[PATCH v4 3/6] i386: Hyper-V XMM fast hypercall input feature

[Vitaly Kuznetsov]

Hyper-V specification allows to pass parameters for certain hypercalls
using XMM registers ("XMM Fast Hypercall Input"). When the feature is
in use, it allows for faster hypercalls processing as KVM can avoid
reading guest's memory.

KVM supports the feature since v5.14.

Rename HV_HYPERCALL_{PARAMS_XMM_AVAILABLE -> XMM_INPUT_AVAILABLE} to
comply with KVM.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 docs/hyperv.txt                | 6 ++++++
 target/i386/cpu.c              | 2 ++
 target/i386/cpu.h              | 1 +
 target/i386/kvm/hyperv-proto.h | 2 +-
 target/i386/kvm/kvm.c          | 7 +++++++
 5 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/docs/hyperv.txt b/docs/hyperv.txt
index 5d85569b9941..af1b10c0b3d1 100644
--- a/docs/hyperv.txt
+++ b/docs/hyperv.txt
@@ -249,6 +249,12 @@ Enlightened VMCS ('hv-evmcs') feature to also be enabled.
 
 Recommended: hv-evmcs (Intel)
 
+3.23. hv-xmm-input
+===================
+Hyper-V specification allows to pass parameters for certain hypercalls using 
XMM
+registers ("XMM Fast Hypercall Input"). When the feature is in use, it allows
+for faster hypercalls processing as KVM can avoid reading guest's memory.
+
 4. Supplementary features
 =========================
 
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 5aabf0c12e8d..cb86c11f71d4 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6962,6 +6962,8 @@ static Property x86_cpu_properties[] = {
                       HYPERV_FEAT_AVIC, 0),
     DEFINE_PROP_BIT64("hv-emsr-bitmap", X86CPU, hyperv_features,
                       HYPERV_FEAT_MSR_BITMAP, 0),
+    DEFINE_PROP_BIT64("hv-xmm-input", X86CPU, hyperv_features,
+                      HYPERV_FEAT_XMM_INPUT, 0),
     DEFINE_PROP_ON_OFF_AUTO("hv-no-nonarch-coresharing", X86CPU,
                             hyperv_no_nonarch_cs, ON_OFF_AUTO_OFF),
     DEFINE_PROP_BIT64("hv-syndbg", X86CPU, hyperv_features,
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index c7882857366d..37e95535843b 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1107,6 +1107,7 @@ uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
 #define HYPERV_FEAT_AVIC                15
 #define HYPERV_FEAT_SYNDBG              16
 #define HYPERV_FEAT_MSR_BITMAP          17
+#define HYPERV_FEAT_XMM_INPUT           18
 
 #ifndef HYPERV_SPINLOCK_NEVER_NOTIFY
 #define HYPERV_SPINLOCK_NEVER_NOTIFY             0xFFFFFFFF
diff --git a/target/i386/kvm/hyperv-proto.h b/target/i386/kvm/hyperv-proto.h
index cea18dbc0e23..f5f16474fa25 100644
--- a/target/i386/kvm/hyperv-proto.h
+++ b/target/i386/kvm/hyperv-proto.h
@@ -54,7 +54,7 @@
 #define HV_GUEST_DEBUGGING_AVAILABLE            (1u << 1)
 #define HV_PERF_MONITOR_AVAILABLE               (1u << 2)
 #define HV_CPU_DYNAMIC_PARTITIONING_AVAILABLE   (1u << 3)
-#define HV_HYPERCALL_PARAMS_XMM_AVAILABLE       (1u << 4)
+#define HV_HYPERCALL_XMM_INPUT_AVAILABLE        (1u << 4)
 #define HV_GUEST_IDLE_STATE_AVAILABLE           (1u << 5)
 #define HV_FREQUENCY_MSRS_AVAILABLE             (1u << 8)
 #define HV_GUEST_CRASH_MSR_AVAILABLE            (1u << 10)
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 82d1f0275c42..96d6c50ad5d9 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -980,6 +980,13 @@ static struct {
              .bits = HV_NESTED_MSR_BITMAP}
         }
     },
+    [HYPERV_FEAT_XMM_INPUT] = {
+        .desc = "XMM fast hypercall input (hv-xmm-input)",
+        .flags = {
+            {.func = HV_CPUID_FEATURES, .reg = R_EDX,
+             .bits = HV_HYPERCALL_XMM_INPUT_AVAILABLE}
+        }
+    },
 };
 
 static struct kvm_cpuid2 *try_get_hv_cpuid(CPUState *cs, int max,
-- 
2.35.3