From: Maxim Levitsky <mlevitsk@redhat.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Wanpeng Li <wanpengli@tencent.com>,
Borislav Petkov <bp@alien8.de>,
Paolo Bonzini <pbonzini@redhat.com>,
Joerg Roedel <joro@8bytes.org>, Jim Mattson <jmattson@google.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Sean Christopherson <seanjc@google.com>,
x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
Thomas Gleixner <tglx@linutronix.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH 7/7] KVM: nSVM: call nested_svm_load_cr3 on nested state load
Date: Wed, 17 Feb 2021 16:57:18 +0200 [thread overview]
Message-ID: <20210217145718.1217358-8-mlevitsk@redhat.com> (raw)
In-Reply-To: <20210217145718.1217358-1-mlevitsk@redhat.com>
While KVM's MMU should be fully reset by loading of nested CR0/CR3/CR4
by KVM_SET_SREGS, we are not in nested mode yet when we do it and therefore
only root_mmu is reset.
On regular nested entries we call nested_svm_load_cr3 which both updates the
guest's CR3 in the MMU when it is needed, and it also initializes
the mmu again which makes it initialize the walk_mmu as well when nested
paging is enabled in both host and guest.
Since we don't call nested_svm_load_cr3 on nested state load,
the walk_mmu can be left uninitialized, which can lead to a NULL pointer
dereference while accessing it, if we happen to get a nested page fault
right after entering the nested guest first time after the migration and
if we decide to emulate it.
This makes the emulator access NULL walk_mmu->gva_to_gpa.
Therefore we should call this function on nested state load as well.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/svm/nested.c | 40 +++++++++++++++++++++------------------
1 file changed, 22 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 53b9037259b5..ebc7dfaa9f13 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -215,24 +215,6 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
return true;
}
-static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
-{
- struct vcpu_svm *svm = to_svm(vcpu);
-
- if (WARN_ON(!is_guest_mode(vcpu)))
- return true;
-
- if (!nested_svm_vmrun_msrpm(svm)) {
- vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
- vcpu->run->internal.suberror =
- KVM_INTERNAL_ERROR_EMULATION;
- vcpu->run->internal.ndata = 0;
- return false;
- }
-
- return true;
-}
-
static bool nested_vmcb_check_controls(struct vmcb_control_area *control)
{
if (CC(!vmcb_is_intercept(control, INTERCEPT_VMRUN)))
@@ -1311,6 +1293,28 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
return ret;
}
+static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (WARN_ON(!is_guest_mode(vcpu)))
+ return true;
+
+ if (nested_svm_load_cr3(&svm->vcpu, vcpu->arch.cr3,
+ nested_npt_enabled(svm)))
+ return false;
+
+ if (!nested_svm_vmrun_msrpm(svm)) {
+ vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+ vcpu->run->internal.suberror =
+ KVM_INTERNAL_ERROR_EMULATION;
+ vcpu->run->internal.ndata = 0;
+ return false;
+ }
+
+ return true;
+}
+
struct kvm_x86_nested_ops svm_nested_ops = {
.check_events = svm_check_nested_events,
.get_nested_state_pages = svm_get_nested_state_pages,
--
2.26.2
prev parent reply other threads:[~2021-02-17 15:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 14:57 [PATCH 0/7] KVM: random nested fixes Maxim Levitsky
2021-02-17 14:57 ` [PATCH 1/7] KVM: VMX: read idt_vectoring_info a bit earlier Maxim Levitsky
2021-02-17 16:06 ` Paolo Bonzini
2021-02-17 16:18 ` Maxim Levitsky
2021-02-17 16:21 ` Sean Christopherson
2021-02-17 16:29 ` Paolo Bonzini
2021-02-17 14:57 ` [PATCH 2/7] KVM: nSVM: move nested vmrun tracepoint to enter_svm_guest_mode Maxim Levitsky
2021-02-17 14:57 ` [PATCH 3/7] KVM: x86: add .complete_mmu_init arch callback Maxim Levitsky
2021-02-17 14:57 ` [PATCH 4/7] KVM: nVMX: move inject_page_fault tweak to .complete_mmu_init Maxim Levitsky
2021-02-17 17:29 ` Sean Christopherson
2021-02-17 17:37 ` Paolo Bonzini
2021-02-17 17:57 ` Sean Christopherson
2021-02-17 18:00 ` Paolo Bonzini
2021-02-17 18:49 ` Maxim Levitsky
2021-02-17 18:43 ` Maxim Levitsky
2021-02-18 9:45 ` Paolo Bonzini
2021-02-17 14:57 ` [PATCH 5/7] KVM: nSVM: fix running nested guests when npt=0 Maxim Levitsky
2021-02-17 15:27 ` Maxim Levitsky
2021-02-17 14:57 ` [PATCH 6/7] KVM: nVMX: don't load PDPTRS right after nested state set Maxim Levitsky
2021-02-17 17:52 ` Sean Christopherson
2021-02-17 18:06 ` Paolo Bonzini
2021-02-17 14:57 ` Maxim Levitsky [this message]
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