[PATCH v3 41/49] i386/sev: Add support for populating OVMF metadata pages

[Michael Roth <michael.roth@amd.com>]

From: Brijesh Singh <brijesh.singh@amd.com>

OVMF reserves various pages so they can be pre-initialized/validated
prior to launching the guest. Add support for populating these pages
with the expected content.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 target/i386/sev.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/target/i386/sev.c b/target/i386/sev.c
index 4d862eef78..6c5166c729 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -949,6 +949,67 @@ sev_launch_finish(SevGuestState *sev_guest)
     migrate_add_blocker(&sev_mig_blocker, &error_fatal);
 }
 
+static int
+snp_launch_update_data(uint64_t gpa, void *hva, uint32_t len, int type)
+{
+    SevLaunchUpdateData *data;
+
+    data = g_new0(SevLaunchUpdateData, 1);
+    data->gpa = gpa;
+    data->hva = hva;
+    data->len = len;
+    data->type = type;
+
+    QTAILQ_INSERT_TAIL(&launch_update, data, next);
+
+    return 0;
+}
+
+static int
+snp_metadata_desc_to_page_type(int desc_type)
+{
+    switch(desc_type) {
+    /* Add the umeasured prevalidated pages as a zero page */
+    case SEV_DESC_TYPE_SNP_SEC_MEM: return KVM_SEV_SNP_PAGE_TYPE_ZERO;
+    case SEV_DESC_TYPE_SNP_SECRETS: return KVM_SEV_SNP_PAGE_TYPE_SECRETS;
+    case SEV_DESC_TYPE_CPUID: return KVM_SEV_SNP_PAGE_TYPE_CPUID;
+    default: return -1;
+    }
+}
+
+static void
+snp_populate_metadata_pages(SevSnpGuestState *sev_snp, OvmfSevMetadata *metadata)
+{
+    OvmfSevMetadataDesc *desc;
+    int type, ret, i;
+    void *hva;
+    MemoryRegion *mr = NULL;
+
+    for (i = 0; i < metadata->num_desc; i++) {
+        desc = &metadata->descs[i];
+
+        type = snp_metadata_desc_to_page_type(desc->type);
+        if (type < 0) {
+            error_report("%s: Invalid memory type '%d'\n", __func__, desc->type);
+            exit(1);
+        }
+
+        hva = gpa2hva(&mr, desc->base, desc->len, NULL);
+        if (!hva) {
+            error_report("%s: Failed to get HVA for GPA 0x%x sz 0x%x\n",
+                         __func__, desc->base, desc->len);
+            exit(1);
+        }
+
+        ret = snp_launch_update_data(desc->base, hva, desc->len, type);
+        if (ret) {
+            error_report("%s: Failed to add metadata page gpa 0x%x+%x type %d\n",
+                         __func__, desc->base, desc->len, desc->type);
+            exit(1);
+        }
+    }
+}
+
 static void
 sev_snp_launch_finish(SevSnpGuestState *sev_snp)
 {
@@ -958,6 +1019,20 @@ sev_snp_launch_finish(SevSnpGuestState *sev_snp)
     SevLaunchUpdateData *data;
     struct kvm_sev_snp_launch_finish *finish = &sev_snp->kvm_finish_conf;
 
+    /*
+     * To boot the SNP guest, the hypervisor is required to populate the CPUID
+     * and Secrets page before finalizing the launch flow. The location of
+     * the secrets and CPUID page is available through the OVMF metadata GUID.
+     */
+    metadata = pc_system_get_ovmf_sev_metadata_ptr();
+    if (metadata == NULL) {
+        error_report("%s: Failed to locate SEV metadata header\n", __func__);
+        exit(1);
+    }
+
+    /* Populate all the metadata pages */
+    snp_populate_metadata_pages(sev_snp, metadata);
+
     QTAILQ_FOREACH(data, &launch_update, next) {
         ret = sev_snp_launch_update(sev_snp, data);
         if (ret) {
-- 
2.25.1