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. E.g., TD HOB and TEMP MEM that needed by TDVF.

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

Then turn 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 <xiaoyao.li@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
---
Changes in v3:
- use enum TdxRamType in struct TdxRamEntry; (Isaku)
- Fix the indention; (Daniel)

Changes in v1:
  - simplify the algorithm of tdx_accept_ram_range() (Suggested-by: Gerd Hoffman)
    (1) Change the existing entry to cover the accepted ram range.
    (2) If there is room before the accepted ram range add a
	TDX_RAM_UNACCEPTED entry for that.
    (3) If there is room after the accepted ram range add a
	TDX_RAM_UNACCEPTED entry for that.
---
 target/i386/kvm/tdx.c | 111 ++++++++++++++++++++++++++++++++++++++++++
 target/i386/kvm/tdx.h |  14 ++++++
 2 files changed, 125 insertions(+)

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 825a432255ff..c8c6ed9f811b 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -22,6 +22,7 @@
 #include "sysemu/sysemu.h"
 #include "exec/address-spaces.h"
 
+#include "hw/i386/e820_memory_layout.h"
 #include "hw/i386/x86.h"
 #include "hw/i386/tdvf.h"
 #include "kvm_i386.h"
@@ -466,11 +467,117 @@ static void update_tdx_cpuid_lookup_by_tdx_caps(void)
             (tdx_caps->xfam_fixed1 & CPUID_XSTATE_XSS_MASK) >> 32;
 }
 
+static void tdx_add_ram_entry(uint64_t address, uint64_t length,
+                              enum TdxRamType 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)
+{
+    uint64_t head_start, tail_start, head_length, tail_length;
+    uint64_t tmp_address, tmp_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;
+        }
+
+        /*
+         * The to-be-accepted ram range must be fully contained by one
+         * RAM entry.
+         */
+        if (e->address > address ||
+            e->address + e->length < address + length) {
+            return -EINVAL;
+        }
+
+        if (e->type == TDX_RAM_ADDED) {
+            return -EINVAL;
+        }
+
+        break;
+    }
+
+    if (i == tdx_guest->nr_ram_entries) {
+        return -1;
+    }
+
+    tmp_address = e->address;
+    tmp_length = e->length;
+
+    e->address = address;
+    e->length = length;
+    e->type = TDX_RAM_ADDED;
+
+    head_length = address - tmp_address;
+    if (head_length > 0) {
+        head_start = tmp_address;
+        tdx_add_ram_entry(head_start, head_length, TDX_RAM_UNACCEPTED);
+    }
+
+    tail_start = address + length;
+    if (tail_start < tmp_address + tmp_length) {
+        tail_length = tmp_address + tmp_length - tail_start;
+        tdx_add_ram_entry(tail_start, tail_length, TDX_RAM_UNACCEPTED);
+    }
+
+    return 0;
+}
+
+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)
 {
     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:
@@ -481,12 +588,16 @@ static void tdx_finalize_vm(Notifier *notifier, void *unused)
         case TDVF_SECTION_TYPE_TEMP_MEM:
             entry->mem_ptr = qemu_ram_mmap(-1, entry->size,
                                            qemu_real_host_page_size(), 0, 0);
+            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 a46af433135f..3a35a2bc0900 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;
+    enum TdxRamType type;
+} TdxRamEntry;
+
 typedef struct TdxGuest {
     ConfidentialGuestSupport parent_obj;
 
@@ -27,6 +38,9 @@ typedef struct TdxGuest {
     char *mrownerconfig;    /* base64 encoded sha348 digest */
 
     TdxFirmware tdvf;
+
+    uint32_t nr_ram_entries;
+    TdxRamEntry *ram_entries;
 } TdxGuest;
 
 #ifdef CONFIG_TDX
-- 
2.34.1