]> www.infradead.org Git - users/jedix/linux-maple.git/commit
KVM: SVM: Fix a benign off-by-one bug in AVIC physical table mask
authorSean Christopherson <seanjc@google.com>
Tue, 7 Feb 2023 00:21:54 +0000 (00:21 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 22 Mar 2023 12:33:59 +0000 (13:33 +0100)
commitacb0288bdd42dd6fc0baa9f52a1db88c62fed4af
treebe19578a307c57a26a67c0f3108f4ea4ff054ae5
parent72f90f9cf032de1b0cf37d9d211d8c34619fda33
KVM: SVM: Fix a benign off-by-one bug in AVIC physical table mask

commit 3ec7a1b2743c07c45f4a0c508114f6cb410ddef3 upstream.

Define the "physical table max index mask" as bits 8:0, not 9:0.  x2AVIC
currently supports a max of 512 entries, i.e. the max index is 511, and
the inputs to GENMASK_ULL() are inclusive.  The bug is benign as bit 9 is
reserved and never set by KVM, i.e. KVM is just clearing bits that are
guaranteed to be zero.

Note, as of this writing, APM "Rev. 3.39-October 2022" incorrectly states
that bits 11:8 are reserved in Table B-1. VMCB Layout, Control Area.  I.e.
that table wasn't updated when x2AVIC support was added.

Opportunistically fix the comment for the max AVIC ID to align with the
code, and clean up comment formatting too.

Fixes: 4d1d7942e36a ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode")
Cc: stable@vger.kernel.org
Cc: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20230207002156.521736-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/x86/include/asm/svm.h