Re: [PATCH RFC v3 00/49] Add AMD Secure Nested Paging (SEV-SNP) support

[Ani Sinha]

> On 20 Mar 2024, at 14:08, Michael Roth <michael.roth@amd.com> wrote:
> 
> These patches implement SEV-SNP base support along with CPUID enforcement
> support for QEMU, and are also available at:
> 
>  https://github.com/amdese/qemu/commits/snp-v3-rfc
> 
> they are based on top of the following patchset from Paolo:
> 
>  "[PATCH 0/7] target/i386: VM type infrastructure and KVM_SEV_INIT2 support"
>  https://lists.gnu.org/archive/html/qemu-devel/2024-03/msg04663.html

Can you please also CC me on future revisions of this patchset? 

Thanks!


> 
> 
> Patch Layout
> ------------
> 
> 01-05: Various changes needed to handle new header files in kvm-next tree
>       and some hacks to get a functional header sync in place for building
>       this series.
> 06-18: These are patches directly plucked from Xiaoyao's TDX v5 patchset[1]
>       that implement common dependencies between SNP/TDX like base
>       guest_memfd, KVM_EXIT_MEMORY_FAULT handling (with a small FIXUP), and
>       mechanisms to disable SMM. We would've also needed some of the basic
>       infrastructure for handling specifying VM types for KVM_CREATE, but
>       much of that is now part of the sevinit2 series this patchset is based
>       on. Ideally all these patches, once stable, could be maintained in a
>       common tree so that future SNP/TDX patchsets can be more easily
>       iterated on/reviewed.
> 19-20: Patches introduced by this series that are  possible candidate for a
>       common tree.
>       shared/private pages when things like VFIO are in use.
> 21-32: Introduction of sev-snp-guest object and various configuration
>       requirements for SNP.
> 33-36: Handling for various KVM_EXIT_VMGEXIT events that are handled in
>       userspace.
> 37-49: Support for creating a cryptographic "launch" context and populating
>       various OVMF metadata pages, BIOS regions, and vCPU/VMSA pages with
>       the initial encrypted/measured/validated launch data prior to
>       launching the SNP guest.
> 
> 
> Testing
> -------
> 
> This series has been tested against the following host kernel tree, which
> is a snapshot of the latest WIP SNP hypervisor tree at the time of this
> posting. It will likely not be kept up to date afterward, so please keep an
> eye upstream or official AMDESE github if you are looking for the latest
> some time after this posting:
> 
>  https://github.com/mdroth/linux/commits/snp-host-v12-wip40/
> 
> A patched OVMF is also needed due to upstream KVM no longer supporting MMIO
> ranges that are mapped as private. It is recommended you build the AmdSevX64
> variant as it provides the kernel-hashing support present in this series:
> 
>  https://github.com/mdroth/edk2/commits/apic-mmio-fix1c/
> 
> A basic command-line invocation for SNP would be:
> 
> qemu-system-x86_64 -smp 32,maxcpus=255 -cpu EPYC-Milan-v2
>  -machine q35,confidential-guest-support=sev0,memory-backend=ram1
>  -object memory-backend-memfd,id=ram1,size=4G,share=true,reserve=false
>  -object sev-snp-guest,id=sev0,cbitpos=51,reduced-phys-bits=1,id-auth=
>  -bios /home/mroth/ovmf/OVMF_CODE-upstream-20240228-apicfix-1c-AmdSevX64.fd
> 
> With kernel-hashing and certificate data supplied:
> 
> qemu-system-x86_64 -smp 32,maxcpus=255 -cpu EPYC-Milan-v2
>  -machine q35,confidential-guest-support=sev0,memory-backend=ram1
>  -object memory-backend-memfd,id=ram1,size=4G,share=true,reserve=false
>  -object 
> sev-snp-guest,id=sev0,cbitpos=51,reduced-phys-bits=1,id-auth=,certs-path=/home/mroth/cert.blob,kernel-hashes=on
>  -bios /home/mroth/ovmf/OVMF_CODE-upstream-20240228-apicfix-1c-AmdSevX64.fd
>  -kernel /boot/vmlinuz-6.8.0-snp-host-v12-wip40+
>  -initrd /boot/initrd.img-6.8.0-snp-host-v12-wip40+
>  -append "root=UUID=d72a6d1c-06cf-4b79-af43-f1bac4f620f9 ro 
> console=ttyS0,115200n8"
> 
> Any comments/feedback would be very much appreciated.
> 
> [1] https://github.com/amdese/linux
>    https://github.com/amdese/amdsev/tree/snp-latest
> 
> Changes since rfc2:
> 
> - reworked on top of guest_memfd support
> - added handling for various KVM_EXIT_VMGEXIT events
> - various changes/considerations for PCI passthrough support
> - general bugfixes/hardening/cleanups
> - qapi cmdline doc fixes/rework (Dov, Markus)
> - switch to qbase64_decode, more error-checking for cmdline opts (Dov)
> - unset id_block_en for 0 input (Dov)
> - use error_setg in snp init (Dov)
> - report more info in trace_kvm_sev_init (Dov)
> - rework bounds-checking for kvm_cpuid_info, rework existing checks for 
> readability, add additional checks (Dov)
> - fixups for validated_ranges handling (Dov)
> - rename 'policy' field to 'snp-policy' in query-sev when sev-type is SNP
> 
> Changes since rfc1:
> 
> - rebased onto latest master
> - drop SNP config file in favor of a new 'sev-snp-guest' object where all
>   SNP-related params are passed as strings/integers via command-line
> - report specific error if BIOS reports invalid address/len for
>   reserved/pre-validated regions (Connor)
> - use Range helpers for handling validated region overlaps (Dave)
> - simplify error handling in sev_snp_launch_start, and report the correct
>   return code when handling LAUNCH_START failures (Dov)
> - add SEV-SNP bit to CPUID 0x8000001f when SNP enabled
> - updated query-sev to handle differences between SEV and SEV-SNP
> - updated to work against v5 of SEV-SNP host kernel / hypervisor patches
> 
> ----------------------------------------------------------------
> Brijesh Singh (5):
>      i386/sev: Introduce 'sev-snp-guest' object
>      i386/sev: Add the SNP launch start context
>      i386/sev: Add handling to encrypt/finalize guest launch data
>      hw/i386/sev: Add function to get SEV metadata from OVMF header
>      i386/sev: Add support for populating OVMF metadata pages
> 
> Chao Peng (2):
>      kvm: Enable KVM_SET_USER_MEMORY_REGION2 for memslot
>      kvm: handle KVM_EXIT_MEMORY_FAULT
> 
> Dov Murik (4):
>      qapi, i386: Move kernel-hashes to SevCommonProperties
>      i386/sev: Extract build_kernel_loader_hashes
>      i386/sev: Reorder struct declarations
>      i386/sev: Allow measured direct kernel boot on SNP
> 
> Isaku Yamahata (2):
>      pci-host/q35: Move PAM initialization above SMRAM initialization
>      q35: Introduce smm_ranges property for q35-pci-host
> 
> Michael Roth (30):
>      Revert "linux-headers hack" from sevinit2 base tree
>      scripts/update-linux-headers: Add setup_data.h to import list
>      scripts/update-linux-headers: Add bits.h to file imports
>      [HACK] linux-headers: Update headers for 6.8 + kvm-coco-queue + SNP
>      [TEMP] hw/i386: Remove redeclaration of struct setup_data
>      RAMBlock: Add support of KVM private guest memfd
>      [FIXUP] "kvm: handle KVM_EXIT_MEMORY_FAULT": drop qemu_host_page_size
>      trace/kvm: Add trace for page convertion between shared and private
>      kvm: Make kvm_convert_memory() obey ram_block_discard_is_enabled()
>      trace/kvm: Add trace for KVM_EXIT_MEMORY_FAULT
>      i386/sev: Introduce "sev-common" type to encapsulate common SEV state
>      i386/sev: Add a sev_snp_enabled() helper
>      target/i386: Add handling for KVM_X86_SNP_VM VM type
>      i386/sev: Skip RAMBlock notifiers for SNP
>      i386/sev: Skip machine-init-done notifiers for SNP
>      i386/sev: Set ms->require_guest_memfd for SNP
>      i386/sev: Disable SMM for SNP
>      i386/sev: Don't disable block discarding for SNP
>      i386/cpu: Set SEV-SNP CPUID bit when SNP enabled
>      i386/sev: Update query-sev QAPI format to handle SEV-SNP
>      i386/sev: Don't return launch measurements for SEV-SNP guests
>      kvm: Make kvm_convert_memory() non-static
>      i386/sev: Add KVM_EXIT_VMGEXIT handling for Page State Changes
>      i386/sev: Add KVM_EXIT_VMGEXIT handling for Page State Changes 
> (MSR-based)
>      i386/sev: Add KVM_EXIT_VMGEXIT handling for Extended Guest Requests
>      i386/sev: Set CPU state to protected once SNP guest payload is finalized
>      i386/sev: Add support for SNP CPUID validation
>      hw/i386/sev: Add support to encrypt BIOS when SEV-SNP is enabled
>      hw/i386/sev: Use guest_memfd for legacy ROMs
>      hw/i386: Add support for loading BIOS using guest_memfd
> 
> Xiaoyao Li (6):
>      HostMem: Add mechanism to opt in kvm guest memfd via MachineState
>      trace/kvm: Split address space and slot id in trace_kvm_set_user_memory()
>      kvm: Introduce support for memory_attributes
>      physmem: Introduce ram_block_discard_guest_memfd_range()
>      kvm/memory: Make memory type private by default if it has guest memfd 
> backend
>      memory: Introduce memory_region_init_ram_guest_memfd()
> 
> accel/kvm/kvm-all.c                                |  241 ++-
> accel/kvm/trace-events                             |    4 +-
> accel/stubs/kvm-stub.c                             |    5 +
> backends/hostmem-file.c                            |    1 +
> backends/hostmem-memfd.c                           |    1 +
> backends/hostmem-ram.c                             |    1 +
> backends/hostmem.c                                 |    1 +
> docs/system/i386/amd-memory-encryption.rst         |   78 +-
> hw/core/machine.c                                  |    5 +
> hw/i386/pc.c                                       |   13 +-
> hw/i386/pc_q35.c                                   |    2 +
> hw/i386/pc_sysfw.c                                 |   25 +-
> hw/i386/pc_sysfw_ovmf.c                            |   33 +
> hw/i386/x86.c                                      |   46 +-
> hw/pci-host/q35.c                                  |   61 +-
> include/exec/cpu-common.h                          |    2 +
> include/exec/memory.h                              |   26 +-
> include/exec/ram_addr.h                            |    2 +-
> include/exec/ramblock.h                            |    1 +
> include/hw/boards.h                                |    2 +
> include/hw/i386/pc.h                               |   31 +-
> include/hw/i386/x86.h                              |    2 +-
> include/hw/pci-host/q35.h                          |    1 +
> include/standard-headers/asm-x86/bootparam.h       |   17 +-
> include/standard-headers/asm-x86/kvm_para.h        |    3 +-
> include/standard-headers/linux/ethtool.h           |   48 +
> include/standard-headers/linux/fuse.h              |   39 +-
> include/standard-headers/linux/input-event-codes.h |    1 +
> include/standard-headers/linux/virtio_gpu.h        |    2 +
> include/standard-headers/linux/virtio_snd.h        |  154 ++
> include/sysemu/hostmem.h                           |    1 +
> include/sysemu/kvm.h                               |    7 +
> include/sysemu/kvm_int.h                           |    2 +
> linux-headers/asm-arm64/kvm.h                      |   15 +-
> linux-headers/asm-arm64/sve_context.h              |   11 +
> linux-headers/asm-generic/bitsperlong.h            |    4 +
> linux-headers/asm-loongarch/kvm.h                  |    2 -
> linux-headers/asm-mips/kvm.h                       |    2 -
> linux-headers/asm-powerpc/kvm.h                    |   45 +-
> linux-headers/asm-riscv/kvm.h                      |    3 +-
> linux-headers/asm-s390/kvm.h                       |  315 +++-
> linux-headers/asm-x86/kvm.h                        |  372 ++++-
> linux-headers/asm-x86/setup_data.h                 |   83 +
> linux-headers/linux/bits.h                         |   15 +
> linux-headers/linux/kvm.h                          |  719 +--------
> linux-headers/linux/psp-sev.h                      |   71 +
> qapi/misc-target.json                              |   71 +-
> qapi/qom.json                                      |   96 +-
> scripts/update-linux-headers.sh                    |    5 +-
> system/memory.c                                    |   30 +
> system/physmem.c                                   |   47 +-
> target/i386/cpu.c                                  |    1 +
> target/i386/kvm/kvm.c                              |    4 +
> target/i386/sev-sysemu-stub.c                      |    2 +-
> target/i386/sev.c                                  | 1631 ++++++++++++++++----
> target/i386/sev.h                                  |   13 +-
> target/i386/trace-events                           |    3 +
> 57 files changed, 3272 insertions(+), 1146 deletions(-)
> create mode 100644 linux-headers/asm-x86/setup_data.h
> create mode 100644 linux-headers/linux/bits.h
> 
> 
> 
>