[PATCH] target/i386/hvf: add vmware-cpuid-freq cpu feature

[yaroshchuk2000@gmail.com]

From: Vladislav Yaroshchuk <yaroshchuk2000@gmail.com>

For `-accel hvf` cpu_x86_cpuid() is wrapped with hvf_cpu_x86_cpuid() to
add paravirtualization cpuid leaf 0x40000010
https://lkml.org/lkml/2008/10/1/246

Leaf 0x40000010, Timing Information:
EAX: (Virtual) TSC frequency in kHz.
EBX: (Virtual) Bus (local apic timer) frequency in kHz.
ECX, EDX: RESERVED (Per above, reserved fields are set to zero).

On macOS TSC and APIC Bus frequencies can be readed by sysctl call with
names `machdep.tsc.frequency` and `hw.busfrequency`

This options is required for Darwin-XNU guest to be synchronized with
host

Signed-off-by: Vladislav Yaroshchuk <yaroshchuk2000@gmail.com>
---
 target/i386/hvf/hvf.c | 92 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 91 insertions(+), 1 deletion(-)

diff --git a/target/i386/hvf/hvf.c b/target/i386/hvf/hvf.c
index ed9356565c..0873e4969e 100644
--- a/target/i386/hvf/hvf.c
+++ b/target/i386/hvf/hvf.c
@@ -65,6 +65,7 @@
 
 #include <Hypervisor/hv.h>
 #include <Hypervisor/hv_vmx.h>
+#include <sys/sysctl.h>
 
 #include "exec/address-spaces.h"
 #include "hw/i386/apic_internal.h"
@@ -456,6 +457,50 @@ static void dummy_signal(int sig)
 {
 }
 
+static void init_tsc_freq(CPUX86State *env)
+{
+    size_t length;
+    uint64_t tsc_freq;
+
+    if (env->tsc_khz != 0) {
+        return;
+    }
+
+    length = sizeof(uint64_t);
+    if (sysctlbyname("machdep.tsc.frequency", &tsc_freq, &length, NULL, 0)) {
+        /* fprintf(stderr, "%s: sysctl machdep.tsc.frequency errored\n", __func__); */
+        return;
+    }
+    env->tsc_khz = tsc_freq / 1000;  /* Hz to KHz */
+}
+
+static void init_apic_bus_freq(CPUX86State *env)
+{
+    size_t length;
+    uint64_t bus_freq;
+
+    if (env->apic_bus_freq != 0) {
+        return;
+    }
+
+    length = sizeof(uint64_t);
+    if (sysctlbyname("hw.busfrequency", &bus_freq, &length, NULL, 0)) {
+        /* fprintf(stderr, "%s: sysctl hw.busfrequency errored\n", __func__); */
+        return;
+    }
+    env->apic_bus_freq = bus_freq;
+}
+
+static inline bool tsc_is_known(CPUX86State *env)
+{
+    return env->tsc_khz != 0;
+}
+
+static inline bool apic_bus_freq_is_known(CPUX86State *env)
+{
+    return env->apic_bus_freq != 0;
+}
+
 int hvf_init_vcpu(CPUState *cpu)
 {
 
@@ -480,6 +525,15 @@ int hvf_init_vcpu(CPUState *cpu)
     hvf_state->hvf_caps = g_new0(struct hvf_vcpu_caps, 1);
     env->hvf_mmio_buf = g_new(char, 4096);
 
+    if (x86cpu->vmware_cpuid_freq) {
+        init_tsc_freq(env);
+        init_apic_bus_freq(env);
+
+        if (!tsc_is_known(env) || !apic_bus_freq_is_known(env)) {
+            error_report("vmware-cpuid-freq: feature couldn't be enabled");
+        }
+    }
+
     r = hv_vcpu_create((hv_vcpuid_t *)&cpu->hvf_fd, HV_VCPU_DEFAULT);
     cpu->vcpu_dirty = 1;
     assert_hvf_ok(r);
@@ -597,6 +651,42 @@ static void hvf_store_events(CPUState *cpu, uint32_t ins_len, uint64_t idtvec_in
     }
 }
 
+static void hvf_cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
+                              uint32_t *eax, uint32_t *ebx,
+                              uint32_t *ecx, uint32_t *edx)
+{
+    /*
+     * A wrapper extends cpu_x86_cpuid with 0x40000000 and 0x40000010 leafs
+     * Provides vmware-cpuid-freq support to hvf
+     */
+
+    uint32_t signature[3];
+
+    if (!tsc_is_known(env) || !apic_bus_freq_is_known(env)) {
+        cpu_x86_cpuid(env, index, count, eax, ebx, ecx, edx);
+        return;
+    }
+
+    switch (index) {
+        case 0x40000000:
+            memcpy(signature, "TCGTCGTCGTCG", 12); /* QEMU Signature */
+            *eax = 0x40000010;                     /* Max available cpuid leaf */
+            *ebx = signature[0];
+            *ecx = signature[1];
+            *edx = signature[2];
+            break;
+        case 0x40000010:
+            *eax = env->tsc_khz;
+            *ebx = env->apic_bus_freq / 1000; /* Hz to KHz */
+            *ecx = 0;
+            *edx = 0;
+            break;
+        default:
+            cpu_x86_cpuid(env, index, count, eax, ebx, ecx, edx);
+            break;
+    }
+}
+
 int hvf_vcpu_exec(CPUState *cpu)
 {
     X86CPU *x86_cpu = X86_CPU(cpu);
@@ -734,7 +824,7 @@ int hvf_vcpu_exec(CPUState *cpu)
             uint32_t rcx = (uint32_t)rreg(cpu->hvf_fd, HV_X86_RCX);
             uint32_t rdx = (uint32_t)rreg(cpu->hvf_fd, HV_X86_RDX);
 
-            cpu_x86_cpuid(env, rax, rcx, &rax, &rbx, &rcx, &rdx);
+            hvf_cpu_x86_cpuid(env, rax, rcx, &rax, &rbx, &rcx, &rdx);
 
             wreg(cpu->hvf_fd, HV_X86_RAX, rax);
             wreg(cpu->hvf_fd, HV_X86_RBX, rbx);
-- 
2.28.0