| Message ID | 20240421180122.1650812-1-michael.roth@amd.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support | expand |
Quoting Michael Roth (2024-04-21 13:01:00) > This patchset is also available at: > > https://github.com/amdese/linux/commits/snp-host-v14 > > and is based on commit 20cc50a0410f (just before the v13 SNP patches) from: > > https://git.kernel.org/pub/scm/virt/kvm/kvm.git/log/?h=kvm-coco-queue > > > Patch Layout > ------------ > > 01-04: These patches add some basic infrastructure and introduces a new > KVM_X86_SNP_VM vm_type to handle differences verses the existing > KVM_X86_SEV_VM and KVM_X86_SEV_ES_VM types. > > 05-07: These implement the KVM API to handle the creation of a > cryptographic launch context, encrypt/measure the initial image > into guest memory, and finalize it before launching it. > > 08-13: These implement handling for various guest-generated events such > as page state changes, onlining of additional vCPUs, etc. > > 14-17: These implement the gmem hooks needed to prepare gmem-allocated > pages before mapping them into guest private memory ranges as > well as cleaning them up prior to returning them to the host for > use as normal memory. Because this supplants certain activities > like issued WBINVDs during KVM MMU invalidations, there's also > a patch to avoid duplicating that work to avoid unecessary > overhead. > > 18: With all the core support in place, the patch adds a kvm_amd module > parameter to enable SNP support. > > 19-22: These patches all deal with the servicing of guest requests to handle > things like attestation, as well as some related host-management > interfaces. I just sent an additional set of fixups, patches 23-29. These add some additional input validation on GHCB requests, mainly ensuring that SNP-specific requests from non-SNP guests result in an error as soon as they are received rather than reaching an error state indirectly further into the call stack. It's a small diff (included below), but a bit of a pain to squash in patch by patch due to close proximity with each other, so I've pushed an updated branch here that already has them squashed in: https://github.com/amdese/linux/commits/snp-host-v14b If preferred I can also resubmit as v15, just let me know. Full diff is below. Thanks! -Mike diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 1cec466e593b..1137a7f4136b 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3280,6 +3280,8 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm) goto vmgexit_err; break; case SVM_VMGEXIT_AP_CREATION: + if (!sev_snp_guest(vcpu->kvm)) + goto vmgexit_err; if (lower_32_bits(control->exit_info_1) != SVM_VMGEXIT_AP_DESTROY) if (!kvm_ghcb_rax_is_valid(svm)) goto vmgexit_err; @@ -3289,10 +3291,19 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm) case SVM_VMGEXIT_AP_JUMP_TABLE: case SVM_VMGEXIT_UNSUPPORTED_EVENT: case SVM_VMGEXIT_HV_FEATURES: - case SVM_VMGEXIT_PSC: case SVM_VMGEXIT_TERM_REQUEST: + break; + case SVM_VMGEXIT_PSC: case SVM_VMGEXIT_GUEST_REQUEST: + if (!sev_snp_guest(vcpu->kvm)) + goto vmgexit_err; + break; case SVM_VMGEXIT_EXT_GUEST_REQUEST: + if (!sev_snp_guest(vcpu->kvm)) + goto vmgexit_err; + if (!kvm_ghcb_rax_is_valid(svm) || + !kvm_ghcb_rbx_is_valid(svm)) + goto vmgexit_err; break; default: reason = GHCB_ERR_INVALID_EVENT; @@ -3970,6 +3981,9 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) GHCB_MSR_INFO_MASK, GHCB_MSR_INFO_POS); break; case GHCB_MSR_PREF_GPA_REQ: + if (!sev_snp_guest(vcpu->kvm)) + goto out_terminate; + set_ghcb_msr_bits(svm, GHCB_MSR_PREF_GPA_NONE, GHCB_MSR_GPA_VALUE_MASK, GHCB_MSR_GPA_VALUE_POS); set_ghcb_msr_bits(svm, GHCB_MSR_PREF_GPA_RESP, GHCB_MSR_INFO_MASK, @@ -3978,6 +3992,9 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) case GHCB_MSR_REG_GPA_REQ: { u64 gfn; + if (!sev_snp_guest(vcpu->kvm)) + goto out_terminate; + gfn = get_ghcb_msr_bits(svm, GHCB_MSR_GPA_VALUE_MASK, GHCB_MSR_GPA_VALUE_POS); @@ -3990,6 +4007,9 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) break; } case GHCB_MSR_PSC_REQ: + if (!sev_snp_guest(vcpu->kvm)) + goto out_terminate; + ret = snp_begin_psc_msr(vcpu, control->ghcb_gpa); break; case GHCB_MSR_TERM_REQ: { @@ -4004,12 +4024,7 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) pr_info("SEV-ES guest requested termination: %#llx:%#llx\n", reason_set, reason_code); - vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT; - vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SEV_TERM; - vcpu->run->system_event.ndata = 1; - vcpu->run->system_event.data[0] = control->ghcb_gpa; - - return 0; + goto out_terminate; } default: /* Error, keep GHCB MSR value as-is */ @@ -4020,6 +4035,14 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) control->ghcb_gpa, ret); return ret; + +out_terminate: + vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT; + vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SEV_TERM; + vcpu->run->system_event.ndata = 1; + vcpu->run->system_event.data[0] = control->ghcb_gpa; + + return 0; } int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
On Tue, Apr 23, 2024 at 6:32 PM Michael Roth <michael.roth@amd.com> wrote: > I just sent an additional set of fixups, patches 23-29. These add some > additional input validation on GHCB requests, mainly ensuring that > SNP-specific requests from non-SNP guests result in an error as soon as > they are received rather than reaching an error state indirectly further > into the call stack. > > It's a small diff (included below), but a bit of a pain to squash in > patch by patch due to close proximity with each other, so I've pushed an > updated branch here that already has them squashed in: > > https://github.com/amdese/linux/commits/snp-host-v14b Thanks, I pushed that to kvm-coco-queue. There was a missing signoff - I just added it since you actually added it in the past[1] and the patch only differs in context. Now off to getting those mm acks. Paolo [1] https://patchew.org/linux/20231230172351.574091-1-michael.roth@amd.com/20231230172351.574091-33-michael.roth@amd.com/
This patchset is also available at: https://github.com/amdese/linux/commits/snp-host-v14 and is based on commit 20cc50a0410f (just before the v13 SNP patches) from: https://git.kernel.org/pub/scm/virt/kvm/kvm.git/log/?h=kvm-coco-queue Patch Layout ------------ 01-04: These patches add some basic infrastructure and introduces a new KVM_X86_SNP_VM vm_type to handle differences verses the existing KVM_X86_SEV_VM and KVM_X86_SEV_ES_VM types. 05-07: These implement the KVM API to handle the creation of a cryptographic launch context, encrypt/measure the initial image into guest memory, and finalize it before launching it. 08-13: These implement handling for various guest-generated events such as page state changes, onlining of additional vCPUs, etc. 14-17: These implement the gmem hooks needed to prepare gmem-allocated pages before mapping them into guest private memory ranges as well as cleaning them up prior to returning them to the host for use as normal memory. Because this supplants certain activities like issued WBINVDs during KVM MMU invalidations, there's also a patch to avoid duplicating that work to avoid unecessary overhead. 18: With all the core support in place, the patch adds a kvm_amd module parameter to enable SNP support. 19-22: These patches all deal with the servicing of guest requests to handle things like attestation, as well as some related host-management interfaces. Testing ------- For testing this via QEMU, use the following tree: https://github.com/amdese/qemu/commits/snp-v4-wip3b 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/amdese/ovmf/commits/apic-mmio-fix1d 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 OVMF_CODE-upstream-20240410-apic-mmio-fix1d-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 OVMF_CODE-upstream-20240410-apic-mmio-fix1d-AmdSevX64.fd -kernel /boot/vmlinuz-$ver -initrd /boot/initrd.img-$ver -append "root=UUID=d72a6d1c-06cf-4b79-af43-f1bac4f620f9 ro console=ttyS0,115200n8" With standard X64 OVMF package with separate image for persistent NVRAM: 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 OVMF_CODE-upstream-20240410-apic-mmio-fix1d.fd -drive if=pflash,format=raw,unit=0,file=OVMF_VARS-upstream-20240410-apic-mmio-fix1d.fd,readonly=off Known issues / TODOs -------------------- * Base tree in some cases reports "Unpatched return thunk in use. This should not happen!" the first time it runs an SVM/SEV/SNP guests. This a recent regression upstream and unrelated to this series: https://lore.kernel.org/linux-kernel/CANpmjNOcKzEvLHoGGeL-boWDHJobwfwyVxUqMq2kWeka3N4tXA@mail.gmail.com/T/ * 2MB hugepage support has been dropped pending discussion on how we plan to re-enable it in gmem. * Host kexec should work, but there is a known issue with host kdump support while SNP guests are running that will be addressed as a follow-up. * SNP kselftests are currently a WIP and will be included as part of SNP upstreaming efforts in the near-term. SEV-SNP Overview ---------------- This part of the Secure Encrypted Paging (SEV-SNP) series focuses on the changes required to add KVM support for SEV-SNP. This series builds upon SEV-SNP guest support, which is now in mainline, and and SEV-SNP host initialization support, which is now in linux-next. While series provides the basic building blocks to support booting the SEV-SNP VMs, it does not cover all the security enhancement introduced by the SEV-SNP such as interrupt protection, which will added in the future. With SNP, when pages are marked as guest-owned in the RMP table, they are assigned to a specific guest/ASID, as well as a specific GFN with in the guest. Any attempts to map it in the RMP table to a different guest/ASID, or a different GFN within a guest/ASID, will result in an RMP nested page fault. Prior to accessing a guest-owned page, the guest must validate it with a special PVALIDATE instruction which will set a special bit in the RMP table for the guest. This is the only way to set the validated bit outside of the initial pre-encrypted guest payload/image; any attempts outside the guest to modify the RMP entry from that point forward will result in the validated bit being cleared, at which point the guest will trigger an exception if it attempts to access that page so it can be made aware of possible tampering. One exception to this is the initial guest payload, which is pre-validated by the firmware prior to launching. The guest can use Guest Message requests to fetch an attestation report which will include the measurement of the initial image so that the guest can verify it was booted with the expected image/environment. After boot, guests can use Page State Change requests to switch pages between shared/hypervisor-owned and private/guest-owned to share data for things like DMA, virtio buffers, and other GHCB requests. In this implementation of SEV-SNP, private guest memory is managed by a new kernel framework called guest_memfd (gmem). With gmem, a new KVM_SET_MEMORY_ATTRIBUTES KVM ioctl has been added to tell the KVM MMU whether a particular GFN should be backed by shared (normal) memory or private (gmem-allocated) memory. To tie into this, Page State Change requests are forward to userspace via KVM_EXIT_VMGEXIT exits, which will then issue the corresponding KVM_SET_MEMORY_ATTRIBUTES call to set the private/shared state in the KVM MMU. The gmem / KVM MMU hooks implemented in this series will then update the RMP table entries for the backing PFNs to set them to guest-owned/private when mapping private pages into the guest via KVM MMU, or use the normal KVM MMU handling in the case of shared pages where the corresponding RMP table entries are left in the default shared/hypervisor-owned state. Feedback/review is very much appreciated! -Mike Changes since v13: * rebase to new kvm-coco-queue and wire up to PFERR_PRIVATE_ACCESS (Paolo) * handle setting kvm->arch.has_private_mem in same location as kvm->arch.has_protected_state (Paolo) * add flags and additional padding fields to snp_launch{start,update,finish} APIs to address alignment and expandability (Paolo) * update snp_launch_update() to update input struct values to reflect current progress of command in situations where mulitple calls are needed (Paolo) * update snp_launch_update() to avoid copying/accessing 'src' parameter when dealing with zero pages. (Paolo) * update snp_launch_update() to use u64 as length input parameter instead of u32 and adjust padding accordingly * modify ordering of SNP_POLICY_MASK_* definitions to be consistent with bit order of corresponding flags * let firmware handle enforcement of policy bits corresponding to user-specified minimum API version * add missing "0x" prefixs in pr_debug()'s for snp_launch_start() * fix handling of VMSAs during in-place migration (Paolo) Changes since v12: * rebased to latest kvm-coco-queue branch (commit 4d2deb62185f) * add more input validation for SNP_LAUNCH_START, especially for handling things like MBO/MBZ policy bits, and API major/minor minimums. (Paolo) * block SNP KVM instances from being able to run legacy SEV commands (Paolo) * don't attempt to measure VMSA for vcpu 0/BSP before the others, let userspace deal with the ordering just like with SEV-ES (Paolo) * fix up docs for SNP_LAUNCH_FINISH (Paolo) * introduce svm->sev_es.snp_has_guest_vmsa flag to better distinguish handling for guest-mapped vs non-guest-mapped VMSAs, rename 'snp_ap_create' flag to 'snp_ap_waiting_for_reset' (Paolo) * drop "KVM: SEV: Use a VMSA physical address variable for populating VMCB" as it is no longer needed due to above VMSA rework * replace pr_debug_ratelimited() messages for RMP #NPFs with a single trace event * handle transient PSMASH_FAIL_INUSE return codes in kvm_gmem_invalidate(), switch to WARN_ON*()'s to indicate remaining error cases are not expected and should not be seen in practice. (Paolo) * add a cond_resched() in kvm_gmem_invalidate() to avoid soft lock-ups when cleaning up large guest memory ranges. * rename VLEK_REQUIRED to VCEK_DISABLE. it's be more applicable if another key type ever gets added. * don't allow attestation to be paused while an attestation request is being processed by firmware (Tom) * add missing Documentation entry for SNP_VLEK_LOAD * collect Reviewed-by's from Paolo and Tom Changes since v11: * Rebase series on kvm-coco-queue and re-work to leverage more infrastructure between SNP/TDX series. * Drop KVM_SNP_INIT in favor of the new KVM_SEV_INIT2 interface introduced here (Paolo): https://lore.kernel.org/lkml/20240318233352.2728327-1-pbonzini@redhat.com/ * Drop exposure API fields related to things like VMPL levels, migration agents, etc., until they are actually supported/used (Sean) * Rework KVM_SEV_SNP_LAUNCH_UPDATE handling to use a new kvm_gmem_populate() interface instead of copying data directly into gmem-allocated pages (Sean) * Add support for SNP_LOAD_VLEK, rework the SNP_SET_CONFIG_{START,END} to have simpler semantics that are applicable to management of SNP_LOAD_VLEK updates as well, rename interfaces to the now more appropriate SNP_{PAUSE,RESUME}_ATTESTATION * Fix up documentation wording and do print warnings for userspace-triggerable failures (Peter, Sean) * Fix a race with AP_CREATION wake-up events (Jacob, Sean) * Fix a memory leak with VMSA pages (Sean) * Tighten up handling of RMP page faults to better distinguish between real and spurious cases (Tom) * Various patch/documentation rewording, cleanups, etc. ---------------------------------------------------------------- Ashish Kalra (1): KVM: SEV: Avoid WBINVD for HVA-based MMU notifications for SNP Brijesh Singh (11): KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests KVM: SEV: Add initial SEV-SNP support KVM: SEV: Add KVM_SEV_SNP_LAUNCH_START command KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command KVM: SEV: Add KVM_SEV_SNP_LAUNCH_FINISH command KVM: SEV: Add support to handle GHCB GPA register VMGEXIT KVM: SEV: Add support to handle MSR based Page State Change VMGEXIT KVM: SEV: Add support to handle Page State Change VMGEXIT KVM: SEV: Add support to handle RMP nested page faults KVM: SVM: Add module parameter to enable SEV-SNP KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event Michael Roth (8): KVM: SEV: Select KVM_GENERIC_PRIVATE_MEM when CONFIG_KVM_AMD_SEV=y KVM: SEV: Add support for GHCB-based termination requests KVM: SEV: Implement gmem hook for initializing private pages KVM: SEV: Implement gmem hook for invalidating private pages KVM: x86: Implement gmem hook for determining max NPT mapping level crypto: ccp: Add the SNP_VLEK_LOAD command crypto: ccp: Add the SNP_{PAUSE,RESUME}_ATTESTATION commands KVM: SEV: Provide support for SNP_EXTENDED_GUEST_REQUEST NAE event Tom Lendacky (2): KVM: SEV: Add support to handle AP reset MSR protocol KVM: SEV: Support SEV-SNP AP Creation NAE event Documentation/virt/coco/sev-guest.rst | 69 +- Documentation/virt/kvm/api.rst | 73 + .../virt/kvm/x86/amd-memory-encryption.rst | 110 +- arch/x86/include/asm/kvm_host.h | 2 + arch/x86/include/asm/sev-common.h | 22 +- arch/x86/include/asm/sev.h | 15 + arch/x86/include/asm/svm.h | 9 +- arch/x86/include/uapi/asm/kvm.h | 48 + arch/x86/kvm/Kconfig | 3 + arch/x86/kvm/mmu.h | 2 - arch/x86/kvm/mmu/mmu.c | 1 + arch/x86/kvm/svm/sev.c | 1447 +++++++++++++++++++- arch/x86/kvm/svm/svm.c | 44 +- arch/x86/kvm/svm/svm.h | 50 + arch/x86/kvm/trace.h | 31 + arch/x86/kvm/x86.c | 17 + arch/x86/virt/svm/sev.c | 80 ++ drivers/crypto/ccp/sev-dev.c | 83 ++ include/linux/psp-sev.h | 4 +- include/uapi/linux/kvm.h | 28 + include/uapi/linux/psp-sev.h | 39 + include/uapi/linux/sev-guest.h | 9 + virt/kvm/guest_memfd.c | 4 +- 23 files changed, 2155 insertions(+), 35 deletions(-)