The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 2368048bf5c2ec4b604ac3431564071e89a0bc71 Mon Sep 17 00:00:00 2001 From: Sean Christopherson seanjc@google.com Date: Thu, 12 May 2022 22:27:14 +0000 Subject: [PATCH] KVM: x86: Signal #GP, not -EPERM, on bad WRMSR(MCi_CTL/STATUS)
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
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7ce0c6fe166d..891ca973c838 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3239,13 +3239,13 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info) */ 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;