[RFC,v2,15/44] i386/tdx: Add hook to require generic device loader

Commit Message

Isaku Yamahata July 8, 2021, 12:54 a.m. UTC

From: Sean Christopherson <[e-mail]>

Add a hook for TDX to denote that the TD Virtual Firmware must be
provided via the "generic" device loader.  Error out if pflash is used
in conjuction with TDX.

Suggested-by: Isaku Yamahata <[e-mail]>
Signed-off-by: Sean Christopherson <[e-mail]>
Signed-off-by: Isaku Yamahata <[e-mail]>
---
 hw/i386/pc_sysfw.c         |  6 ++++++
 include/sysemu/tdx.h       |  2 ++
 target/i386/kvm/tdx-stub.c |  5 +++++
 target/i386/kvm/tdx.c      | 25 +++++++++++++++++++++++++
 4 files changed, 38 insertions(+)

Comments

Gerd Hoffmann Aug. 26, 2021, 10:41 a.m. UTC | #1

> +    /*
> +     * Sanitiy check for tdx:
> +     * TDX uses generic loader to load bios instead of pflash.
> +     */
> +    for (i = 0; i < ARRAY_SIZE(pcms->flash); i++) {
> +        if (drive_get(IF_PFLASH, 0, i)) {
> +            error_report("pflash not supported by VM type, "
> +                         "use -device loader,file=<path>");
> +            exit(1);
> +        }

I suspect that catches only "-drive if=pflash,..."
but not "-machine pflash0=..."

Also: why does tdx not support flash?
Should be explained in the commit message.

thanks,
  Gerd

Patch

diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 6ce37a2b05..5ff571af36 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -38,6 +38,7 @@ 
 #include "hw/block/flash.h"
 #include "sysemu/kvm.h"
 #include "sysemu/sev.h"
+#include "sysemu/tdx.h"
 
 #define FLASH_SECTOR_SIZE 4096
 
@@ -328,6 +329,11 @@  void pc_system_firmware_init(PCMachineState *pcms,
     int i;
     BlockBackend *pflash_blk[ARRAY_SIZE(pcms->flash)];
 
+    if (!tdx_system_firmware_init(pcms, rom_memory)) {
+        pc_system_flash_cleanup_unused(pcms);
+        return;
+    }
+
     if (!pcmc->pci_enabled) {
         x86_bios_rom_init(MACHINE(pcms), "bios.bin", rom_memory, true);
         return;
diff --git a/include/sysemu/tdx.h b/include/sysemu/tdx.h
index 03461b6ae8..70eb01348f 100644
--- a/include/sysemu/tdx.h
+++ b/include/sysemu/tdx.h
@@ -3,8 +3,10 @@ 
 
 #ifndef CONFIG_USER_ONLY
 #include "sysemu/kvm.h"
+#include "hw/i386/pc.h"
 
 bool kvm_has_tdx(KVMState *s);
+int tdx_system_firmware_init(PCMachineState *pcms, MemoryRegion *rom_memory);
 #endif
 
 void tdx_pre_create_vcpu(CPUState *cpu);
diff --git a/target/i386/kvm/tdx-stub.c b/target/i386/kvm/tdx-stub.c
index 93afe07ddb..4e1a0a4280 100644
--- a/target/i386/kvm/tdx-stub.c
+++ b/target/i386/kvm/tdx-stub.c
@@ -7,6 +7,11 @@  bool kvm_has_tdx(KVMState *s)
 {
         return false;
 }
+
+int tdx_system_firmware_init(PCMachineState *pcms, MemoryRegion *rom_memory)
+{
+    return -ENOSYS;
+}
 #endif
 
 void tdx_pre_create_vcpu(CPUState *cpu)
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 67fb03b4b5..48c04d344d 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -109,6 +109,31 @@  int tdx_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
     return 0;
 }
 
+int tdx_system_firmware_init(PCMachineState *pcms, MemoryRegion *rom_memory)
+{
+    MachineState *ms = MACHINE(pcms);
+    TdxGuest *tdx = (TdxGuest *)object_dynamic_cast(OBJECT(ms->cgs),
+                                                    TYPE_TDX_GUEST);
+    int i;
+
+    if (!tdx) {
+        return -ENOSYS;
+    }
+
+    /*
+     * Sanitiy check for tdx:
+     * TDX uses generic loader to load bios instead of pflash.
+     */
+    for (i = 0; i < ARRAY_SIZE(pcms->flash); i++) {
+        if (drive_get(IF_PFLASH, 0, i)) {
+            error_report("pflash not supported by VM type, "
+                         "use -device loader,file=<path>");
+            exit(1);
+        }
+    }
+    return 0;
+}
+
 void tdx_get_supported_cpuid(KVMState *s, uint32_t function,
                              uint32_t index, int reg, uint32_t *ret)
 {