lkml.org 
[lkml]   [2022]   [Aug]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.19 1064/1157] KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS)
    Date
    From: Sean Christopherson <seanjc@google.com>

    [ Upstream commit 2368048bf5c2ec4b604ac3431564071e89a0bc71 ]

    Return '1', not '-1', when handling an illegal WRMSR to a MCi_CTL or
    MCi_STATUS MSR. The behavior of "all zeros' or "all ones" for CTL MSRs
    is architectural, as is the "only zeros" behavior for STATUS MSRs. I.e.
    the intent is to inject a #GP, not exit to userspace due to an unhandled
    emulation case. Returning '-1' gets interpreted as -EPERM up the stack
    and effecitvely kills the guest.

    Fixes: 890ca9aefa78 ("KVM: Add MCE support")
    Fixes: 9ffd986c6e4e ("KVM: X86: #GP when guest attempts to write MCi_STATUS register w/o 0")
    Cc: stable@vger.kernel.org
    Signed-off-by: Sean Christopherson <seanjc@google.com>
    Reviewed-by: Jim Mattson <jmattson@google.com>
    Link: https://lore.kernel.org/r/20220512222716.4112548-2-seanjc@google.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/kvm/x86.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -3252,13 +3252,13 @@ static int set_msr_mce(struct kvm_vcpu *
    */
    if ((offset & 0x3) == 0 &&
    data != 0 && (data | (1 << 10) | 1) != ~(u64)0)
    - return -1;
    + return 1;

    /* MCi_STATUS */
    if (!msr_info->host_initiated &&
    (offset & 0x3) == 1 && data != 0) {
    if (!can_set_mci_status(vcpu))
    - return -1;
    + return 1;
    }

    vcpu->arch.mce_banks[offset] = data;

    \
     
     \ /
      Last update: 2022-08-16 06:54    [W:2.747 / U:5.160 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site