >    KVM: TDX: allocate/free TDX vcpu structure
> >    KVM: TDX: allocate/free TDX vcpu structure
> >    [MARKER] The start of TDX KVM patch series: KVM MMU GPA shared bits
> >    KVM: x86/mmu: introduce config for PRIVATE KVM MMU
> >    [MARKER] The start of TDX KVM patch series: KVM TDP refactoring for
> >      TDX
> >    KVM: x86/mmu: Disallow fast page fault on private GPA
> >    KVM: VMX: Introduce test mode related to EPT violation VE
> >    [MARKER] The start of TDX KVM patch series: KVM TDP MMU hooks
> >    KVM: x86/mmu: Focibly use TDP MMU for TDX
> >    KVM: x86/mmu: Add a private pointer to struct kvm_mmu_page
> >    KVM: x86/tdp_mmu: refactor kvm_tdp_mmu_map()
> >    KVM: x86/tdp_mmu: Support TDX private mapping for TDP MMU
> >    [MARKER] The start of TDX KVM patch series: TDX EPT violation
> >    KVM: x86/tdp_mmu: Ignore unsupported mmu operation on private GFNs
> >    KVM: TDX: don't request KVM_REQ_APIC_PAGE_RELOAD
> >    KVM: TDX: TDP MMU TDX support
> >    [MARKER] The start of TDX KVM patch series: KVM TDP MMU MapGPA
> >    KVM: x86/mmu: steal software usable git to record if GFN is for shared
> >      or not
> >    KVM: x86/tdp_mmu: implement MapGPA hypercall for TDX
> >    [MARKER] The start of TDX KVM patch series: TD finalization
> >    KVM: TDX: Create initial guest memory
> >    KVM: TDX: Finalize VM initialization
> >    [MARKER] The start of TDX KVM patch series: TD vcpu enter/exit
> >    KVM: TDX: Add helper assembly function to TDX vcpu
> >    KVM: TDX: Implement TDX vcpu enter/exit path
> >    KVM: TDX: vcpu_run: save/restore host state(host kernel gs)
> >    KVM: TDX: restore host xsave state when exit from the guest TD
> >    KVM: TDX: restore user ret MSRs
> >    [MARKER] The start of TDX KVM patch series: TD vcpu
> >      exits/interrupts/hypercalls
> >    KVM: TDX: complete interrupts after tdexit
> >    KVM: TDX: restore debug store when TD exit
> >    KVM: TDX: handle vcpu migration over logical processor
> >    KVM: x86: Add a switch_db_regs flag to handle TDX's auto-switched
> >      behavior
> >    KVM: TDX: remove use of struct vcpu_vmx from posted_interrupt.c
> >    KVM: TDX: Implement interrupt injection
> >    KVM: TDX: Implements vcpu request_immediate_exit
> >    KVM: TDX: Implement methods to inject NMI
> >    KVM: TDX: Add a place holder to handle TDX VM exit
> >    KVM: TDX: handle EXIT_REASON_OTHER_SMI
> >    KVM: TDX: handle ept violation/misconfig exit
> >    KVM: TDX: handle EXCEPTION_NMI and EXTERNAL_INTERRUPT
> >    KVM: TDX: Add a place holder for handler of TDX hypercalls
> >      (TDG.VP.VMCALL)
> >    KVM: TDX: handle KVM hypercall with TDG.VP.VMCALL
> >    KVM: TDX: Handle TDX PV CPUID hypercall
> >    KVM: TDX: Handle TDX PV HLT hypercall
> >    KVM: TDX: Handle TDX PV port io hypercall
> >    KVM: TDX: Implement callbacks for MSR operations for TDX
> >    KVM: TDX: Handle TDX PV rdmsr/wrmsr hypercall
> >    KVM: TDX: Handle TDX PV report fatal error hypercall
> >    KVM: TDX: Handle TDX PV map_gpa hypercall
> >    KVM: TDX: Handle TDG.VP.VMCALL<GetTdVmCallInfo> hypercall
> >    KVM: TDX: Silently discard SMI request
> >    KVM: TDX: Silently ignore INIT/SIPI
> >    Documentation/virtual/kvm: Document on Trust Domain Extensions(TDX)
> >    KVM: x86: design documentation on TDX support of x86 KVM TDP MMU
> >    [MARKER] the end of (the first phase of) TDX KVM patch series
> > 
> > Rick Edgecombe (1):
> >    KVM: x86/mmu: Add address conversion functions for TDX shared bits
> > 
> > Sean Christopherson (25):
> >    KVM: VMX: Move out vmx_x86_ops to 'main.c' to wrap VMX and TDX
> >    KVM: Enable hardware before doing arch VM initialization
> >    KVM: x86: Introduce vm_type to differentiate default VMs from
> >      confidential VMs
> >    KVM: TDX: Add TDX "architectural" error codes
> >    KVM: TDX: Stub in tdx.h with structs, accessors, and VMCS helpers
> >    KVM: TDX: create/destroy VM structure
> >    KVM: TDX: x86: Add ioctl to get TDX systemwide parameters
> >    KVM: TDX: Do TDX specific vcpu initialization
> >    KVM: x86/mmu: Explicitly check for MMIO spte in fast page fault
> >    KVM: x86/mmu: Allow non-zero value for non-present SPTE
> >    KVM: x86/mmu: Track shadow MMIO value/mask on a per-VM basis
> >    KVM: x86/mmu: Allow per-VM override of the TDP max page level
> >    KVM: x86/mmu: Zap only leaf SPTEs for deleted/moved memslot for
> >      private mmu
> >    KVM: x86/mmu: Disallow dirty logging for x86 TDX
> >    KVM: VMX: Split out guts of EPT violation to common/exposed function
> >    KVM: VMX: Move setting of EPT MMU masks to common VT-x code
> >    KVM: TDX: Add load_mmu_pgd method for TDX
> >    KVM: x86/mmu: Introduce kvm_mmu_map_tdp_page() for use by TDX
> >    KVM: TDX: Add support for find pending IRQ in a protected local APIC
> >    KVM: x86: Assume timer IRQ was injected if APIC state is proteced
> >    KVM: VMX: Modify NMI and INTR handlers to take intr_info as function
> >      argument
> >    KVM: VMX: Move NMI/exception handler to common helper
> >    KVM: x86: Split core of hypercall emulation to helper function
> >    KVM: TDX: Handle TDX PV MMIO hypercall
> >    KVM: TDX: Add methods to ignore accesses to CPU state
> > 
> > Xiaoyao Li (1):
> >    KVM: TDX: initialize VM with TDX specific parameters
> > 
> >   Documentation/virt/kvm/api.rst         |   30 +-
> >   Documentation/virt/kvm/intel-tdx.rst   |  381 ++++
> >   Documentation/virt/kvm/tdx-tdp-mmu.rst |  466 +++++
> >   arch/arm64/kvm/arm.c                   |    2 +-
> >   arch/mips/kvm/mips.c                   |   14 +-
> >   arch/powerpc/kvm/powerpc.c             |    2 +-
> >   arch/riscv/kvm/main.c                  |    2 +-
> >   arch/s390/kvm/kvm-s390.c               |    2 +-
> >   arch/x86/events/intel/ds.c             |    1 +
> >   arch/x86/include/asm/kvm-x86-ops.h     |   10 +
> >   arch/x86/include/asm/kvm_host.h        |   56 +-
> >   arch/x86/include/asm/tdx.h             |   66 +
> >   arch/x86/include/asm/vmx.h             |   14 +
> >   arch/x86/include/uapi/asm/kvm.h        |   95 +
> >   arch/x86/include/uapi/asm/vmx.h        |    5 +-
> >   arch/x86/kvm/Kconfig                   |    4 +
> >   arch/x86/kvm/Makefile                  |    3 +-
> >   arch/x86/kvm/irq.c                     |    3 +
> >   arch/x86/kvm/lapic.c                   |   37 +-
> >   arch/x86/kvm/lapic.h                   |    2 +
> >   arch/x86/kvm/mmu.h                     |   48 +-
> >   arch/x86/kvm/mmu/mmu.c                 |  371 +++-
> >   arch/x86/kvm/mmu/mmu_internal.h        |  120 ++
> >   arch/x86/kvm/mmu/paging_tmpl.h         |    5 +-
> >   arch/x86/kvm/mmu/spte.c                |   46 +-
> >   arch/x86/kvm/mmu/spte.h                |   65 +-
> >   arch/x86/kvm/mmu/tdp_iter.c            |    1 +
> >   arch/x86/kvm/mmu/tdp_iter.h            |    5 +-
> >   arch/x86/kvm/mmu/tdp_mmu.c             |  683 ++++++-
> >   arch/x86/kvm/mmu/tdp_mmu.h             |   12 +-
> >   arch/x86/kvm/svm/svm.c                 |   13 +-
> >   arch/x86/kvm/vmx/common.h              |  154 ++
> >   arch/x86/kvm/vmx/evmcs.c               |    2 +-
> >   arch/x86/kvm/vmx/evmcs.h               |    2 +-
> >   arch/x86/kvm/vmx/main.c                | 1073 ++++++++++
> >   arch/x86/kvm/vmx/pmu_intel.c           |   33 +
> >   arch/x86/kvm/vmx/pmu_intel.h           |   29 +
> >   arch/x86/kvm/vmx/posted_intr.c         |   43 +-
> >   arch/x86/kvm/vmx/posted_intr.h         |   13 +
> >   arch/x86/kvm/vmx/tdx.c                 | 2470 ++++++++++++++++++++++++
> >   arch/x86/kvm/vmx/tdx.h                 |  275 +++
> >   arch/x86/kvm/vmx/tdx_arch.h            |  157 ++
> >   arch/x86/kvm/vmx/tdx_errno.h           |   29 +
> >   arch/x86/kvm/vmx/tdx_error.c           |   22 +
> >   arch/x86/kvm/vmx/tdx_ops.h             |  188 ++
> >   arch/x86/kvm/vmx/vmenter.S             |  146 ++
> >   arch/x86/kvm/vmx/vmx.c                 |  716 +++----
> >   arch/x86/kvm/vmx/vmx.h                 |   41 +-
> >   arch/x86/kvm/vmx/x86_ops.h             |  235 +++
> >   arch/x86/kvm/x86.c                     |  155 +-
> >   arch/x86/virt/vmx/tdx/seamcall.S       |    1 +
> >   arch/x86/virt/vmx/tdx/tdx.c            |   53 +-
> >   arch/x86/virt/vmx/tdx/tdx.h            |   52 -
> >   include/linux/kvm_host.h               |    4 +-
> >   include/uapi/linux/kvm.h               |    2 +
> >   tools/arch/x86/include/uapi/asm/kvm.h  |   95 +
> >   tools/include/uapi/linux/kvm.h         |    1 +
> >   virt/kvm/kvm_main.c                    |   67 +-
> >   58 files changed, 7839 insertions(+), 783 deletions(-)
> >   create mode 100644 Documentation/virt/kvm/intel-tdx.rst
> >   create mode 100644 Documentation/virt/kvm/tdx-tdp-mmu.rst
> >   create mode 100644 arch/x86/kvm/vmx/common.h
> >   create mode 100644 arch/x86/kvm/vmx/main.c
> >   create mode 100644 arch/x86/kvm/vmx/pmu_intel.h
> >   create mode 100644 arch/x86/kvm/vmx/tdx.c
> >   create mode 100644 arch/x86/kvm/vmx/tdx.h
> >   create mode 100644 arch/x86/kvm/vmx/tdx_arch.h
> >   create mode 100644 arch/x86/kvm/vmx/tdx_errno.h
> >   create mode 100644 arch/x86/kvm/vmx/tdx_error.c
> >   create mode 100644 arch/x86/kvm/vmx/tdx_ops.h
> >   create mode 100644 arch/x86/kvm/vmx/x86_ops.h
> > 
> 

-- 
Isaku Yamahata <isaku.yamahata@gmail.com>