From: Brijesh Singh <brijesh.singh@xxxxxxx> KVM_SEV_SNP_LAUNCH_START begins the launch process for an SEV-SNP guest. The command initializes a cryptographic digest context used to construct the measurement of the guest. If the guest is expected to be migrated, the command also binds a migration agent (MA) to the guest. For more information see the SEV-SNP specification. Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx> [mdr: hold sev_deactivate_lock when calling SEV_CMD_SNP_DECOMMISSION] Signed-off-by: Michael Roth <michael.roth@xxxxxxx> --- .../virt/kvm/x86/amd-memory-encryption.rst | 24 +++ arch/x86/kvm/svm/sev.c | 144 +++++++++++++++++- arch/x86/kvm/svm/svm.h | 1 + include/uapi/linux/kvm.h | 10 ++ 4 files changed, 176 insertions(+), 3 deletions(-) diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst index b1a19c9a577a..b1beb2fe8766 100644 --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst @@ -461,6 +461,30 @@ The flags bitmap is defined as:: If the specified flags is not supported then return -EOPNOTSUPP, and the supported flags are returned. +19. KVM_SNP_LAUNCH_START +------------------------ + +The KVM_SNP_LAUNCH_START command is used for creating the memory encryption +context for the SEV-SNP guest. To create the encryption context, user must +provide a guest policy, migration agent (if any) and guest OS visible +workarounds value as defined SEV-SNP specification. + +Parameters (in): struct kvm_snp_launch_start + +Returns: 0 on success, -negative on error + +:: + + struct kvm_sev_snp_launch_start { + __u64 policy; /* Guest policy to use. */ + __u64 ma_uaddr; /* userspace address of migration agent */ + __u8 ma_en; /* 1 if the migration agent is enabled */ + __u8 imi_en; /* set IMI to 1. */ + __u8 gosvw[16]; /* guest OS visible workarounds */ + }; + +See the SEV-SNP specification for further detail on the launch input. + References ========== diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 43b8ae7b74f8..e2f4d4bc125c 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -24,6 +24,7 @@ #include <asm/trapnr.h> #include <asm/fpu/xcr.h> #include <asm/debugreg.h> +#include <asm/sev.h> #include "mmu.h" #include "x86.h" @@ -72,6 +73,10 @@ static bool sev_snp_enabled; #define AP_RESET_HOLD_NAE_EVENT 1 #define AP_RESET_HOLD_MSR_PROTO 2 +/* As defined by SEV-SNP Firmware ABI, under "Guest Policy". */ +#define SNP_POLICY_MASK_SMT BIT_ULL(16) +#define SNP_POLICY_MASK_SINGLE_SOCKET BIT_ULL(20) + static u8 sev_enc_bit; static DECLARE_RWSEM(sev_deactivate_lock); static DEFINE_MUTEX(sev_bitmap_lock); @@ -82,6 +87,8 @@ static unsigned int nr_asids; static unsigned long *sev_asid_bitmap; static unsigned long *sev_reclaim_asid_bitmap; +static int snp_decommission_context(struct kvm *kvm); + struct enc_region { struct list_head list; unsigned long npages; @@ -107,12 +114,17 @@ static int sev_flush_asids(int min_asid, int max_asid) down_write(&sev_deactivate_lock); wbinvd_on_all_cpus(); - ret = sev_guest_df_flush(&error); + + if (sev_snp_enabled) + ret = sev_do_cmd(SEV_CMD_SNP_DF_FLUSH, NULL, &error); + else + ret = sev_guest_df_flush(&error); up_write(&sev_deactivate_lock); if (ret) - pr_err("SEV: DF_FLUSH failed, ret=%d, error=%#x\n", ret, error); + pr_err("SEV%s: DF_FLUSH failed, ret=%d, error=%#x\n", + sev_snp_enabled ? "-SNP" : "", ret, error); return ret; } @@ -1890,6 +1902,94 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) return ret; } +/* + * The guest context contains all the information, keys and metadata + * associated with the guest that the firmware tracks to implement SEV + * and SNP features. The firmware stores the guest context in hypervisor + * provide page via the SNP_GCTX_CREATE command. + */ +static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp) +{ + struct sev_data_snp_addr data = {}; + void *context; + int rc; + + /* Allocate memory for context page */ + context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT); + if (!context) + return NULL; + + data.gctx_paddr = __psp_pa(context); + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, &data, &argp->error); + if (rc) { + snp_free_firmware_page(context); + return NULL; + } + + return context; +} + +static int snp_bind_asid(struct kvm *kvm, int *error) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + struct sev_data_snp_activate data = {0}; + + data.gctx_paddr = __psp_pa(sev->snp_context); + data.asid = sev_get_asid(kvm); + return sev_issue_cmd(kvm, SEV_CMD_SNP_ACTIVATE, &data, error); +} + +static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + struct sev_data_snp_launch_start start = {0}; + struct kvm_sev_snp_launch_start params; + int rc; + + if (!sev_snp_guest(kvm)) + return -ENOTTY; + + if (copy_from_user(¶ms, (void __user *)(uintptr_t)argp->data, sizeof(params))) + return -EFAULT; + + /* Don't allow userspace to allocate memory for more than 1 SNP context. */ + if (sev->snp_context) + return -EINVAL; + + sev->snp_context = snp_context_create(kvm, argp); + if (!sev->snp_context) + return -ENOTTY; + + if (params.policy & SNP_POLICY_MASK_SINGLE_SOCKET) { + pr_warn("SEV-SNP hypervisor does not support limiting guests to a single socket."); + return -EINVAL; + } + + if (!(params.policy & SNP_POLICY_MASK_SMT)) { + pr_warn("SEV-SNP hypervisor does not support limiting guests to a single SMT thread."); + return -EINVAL; + } + + start.gctx_paddr = __psp_pa(sev->snp_context); + start.policy = params.policy; + memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw)); + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error); + if (rc) + goto e_free_context; + + sev->fd = argp->sev_fd; + rc = snp_bind_asid(kvm, &argp->error); + if (rc) + goto e_free_context; + + return 0; + +e_free_context: + snp_decommission_context(kvm); + + return rc; +} + int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp) { struct kvm_sev_cmd sev_cmd; @@ -1980,6 +2080,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp) case KVM_SEV_RECEIVE_FINISH: r = sev_receive_finish(kvm, &sev_cmd); break; + case KVM_SEV_SNP_LAUNCH_START: + r = snp_launch_start(kvm, &sev_cmd); + break; default: r = -EINVAL; goto out; @@ -2172,6 +2275,33 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd) return ret; } +static int snp_decommission_context(struct kvm *kvm) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + struct sev_data_snp_addr data = {}; + int ret; + + /* If context is not created then do nothing */ + if (!sev->snp_context) + return 0; + + data.gctx_paddr = __sme_pa(sev->snp_context); + down_write(&sev_deactivate_lock); + ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL); + if (WARN_ONCE(ret, "failed to release guest context")) { + up_write(&sev_deactivate_lock); + return ret; + } + + up_write(&sev_deactivate_lock); + + /* free the context page now */ + snp_free_firmware_page(sev->snp_context); + sev->snp_context = NULL; + + return 0; +} + void sev_vm_destroy(struct kvm *kvm) { struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; @@ -2213,7 +2343,15 @@ void sev_vm_destroy(struct kvm *kvm) } } - sev_unbind_asid(kvm, sev->handle); + if (sev_snp_guest(kvm)) { + if (snp_decommission_context(kvm)) { + WARN_ONCE(1, "Failed to free SNP guest context, leaking asid!\n"); + return; + } + } else { + sev_unbind_asid(kvm, sev->handle); + } + sev_asid_free(sev); } diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 07a9eb5b6ce5..9c633173b779 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -95,6 +95,7 @@ struct kvm_sev_info { struct misc_cg *misc_cg; /* For misc cgroup accounting */ atomic_t migration_in_progress; u64 snp_init_flags; + void *snp_context; /* SNP guest context page */ }; struct kvm_svm { diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 73702e9b9d76..9fe36408d55b 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1871,6 +1871,7 @@ enum sev_cmd_id { /* SNP specific commands */ KVM_SEV_SNP_INIT, + KVM_SEV_SNP_LAUNCH_START, KVM_SEV_NR_MAX, }; @@ -1978,6 +1979,15 @@ struct kvm_snp_init { __u64 flags; }; +struct kvm_sev_snp_launch_start { + __u64 policy; + __u64 ma_uaddr; + __u8 ma_en; + __u8 imi_en; + __u8 gosvw[16]; + __u8 pad[6]; +}; + #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0) #define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1) #define KVM_DEV_ASSIGN_MASK_INTX (1 << 2) -- 2.25.1