From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
vkuznets@redhat.com, mlevitsk@redhat.com, dmatlack@google.com
Subject: Re: [PATCH 03/12] KVM: x86: do not deliver asynchronous page faults if CR0.PG=0
Date: Thu, 10 Feb 2022 23:10:57 +0000 [thread overview]
Message-ID: <YgWbgfSrzAhd97LG@google.com> (raw)
In-Reply-To: <20220209170020.1775368-4-pbonzini@redhat.com>
On Wed, Feb 09, 2022, Paolo Bonzini wrote:
> Enabling async page faults is nonsensical if paging is disabled, but
> it is allowed because CR0.PG=0 does not clear the async page fault
> MSR. Just ignore them and only use the artificial halt state,
> similar to what happens in guest mode if async #PF vmexits are disabled.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/kvm/x86.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 5e1298aef9e2..98aca0f2af12 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -12272,7 +12272,9 @@ static inline bool apf_pageready_slot_free(struct kvm_vcpu *vcpu)
>
> static bool kvm_can_deliver_async_pf(struct kvm_vcpu *vcpu)
> {
> - if (!vcpu->arch.apf.delivery_as_pf_vmexit && is_guest_mode(vcpu))
> + if (is_guest_mode(vcpu)
> + ? !vcpu->arch.apf.delivery_as_pf_vmexit
> + : !is_cr0_pg(vcpu->arch.mmu))
As suggested in the previous patch, is_paging(vcpu).
I find a more tradition if-elif marginally easier to understand the implication
that CR0.PG is L2's CR0 and thus irrelevant if is_guest_mode()==true. Not a big
deal though.
if (is_guest_mode(vcpu)) {
if (!vcpu->arch.apf.delivery_as_pf_vmexit)
return false;
} else if (!is_paging(vcpu)) {
return false;
}
> return false;
>
> if (!kvm_pv_async_pf_enabled(vcpu) ||
> --
> 2.31.1
>
>
next prev parent reply other threads:[~2022-02-10 23:11 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 17:00 [PATCH 00/12] KVM: MMU: do not unload MMU roots on all role changes Paolo Bonzini
2022-02-09 17:00 ` [PATCH 01/12] KVM: x86: host-initiated EFER.LME write affects the MMU Paolo Bonzini
2022-02-10 22:49 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 02/12] KVM: MMU: move MMU role accessors to header Paolo Bonzini
2022-02-10 23:00 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 03/12] KVM: x86: do not deliver asynchronous page faults if CR0.PG=0 Paolo Bonzini
2022-02-10 23:10 ` Sean Christopherson [this message]
2022-02-10 23:14 ` Sean Christopherson
2022-02-10 23:16 ` Sean Christopherson
2022-02-11 11:16 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 04/12] KVM: MMU: WARN if PAE roots linger after kvm_mmu_unload Paolo Bonzini
2022-02-10 23:20 ` Sean Christopherson
2022-02-11 11:18 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 05/12] KVM: MMU: avoid NULL-pointer dereference on page freeing bugs Paolo Bonzini
2022-02-11 0:24 ` Sean Christopherson
2022-02-11 11:21 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 06/12] KVM: MMU: rename kvm_mmu_reload Paolo Bonzini
2022-02-11 0:27 ` Sean Christopherson
2022-02-11 10:07 ` Paolo Bonzini
2022-02-11 16:16 ` Sean Christopherson
2022-02-11 16:52 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 07/12] KVM: x86: use struct kvm_mmu_root_info for mmu->root Paolo Bonzini
2022-02-11 17:39 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 08/12] KVM: MMU: do not consult levels when freeing roots Paolo Bonzini
2022-02-11 0:41 ` Sean Christopherson
2022-02-11 0:54 ` Sean Christopherson
2022-02-11 1:07 ` Paolo Bonzini
2022-02-11 1:35 ` Sean Christopherson
2022-02-11 1:44 ` Sean Christopherson
2022-02-11 2:20 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 09/12] KVM: MMU: look for a cached PGD when going from 32-bit to 64-bit Paolo Bonzini
2022-02-11 1:32 ` Sean Christopherson
2022-02-11 1:37 ` Sean Christopherson
2022-02-11 10:09 ` Paolo Bonzini
2022-02-11 11:45 ` Paolo Bonzini
2022-02-11 17:38 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 10/12] KVM: MMU: load new PGD after the shadow MMU is initialized Paolo Bonzini
2022-02-11 17:45 ` Sean Christopherson
2022-02-11 17:47 ` Paolo Bonzini
2022-02-09 17:00 ` [PATCH 11/12] KVM: MMU: remove kvm_mmu_calc_root_page_role Paolo Bonzini
2022-02-11 17:53 ` Sean Christopherson
2022-02-09 17:00 ` [PATCH 12/12] KVM: x86: do not unload MMU roots on all role changes Paolo Bonzini
2022-02-11 9:08 ` Nikunj A. Dadhania
2022-02-11 18:48 ` Sean Christopherson
2022-02-14 16:34 ` Paolo Bonzini
2022-02-14 19:24 ` Sean Christopherson
2022-02-15 8:17 ` Paolo Bonzini
2022-02-09 17:07 ` [PATCH 00/12] KVM: MMU: " Sean Christopherson
2022-02-09 17:11 ` Paolo Bonzini
2022-02-09 17:16 ` Sean Christopherson
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