KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS)
authorSean Christopherson <seanjc@google.com>
Thu, 12 May 2022 22:27:14 +0000 (22:27 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 17 Aug 2022 12:24:22 +0000 (14:24 +0200)
commitf2145a1bf7abb7dcf236a812a80465bd89a658b1
tree1955b6fcbfc1071a664ea5f0f464c8dbe65cf5b1
parent1f71d1f7f49152f74357097ff5b5df0695c2bcea
KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS)

[ 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