[RFC PATCH v2 11/44] i386/tdx: Implement user specified tsc frequency

[isaku . yamahata]

From: Xiaoyao Li <xiaoyao.li@intel.com>

Reuse -cpu,tsc-frequency= to get user wanted tsc frequency and pass it
to KVM_TDX_INIT_VM.

Besides, sanity check the tsc frequency to be in the legal range and
legal granularity (required by SEAM module).

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 target/i386/kvm/kvm.c |  8 ++++++++
 target/i386/kvm/tdx.c | 16 ++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index ecb1714920..be0b96b120 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -763,6 +763,14 @@ static int kvm_arch_set_tsc_khz(CPUState *cs)
     int r, cur_freq;
     bool set_ioctl = false;
 
+    /*
+     * TD guest's TSC is immutable, it cannot be set/changed via
+     * KVM_SET_TSC_KHZ, but only be initialized via KVM_TDX_INIT_VM
+     */
+    if (vm_type == KVM_X86_TDX_VM) {
+        return 0;
+    }
+
     if (!env->tsc_khz) {
         return 0;
     }
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index e8c70f241d..c50a0dcf11 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -29,6 +29,8 @@
 
 #define TDX1_TD_ATTRIBUTE_DEBUG BIT_ULL(0)
 #define TDX1_TD_ATTRIBUTE_PERFMON BIT_ULL(63)
+#define TDX1_MIN_TSC_FREQUENCY_KHZ (100 * 1000)
+#define TDX1_MAX_TSC_FREQUENCY_KHZ (10 * 1000 * 1000)
 
 bool kvm_has_tdx(KVMState *s)
 {
@@ -91,6 +93,19 @@ void tdx_pre_create_vcpu(CPUState *cpu)
         exit(1);
     }
 
+    if (env->tsc_khz && (env->tsc_khz < TDX1_MIN_TSC_FREQUENCY_KHZ ||
+                         env->tsc_khz > TDX1_MAX_TSC_FREQUENCY_KHZ)) {
+        error_report("Invalid TSC %ld KHz, must specify cpu_frequecy between 
[%d, %d] kHz\n",
+                      env->tsc_khz, TDX1_MIN_TSC_FREQUENCY_KHZ,
+                      TDX1_MAX_TSC_FREQUENCY_KHZ);
+        exit(1);
+    }
+
+    if (env->tsc_khz % (25 * 1000)) {
+        error_report("Invalid TSC %ld KHz, it must be multiple of 25MHz\n", 
env->tsc_khz);
+        exit(1);
+    }
+
     qemu_mutex_lock(&tdx->lock);
     if (tdx->initialized) {
         goto out;
@@ -103,6 +118,7 @@ void tdx_pre_create_vcpu(CPUState *cpu)
     cpuid_data.cpuid.padding = 0;
 
     init_vm.max_vcpus = ms->smp.cpus;
+    init_vm.tsc_khz = env->tsc_khz;
     init_vm.attributes = 0;
     init_vm.attributes |= tdx->debug ? TDX1_TD_ATTRIBUTE_DEBUG : 0;
     init_vm.attributes |= x86cpu->enable_pmu ? TDX1_TD_ATTRIBUTE_PERFMON : 0;
-- 
2.25.1