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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)


  reply	other threads:[~2021-10-06 13:36 UTC|newest]

Thread overview: 19+ 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 13:30 ` [PATCH MANUALSEL 5.14 9/9] ALSA: pcsp: Make hrtimer forwarding more robust Sasha Levin
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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