[PATCH v6 34/60] i386/tdx: implement tdx_cpu_realizefn()

[Xiaoyao Li <xiaoyao.li@xxxxxxxxx>]

For TDX guest, KVM doesn't allow phys_bits configuration and the
phys_bits can only be native/host value.

Add the logic to set cpu->phys_bits to host value when user doesn't
give a explicit one and error out when user desires a different one
than host value.

Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
Changes in v6:
 - new patches;
---
 target/i386/host-cpu.c |  2 +-
 target/i386/host-cpu.h |  1 +
 target/i386/kvm/tdx.c  | 17 +++++++++++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/target/i386/host-cpu.c b/target/i386/host-cpu.c
index 03b9d1b169a5..e2c59e5ae288 100644
--- a/target/i386/host-cpu.c
+++ b/target/i386/host-cpu.c
@@ -15,7 +15,7 @@
 #include "sysemu/sysemu.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 61fb1f184149..289722a129ce 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -23,6 +23,8 @@
 
 #include <linux/kvm_para.h>
 
+#include "cpu.h"
+#include "host-cpu.h"
 #include "hw/i386/e820_memory_layout.h"
 #include "hw/i386/x86.h"
 #include "hw/i386/tdvf.h"
@@ -389,6 +391,20 @@ static void tdx_cpu_instance_init(X86ConfidentialGuest *cg, CPUState *cpu)
     object_property_set_bool(OBJECT(cpu), "pmu", false, &error_abort);
 }
 
+static void tdx_cpu_realizefn(X86ConfidentialGuest *cg, CPUState *cs,
+                              Error **errp)
+{
+    X86CPU *cpu = X86_CPU(cs);
+    uint32_t host_phys_bits = host_cpu_phys_bits();
+
+    if (!cpu->phys_bits) {
+        cpu->phys_bits = host_phys_bits;
+    } else if (cpu->phys_bits != host_phys_bits) {
+        error_setg(errp, "TDX only supports host physical bits (%u)",
+                   host_phys_bits);
+    }
+}
+
 static int tdx_validate_attributes(TdxGuest *tdx, Error **errp)
 {
     if ((tdx->attributes & ~tdx_caps->supported_attrs)) {
@@ -733,4 +749,5 @@ static void tdx_guest_class_init(ObjectClass *oc, void *data)
     klass->kvm_init = tdx_kvm_init;
     x86_klass->kvm_type = tdx_kvm_type;
     x86_klass->cpu_instance_init = tdx_cpu_instance_init;
+    x86_klass->cpu_realizefn = tdx_cpu_realizefn;
 }
-- 
2.34.1