KVM: x86: PIT: Preserve state of speaker port data bit

Currently the state of the speaker port (0x61) data bit (bit 1) is not
saved in the exported state (kvm_pit_state2) and hence is lost when
re-constructing guest state.

This patch removes the 'speaker_data_port' field from kvm_kpit_state and
instead tracks the state using a new KVM_PIT_FLAGS_SPEAKER_DATA_ON flag
defined in the API.
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Message-Id: <20220531124421.1427-1-pdurrant@amazon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Documentation/virt/kvm/api.rst

@@ -3007,6 +3007,8 @@ Valid flags are::
 
   /* disable PIT in HPET legacy mode */
   #define KVM_PIT_FLAGS_HPET_LEGACY     0x00000001
+  /* speaker port data bit enabled */
+  #define KVM_PIT_FLAGS_SPEAKER_DATA_ON 0x00000002
 
 This IOCTL replaces the obsolete KVM_GET_PIT.
 

arch/x86/include/uapi/asm/kvm.h

@@ -307,6 +307,7 @@ struct kvm_pit_state {
 };
 
 #define KVM_PIT_FLAGS_HPET_LEGACY     0x00000001
+#define KVM_PIT_FLAGS_SPEAKER_DATA_ON 0x00000002
 
 struct kvm_pit_state2 {
 	struct kvm_pit_channel_state channels[3];

arch/x86/kvm/i8254.c

@@ -591,7 +591,10 @@ static int speaker_ioport_write(struct kvm_vcpu *vcpu,
 		return -EOPNOTSUPP;
 
 	mutex_lock(&pit_state->lock);
-	pit_state->speaker_data_on = (val >> 1) & 1;
+	if (val & (1 << 1))
+		pit_state->flags |= KVM_PIT_FLAGS_SPEAKER_DATA_ON;
+	else
+		pit_state->flags &= ~KVM_PIT_FLAGS_SPEAKER_DATA_ON;
 	pit_set_gate(pit, 2, val & 1);
 	mutex_unlock(&pit_state->lock);
 	return 0;
@@ -612,8 +615,9 @@ static int speaker_ioport_read(struct kvm_vcpu *vcpu,
 	refresh_clock = ((unsigned int)ktime_to_ns(ktime_get()) >> 14) & 1;
 
 	mutex_lock(&pit_state->lock);
-	ret = ((pit_state->speaker_data_on << 1) | pit_get_gate(pit, 2) |
-		(pit_get_out(pit, 2) << 5) | (refresh_clock << 4));
+	ret = (!!(pit_state->flags & KVM_PIT_FLAGS_SPEAKER_DATA_ON) << 1) |
+		pit_get_gate(pit, 2) | (pit_get_out(pit, 2) << 5) |
+		(refresh_clock << 4);
 	if (len > sizeof(ret))
 		len = sizeof(ret);
 	memcpy(data, (char *)&ret, len);

arch/x86/kvm/i8254.h

@@ -29,7 +29,6 @@ struct kvm_kpit_state {
 	bool is_periodic;
 	s64 period; 				/* unit: ns */
 	struct hrtimer timer;
-	u32    speaker_data_on;
 
 	struct mutex lock;
 	atomic_t reinject;