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KVM: x86: drop TSC offsetting kvm_x86_ops to fix KVM_GET/SET_CLOCK

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Since commit a545ab6a00 ("kvm: x86: add tsc_offset field to struct
kvm_vcpu_arch", 2016-09-07) the offset between host and L1 TSC is
cached and need not be fished out of the VMCS or VMCB.  This means
that we can implement adjust_tsc_offset_guest and read_l1_tsc
entirely in generic code.  The simplification is particularly
significant for VMX code, where vmx->nested.vmcs01_tsc_offset
was duplicating what is now in vcpu->arch.tsc_offset.  Therefore
the vmcs01_tsc_offset can be dropped completely.

More importantly, this fixes KVM_GET_CLOCK/KVM_SET_CLOCK
which, after commit 108b249c45 ("KVM: x86: introduce get_kvmclock_ns",
2016-09-01) called read_l1_tsc while the VMCS was not loaded.
It thus returned bogus values on Intel CPUs.

Fixes: 108b249c45
Reported-by: Roman Kagan <rkagan@virtuozzo.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini
2016-11-01 00:39:48 +01:00
parent bd768e1466
commit ea26e4ec08
4 changed files with 6 additions and 65 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
arch/x86/kvm/svm.c
View File

@@ -1138,21 +1138,6 @@ static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
}
static void svm_adjust_tsc_offset_guest(struct kvm_vcpu *vcpu, s64 adjustment)
{
struct vcpu_svm *svm = to_svm(vcpu);
svm->vmcb->control.tsc_offset += adjustment;
if (is_guest_mode(vcpu))
svm->nested.hsave->control.tsc_offset += adjustment;
else
trace_kvm_write_tsc_offset(vcpu->vcpu_id,
svm->vmcb->control.tsc_offset - adjustment,
svm->vmcb->control.tsc_offset);
mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
}
static void avic_init_vmcb(struct vcpu_svm *svm)
{
struct vmcb *vmcb = svm->vmcb;
@@ -3449,12 +3434,6 @@ static int cr8_write_interception(struct vcpu_svm *svm)
return 0;
}
static u64 svm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
{
struct vmcb *vmcb = get_host_vmcb(to_svm(vcpu));
return vmcb->control.tsc_offset + host_tsc;
}
static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -5422,8 +5401,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
.has_wbinvd_exit = svm_has_wbinvd_exit,
.write_tsc_offset = svm_write_tsc_offset,
.adjust_tsc_offset_guest = svm_adjust_tsc_offset_guest,
.read_l1_tsc = svm_read_l1_tsc,
.set_tdp_cr3 = set_tdp_cr3,