Re: [PATCH] kvm-userspace: Make PC speaker emulation aware of in-kernel PIT

[Avi Kivity]

Jan Kiszka wrote:

When using the in-kernel PIT the speaker emulation has to synchronize
the PIT state with KVM. Enhance the existing speaker sound device and
allow it to take over port 0x61 by using KVM_CREATE_PIT_NOSPKR when
available. This unbreaks -soundhw pcspk in KVM mode.

diff --git a/qemu/hw/pcspk.c b/qemu/hw/pcspk.c
index ec1d0c6..4752518 100644
--- a/qemu/hw/pcspk.c
+++ b/qemu/hw/pcspk.c
@@ -27,6 +27,8 @@
 #include "isa.h"
 #include "audio/audio.h"
 #include "qemu-timer.h"
+#include "i8254.h"
+#include "qemu-kvm.h"

#define PCSPK_BUF_LEN 1792

 #define PCSPK_SAMPLE_RATE 32000
@@ -71,7 +73,15 @@ static void pcspk_callback(void *opaque, int free)
 {
     PCSpkState *s = opaque;
     unsigned int n;
+#ifdef USE_KVM_PIT
+    struct kvm_pit_state pit_state;

+ if (kvm_enabled() && qemu_kvm_pit_in_kernel()) {

+        kvm_get_pit(kvm_context, &pit_state);
+        s->pit->channels[2].mode = pit_state.channels[2].mode;
+        s->pit->channels[2].count = pit_state.channels[2].count;
+    }
+#endif
     if (pit_get_mode(s->pit, 2) != 3)
         return;

@@ -120,7 +130,17 @@ static uint32_t pcspk_ioport_read(void *opaque, uint32_t addr)

 {
     PCSpkState *s = opaque;
     int out;
-
+#ifdef USE_KVM_PIT
+    struct kvm_pit_state pit_state;
+
+    if (kvm_enabled() && qemu_kvm_pit_in_kernel()) {
+        kvm_get_pit(kvm_context, &pit_state);
+        s->pit->channels[2].mode = pit_state.channels[2].mode;
+        s->pit->channels[2].count = pit_state.channels[2].count;
+        s->pit->channels[2].count_load_time = 
pit_state.channels[2].count_load_time;
+        s->pit->channels[2].gate = pit_state.channels[2].gate;
+    }
+#endif
     s->dummy_refresh_clock ^= (1 << 4);
     out = pit_get_out(s->pit, 2, qemu_get_clock(vm_clock)) << 5;

@@ -131,7 +151,17 @@ static void pcspk_ioport_write(void *opaque, uint32_t addr, uint32_t val)

 {
     PCSpkState *s = opaque;
     const int gate = val & 1;
-
+#ifdef USE_KVM_PIT
+    struct kvm_pit_state pit_state;
+
+    if (kvm_enabled() && qemu_kvm_pit_in_kernel()) {
+        kvm_get_pit(kvm_context, &pit_state);
+        s->pit->channels[2].mode = pit_state.channels[2].mode;
+        s->pit->channels[2].count = pit_state.channels[2].count;
+        s->pit->channels[2].count_load_time = 
pit_state.channels[2].count_load_time;
+        s->pit->channels[2].gate = pit_state.channels[2].gate;
+    }
+#endif
     s->data_on = (val >> 1) & 1;
     pit_set_gate(s->pit, 2, gate);
     if (s->voice) {
@@ -139,6 +169,15 @@ static void pcspk_ioport_write(void *opaque, uint32_t 
addr, uint32_t val)
             s->play_pos = 0;
         AUD_set_active_out(s->voice, gate & s->data_on);
     }
+#ifdef USE_KVM_PIT
+    if (kvm_enabled() && qemu_kvm_pit_in_kernel()) {
+        pit_state.channels[2].mode = s->pit->channels[2].mode;
+        pit_state.channels[2].count = s->pit->channels[2].count;
+        pit_state.channels[2].count_load_time = 
s->pit->channels[2].count_load_time;
+        pit_state.channels[2].gate = s->pit->channels[2].gate;
+        kvm_set_pit(kvm_context, &pit_state);
+    }
+#endif
 }

void pcspk_init(PITState *pit)

Please extract those bits into functions.

--
Do not meddle in the internals of kernels, for they are subtle and quick to 
panic.

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