[RFC,v3,22/36] i386/tdx: Track RAM entries for TDX VM

Commit Message

Xiaoyao Li March 17, 2022, 1:58 p.m. UTC

The RAM of TDX VM can be classified into two types:

 - TDX_RAM_UNACCEPTED: default type of TDX memory, which needs to be
   accepted by TDX guest before it can be used and will be all-zeros
   after being accepted.

 - TDX_RAM_ADDED: the RAM that is ADD'ed to TD guest before running, and
   can be used directly without being accepted. It's used to initialized
   TDVF TD HOB and TEMP MEM.

Maintain TdxRamEntries[] which grabs the initial RAM infos from e820 table
and mark each RAM range as default type TDX_RAM_UNACCEPTED.

Then it turns the range of TD HOB and TEMP MEM to TDX_RAM_ADDED since these
ranges will be ADD'ed before TD runs and no need to be accepted runtime.

The TdxRamEntries[] are later used to setup the memory TD resource HOB
that passes memory info from QEMU to TDVF.

Signed-off-by: Xiaoyao Li <[e-mail]>
---
 target/i386/kvm/tdx.c | 99 +++++++++++++++++++++++++++++++++++++++++++
 target/i386/kvm/tdx.h | 14 ++++++
 2 files changed, 113 insertions(+)

Patch

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index fe8554dcebb0..59446ed10ce4 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -18,6 +18,7 @@ 
 #include "sysemu/kvm.h"
 #include "sysemu/sysemu.h"
 
+#include "hw/i386/e820_memory_layout.h"
 #include "hw/i386/x86.h"
 #include "hw/i386/tdvf.h"
 #include "kvm_i386.h"
@@ -105,6 +106,98 @@  static void get_tdx_capabilities(void)
     tdx_caps = caps;
 }
 
+static void tdx_add_ram_entry(uint64_t address, uint64_t length, uint32_t type)
+{
+    uint32_t nr_entries = tdx_guest->nr_ram_entries;
+    tdx_guest->ram_entries = g_renew(TdxRamEntry, tdx_guest->ram_entries,
+                                     nr_entries + 1);
+
+    tdx_guest->ram_entries[nr_entries].address = address;
+    tdx_guest->ram_entries[nr_entries].length = length;
+    tdx_guest->ram_entries[nr_entries].type = type;
+    tdx_guest->nr_ram_entries++;
+}
+
+static int tdx_accept_ram_range(uint64_t address, uint64_t length)
+{
+    TdxRamEntry *e;
+    int i;
+
+    for (i = 0; i < tdx_guest->nr_ram_entries; i++) {
+        e = &tdx_guest->ram_entries[i];
+
+        if (address + length < e->address ||
+            e->address + e->length < address) {
+                continue;
+        }
+
+        if (e->address > address ||
+            e->address + e->length < address + length) {
+            return -EINVAL;
+        }
+
+        if (e->address == address && e->length == length) {
+            e->type = TDX_RAM_ADDED;
+        } else if (e->address == address) {
+            e->address += length;
+            e->length -= length;
+            tdx_add_ram_entry(address, length, TDX_RAM_ADDED);
+        } else if (e->address + e->length == address + length) {
+            e->length -= length;
+            tdx_add_ram_entry(address, length, TDX_RAM_ADDED);
+        } else {
+            TdxRamEntry tmp = {
+                .address = e->address,
+                .length = e->length,
+            };
+            e->length = address - tmp.address;
+
+            tdx_add_ram_entry(address, length, TDX_RAM_ADDED);
+            tdx_add_ram_entry(address + length,
+                              tmp.address + tmp.length - (address + length),
+                              TDX_RAM_UNACCEPTED);
+        }
+
+        return 0;
+    }
+
+    return -1;
+}
+
+static int tdx_ram_entry_compare(const void *lhs_, const void* rhs_)
+{
+    const TdxRamEntry *lhs = lhs_;
+    const TdxRamEntry *rhs = rhs_;
+
+    if (lhs->address == rhs->address) {
+        return 0;
+    }
+    if (le64_to_cpu(lhs->address) > le64_to_cpu(rhs->address)) {
+        return 1;
+    }
+    return -1;
+}
+
+static void tdx_init_ram_entries(void)
+{
+    unsigned i, j, nr_e820_entries;
+
+    nr_e820_entries = e820_get_num_entries();
+    tdx_guest->ram_entries = g_new(TdxRamEntry, nr_e820_entries);
+
+    for (i = 0, j = 0; i < nr_e820_entries; i++) {
+        uint64_t addr, len;
+
+        if (e820_get_entry(i, E820_RAM, &addr, &len)) {
+            tdx_guest->ram_entries[j].address = addr;
+            tdx_guest->ram_entries[j].length = len;
+            tdx_guest->ram_entries[j].type = TDX_RAM_UNACCEPTED;
+            j++;
+        }
+    }
+    tdx_guest->nr_ram_entries = j;
+}
+
 static void tdx_finalize_vm(Notifier *notifier, void *unused)
 {
     MachineState *ms = MACHINE(qdev_get_machine());
@@ -112,6 +205,8 @@  static void tdx_finalize_vm(Notifier *notifier, void *unused)
     TdxFirmware *tdvf = &tdx_guest->tdvf;
     TdxFirmwareEntry *entry;
 
+    tdx_init_ram_entries();
+
     for_each_tdx_fw_entry(tdvf, entry) {
         switch (entry->type) {
         case TDVF_SECTION_TYPE_BFV:
@@ -131,12 +226,16 @@  static void tdx_finalize_vm(Notifier *notifier, void *unused)
         case TDVF_SECTION_TYPE_TD_HOB:
         case TDVF_SECTION_TYPE_TEMP_MEM:
             entry->mem_ptr = base_ram_ptr + entry->address;
+            tdx_accept_ram_range(entry->address, entry->size);
             break;
         default:
             error_report("Unsupported TDVF section %d", entry->type);
             exit(1);
         }
     }
+
+    qsort(tdx_guest->ram_entries, tdx_guest->nr_ram_entries,
+          sizeof(TdxRamEntry), &tdx_ram_entry_compare);
 }
 
 static Notifier tdx_machine_done_notify = {
diff --git a/target/i386/kvm/tdx.h b/target/i386/kvm/tdx.h
index b3cedd0d5d0c..1e2d5d6f2a24 100644
--- a/target/i386/kvm/tdx.h
+++ b/target/i386/kvm/tdx.h
@@ -15,6 +15,17 @@  typedef struct TdxGuestClass {
     ConfidentialGuestSupportClass parent_class;
 } TdxGuestClass;
 
+enum TdxRamType{
+    TDX_RAM_UNACCEPTED,
+    TDX_RAM_ADDED,
+};
+
+typedef struct TdxRamEntry {
+    uint64_t address;
+    uint64_t length;
+    uint32_t type;
+} TdxRamEntry;
+
 typedef struct TdxGuest {
     ConfidentialGuestSupport parent_obj;
 
@@ -24,6 +35,9 @@  typedef struct TdxGuest {
     uint64_t attributes;    /* TD attributes */
 
     TdxFirmware tdvf;
+
+    uint32_t nr_ram_entries;
+    TdxRamEntry *ram_entries;
 } TdxGuest;
 
 #ifdef CONFIG_TDX