[PULL 14/17] i386: Hyper-V XMM fast hypercall input feature

[Paolo Bonzini]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

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>
Message-Id: <20220525115949.1294004-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 docs/hyperv.txt                | 6 ++++++
 target/i386/cpu.h              | 1 +
 target/i386/kvm/hyperv-proto.h | 2 +-
 target/i386/cpu.c              | 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 5d85569b99..af1b10c0b3 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.h b/target/i386/cpu.h
index c788285736..37e9553584 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 cea18dbc0e..f5f16474fa 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/cpu.c b/target/i386/cpu.c
index 474e9b582e..63cec0ea68 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6970,6 +6970,8 @@ 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/kvm/kvm.c b/target/i386/kvm/kvm.c
index f389bbedf2..7e6f934eda 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,
-- 
2.36.1