From: Paolo Bonzini <pbonzini@redhat.com>
To: Sasha Levin <sashal@kernel.org>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Sean Christopherson <seanjc@google.com>,
Liam Merwick <liam.merwick@oracle.com>,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH MANUALSEL 5.10 5/6] KVM: SVM: Don't kill SEV guest if SMAP erratum triggers in usermode
Date: Thu, 10 Feb 2022 17:41:48 +0100 [thread overview]
Message-ID: <0ed5a95c-39d7-1139-4234-83b1857504b4@redhat.com> (raw)
In-Reply-To: <20220209185714.48936-5-sashal@kernel.org>
On 2/9/22 19:57, Sasha Levin wrote:
> From: Sean Christopherson <seanjc@google.com>
>
> [ Upstream commit cdf85e0c5dc766fc7fc779466280e454a6d04f87 ]
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo
> Inject a #GP instead of synthesizing triple fault to try to avoid killing
> the guest if emulation of an SEV guest fails due to encountering the SMAP
> erratum. The injected #GP may still be fatal to the guest, e.g. if the
> userspace process is providing critical functionality, but KVM should
> make every attempt to keep the guest alive.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
> Message-Id: <20220120010719.711476-10-seanjc@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> arch/x86/kvm/svm/svm.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index fa543c355fbdb..d515c8e68314c 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -4155,7 +4155,21 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, void *insn, int i
> return true;
>
> pr_err_ratelimited("KVM: SEV Guest triggered AMD Erratum 1096\n");
> - kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
> +
> + /*
> + * If the fault occurred in userspace, arbitrarily inject #GP
> + * to avoid killing the guest and to hopefully avoid confusing
> + * the guest kernel too much, e.g. injecting #PF would not be
> + * coherent with respect to the guest's page tables. Request
> + * triple fault if the fault occurred in the kernel as there's
> + * no fault that KVM can inject without confusing the guest.
> + * In practice, the triple fault is moot as no sane SEV kernel
> + * will execute from user memory while also running with SMAP=1.
> + */
> + if (is_user)
> + kvm_inject_gp(vcpu, 0);
> + else
> + kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
> }
>
> return false;
next prev parent reply other threads:[~2022-02-10 16:42 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 18:57 [PATCH MANUALSEL 5.10 1/6] KVM: eventfd: Fix false positive RCU usage warning Sasha Levin
2022-02-09 18:57 ` [PATCH MANUALSEL 5.10 2/6] KVM: nVMX: eVMCS: Filter out VM_EXIT_SAVE_VMX_PREEMPTION_TIMER Sasha Levin
2022-02-10 16:40 ` Paolo Bonzini
2022-02-09 18:57 ` [PATCH MANUALSEL 5.10 3/6] KVM: nVMX: Also filter MSR_IA32_VMX_TRUE_PINBASED_CTLS when eVMCS Sasha Levin
2022-02-10 16:40 ` Paolo Bonzini
2022-02-09 18:57 ` [PATCH MANUALSEL 5.10 4/6] KVM: nVMX: WARN on any attempt to allocate shadow VMCS for vmcs02 Sasha Levin
2022-02-10 16:35 ` Paolo Bonzini
2022-02-09 18:57 ` [PATCH MANUALSEL 5.10 5/6] KVM: SVM: Don't kill SEV guest if SMAP erratum triggers in usermode Sasha Levin
2022-02-10 16:40 ` Paolo Bonzini
2022-02-10 16:41 ` Paolo Bonzini [this message]
2022-02-09 18:57 ` [PATCH MANUALSEL 5.10 6/6] KVM: VMX: Set vmcs.PENDING_DBG.BS on #DB in STI/MOVSS blocking shadow Sasha Levin
2022-02-10 16:36 ` Paolo Bonzini
2022-02-10 16:40 ` [PATCH MANUALSEL 5.10 1/6] KVM: eventfd: Fix false positive RCU usage warning Paolo Bonzini
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