X86/KVM: Properly update 'tsc_offset' to represent the running guest

Update 'tsc_offset' on vmentry/vmexit of L2 guests to ensure that it always
captures the TSC_OFFSET of the running guest whether it is the L1 or L2
guest.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Jim Mattson <jmattson@google.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
[AMD changes, fix update_ia32_tsc_adjust_msr. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b3ebc8ad6891..e77a536d0b7c 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1424,12 +1424,23 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type)
         seg->base = 0;
 }
 
+static u64 svm_read_l1_tsc_offset(struct kvm_vcpu *vcpu)
+{
+        struct vcpu_svm *svm = to_svm(vcpu);
+
+        if (is_guest_mode(vcpu))
+                return svm->nested.hsave->control.tsc_offset;
+
+        return vcpu->arch.tsc_offset;
+}
+
 static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
         u64 g_tsc_offset = 0;
 
         if (is_guest_mode(vcpu)) {
+                /* Write L1's TSC offset.  */
                 g_tsc_offset = svm->vmcb->control.tsc_offset -
                                svm->nested.hsave->control.tsc_offset;
                 svm->nested.hsave->control.tsc_offset = offset;
@@ -3323,6 +3334,7 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
         /* Restore the original control entries */
         copy_vmcb_control_area(vmcb, hsave);
 
+        svm->vcpu.arch.tsc_offset = svm->vmcb->control.tsc_offset;
         kvm_clear_exception_queue(&svm->vcpu);
         kvm_clear_interrupt_queue(&svm->vcpu);
 
@@ -3483,10 +3495,12 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
         /* We don't want to see VMMCALLs from a nested guest */
         clr_intercept(svm, INTERCEPT_VMMCALL);
 
+        svm->vcpu.arch.tsc_offset += nested_vmcb->control.tsc_offset;
+        svm->vmcb->control.tsc_offset = svm->vcpu.arch.tsc_offset;
+
         svm->vmcb->control.virt_ext = nested_vmcb->control.virt_ext;
         svm->vmcb->control.int_vector = nested_vmcb->control.int_vector;
         svm->vmcb->control.int_state = nested_vmcb->control.int_state;
-        svm->vmcb->control.tsc_offset += nested_vmcb->control.tsc_offset;
         svm->vmcb->control.event_inj = nested_vmcb->control.event_inj;
         svm->vmcb->control.event_inj_err = nested_vmcb->control.event_inj_err;
 
@@ -7102,6 +7116,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 
         .has_wbinvd_exit = svm_has_wbinvd_exit,
 
+        .read_l1_tsc_offset = svm_read_l1_tsc_offset,
         .write_tsc_offset = svm_write_tsc_offset,
 
         .set_tdp_cr3 = set_tdp_cr3,