[v7,51/52] i386/tdx: Validate phys_bits against host value

Commit Message

Xiaoyao Li Jan. 24, 2025, 1:20 p.m. UTC

For TDX guest, the phys_bits is not configurable and can only be
host/native value.

Validate phys_bits inside tdx_check_features().

Signed-off-by: Xiaoyao Li <[e-mail]>
---
 target/i386/host-cpu.c | 2 +-
 target/i386/host-cpu.h | 1 +
 target/i386/kvm/tdx.c  | 8 ++++++++
 3 files changed, 10 insertions(+), 1 deletion(-)

Patch

diff --git a/target/i386/host-cpu.c b/target/i386/host-cpu.c
index 3e4e85e729c8..8a15af458b05 100644
--- a/target/i386/host-cpu.c
+++ b/target/i386/host-cpu.c
@@ -15,7 +15,7 @@ 
 #include "system/system.h"
 
 /* Note: Only safe for use on x86(-64) hosts */
-static uint32_t host_cpu_phys_bits(void)
+uint32_t host_cpu_phys_bits(void)
 {
     uint32_t eax;
     uint32_t host_phys_bits;
diff --git a/target/i386/host-cpu.h b/target/i386/host-cpu.h
index 6a9bc918baa4..b97ec01c9bec 100644
--- a/target/i386/host-cpu.h
+++ b/target/i386/host-cpu.h
@@ -10,6 +10,7 @@ 
 #ifndef HOST_CPU_H
 #define HOST_CPU_H
 
+uint32_t host_cpu_phys_bits(void);
 void host_cpu_instance_init(X86CPU *cpu);
 void host_cpu_max_instance_init(X86CPU *cpu);
 bool host_cpu_realizefn(CPUState *cs, Error **errp);
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index bb75eb06dad9..c906a76c4c0e 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -24,6 +24,7 @@ 
 
 #include "cpu.h"
 #include "cpu-internal.h"
+#include "host-cpu.h"
 #include "hw/i386/e820_memory_layout.h"
 #include "hw/i386/x86.h"
 #include "hw/i386/tdvf.h"
@@ -838,6 +839,13 @@  static int tdx_check_features(X86ConfidentialGuest *cg, CPUState *cs)
         return -1;
     }
 
+    if (cpu->phys_bits != host_cpu_phys_bits()) {
+        error_report("TDX requires guest CPU physical bits (%u) "
+                     "to match host CPU physical bits (%u)",
+                     cpu->phys_bits, host_cpu_phys_bits());
+        exit(1);
+    }
+
     return 0;
 }