From: Sean Christopherson <seanjc@google.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: kvm@vger.kernel.org, iommu@lists.linux.dev,
"H. Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>, Joerg Roedel <joro@8bytes.org>,
x86@kernel.org,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
linux-kernel@vger.kernel.org,
Dave Hansen <dave.hansen@linux.intel.com>,
Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Robin Murphy <robin.murphy@arm.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v2 1/4] x86: KVM: SVM: always update the x2avic msr interception
Date: Thu, 28 Sep 2023 17:24:18 -0700 [thread overview]
Message-ID: <ZRYZMr4fuaywW7fP@google.com> (raw)
In-Reply-To: <20230928173354.217464-2-mlevitsk@redhat.com>
On Thu, Sep 28, 2023, Maxim Levitsky wrote:
> The following problem exists since x2avic was enabled in the KVM:
>
> svm_set_x2apic_msr_interception is called to enable the interception of
Nit, svm_set_x2apic_msr_interception().
Definitely not worth another version though.
> the x2apic msrs.
>
> In particular it is called at the moment the guest resets its apic.
>
> Assuming that the guest's apic was in x2apic mode, the reset will bring
> it back to the xapic mode.
>
> The svm_set_x2apic_msr_interception however has an erroneous check for
> '!apic_x2apic_mode()' which prevents it from doing anything in this case.
>
> As a result of this, all x2apic msrs are left unintercepted, and that
> exposes the bare metal x2apic (if enabled) to the guest.
> Oops.
>
> Remove the erroneous '!apic_x2apic_mode()' check to fix that.
>
> This fixes CVE-2023-5090
>
> Fixes: 4d1d7942e36a ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode")
> Cc: stable@vger.kernel.org
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
Reviewed-by: Sean Christopherson <seanjc@google.com>
next prev parent reply other threads:[~2023-09-29 0:24 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-28 17:33 [PATCH v2 0/4] AVIC bugfixes and workarounds Maxim Levitsky
2023-09-28 17:33 ` [PATCH v2 1/4] x86: KVM: SVM: always update the x2avic msr interception Maxim Levitsky
2023-09-29 0:24 ` Sean Christopherson [this message]
2023-10-03 3:17 ` Suthikulpanit, Suravee
2023-09-28 17:33 ` [PATCH v2 2/4] x86: KVM: SVM: add support for Invalid IPI Vector interception Maxim Levitsky
2023-09-29 0:42 ` Sean Christopherson
2023-09-28 17:33 ` [PATCH v2 3/4] x86: KVM: SVM: refresh AVIC inhibition in svm_leave_nested() Maxim Levitsky
2023-09-29 0:42 ` Sean Christopherson
2023-09-28 17:33 ` [PATCH v2 4/4] x86: KVM: SVM: workaround for AVIC's errata #1235 Maxim Levitsky
2023-09-29 2:06 ` Sean Christopherson
2023-09-29 2:09 ` [PATCH v2 0/4] AVIC bugfixes and workarounds Sean Christopherson
2023-09-29 17:42 ` Paolo Bonzini
2023-10-12 14:46 ` Paolo Bonzini
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