From: Paolo Bonzini <pbonzini@redhat.com>
To: Sasha Levin <sashal@kernel.org>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Maxim Levitsky <mlevitsk@redhat.com>,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
x86@kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH MANUALSEL 5.14 6/9] KVM: x86: nVMX: don't fail nested VM entry on invalid guest state if !from_vmentry
Date: Wed, 6 Oct 2021 15:36:04 +0200 [thread overview]
Message-ID: <a37798f3-708a-049d-34dc-0d0d23bc499a@redhat.com> (raw)
In-Reply-To: <20211006133021.271905-6-sashal@kernel.org>
On 06/10/21 15:30, Sasha Levin wrote:
> From: Maxim Levitsky <mlevitsk@redhat.com>
>
> [ Upstream commit c8607e4a086fae05efe5bffb47c5199c65e7216e ]
>
> It is possible that when non root mode is entered via special entry
> (!from_vmentry), that is from SMM or from loading the nested state,
> the L2 state could be invalid in regard to non unrestricted guest mode,
> but later it can become valid.
>
> (for example when RSM emulation restores segment registers from SMRAM)
>
> Thus delay the check to VM entry, where we will check this and fail.
>
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> Message-Id: <20210913140954.165665-7-mlevitsk@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> arch/x86/kvm/vmx/nested.c | 7 ++++++-
> arch/x86/kvm/vmx/vmx.c | 5 ++++-
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index ac1803dac435..2e8a46f9f552 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -2576,8 +2576,13 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
> * Guest state is invalid and unrestricted guest is disabled,
> * which means L1 attempted VMEntry to L2 with invalid state.
> * Fail the VMEntry.
> + *
> + * However when force loading the guest state (SMM exit or
> + * loading nested state after migration, it is possible to
> + * have invalid guest state now, which will be later fixed by
> + * restoring L2 register state
> */
> - if (CC(!vmx_guest_state_valid(vcpu))) {
> + if (CC(from_vmentry && !vmx_guest_state_valid(vcpu))) {
> *entry_failure_code = ENTRY_FAIL_DEFAULT;
> return -EINVAL;
> }
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 339116ff236f..974029917713 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6613,7 +6613,10 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
> * consistency check VM-Exit due to invalid guest state and bail.
> */
> if (unlikely(vmx->emulation_required)) {
> - vmx->fail = 0;
> +
> + /* We don't emulate invalid state of a nested guest */
> + vmx->fail = is_guest_mode(vcpu);
> +
> vmx->exit_reason.full = EXIT_REASON_INVALID_STATE;
> vmx->exit_reason.failed_vmentry = 1;
> kvm_register_mark_available(vcpu, VCPU_EXREG_EXIT_INFO_1);
>
NACK (depends on patch 5)
next prev parent reply other threads:[~2021-10-06 13:36 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 13:30 [PATCH MANUALSEL 5.14 1/9] selftests: KVM: Align SMCCC call with the spec in steal_time Sasha Levin
2021-10-06 13:30 ` [PATCH MANUALSEL 5.14 2/9] KVM: x86: Handle SRCU initialization failure during page track init Sasha Levin
2021-10-06 13:36 ` Paolo Bonzini
2021-10-06 13:30 ` [PATCH MANUALSEL 5.14 3/9] KVM: do not shrink halt_poll_ns below grow_start Sasha Levin
2021-10-06 13:36 ` Paolo Bonzini
2021-10-06 13:30 ` [PATCH MANUALSEL 5.14 4/9] KVM: x86: reset pdptrs_from_userspace when exiting smm Sasha Levin
2021-10-06 13:36 ` Paolo Bonzini
2021-10-07 15:23 ` Naresh Kamboju
2021-10-07 17:47 ` Paolo Bonzini
2021-10-06 13:30 ` [PATCH MANUALSEL 5.14 5/9] KVM: x86: VMX: synthesize invalid VM exit when emulating invalid guest state Sasha Levin
2021-10-06 13:35 ` Paolo Bonzini
2021-10-06 13:30 ` [PATCH MANUALSEL 5.14 6/9] KVM: x86: nVMX: don't fail nested VM entry on invalid guest state if !from_vmentry Sasha Levin
2021-10-06 13:36 ` Paolo Bonzini [this message]
2021-10-06 13:30 ` [PATCH MANUALSEL 5.14 7/9] kvm: x86: Add AMD PMU MSRs to msrs_to_save_all[] Sasha Levin
2021-10-06 13:36 ` Paolo Bonzini
2021-10-06 13:30 ` [PATCH MANUALSEL 5.14 8/9] KVM: x86: nSVM: restore int_vector in svm_clear_vintr Sasha Levin
2021-10-06 13:36 ` Paolo Bonzini
2021-10-06 13:36 ` [PATCH MANUALSEL 5.14 1/9] selftests: KVM: Align SMCCC call with the spec in steal_time Paolo Bonzini
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