Re: [PATCH v9 05/19] KVM: selftests: Update kvm_init_vm_address_properties() for TDX

[Binbin Wu]

On 8/21/2025 12:28 PM, Sagi Shahar wrote:

From: Isaku Yamahata <isaku.yamah...@intel.com>

Let kvm_init_vm_address_properties() initialize vm->arch.{s_bit, tag_mask}
similar to SEV.

TDX sets the shared bit based on the guest physical address width and
currently supports 48 and 52 widths.

Co-developed-by: Adrian Hunter <adrian.hun...@intel.com>
Signed-off-by: Adrian Hunter <adrian.hun...@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamah...@intel.com>
Co-developed-by: Sagi Shahar <sa...@google.com>
Signed-off-by: Sagi Shahar <sa...@google.com>
---
  .../selftests/kvm/include/x86/tdx/tdx_util.h       | 14 ++++++++++++++
  tools/testing/selftests/kvm/lib/x86/processor.c    | 12 ++++++++++--
  2 files changed, 24 insertions(+), 2 deletions(-)
  create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h

diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h 
b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
new file mode 100644
index 000000000000..286d5e3c24b1
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef SELFTESTS_TDX_TDX_UTIL_H
+#define SELFTESTS_TDX_TDX_UTIL_H
+
+#include <stdbool.h>
+
+#include "kvm_util.h"
+
+static inline bool is_tdx_vm(struct kvm_vm *vm)
+{
+       return vm->type == KVM_X86_TDX_VM;
+}

If the branch "vm->type != KVM_X86_TDX_VM" in patch 04/19
is still needed, this helper could be added earlier and used instead of
open code.

+
+#endif // SELFTESTS_TDX_TDX_UTIL_H
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c 
b/tools/testing/selftests/kvm/lib/x86/processor.c
index 1eae92957456..6dbf40cbbc2a 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -8,6 +8,7 @@
  #include "kvm_util.h"
  #include "processor.h"
  #include "sev.h"
+#include "tdx/tdx_util.h"

#ifndef NUM_INTERRUPTS

  #define NUM_INTERRUPTS 256
@@ -1190,12 +1191,19 @@ void kvm_get_cpu_address_width(unsigned int *pa_bits, 
unsigned int *va_bits)

void kvm_init_vm_address_properties(struct kvm_vm *vm)

  {
+       uint32_t gpa_bits = kvm_cpu_property(X86_PROPERTY_GUEST_MAX_PHY_ADDR);
+
+       vm->arch.sev_fd = -1;
+
        if (is_sev_vm(vm)) {
                vm->arch.sev_fd = open_sev_dev_path_or_exit();
                vm->arch.c_bit = 
BIT_ULL(this_cpu_property(X86_PROPERTY_SEV_C_BIT));
                vm->gpa_tag_mask = vm->arch.c_bit;
-       } else {
-               vm->arch.sev_fd = -1;
+       } else if (is_tdx_vm(vm)) {
+               TEST_ASSERT(gpa_bits == 48 || gpa_bits == 52,
+                           "TDX: bad X86_PROPERTY_GUEST_MAX_PHY_ADDR value: 
%u", gpa_bits);
+               vm->arch.s_bit = 1ULL << (gpa_bits - 1);

Nit: Use BIT_ULL().

+               vm->gpa_tag_mask = vm->arch.s_bit;
        }
  }