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| author | Krish Sadhukhan <krish.sadhukhan@oracle.com> | 2021-03-23 20:50:03 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-04-17 15:30:52 +0300 |
| commit | 9a7de6ecc3ed80efb95fe1d97b6440922e55dbda (patch) | |
| tree | 9f1189fa6223ecbdeb130ff9fc8e427284e27e9e /arch/x86/kvm/svm/nested.c | |
| parent | 4a38162ee9f10f5f67c36f4f5aa4f6be2657efd5 (diff) | |
| download | linux-9a7de6ecc3ed80efb95fe1d97b6440922e55dbda.tar.xz | |
KVM: nSVM: If VMRUN is single-stepped, queue the #DB intercept in nested_svm_vmexit()
According to APM, the #DB intercept for a single-stepped VMRUN must happen
after the completion of that instruction, when the guest does #VMEXIT to
the host. However, in the current implementation of KVM, the #DB intercept
for a single-stepped VMRUN happens after the completion of the instruction
that follows the VMRUN instruction. When the #DB intercept handler is
invoked, it shows the RIP of the instruction that follows VMRUN, instead of
of VMRUN itself. This is an incorrect RIP as far as single-stepping VMRUN
is concerned.
This patch fixes the problem by checking, in nested_svm_vmexit(), for the
condition that the VMRUN instruction is being single-stepped and if so,
queues the pending #DB intercept so that the #DB is accounted for before
we execute L1's next instruction.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oraacle.com>
Message-Id: <20210323175006.73249-2-krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/svm/nested.c')
| -rw-r--r-- | arch/x86/kvm/svm/nested.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 9bed4847ad55..b974bd9c53c3 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -764,6 +764,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm) nested_svm_copy_common_state(svm->nested.vmcb02.ptr, svm->vmcb01.ptr); svm_switch_vmcb(svm, &svm->vmcb01); + WARN_ON_ONCE(svm->vmcb->control.exit_code != SVM_EXIT_VMRUN); /* * On vmexit the GIF is set to false and @@ -817,6 +818,15 @@ int nested_svm_vmexit(struct vcpu_svm *svm) kvm_clear_exception_queue(vcpu); kvm_clear_interrupt_queue(vcpu); + /* + * If we are here following the completion of a VMRUN that + * is being single-stepped, queue the pending #DB intercept + * right now so that it an be accounted for before we execute + * L1's next instruction. + */ + if (unlikely(svm->vmcb->save.rflags & X86_EFLAGS_TF)) + kvm_queue_exception(&(svm->vcpu), DB_VECTOR); + return 0; } |