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KVM: nSVM: synchronize VMCB controls updated by the processor on every vmexit 

The control state changes on every L2->L0 vmexit, and we will have to
serialize it in the nested state.  So keep it up to date in svm->nested.ctl
and just copy them back to the nested VMCB in nested_svm_vmexit.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2020-05-22 03:50:14 -04:00
parent d8e4e58f4b
commit 2d8a42be0e
3 changed files with 38 additions and 25 deletions
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57
arch/x86/kvm/svm/nested.c
View File

@ -234,6 +234,34 @@ static void load_nested_vmcb_control(struct vcpu_svm *svm,
svm->nested.ctl.iopm_base_pa &= ~0x0fffULL;
}
/*
* Synchronize fields that are written by the processor, so that
* they can be copied back into the nested_vmcb.
*/
void sync_nested_vmcb_control(struct vcpu_svm *svm)
{
u32 mask;
svm->nested.ctl.event_inj = svm->vmcb->control.event_inj;
svm->nested.ctl.event_inj_err = svm->vmcb->control.event_inj_err;
/* Only a few fields of int_ctl are written by the processor. */
mask = V_IRQ_MASK | V_TPR_MASK;
if (!(svm->nested.ctl.int_ctl & V_INTR_MASKING_MASK) &&
is_intercept(svm, SVM_EXIT_VINTR)) {
/*
* In order to request an interrupt window, L0 is usurping
* svm->vmcb->control.int_ctl and possibly setting V_IRQ
* even if it was clear in L1's VMCB. Restoring it would be
* wrong. However, in this case V_IRQ will remain true until
* interrupt_window_interception calls svm_clear_vintr and
* restores int_ctl. We can just leave it aside.
*/
mask &= ~V_IRQ_MASK;
}
svm->nested.ctl.int_ctl &= ~mask;
svm->nested.ctl.int_ctl |= svm->vmcb->control.int_ctl & mask;
}
static void nested_prepare_vmcb_save(struct vcpu_svm *svm, struct vmcb *nested_vmcb)
{
/* Load the nested guest state */
@ -471,6 +499,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
/* Exit Guest-Mode */
leave_guest_mode(&svm->vcpu);
svm->nested.vmcb = 0;
WARN_ON_ONCE(svm->nested.nested_run_pending);
/* in case we halted in L2 */
svm->vcpu.arch.mp_state = KVM_MP_STATE_RUNNABLE;
@ -497,8 +526,6 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
nested_vmcb->save.dr6 = svm->vcpu.arch.dr6;
nested_vmcb->save.cpl = vmcb->save.cpl;
nested_vmcb->control.int_ctl = vmcb->control.int_ctl;
nested_vmcb->control.int_vector = vmcb->control.int_vector;
nested_vmcb->control.int_state = vmcb->control.int_state;
nested_vmcb->control.exit_code = vmcb->control.exit_code;
nested_vmcb->control.exit_code_hi = vmcb->control.exit_code_hi;
@ -510,34 +537,16 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
if (svm->nrips_enabled)
nested_vmcb->control.next_rip = vmcb->control.next_rip;
/*
* If we emulate a VMRUN/#VMEXIT in the same host #vmexit cycle we have
* to make sure that we do not lose injected events. So check event_inj
* here and copy it to exit_int_info if it is valid.
* Exit_int_info and event_inj can't be both valid because the case
* below only happens on a VMRUN instruction intercept which has
* no valid exit_int_info set.
*/
if (vmcb->control.event_inj & SVM_EVTINJ_VALID) {
struct vmcb_control_area *nc = &nested_vmcb->control;
nc->exit_int_info = vmcb->control.event_inj;
nc->exit_int_info_err = vmcb->control.event_inj_err;
}
nested_vmcb->control.tlb_ctl = 0;
nested_vmcb->control.event_inj = 0;
nested_vmcb->control.event_inj_err = 0;
nested_vmcb->control.int_ctl = svm->nested.ctl.int_ctl;
nested_vmcb->control.tlb_ctl = svm->nested.ctl.tlb_ctl;
nested_vmcb->control.event_inj = svm->nested.ctl.event_inj;
nested_vmcb->control.event_inj_err = svm->nested.ctl.event_inj_err;
nested_vmcb->control.pause_filter_count =
svm->vmcb->control.pause_filter_count;
nested_vmcb->control.pause_filter_thresh =
svm->vmcb->control.pause_filter_thresh;
/* We always set V_INTR_MASKING and remember the old value in hflags */
if (!(svm->vcpu.arch.hflags & HF_VINTR_MASK))
nested_vmcb->control.int_ctl &= ~V_INTR_MASKING_MASK;
/* Restore the original control entries */
copy_vmcb_control_area(&vmcb->control, &hsave->control);

5
arch/x86/kvm/svm/svm.c
View File

@ -3427,7 +3427,10 @@ static fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
sync_cr8_to_lapic(vcpu);
svm->next_rip = 0;
svm->nested.nested_run_pending = 0;
if (is_guest_mode(&svm->vcpu)) {
sync_nested_vmcb_control(svm);
svm->nested.nested_run_pending = 0;
}
svm->vmcb->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;

1
arch/x86/kvm/svm/svm.h
View File

@ -394,6 +394,7 @@ int nested_svm_check_permissions(struct vcpu_svm *svm);
int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
bool has_error_code, u32 error_code);
int nested_svm_exit_special(struct vcpu_svm *svm);
void sync_nested_vmcb_control(struct vcpu_svm *svm);
extern struct kvm_x86_nested_ops svm_nested_ops;