From: Joerg Roedel <[email protected]> Advertise and handle the GHCB APIC ID list feature so that SNP guests can discover the vCPUs for which they need to create VMSAs without relying on INIT-SIPI.
Return the required page count for undersized buffers. For sufficiently large requests, validate the GPA range and use KVM's SRCU-protected guest write path to copy an exact snapshot of the online vCPU APIC IDs. Assisted-by: LLM Signed-off-by: Joerg Roedel <[email protected]> --- arch/x86/include/asm/sev-common.h | 1 + arch/x86/include/uapi/asm/svm.h | 1 + arch/x86/kvm/svm/sev.c | 67 ++++++++++++++++++++++++++++++- 3 files changed, 67 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index 01a6e4dbe423..c041f85dfd5c 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -136,6 +136,7 @@ enum psc_op { #define GHCB_HV_FT_SNP BIT_ULL(0) #define GHCB_HV_FT_SNP_AP_CREATION BIT_ULL(1) +#define GHCB_HV_FT_APIC_ID_LIST BIT_ULL(4) #define GHCB_HV_FT_SNP_MULTI_VMPL BIT_ULL(5) /* diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h index 010a45c9f614..05e5e31e23e1 100644 --- a/arch/x86/include/uapi/asm/svm.h +++ b/arch/x86/include/uapi/asm/svm.h @@ -117,6 +117,7 @@ #define SVM_VMGEXIT_AP_CREATE_ON_INIT 0 #define SVM_VMGEXIT_AP_CREATE 1 #define SVM_VMGEXIT_AP_DESTROY 2 +#define SVM_VMGEXIT_GET_APIC_IDS 0x80000017ull #define SVM_VMGEXIT_SNP_RUN_VMPL 0x80000018ull #define SVM_VMGEXIT_SAVIC 0x8000001aull #define SVM_VMGEXIT_SAVIC_REGISTER_GPA 0 diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 5705723f1f41..c16eca9983f3 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -40,7 +40,9 @@ #define GHCB_VERSION_MAX 2ULL #define GHCB_VERSION_MIN 1ULL -#define GHCB_HV_FT_SUPPORTED (GHCB_HV_FT_SNP | GHCB_HV_FT_SNP_AP_CREATION) +#define GHCB_HV_FT_SUPPORTED (GHCB_HV_FT_SNP | \ + GHCB_HV_FT_SNP_AP_CREATION | \ + GHCB_HV_FT_APIC_ID_LIST) /* * The GHCB spec essentially states that all non-zero error codes other than @@ -3493,7 +3495,8 @@ static bool sev_es_are_required_ghcb_fields_valid(struct vcpu_svm *svm) case SVM_VMGEXIT_AP_CREATION: return kvm_ghcb_rax_is_valid(svm) || lower_32_bits(control->exit_info_1) == SVM_VMGEXIT_AP_DESTROY; - break; + case SVM_VMGEXIT_GET_APIC_IDS: + return kvm_ghcb_rax_is_valid(svm); case SVM_VMGEXIT_MMIO_READ: case SVM_VMGEXIT_MMIO_WRITE: case SVM_VMGEXIT_PSC: @@ -4215,6 +4218,63 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm) return 0; } +struct sev_apic_id_desc { + u32 num_entries; + u32 apic_ids[]; +}; + +static int sev_snp_get_apic_ids(struct vcpu_svm *svm) +{ + struct kvm_vcpu *vcpu = &svm->vcpu; + struct kvm *kvm = vcpu->kvm; + struct sev_apic_id_desc *desc; + unsigned int nr_vcpus, size; + unsigned int i; + gpa_t gpa, end_gpa; + u64 pages; + + nr_vcpus = atomic_read(&kvm->online_vcpus); + size = sizeof(*desc) + (nr_vcpus * sizeof(desc->apic_ids[0])); + + pages = vcpu->arch.regs[VCPU_REGS_RAX]; + if (pages < PFN_UP(size)) { + vcpu->arch.regs[VCPU_REGS_RAX] = PFN_UP(size); + return 1; + } + + gpa = svm->vmcb->control.exit_info_1; + if (!PAGE_ALIGNED(gpa) || + check_add_overflow(gpa, size - 1, &end_gpa) || + !page_address_valid(vcpu, gpa) || + !page_address_valid(vcpu, end_gpa & PAGE_MASK)) + goto invalid_buffer; + + desc = kvzalloc(size, GFP_KERNEL_ACCOUNT); + if (!desc) + return -ENOMEM; + + desc->num_entries = nr_vcpus; + for (i = 0; i < nr_vcpus; i++) { + struct kvm_vcpu *listed_vcpu = kvm_get_vcpu(kvm, i); + + if (WARN_ON_ONCE(!listed_vcpu)) + goto invalid_buffer_free; + desc->apic_ids[i] = listed_vcpu->vcpu_id; + } + + if (kvm_write_guest(kvm, gpa, desc, size)) + goto invalid_buffer_free; + + kvfree(desc); + return 1; + +invalid_buffer_free: + kvfree(desc); +invalid_buffer: + svm_vmgexit_bad_input(svm, GHCB_ERR_INVALID_INPUT); + return 1; +} + static int snp_handle_guest_req(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_gpa) { struct sev_data_snp_guest_request data = {0}; @@ -4494,6 +4554,7 @@ static bool is_snp_only_vmgexit(u64 exit_code) { switch (exit_code) { case SVM_VMGEXIT_AP_CREATION: + case SVM_VMGEXIT_GET_APIC_IDS: case SVM_VMGEXIT_GUEST_REQUEST: case SVM_VMGEXIT_EXT_GUEST_REQUEST: case SVM_VMGEXIT_PSC: @@ -4665,6 +4726,8 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) if (sev_snp_ap_creation(svm)) svm_vmgexit_bad_input(svm, GHCB_ERR_INVALID_INPUT); return 1; + case SVM_VMGEXIT_GET_APIC_IDS: + return sev_snp_get_apic_ids(svm); case SVM_VMGEXIT_GUEST_REQUEST: case SVM_VMGEXIT_EXT_GUEST_REQUEST: if (!PAGE_ALIGNED(control->exit_info_1) || -- 2.53.0
