[Qemu-devel] [PATCH] WHPX Add signature CPUID

[petrutlucian94@gmail.com]

From: Lucian Petrut <lpetrut@cloudbasesolutions.com>

Adds the CPUID trap for CPUID 0x40000000, sending the WHPX signature
to the guest upon request. This is consistent with other QEMU
accelerators (KVM).

Signed-off-by: Alessandro Pilotti <apilotti@cloudbasesolutions.com>
Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>
Signed-off-by: Lucian Petrut <lpetrut@cloudbasesolutions.com>
---
As opposed to the previous patch, this one will set the result of
this specific CPUID leaf when initializing the accelerator so that
we avoid a vcpu exit.

 target/i386/whpx-all.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/target/i386/whpx-all.c b/target/i386/whpx-all.c
index 5843517..c8310de 100644
--- a/target/i386/whpx-all.c
+++ b/target/i386/whpx-all.c
@@ -29,6 +29,8 @@
 #include <WinHvPlatform.h>
 #include <WinHvEmulation.h>
 
+#define WHPX_CPUID_SIGNATURE 0x40000000
+
 struct whpx_state {
     uint64_t mem_quota;
     WHV_PARTITION_HANDLE partition;
@@ -1342,6 +1344,27 @@ static int whpx_accel_init(MachineState *ms)
                                  cpuidExitList,
                                  RTL_NUMBER_OF(cpuidExitList) * sizeof(UINT32));
 
+    UINT32 signature[3] = {0};
+    memcpy(signature, "WHPXWHPXWHPX", 12);
+
+    WHV_X64_CPUID_RESULT cpuidResultList[1] = {0};
+    cpuidResultList[0].Function = WHPX_CPUID_SIGNATURE;
+    cpuidResultList[0].Eax = 0;
+    cpuidResultList[0].Ebx = signature[0];
+    cpuidResultList[0].Ecx = signature[1];
+    cpuidResultList[0].Edx = signature[2];
+    hr = WHvSetPartitionProperty(whpx->partition,
+                                 WHvPartitionPropertyCodeCpuidResultList,
+                                 cpuidResultList,
+                                 RTL_NUMBER_OF(cpuidResultList) *
+                                    sizeof(WHV_X64_CPUID_RESULT));
+    if (FAILED(hr)) {
+        error_report("WHPX: Failed to set partition CpuidResultList hr=%08lx",
+                     hr);
+        ret = -EINVAL;
+        goto error;
+    }
+
     if (FAILED(hr)) {
         error_report("WHPX: Failed to set partition CpuidExitList hr=%08lx",
                      hr);
-- 
2.7.4