On 15/12/22 06:40, Michael Roth wrote:
From: Brijesh Singh <brijesh.singh@xxxxxxx>
Version 2 of GHCB specification added the support for two SNP Guest
Request Message NAE events. The events allows for an SEV-SNP guest to
make request to the SEV-SNP firmware through hypervisor using the
SNP_GUEST_REQUEST API define in the SEV-SNP firmware specification.
The SNP_EXT_GUEST_REQUEST is similar to SNP_GUEST_REQUEST with the
difference of an additional certificate blob that can be passed through
the SNP_SET_CONFIG ioctl defined in the CCP driver. The CCP driver
provides snp_guest_ext_guest_request() that is used by the KVM to get
both the report and certificate data at once.
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
---
arch/x86/kvm/svm/sev.c | 185 +++++++++++++++++++++++++++++++++++++++--
arch/x86/kvm/svm/svm.h | 2 +
2 files changed, 181 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 5f2b2092cdae..18efa70553c2 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -331,6 +331,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
if (ret)
goto e_free;
+ mutex_init(&sev->guest_req_lock);
ret = sev_snp_init(&argp->error, false);
} else {
ret = sev_platform_init(&argp->error);
@@ -2051,23 +2052,34 @@ int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd)
*/
static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp)
{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
struct sev_data_snp_addr data = {};
- void *context;
+ void *context, *certs_data;
int rc;
+ /* Allocate memory used for the certs data in SNP guest request */
+ certs_data = kzalloc(SEV_FW_BLOB_MAX_SIZE, GFP_KERNEL_ACCOUNT);
+ if (!certs_data)
+ return NULL;
+
/* Allocate memory for context page */
context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT);
if (!context)
- return NULL;
+ goto e_free;
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;
- }
+ if (rc)
+ goto e_free;
+
+ sev->snp_certs_data = certs_data;
return context;
+
+e_free:
+ snp_free_firmware_page(context);
+ kfree(certs_data);
+ return NULL;
}
static int snp_bind_asid(struct kvm *kvm, int *error)
@@ -2653,6 +2665,8 @@ static int snp_decommission_context(struct kvm *kvm)
snp_free_firmware_page(sev->snp_context);
sev->snp_context = NULL;
+ kfree(sev->snp_certs_data);
+
return 0;
}
@@ -3174,6 +3188,8 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm, u64 *exit_code)
case SVM_VMGEXIT_UNSUPPORTED_EVENT:
case SVM_VMGEXIT_HV_FEATURES:
case SVM_VMGEXIT_PSC:
+ case SVM_VMGEXIT_GUEST_REQUEST:
+ case SVM_VMGEXIT_EXT_GUEST_REQUEST:
break;
default:
reason = GHCB_ERR_INVALID_EVENT;
@@ -3396,6 +3412,149 @@ static int snp_complete_psc(struct kvm_vcpu *vcpu)
return 1;
}
+static unsigned long snp_setup_guest_buf(struct vcpu_svm *svm,
+ struct sev_data_snp_guest_request *data,
+ gpa_t req_gpa, gpa_t resp_gpa)
+{
+ struct kvm_vcpu *vcpu = &svm->vcpu;
+ struct kvm *kvm = vcpu->kvm;
+ kvm_pfn_t req_pfn, resp_pfn;
+ struct kvm_sev_info *sev;
+
+ sev = &to_kvm_svm(kvm)->sev_info;
+
+ if (!IS_ALIGNED(req_gpa, PAGE_SIZE) || !IS_ALIGNED(resp_gpa, PAGE_SIZE))
+ return SEV_RET_INVALID_PARAM;
+
+ req_pfn = gfn_to_pfn(kvm, gpa_to_gfn(req_gpa));
+ if (is_error_noslot_pfn(req_pfn))
+ return SEV_RET_INVALID_ADDRESS;
+
+ resp_pfn = gfn_to_pfn(kvm, gpa_to_gfn(resp_gpa));
+ if (is_error_noslot_pfn(resp_pfn))
+ return SEV_RET_INVALID_ADDRESS;
+
+ if (rmp_make_private(resp_pfn, 0, PG_LEVEL_4K, 0, true))
+ return SEV_RET_INVALID_ADDRESS;
+
+ data->gctx_paddr = __psp_pa(sev->snp_context);
+ data->req_paddr = __sme_set(req_pfn << PAGE_SHIFT);
+ data->res_paddr = __sme_set(resp_pfn << PAGE_SHIFT);
+
+ return 0;
+}
+
+static void snp_cleanup_guest_buf(struct sev_data_snp_guest_request *data, unsigned long *rc)
+{
+ u64 pfn = __sme_clr(data->res_paddr) >> PAGE_SHIFT;
+ int ret;
+
+ ret = snp_page_reclaim(pfn);
+ if (ret)
+ *rc = SEV_RET_INVALID_ADDRESS;
+
+ ret = rmp_make_shared(pfn, PG_LEVEL_4K);
+ if (ret)
+ *rc = SEV_RET_INVALID_ADDRESS;
+}
+
+static void snp_handle_guest_request(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_gpa)
+{
+ struct sev_data_snp_guest_request data = {0};
+ struct kvm_vcpu *vcpu = &svm->vcpu;
+ struct kvm *kvm = vcpu->kvm;
+ struct kvm_sev_info *sev;
+ unsigned long rc;
+ int err;
+
+ if (!sev_snp_guest(vcpu->kvm)) {
+ rc = SEV_RET_INVALID_GUEST;
+ goto e_fail;
+ }
+
+ sev = &to_kvm_svm(kvm)->sev_info;
+
+ mutex_lock(&sev->guest_req_lock);
+
+ rc = snp_setup_guest_buf(svm, &data, req_gpa, resp_gpa);
+ if (rc)
+ goto unlock;
+
+ rc = sev_issue_cmd(kvm, SEV_CMD_SNP_GUEST_REQUEST, &data, &err);
This one goes via sev_issue_cmd_external_user() and uses sev-fd...
+ if (rc)
+ /* use the firmware error code */
+ rc = err;
+
+ snp_cleanup_guest_buf(&data, &rc);
+
+unlock:
+ mutex_unlock(&sev->guest_req_lock);
+
+e_fail:
+ svm_set_ghcb_sw_exit_info_2(vcpu, rc);
+}
+
+static void snp_handle_ext_guest_request(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_gpa)
+{
+ struct sev_data_snp_guest_request req = {0};
+ struct kvm_vcpu *vcpu = &svm->vcpu;
+ struct kvm *kvm = vcpu->kvm;
+ unsigned long data_npages;
+ struct kvm_sev_info *sev;
+ unsigned long rc, err;
+ u64 data_gpa;
+
+ if (!sev_snp_guest(vcpu->kvm)) {
+ rc = SEV_RET_INVALID_GUEST;
+ goto e_fail;
+ }
+
+ sev = &to_kvm_svm(kvm)->sev_info;
+
+ data_gpa = vcpu->arch.regs[VCPU_REGS_RAX];
+ data_npages = vcpu->arch.regs[VCPU_REGS_RBX];
+
+ if (!IS_ALIGNED(data_gpa, PAGE_SIZE)) {
+ rc = SEV_RET_INVALID_ADDRESS;
+ goto e_fail;
+ }
+
+ mutex_lock(&sev->guest_req_lock);
+
+ rc = snp_setup_guest_buf(svm, &req, req_gpa, resp_gpa);
+ if (rc)
+ goto unlock;
+
+ rc = snp_guest_ext_guest_request(&req, (unsigned long)sev->snp_certs_data,
+ &data_npages, &err);
but this one does not and jump straight to drivers/crypto/ccp/sev-dev.c
ignoring sev->fd. Why different? Can these two be unified?
sev_issue_cmd_external_user() only checks if fd is /dev/sev which is
hardly useful.
"[PATCH RFC v7 32/64] crypto: ccp: Provide APIs to query extended
attestation report" added this one.
Besides, is sev->fd really needed in the sev struct at all? Thanks,
+ if (rc) {
+ /*
+ * If buffer length is small then return the expected
+ * length in rbx.
+ */
+ if (err == SNP_GUEST_REQ_INVALID_LEN)
+ vcpu->arch.regs[VCPU_REGS_RBX] = data_npages;
+
+ /* pass the firmware error code */
+ rc = err;
+ goto cleanup;
+ }
+
+ /* Copy the certificate blob in the guest memory */
+ if (data_npages &&
+ kvm_write_guest(kvm, data_gpa, sev->snp_certs_data, data_npages << PAGE_SHIFT))
+ rc = SEV_RET_INVALID_ADDRESS;
+
+cleanup:
+ snp_cleanup_guest_buf(&req, &rc);
+
+unlock:
+ mutex_unlock(&sev->guest_req_lock);
+
+e_fail:
+ svm_set_ghcb_sw_exit_info_2(vcpu, rc);
+}
+
static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
{
struct vmcb_control_area *control = &svm->vmcb->control;
@@ -3629,6 +3788,20 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
vcpu->run->vmgexit.ghcb_msr = ghcb_gpa;
vcpu->arch.complete_userspace_io = snp_complete_psc;
break;
+ case SVM_VMGEXIT_GUEST_REQUEST: {
+ snp_handle_guest_request(svm, control->exit_info_1, control->exit_info_2);
+
+ ret = 1;
+ break;
+ }
+ case SVM_VMGEXIT_EXT_GUEST_REQUEST: {
+ snp_handle_ext_guest_request(svm,
+ control->exit_info_1,
+ control->exit_info_2);
+
+ ret = 1;
+ break;
+ }
case SVM_VMGEXIT_UNSUPPORTED_EVENT:
vcpu_unimpl(vcpu,
"vmgexit: unsupported event - exit_info_1=%#llx, exit_info_2=%#llx\n",
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 12b9f4d539fb..7c0f9d00950f 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -101,6 +101,8 @@ struct kvm_sev_info {
u64 snp_init_flags;
void *snp_context; /* SNP guest context page */
spinlock_t psc_lock;
+ void *snp_certs_data;
+ struct mutex guest_req_lock;
};
struct kvm_svm {
--
Alexey
