When a guest is migrated, a time offset is generated in order to
maintain the correct kvmclock based time for the guest. Detect when
all kvmclock time pages are deleted so that the kvmclock offset can
be safely reset to zero.
Cc: Glauber Costa <glommer@xxxxxxxxxx>
Cc: Zachary Amsden <zamsden@xxxxxxxxx>
Signed-off-by: Bruce Rogers <brogers@xxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/x86.c | 5 ++++-
2 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index db7c1f2..112415c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -524,6 +524,7 @@ struct kvm_arch {
unsigned long irq_sources_bitmap;
s64 kvmclock_offset;
+ unsigned int n_time_pages;
raw_spinlock_t tsc_write_lock;
u64 last_tsc_nsec;
u64 last_tsc_write;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 14c290d..350c51b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1511,6 +1511,8 @@ static void kvmclock_reset(struct kvm_vcpu *vcpu)
if (vcpu->arch.time_page) {
kvm_release_page_dirty(vcpu->arch.time_page);
vcpu->arch.time_page = NULL;
+ if (--vcpu->kvm->arch.n_time_pages == 0)
+ vcpu->kvm->arch.kvmclock_offset = 0;
}
}
@@ -1624,7 +1626,8 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
if (is_error_page(vcpu->arch.time_page)) {
kvm_release_page_clean(vcpu->arch.time_page);
vcpu->arch.time_page = NULL;
- }
+ } else
+ vcpu->kvm->arch.n_time_pages++;
break;
}
case MSR_KVM_ASYNC_PF_EN:
--
1.7.7
--
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