[PATCH v3 6/9] target/i386: query mshv accel for supported cpuids

[Magnus Kulke <magnuskulke@linux.microsoft.com>]

We implement mshv_get_supported_cpuid() and invoke it in
x86_cpu_get_supported_feature_word() retrieve the cpu features that the
host is supporting. Initially we mask the virtualization capabilitities
potentially we might need to mask more in the future.

Signed-off-by: Magnus Kulke <magnuskulke@linux.microsoft.com>
---
 include/system/mshv.h       |  3 +++
 target/i386/cpu.c           |  8 ++++++++
 target/i386/mshv/mshv-cpu.c | 27 +++++++++++++++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/include/system/mshv.h b/include/system/mshv.h
index 75286baf16..51b0420735 100644
--- a/include/system/mshv.h
+++ b/include/system/mshv.h
@@ -60,4 +60,7 @@ int mshv_irqchip_add_irqfd_notifier_gsi(const EventNotifier *n,
                                         const EventNotifier *rn, int virq);
 int mshv_irqchip_remove_irqfd_notifier_gsi(const EventNotifier *n, int virq);
 
+/* cpuid */
+uint32_t mshv_get_supported_cpuid(uint32_t func, uint32_t idx, int reg);
+
 #endif
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index b5e483e8cd..21e42fb4f6 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -26,6 +26,7 @@
 #include "tcg/helper-tcg.h"
 #include "exec/translation-block.h"
 #include "system/hvf.h"
+#include "system/mshv.h"
 #include "hvf/hvf-i386.h"
 #include "kvm/kvm_i386.h"
 #include "kvm/tdx.h"
@@ -8087,6 +8088,13 @@ uint64_t x86_cpu_get_supported_feature_word(X86CPU *cpu, FeatureWord w)
         r = hvf_get_supported_cpuid(wi->cpuid.eax,
                                     wi->cpuid.ecx,
                                     wi->cpuid.reg);
+     } else if (mshv_enabled()) {
+        if (wi->type != CPUID_FEATURE_WORD) {
+            return 0;
+        }
+        r = mshv_get_supported_cpuid(wi->cpuid.eax,
+                                     wi->cpuid.ecx,
+                                     wi->cpuid.reg);
     } else if (tcg_enabled()) {
         r = wi->tcg_features;
     } else {
diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
index 09878ef357..3b392533b4 100644
--- a/target/i386/mshv/mshv-cpu.c
+++ b/target/i386/mshv/mshv-cpu.c
@@ -1639,6 +1639,33 @@ void mshv_arch_destroy_vcpu(CPUState *cpu)
     g_clear_pointer(&env->emu_mmio_buf, g_free);
 }
 
+uint32_t mshv_get_supported_cpuid(uint32_t func, uint32_t idx, int reg)
+{
+    uint32_t eax, ebx, ecx, edx;
+    uint32_t ret = 0;
+
+    host_cpuid(func, idx, &eax, &ebx, &ecx, &edx);
+    switch (reg) {
+    case R_EAX:
+        ret = eax; break;
+    case R_EBX:
+        ret = ebx; break;
+    case R_ECX:
+        ret = ecx; break;
+    case R_EDX:
+        ret = edx; break;
+    }
+
+    /* Disable nested virtualization features not yet supported by MSHV */
+    if (func == 0x80000001 && reg == R_ECX) {
+        ret &= ~CPUID_EXT3_SVM;
+    }
+    if (func == 0x01       && reg == R_ECX) {
+        ret &= ~CPUID_EXT_VMX;
+    }
+    return ret;
+}
+
 /*
  * Default Microsoft Hypervisor behavior for unimplemented MSR is to send a
  * fault to the guest if it tries to access it. It is possible to override
-- 
2.34.1