From: Emanuele Giuseppe Esposito <eesposit@redhat.com>
To: kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org,
Emanuele Giuseppe Esposito <eesposit@redhat.com>
Subject: [PATCH v2 0/4] KVM: nSVM: avoid TOC/TOU race when checking vmcb12
Date: Fri, 17 Sep 2021 08:03:25 -0400 [thread overview]
Message-ID: <20210917120329.2013766-1-eesposit@redhat.com> (raw)
Currently there is a TOC/TOU race between the check of vmcb12's
efer, cr0 and cr4 registers and the later save of their values in
svm_set_*, because the guest could modify the values in the meanwhile.
To solve this issue, this serie introuces and uses svm->nested.save
structure in enter_svm_guest_mode to save the current value of efer,
cr0 and cr4 and later use these to set the vcpu->arch.* state.
Patch 1 just refactor the code to simplify the next two patches,
patch 2 introduces svm->nested.save to cache the efer, cr0 and cr4 fields
and in patch 3 and 4 we use it to avoid TOC/TOU races.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
RFC:
* use svm->nested.save instead of local variables.
* not dependent anymore from "KVM: nSVM: remove useless kvm_clear_*_queue"
* simplified patches, we just use the struct and not move the check
nearer to the TOU.
v2:
* svm->nested.save is a separate struct vmcb_save_area_cached,
and not vmcb_save_area.
* update also vmcb02->cr3 with svm->nested.save.cr3
Emanuele Giuseppe Esposito (4):
KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in
nested_vmcb_valid_sregs
nSVM: introduce smv->nested.save to cache save area fields
nSVM: use vmcb_save_area_cached in nested_vmcb_valid_sregs()
nSVM: use svm->nested.save to load vmcb12 registers and avoid TOC/TOU
races
arch/x86/kvm/svm/nested.c | 95 +++++++++++++++++++++------------------
arch/x86/kvm/svm/svm.c | 1 +
arch/x86/kvm/svm/svm.h | 12 +++++
3 files changed, 64 insertions(+), 44 deletions(-)
--
2.27.0
next reply other threads:[~2021-09-17 12:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-17 12:03 Emanuele Giuseppe Esposito [this message]
2021-09-17 12:03 ` [PATCH v2 1/4] KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in nested_vmcb_valid_sregs Emanuele Giuseppe Esposito
2021-09-17 12:03 ` [PATCH v2 2/4] nSVM: introduce smv->nested.save to cache save area fields Emanuele Giuseppe Esposito
2021-09-28 16:51 ` Paolo Bonzini
2021-09-17 12:03 ` [PATCH v2 3/4] nSVM: use vmcb_save_area_cached in nested_vmcb_valid_sregs() Emanuele Giuseppe Esposito
2021-09-17 12:03 ` [PATCH v2 4/4] nSVM: use svm->nested.save to load vmcb12 registers and avoid TOC/TOU races Emanuele Giuseppe Esposito
2021-09-28 16:52 ` [PATCH v2 0/4] KVM: nSVM: avoid TOC/TOU race when checking vmcb12 Paolo Bonzini
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