KVM: X86: Update last_guest_tsc in vcpu_put

The last_guest_tsc is used in vcpu_load to adjust the
tsc_offset since tsc-scaling is merged. So the
last_guest_tsc needs to be updated in vcpu_put instead of
the the last_host_tsc. This is fixed with this patch.

Reported-by: Jan Kiszka <jan.kiszka@web.de>
Tested-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3e03f37..e50bffc 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -393,7 +393,6 @@ struct kvm_vcpu_arch {
        unsigned int hw_tsc_khz;
        unsigned int time_offset;
        struct page *time_page;
-       u64 last_host_tsc;
        u64 last_guest_tsc;
        u64 last_kernel_ns;
        u64 last_tsc_nsec;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b05e3fc..6aa1377 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2146,7 +2146,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
        kvm_x86_ops->vcpu_put(vcpu);
        kvm_put_guest_fpu(vcpu);
-       vcpu->arch.last_host_tsc = native_read_tsc();
+       kvm_get_msr(vcpu, MSR_IA32_TSC, &vcpu->arch.last_guest_tsc);
 }
 
 static int is_efer_nx(void)