i386/tdx: register TDVF as private memory

Allocate the dedicated memory to hold bios image instead of re-using
mmapped guest memory because the initial memory conversion to private
memory wipes out the bios image by madvise(REMOVE).

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>

accel/kvm/kvm-all.c

@@ -2841,7 +2841,7 @@ static void kvm_eat_signals(CPUState *cpu)
     } while (sigismember(&chkset, SIG_IPI));
 }
 
-static int kvm_encrypt_reg_region(hwaddr start, hwaddr size, bool reg_region)
+int kvm_encrypt_reg_region(hwaddr start, hwaddr size, bool reg_region)
 {
     int r;
     struct kvm_memory_attributes  attr;

hw/i386/x86.c

@@ -27,6 +27,7 @@
 #include "qemu/units.h"
 #include "qemu/datadir.h"
 #include "qemu/guest-random.h"
+#include "qom/object_interfaces.h"
 #include "qapi/error.h"
 #include "qapi/qmp/qerror.h"
 #include "qapi/qapi-visit-common.h"
@@ -1188,8 +1189,15 @@ void x86_bios_rom_init(MachineState *ms, const char *default_firmware,
         (bios_size % 65536) != 0) {
         goto bios_error;
     }
+
     bios = g_malloc(sizeof(*bios));
-    memory_region_init_ram(bios, NULL, "pc.bios", bios_size, &error_fatal);
+    if (is_tdx_vm()) {
+        memory_region_init_ram_restricted(bios, NULL, "pc.bios", bios_size, &error_fatal);
+        tdx_set_tdvf_region(bios);
+    } else {
+        memory_region_init_ram(bios, NULL, "pc.bios", bios_size, &error_fatal);
+    }
+
     if (sev_enabled() || is_tdx_vm()) {
         /*
          * The concept of a "reset" simply doesn't exist for

include/sysemu/kvm.h

@@ -583,4 +583,6 @@ bool kvm_arch_cpu_check_are_resettable(void);
 bool kvm_dirty_ring_enabled(void);
 
 uint32_t kvm_dirty_ring_size(void);
+
+int kvm_encrypt_reg_region(hwaddr start, hwaddr size, bool reg_region);
 #endif

target/i386/kvm/tdx.c

@@ -19,6 +19,9 @@
 #include "sysemu/kvm.h"
 #include "sysemu/sysemu.h"
 
+#include "exec/address-spaces.h"
+#include "exec/ramblock.h"
+#include "hw/i386/apic_internal.h"
 #include "hw/i386/e820_memory_layout.h"
 #include "hw/i386/x86.h"
 #include "hw/i386/tdvf.h"
@@ -450,6 +453,12 @@ static void update_tdx_cpuid_lookup_by_tdx_caps(void)
             (tdx_caps->xfam_fixed1 & CPUID_XSTATE_XSS_MASK) >> 32;
 }
 
+void tdx_set_tdvf_region(MemoryRegion *tdvf_region)
+{
+    assert(!tdx_guest->tdvf_region);
+    tdx_guest->tdvf_region = tdvf_region;
+}
+
 static TdxFirmwareEntry *tdx_get_hob_entry(TdxGuest *tdx)
 {
     TdxFirmwareEntry *entry;
@@ -570,6 +579,7 @@ static void tdx_finalize_vm(Notifier *notifier, void *unused)
 {
     TdxFirmware *tdvf = &tdx_guest->tdvf;
     TdxFirmwareEntry *entry;
+    RAMBlock *ram_block;
     int r;
 
     tdx_init_ram_entries();
@@ -604,6 +614,12 @@ static void tdx_finalize_vm(Notifier *notifier, void *unused)
             .nr_pages = entry->size / 4096,
         };
 
+        r = kvm_encrypt_reg_region(entry->address, entry->size, true);
+        if (r < 0) {
+             error_report("Reserve initial private memory failed %s", strerror(-r));
+             exit(1);
+        }
+
         __u32 flags = entry->attributes & TDVF_SECTION_ATTRIBUTES_MR_EXTEND ?
                       KVM_TDX_MEASURE_MEMORY_REGION : 0;
 
@@ -619,6 +635,10 @@ static void tdx_finalize_vm(Notifier *notifier, void *unused)
             entry->mem_ptr = NULL;
         }
     }
+
+    /* Tdvf image was copied into private region above. It becomes unnecessary. */
+    ram_block = tdx_guest->tdvf_region->ram_block;
+    ram_block_discard_range(ram_block, 0, ram_block->max_length);
 }
 
 static Notifier tdx_machine_done_notify = {

target/i386/kvm/tdx.h

@@ -35,6 +35,7 @@ typedef struct TdxGuest {
     uint64_t attributes;    /* TD attributes */
 
     TdxFirmware tdvf;
+    MemoryRegion *tdvf_region;
 
     uint32_t nr_ram_entries;
     TdxRamEntry *ram_entries;
@@ -50,6 +51,7 @@ int tdx_kvm_init(MachineState *ms, Error **errp);
 void tdx_get_supported_cpuid(uint32_t function, uint32_t index, int reg,
                              uint32_t *ret);
 int tdx_pre_create_vcpu(CPUState *cpu);
+void tdx_set_tdvf_region(MemoryRegion *tdvf_region);
 int tdx_parse_tdvf(void *flash_ptr, int size);
 
 #endif /* QEMU_I386_TDX_H */