KVM: Track TSC synchronization in generations (e26101b1) · Commits · 戴 / test

arch/x86/include/asm/kvm_host.h

+7 −3

Original line number	Diff line number	Diff line
		@@ -420,10 +420,11 @@ struct kvm_vcpu_arch {

		u64 last_guest_tsc;
		u64 last_kernel_ns;
		u64 last_tsc_nsec;
		u64 last_tsc_write;
		u64 last_host_tsc;
		u64 tsc_offset_adjustment;
		u64 this_tsc_nsec;
		u64 this_tsc_write;
		u8 this_tsc_generation;
		bool tsc_catchup;
		bool tsc_always_catchup;
		s8 virtual_tsc_shift;
		@@ -513,9 +514,12 @@ struct kvm_arch {
		s64 kvmclock_offset;
		raw_spinlock_t tsc_write_lock;
		u64 last_tsc_nsec;
		u64 last_tsc_offset;
		u64 last_tsc_write;
		u32 last_tsc_khz;
		u64 cur_tsc_nsec;
		u64 cur_tsc_write;
		u64 cur_tsc_offset;
		u8 cur_tsc_generation;

		struct kvm_xen_hvm_config xen_hvm_config;

arch/x86/kvm/x86.c

+33 −8

Original line number	Diff line number	Diff line
		@@ -1013,10 +1013,10 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)

		static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
		{
		u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.last_tsc_nsec,
		u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.this_tsc_nsec,
		vcpu->arch.virtual_tsc_mult,
		vcpu->arch.virtual_tsc_shift);
		tsc += vcpu->arch.last_tsc_write;
		tsc += vcpu->arch.this_tsc_write;
		return tsc;
		}

		@@ -1059,7 +1059,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
		if (nsdiff < NSEC_PER_SEC &&
		vcpu->arch.virtual_tsc_khz == kvm->arch.last_tsc_khz) {
		if (!check_tsc_unstable()) {
		offset = kvm->arch.last_tsc_offset;
		offset = kvm->arch.cur_tsc_offset;
		pr_debug("kvm: matched tsc offset for %llu\n", data);
		} else {
		u64 delta = nsec_to_cycles(vcpu, elapsed);
		@@ -1067,20 +1067,45 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
		offset = kvm_x86_ops->compute_tsc_offset(vcpu, data);
		pr_debug("kvm: adjusted tsc offset by %llu\n", delta);
		}
		} else {
		/*
		* We split periods of matched TSC writes into generations.
		* For each generation, we track the original measured
		* nanosecond time, offset, and write, so if TSCs are in
		* sync, we can match exact offset, and if not, we can match
		* exact software computaion in compute_guest_tsc()
		*
		* These values are tracked in kvm->arch.cur_xxx variables.
		*/
		kvm->arch.cur_tsc_generation++;
		kvm->arch.cur_tsc_nsec = ns;
		kvm->arch.cur_tsc_write = data;
		kvm->arch.cur_tsc_offset = offset;
		pr_debug("kvm: new tsc generation %u, clock %llu\n",
		kvm->arch.cur_tsc_generation, data);
		}

		/*
		* We also track th most recent recorded KHZ, write and time to
		* allow the matching interval to be extended at each write.
		*/
		kvm->arch.last_tsc_nsec = ns;
		kvm->arch.last_tsc_write = data;
		kvm->arch.last_tsc_offset = offset;
		kvm->arch.last_tsc_khz = vcpu->arch.virtual_tsc_khz;
		kvm_x86_ops->write_tsc_offset(vcpu, offset);
		raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);

		/* Reset of TSC must disable overshoot protection below */
		vcpu->arch.hv_clock.tsc_timestamp = 0;
		vcpu->arch.last_tsc_write = data;
		vcpu->arch.last_tsc_nsec = ns;
		vcpu->arch.last_guest_tsc = data;

		/* Keep track of which generation this VCPU has synchronized to */
		vcpu->arch.this_tsc_generation = kvm->arch.cur_tsc_generation;
		vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec;
		vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write;

		kvm_x86_ops->write_tsc_offset(vcpu, offset);
		raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
		}

		EXPORT_SYMBOL_GPL(kvm_write_tsc);

		static int kvm_guest_time_update(struct kvm_vcpu *v)

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