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Subject: Re: [PATCH v4 00/34] SEV-ES hypervisor support
From:   Tom Lendacky <thomas.lendacky@amd.com>
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Brijesh Singh <brijesh.singh@amd.com>
References: <cover.1605632857.git.thomas.lendacky@amd.com>
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On 11/17/20 11:07 AM, Tom Lendacky wrote:
> From: Tom Lendacky <thomas.lendacky@amd.com>
> 
> This patch series provides support for running SEV-ES guests under KVM.

Any comments on this series?

Thanks,
Tom

> 
> Secure Encrypted Virtualization - Encrypted State (SEV-ES) expands on the
> SEV support to protect the guest register state from the hypervisor. See
> "AMD64 Architecture Programmer's Manual Volume 2: System Programming",
> section "15.35 Encrypted State (SEV-ES)" [1].
> 
> In order to allow a hypervisor to perform functions on behalf of a guest,
> there is architectural support for notifying a guest's operating system
> when certain types of VMEXITs are about to occur. This allows the guest to
> selectively share information with the hypervisor to satisfy the requested
> function. The notification is performed using a new exception, the VMM
> Communication exception (#VC). The information is shared through the
> Guest-Hypervisor Communication Block (GHCB) using the VMGEXIT instruction.
> The GHCB format and the protocol for using it is documented in "SEV-ES
> Guest-Hypervisor Communication Block Standardization" [2].
> 
> Under SEV-ES, a vCPU save area (VMSA) must be encrypted. SVM is updated to
> build the initial VMSA and then encrypt it before running the guest. Once
> encrypted, it must not be modified by the hypervisor. Modification of the
> VMSA will result in the VMRUN instruction failing with a SHUTDOWN exit
> code. KVM must support the VMGEXIT exit code in order to perform the
> necessary functions required of the guest. The GHCB is used to exchange
> the information needed by both the hypervisor and the guest.
> 
> Register data from the GHCB is copied into the KVM register variables and
> accessed as usual during handling of the exit. Upon return to the guest,
> updated registers are copied back to the GHCB for the guest to act upon.
> 
> There are changes to some of the intercepts that are needed under SEV-ES.
> For example, CR0 writes cannot be intercepted, so the code needs to ensure
> that the intercept is not enabled during execution or that the hypervisor
> does not try to read the register as part of exit processing. Another
> example is shutdown processing, where the vCPU cannot be directly reset.
> 
> Support is added to handle VMGEXIT events and implement the GHCB protocol.
> This includes supporting standard exit events, like a CPUID instruction
> intercept, to new support, for things like AP processor booting. Much of
> the existing SVM intercept support can be re-used by setting the exit
> code information from the VMGEXIT and calling the appropriate intercept
> handlers.
> 
> Finally, to launch and run an SEV-ES guest requires changes to the vCPU
> initialization, loading and execution.
> 
> [1] https://www.amd.com/system/files/TechDocs/24593.pdf
> [2] https://developer.amd.com/wp-content/resources/56421.pdf
> 
> ---
> 
> These patches are based on the KVM next branch:
> https://git.kernel.org/pub/scm/virt/kvm/kvm.git next
> 
> 6d6a18fdde8b ("KVM: selftests: allow two iterations of dirty_log_perf_test")
> 
> A version of the tree can also be found at:
> https://github.com/AMDESE/linux/tree/sev-es-v4
> 
> Changes from v3:
> - Some krobot fixes.
> - Some checkpatch cleanups.
> 
> Changes from v2:
> - Update the freeing of the VMSA page to account for the encrypted memory
>    cache coherency feature as well as the VM page flush feature.
> - Update the GHCB dump function with a bit more detail.
> - Don't check for RAX being present as part of a string IO operation.
> - Include RSI when syncing from GHCB to support KVM hypercall arguments.
> - Add GHCB usage field validation check.
> 
> Changes from v1:
> - Removed the VMSA indirection support:
>    - On LAUNCH_UPDATE_VMSA, sync traditional VMSA over to the new SEV-ES
>      VMSA area to be encrypted.
>    - On VMGEXIT VMEXIT, directly copy valid registers into vCPU arch
>      register array from GHCB. On VMRUN (following a VMGEXIT), directly
>      copy dirty vCPU arch registers to GHCB.
>    - Removed reg_read_override()/reg_write_override() KVM ops.
> - Added VMGEXIT exit-reason validation.
> - Changed kvm_vcpu_arch variable vmsa_encrypted to guest_state_protected
> - Updated the tracking support for EFER/CR0/CR4/CR8 to minimize changes
>    to the x86.c code
> - Updated __set_sregs to not set any register values (previously supported
>    setting the tracked values of EFER/CR0/CR4/CR8)
> - Added support for reporting SMM capability at the VM-level. This allows
>    an SEV-ES guest to indicate SMM is not supported
> - Updated FPU support to check for a guest FPU save area before using it.
>    Updated SVM to free guest FPU for an SEV-ES guest during KVM create_vcpu
>    op.
> - Removed changes to the kvm_skip_emulated_instruction()
> - Added VMSA validity checks before invoking LAUNCH_UPDATE_VMSA
> - Minor code restructuring in areas for better readability
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
> Cc: Wanpeng Li <wanpengli@tencent.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Brijesh Singh <brijesh.singh@amd.com>
> 
> Tom Lendacky (34):
>    x86/cpu: Add VM page flush MSR availablility as a CPUID feature
>    KVM: SVM: Remove the call to sev_platform_status() during setup
>    KVM: SVM: Add support for SEV-ES capability in KVM
>    KVM: SVM: Add GHCB accessor functions for retrieving fields
>    KVM: SVM: Add support for the SEV-ES VMSA
>    KVM: x86: Mark GPRs dirty when written
>    KVM: SVM: Add required changes to support intercepts under SEV-ES
>    KVM: SVM: Prevent debugging under SEV-ES
>    KVM: SVM: Do not allow instruction emulation under SEV-ES
>    KVM: SVM: Cannot re-initialize the VMCB after shutdown with SEV-ES
>    KVM: SVM: Prepare for SEV-ES exit handling in the sev.c file
>    KVM: SVM: Add initial support for a VMGEXIT VMEXIT
>    KVM: SVM: Create trace events for VMGEXIT processing
>    KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x002
>    KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x004
>    KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x100
>    KVM: SVM: Create trace events for VMGEXIT MSR protocol processing
>    KVM: SVM: Support MMIO for an SEV-ES guest
>    KVM: SVM: Support string IO operations for an SEV-ES guest
>    KVM: SVM: Add support for EFER write traps for an SEV-ES guest
>    KVM: SVM: Add support for CR0 write traps for an SEV-ES guest
>    KVM: SVM: Add support for CR4 write traps for an SEV-ES guest
>    KVM: SVM: Add support for CR8 write traps for an SEV-ES guest
>    KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES
>    KVM: SVM: Do not report support for SMM for an SEV-ES guest
>    KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest
>    KVM: SVM: Add support for booting APs for an SEV-ES guest
>    KVM: SVM: Add NMI support for an SEV-ES guest
>    KVM: SVM: Set the encryption mask for the SVM host save area
>    KVM: SVM: Update ASID allocation to support SEV-ES guests
>    KVM: SVM: Provide support for SEV-ES vCPU creation/loading
>    KVM: SVM: Provide support for SEV-ES vCPU loading
>    KVM: SVM: Provide an updated VMRUN invocation for SEV-ES guests
>    KVM: SVM: Provide support to launch and run an SEV-ES guest
> 
>   arch/x86/include/asm/cpufeatures.h |   1 +
>   arch/x86/include/asm/kvm_host.h    |  12 +-
>   arch/x86/include/asm/msr-index.h   |   1 +
>   arch/x86/include/asm/svm.h         |  40 +-
>   arch/x86/include/uapi/asm/svm.h    |  28 +
>   arch/x86/kernel/cpu/scattered.c    |   1 +
>   arch/x86/kernel/cpu/vmware.c       |  12 +-
>   arch/x86/kvm/Kconfig               |   3 +-
>   arch/x86/kvm/cpuid.c               |   1 +
>   arch/x86/kvm/kvm_cache_regs.h      |  51 +-
>   arch/x86/kvm/svm/sev.c             | 933 +++++++++++++++++++++++++++--
>   arch/x86/kvm/svm/svm.c             | 442 +++++++++++---
>   arch/x86/kvm/svm/svm.h             | 166 ++++-
>   arch/x86/kvm/svm/vmenter.S         |  50 ++
>   arch/x86/kvm/trace.h               |  97 +++
>   arch/x86/kvm/vmx/vmx.c             |   6 +-
>   arch/x86/kvm/x86.c                 | 368 ++++++++++--
>   arch/x86/kvm/x86.h                 |   9 +
>   18 files changed, 1971 insertions(+), 250 deletions(-)
> 
> 
> base-commit: 6d6a18fdde8b86b919b740ad629153de432d12a8
>