From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: allow KVM_REQ_GET_NESTED_STATE_PAGES outside guest mode for VMX
Date: Mon, 25 Jan 2021 11:16:46 -0800 [thread overview]
Message-ID: <YA8ZHrh9ca0lPJgk@google.com> (raw)
In-Reply-To: <20210125172044.1360661-1-pbonzini@redhat.com>
On Mon, Jan 25, 2021, Paolo Bonzini wrote:
> +static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
> +{
> + struct vmcs12 *vmcs12 = get_vmcs12(vcpu);
> + struct vcpu_vmx *vmx = to_vmx(vcpu);
> + struct kvm_host_map *map;
> + struct page *page;
> + u64 hpa;
> +
> + if (!nested_get_evmcs_page(vcpu))
> + return false;
>
> if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
> /*
> @@ -3224,6 +3233,17 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
> return true;
> }
>
> +static bool vmx_get_nested_state_pages(struct kvm_vcpu *vcpu)
> +{
> + if (!nested_get_evmcs_page(vcpu))
> + return false;
> +
> + if (is_guest_mode(vcpu) && !nested_get_vmcs12_pages(vcpu))
> + return false;
nested_get_evmcs_page() will get called twice in the common case of
is_guest_mode() == true. I can't tell if that will ever be fatal, but it's
definitely weird. Maybe this?
if (!is_guest_mode(vcpu))
return nested_get_evmcs_page(vcpu);
return nested_get_vmcs12_pages(vcpu);
> +
> + return true;
> +}
> +
> static int nested_vmx_write_pml_buffer(struct kvm_vcpu *vcpu, gpa_t gpa)
> {
> struct vmcs12 *vmcs12;
> @@ -6602,7 +6622,7 @@ struct kvm_x86_nested_ops vmx_nested_ops = {
> .hv_timer_pending = nested_vmx_preemption_timer_pending,
> .get_state = vmx_get_nested_state,
> .set_state = vmx_set_nested_state,
> - .get_nested_state_pages = nested_get_vmcs12_pages,
> + .get_nested_state_pages = vmx_get_nested_state_pages,
> .write_log_dirty = nested_vmx_write_pml_buffer,
> .enable_evmcs = nested_enable_evmcs,
> .get_evmcs_version = nested_get_evmcs_version,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 9a8969a6dd06..b910aa74ee05 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8802,9 +8802,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
>
> if (kvm_request_pending(vcpu)) {
> if (kvm_check_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu)) {
> - if (WARN_ON_ONCE(!is_guest_mode(vcpu)))
> - ;
> - else if (unlikely(!kvm_x86_ops.nested_ops->get_nested_state_pages(vcpu))) {
> + if (unlikely(!kvm_x86_ops.nested_ops->get_nested_state_pages(vcpu))) {
> r = 0;
> goto out;
> }
> --
> 2.26.2
>
next prev parent reply other threads:[~2021-01-25 19:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-25 17:20 [PATCH] KVM: x86: allow KVM_REQ_GET_NESTED_STATE_PAGES outside guest mode for VMX Paolo Bonzini
2021-01-25 19:16 ` Sean Christopherson [this message]
2021-01-25 19:35 ` Paolo Bonzini
2021-01-25 19:53 ` Sean Christopherson
2021-01-25 21:59 ` Paolo Bonzini
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