[PATCH v3] qemu-kvm: Make PC speaker emulation aware of in-kernel PIT

[Jan Kiszka <jan.kiszka@web.de>]

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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_PIT2 where
available. This unbreaks -soundhw pcspk in KVM mode.

Changes in v3:
 - re-added incorrectly dropped kvm_enabled checks

Changes in v2:
 - rebased over qemu-kvm and KVM_CREATE_PIT2
 - refactored hooks in pcspk

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

 hw/pcspk.c                     |   41 ++++++++++++++++++++++++++++++++++++++++
 kvm/kernel/include/linux/kvm.h |   10 ++++++++++
 kvm/libkvm/libkvm-x86.c        |   26 ++++++++++++++++++-------
 3 files changed, 69 insertions(+), 8 deletions(-)

diff --git a/hw/pcspk.c b/hw/pcspk.c
index ec1d0c6..fea3863 100644
--- a/hw/pcspk.c
+++ b/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
@@ -48,6 +50,37 @@ typedef struct {
 static const char *s_spk = "pcspk";
 static PCSpkState pcspk_state;
 
+#ifdef USE_KVM_PIT
+static void kvm_get_pit_ch2(PITState *pit)
+{
+    struct kvm_pit_state pit_state;
+
+    if (kvm_enabled() && qemu_kvm_pit_in_kernel()) {
+        kvm_get_pit(kvm_context, &pit_state);
+        pit->channels[2].mode = pit_state.channels[2].mode;
+        pit->channels[2].count = pit_state.channels[2].count;
+        pit->channels[2].count_load_time = pit_state.channels[2].count_load_time;
+        pit->channels[2].gate = pit_state.channels[2].gate;
+    }
+}
+
+static void kvm_set_pit_ch2(PITState *pit)
+{
+    struct kvm_pit_state pit_state;
+
+    if (kvm_enabled() && qemu_kvm_pit_in_kernel()) {
+        pit_state.channels[2].mode = pit->channels[2].mode;
+        pit_state.channels[2].count = pit->channels[2].count;
+        pit_state.channels[2].count_load_time = pit->channels[2].count_load_time;
+        pit_state.channels[2].gate = pit->channels[2].gate;
+        kvm_set_pit(kvm_context, &pit_state);
+    }
+}
+#else
+static inline void kvm_get_pit_ch2(PITState *pit) { }
+static inline void kvm_set_pit_ch2(PITState *pit) { }
+#endif
+
 static inline void generate_samples(PCSpkState *s)
 {
     unsigned int i;
@@ -72,6 +105,8 @@ static void pcspk_callback(void *opaque, int free)
     PCSpkState *s = opaque;
     unsigned int n;
 
+    kvm_get_pit_ch2(s->pit);
+
     if (pit_get_mode(s->pit, 2) != 3)
         return;
 
@@ -121,6 +156,8 @@ static uint32_t pcspk_ioport_read(void *opaque, uint32_t addr)
     PCSpkState *s = opaque;
     int out;
 
+    kvm_get_pit_ch2(s->pit);
+
     s->dummy_refresh_clock ^= (1 << 4);
     out = pit_get_out(s->pit, 2, qemu_get_clock(vm_clock)) << 5;
 
@@ -132,6 +169,8 @@ static void pcspk_ioport_write(void *opaque, uint32_t addr, uint32_t val)
     PCSpkState *s = opaque;
     const int gate = val & 1;
 
+    kvm_get_pit_ch2(s->pit);
+
     s->data_on = (val >> 1) & 1;
     pit_set_gate(s->pit, 2, gate);
     if (s->voice) {
@@ -139,6 +178,8 @@ 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);
     }
+
+    kvm_set_pit_ch2(s->pit);
 }
 
 void pcspk_init(PITState *pit)
diff --git a/kvm/kernel/include/linux/kvm.h b/kvm/kernel/include/linux/kvm.h
index f5e9d66..9ed4892 100644
--- a/kvm/kernel/include/linux/kvm.h
+++ b/kvm/kernel/include/linux/kvm.h
@@ -110,6 +110,14 @@ struct kvm_irqchip {
 	} chip;
 };
 
+/* for KVM_CREATE_PIT2 */
+struct kvm_pit_config {
+	__u32 flags;
+	__u32 pad;
+};
+
+#define KVM_PIT_SPEAKER_DUMMY     1
+
 #define KVM_EXIT_UNKNOWN          0
 #define KVM_EXIT_EXCEPTION        1
 #define KVM_EXIT_IO               2
@@ -455,6 +463,7 @@ struct kvm_trace_rec {
 #define KVM_CAP_ASSIGN_DEV_IRQ 29
 /* Another bug in KVM_SET_USER_MEMORY_REGION fixed: */
 #define KVM_CAP_JOIN_MEMORY_REGIONS_WORKS 30
+#define KVM_CAP_PIT2 31
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -538,6 +547,7 @@ struct kvm_irq_routing {
 #define KVM_ASSIGN_SET_MSIX_ENTRY \
 			_IOW(KVMIO, 0x74, struct kvm_assigned_msix_entry)
 #define KVM_DEASSIGN_DEV_IRQ       _IOW(KVMIO, 0x75, struct kvm_assigned_irq)
+#define KVM_CREATE_PIT2		   _IOW(KVMIO, 0x76, struct kvm_pit_config)
 
 /*
  * ioctls for vcpu fds
diff --git a/kvm/libkvm/libkvm-x86.c b/kvm/libkvm/libkvm-x86.c
index a2f6320..9c0d967 100644
--- a/kvm/libkvm/libkvm-x86.c
+++ b/kvm/libkvm/libkvm-x86.c
@@ -59,16 +59,26 @@ static int kvm_create_pit(kvm_context_t kvm)
 
 	kvm->pit_in_kernel = 0;
 	if (!kvm->no_pit_creation) {
-		r = ioctl(kvm->fd, KVM_CHECK_EXTENSION, KVM_CAP_PIT);
-		if (r > 0) {
+#ifdef KVM_CAP_PIT2
+		struct kvm_pit_config config = { .flags = 0 };
+
+		r = ioctl(kvm->fd, KVM_CHECK_EXTENSION, KVM_CAP_PIT2);
+		if (r > 0)
+			r = ioctl(kvm->vm_fd, KVM_CREATE_PIT2, &config);
+		else
+#endif
+		{
+			r = ioctl(kvm->fd, KVM_CHECK_EXTENSION, KVM_CAP_PIT);
+			if (r <= 0)
+				return 0;
+
 			r = ioctl(kvm->vm_fd, KVM_CREATE_PIT);
-			if (r >= 0)
-				kvm->pit_in_kernel = 1;
-			else {
-				fprintf(stderr, "Create kernel PIC irqchip failed\n");
-				return r;
-			}
 		}
+		if (r < 0) {
+			fprintf(stderr, "Create kernel PIC irqchip failed\n");
+			return r;
+		}
+		kvm->pit_in_kernel = 1;
 	}
 #endif
 	return 0;


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