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33d3617a52
Always intercept VMMCALL now that KVM properly synthesizes a #UD as
appropriate, i.e. when L1 doesn't want to intercept VMMCALL, to avoid
putting L2 into an infinite #UD loop if KVM_X86_QUIRK_FIX_HYPERCALL_INSN
is enabled.
By letting L2 execute VMMCALL natively and thus #UD, for all intents and
purposes KVM morphs the VMMCALL intercept into a #UD intercept (KVM always
intercepts #UD). When the hypercall quirk is enabled, KVM "emulates"
VMMCALL in response to the #UD by trying to fixup the opcode to the "right"
vendor, then restarts the guest, without skipping the VMMCALL. As a
result, the guest sees an endless stream of #UDs since it's already
executing the correct vendor hypercall instruction, i.e. the emulator
doesn't anticipate that the #UD could be due to lack of interception, as
opposed to a truly undefined opcode.
Fixes: 0d945bd935 ("KVM: SVM: Don't allow nested guest to VMMCALL into host")
Cc: stable@vger.kernel.org
Reviewed-by: Yosry Ahmed <yosry@kernel.org>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://patch.msgid.link/20260304002223.1105129-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Common Hyper-V on KVM and KVM on Hyper-V definitions (SVM).
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*/
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#ifndef __ARCH_X86_KVM_SVM_HYPERV_H__
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#define __ARCH_X86_KVM_SVM_HYPERV_H__
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#include <asm/mshyperv.h>
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#include "../hyperv.h"
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#include "svm.h"
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#ifdef CONFIG_KVM_HYPERV
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static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu)
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{
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struct vcpu_svm *svm = to_svm(vcpu);
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struct hv_vmcb_enlightenments *hve = &svm->nested.ctl.hv_enlightenments;
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struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
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if (!hv_vcpu)
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return;
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hv_vcpu->nested.pa_page_gpa = hve->partition_assist_page;
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hv_vcpu->nested.vm_id = hve->hv_vm_id;
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hv_vcpu->nested.vp_id = hve->hv_vp_id;
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}
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static inline bool nested_svm_l2_tlb_flush_enabled(struct kvm_vcpu *vcpu)
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{
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struct vcpu_svm *svm = to_svm(vcpu);
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struct hv_vmcb_enlightenments *hve = &svm->nested.ctl.hv_enlightenments;
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struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
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if (!hv_vcpu)
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return false;
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if (!hve->hv_enlightenments_control.nested_flush_hypercall)
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return false;
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return hv_vcpu->vp_assist_page.nested_control.features.directhypercall;
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}
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static inline bool nested_svm_is_l2_tlb_flush_hcall(struct kvm_vcpu *vcpu)
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{
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return guest_hv_cpuid_has_l2_tlb_flush(vcpu) &&
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nested_svm_l2_tlb_flush_enabled(vcpu) &&
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kvm_hv_is_tlb_flush_hcall(vcpu);
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}
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void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu);
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#else /* CONFIG_KVM_HYPERV */
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static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu) {}
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static inline bool nested_svm_is_l2_tlb_flush_hcall(struct kvm_vcpu *vcpu)
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{
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return false;
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}
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static inline void svm_hv_inject_synthetic_vmexit_post_tlb_flush(struct kvm_vcpu *vcpu) {}
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#endif /* CONFIG_KVM_HYPERV */
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#endif /* __ARCH_X86_KVM_SVM_HYPERV_H__ */
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