[PATCH] KVM: nVMX: fixes for preemption timer migration

Paolo Bonzini
2020-07-09T17:15:19Z

Commit 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration",
2020-06-01) accidentally broke nVMX live migration from older version
by changing the userspace ABI. Restore it and, while at it, ensure
that vmx->nested.has_preemption_timer_deadline is always initialized
according to the KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE flag.

Cc: Makarand Sonare <makarandsonare@google.com>
Fixes: 850448f35aaf ("KVM: nVMX: Fix VMX preemption timer migration")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/uapi/asm/kvm.h | 5 +++--
arch/x86/kvm/vmx/nested.c | 3 ++-
2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 17c5a038f42d..0780f97c1850 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -408,14 +408,15 @@ struct kvm_vmx_nested_state_data {
};

struct kvm_vmx_nested_state_hdr {
- __u32 flags;
__u64 vmxon_pa;
__u64 vmcs12_pa;
- __u64 preemption_timer_deadline;

struct {
__u16 flags;
} smm;
+
+ __u32 flags;
+ __u64 preemption_timer_deadline;
};

struct kvm_svm_nested_state_data {
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b26655104d4a..3fc2411edc92 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -6180,7 +6180,8 @@ static int vmx_set_nested_state(struct kvm_vcpu *vcpu,
vmx->nested.has_preemption_timer_deadline = true;
vmx->nested.preemption_timer_deadline =
kvm_state->hdr.vmx.preemption_timer_deadline;
- }
+ } else
+ vmx->nested.has_preemption_timer_deadline = false;

if (nested_vmx_check_controls(vcpu, vmcs12) ||
nested_vmx_check_host_state(vcpu, vmcs12) ||
--
2.26.2