linux-kernel - [PATCH 0/3] KVM: x86: Fix fault-related bugs in LTR/LLDT emulation

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Date:   Mon, 11 Jul 2022 23:27:47 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzbot+760a73552f47a8cd0fd9@...kaller.appspotmail.com,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Hou Wenlong <houwenlong.hwl@...group.com>
Subject: [PATCH 0/3] KVM: x86: Fix fault-related bugs in LTR/LLDT emulation

Patch 1 fixes a bug found by syzkaller where KVM attempts to set the
TSS.busy bit during LTR before checking that the new TSS.base is valid.

Patch 2 fixes a bug found by inspection (when reading the APM to verify
the non-canonical logic is correct) where KVM doesn't provide the correct
error code if the new TSS.base is non-canonical.

Patch 3 makes the "dangling userspace I/O" WARN_ON two separate WARN_ON_ONCE
so that a KVM bug doesn't spam the kernel log (keeping the WARN is desirable
specifically to detect these types of bugs).

Sean Christopherson (3):
  KVM: x86: Mark TSS busy during LTR emulation _after_ all fault checks
  KVM: x86: Set error code to segment selector on LLDT/LTR non-canonical
    #GP
  KVM: x86: WARN only once if KVM leaves a dangling userspace I/O
    request

 arch/x86/kvm/emulate.c | 23 +++++++++++------------
 arch/x86/kvm/x86.c     |  6 ++++--
 2 files changed, 15 insertions(+), 14 deletions(-)

base-commit: b9b71f43683ae9d76b0989249607bbe8c9eb6c5c
-- 
2.37.0.144.g8ac04bfd2-goog