[Devel] [PATCH 14/16] kvm: x86: add tsc_offset field to struct kvm_vcpu_arch

[Roman Kagan]

From: Luiz Capitulino <lcapitulino at redhat.com>

A future commit will want to easily read a vCPU's TSC offset,
so we store it in struct kvm_arch_vcpu_arch for easy access.

Signed-off-by: Luiz Capitulino <lcapitulino at redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
(cherry-picked from commit a545ab6a0085e6df9c7b6e9734b40ba4d2aca8c9)
Signed-off-by: Denis Plotnikov <dplotnikov at virtuozzo.com>
Signed-off-by: Roman Kagan <rkagan at virtuozzo.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/x86.c              | 10 ++++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 830d1cd..1166dc5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -484,6 +484,7 @@ struct kvm_vcpu_arch {
 		struct kvm_steal_time steal;
 	} st;
 
+	u64 tsc_offset;
 	u64 last_guest_tsc;
 	u64 last_host_tsc;
 	u64 tsc_offset_adjustment;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7fcb155..bd8e822 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1385,6 +1385,12 @@ u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
 }
 EXPORT_SYMBOL_GPL(kvm_read_l1_tsc);
 
+static void kvm_vcpu_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
+{
+	kvm_x86_ops->write_tsc_offset(vcpu, offset);
+	vcpu->arch.tsc_offset = offset;
+}
+
 void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -1494,7 +1500,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
 
 	if (guest_cpuid_has_tsc_adjust(vcpu) && !msr->host_initiated)
 		update_ia32_tsc_adjust_msr(vcpu, offset);
-	kvm_x86_ops->write_tsc_offset(vcpu, offset);
+	kvm_vcpu_write_tsc_offset(vcpu, offset);
 	raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags);
 
 	spin_lock(&kvm->arch.pvclock_gtod_sync_lock);
@@ -2959,7 +2965,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 		if (check_tsc_unstable()) {
 			u64 offset = kvm_compute_tsc_offset(vcpu,
 						vcpu->arch.last_guest_tsc);
-			kvm_x86_ops->write_tsc_offset(vcpu, offset);
+			kvm_vcpu_write_tsc_offset(vcpu, offset);
 			vcpu->arch.tsc_catchup = 1;
 		}
 		/*
-- 
2.7.4