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 v2 01/18] KVM: x86: host-initiated EFER.LME write affects the MMU
Date: Fri, 18 Feb 2022 17:08:07 +0000 [thread overview]
Message-ID: <Yg/Sd3UE2aCNimGj@google.com> (raw)
In-Reply-To: <20220217210340.312449-2-pbonzini@redhat.com>
The shortlog doesn't come remotely close to saying what this patch does, it's
simply a statement.
KVM: x86: Reset the MMU context if host userspace toggles EFER.LME
On Thu, Feb 17, 2022, Paolo Bonzini wrote:
> While the guest runs, EFER.LME cannot change unless CR0.PG is clear, and therefore
> EFER.NX is the only bit that can affect the MMU role. However, set_efer accepts
> a host-initiated change to EFER.LME even with CR0.PG=1. In that case, the
> MMU has to be reset.
Wrap at ~75 please.
> Fixes: 11988499e62b ("KVM: x86: Skip EFER vs. guest CPUID checks for host-initiated writes")
> Cc: stable@vger.kernel.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
With nits addressed,
Reviewed-by: Sean Christopherson <seanjc@google.com>
> arch/x86/kvm/mmu.h | 1 +
> arch/x86/kvm/x86.c | 2 +-
> 2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 51faa2c76ca5..a5a50cfeffff 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -48,6 +48,7 @@
> X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_PKE)
>
> #define KVM_MMU_CR0_ROLE_BITS (X86_CR0_PG | X86_CR0_WP)
> +#define KVM_MMU_EFER_ROLE_BITS (EFER_LME | EFER_NX)
>
> static __always_inline u64 rsvd_bits(int s, int e)
> {
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index d3da64106685..99a58c25f5c2 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1647,7 +1647,7 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> }
>
> /* Update reserved bits */
This comment needs to be dropped, toggling EFER.LME affects more than just reserved
bits.
> - if ((efer ^ old_efer) & EFER_NX)
> + if ((efer ^ old_efer) & KVM_MMU_EFER_ROLE_BITS)
> kvm_mmu_reset_context(vcpu);
>
> return 0;
> --
> 2.31.1
>
>
next prev parent reply other threads:[~2022-02-18 17:08 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-17 21:03 [PATCH v2 00/18] KVM: MMU: do not unload MMU roots on all role changes Paolo Bonzini
2022-02-17 21:03 ` [PATCH v2 01/18] KVM: x86: host-initiated EFER.LME write affects the MMU Paolo Bonzini
2022-02-18 17:08 ` Sean Christopherson [this message]
2022-02-18 17:26 ` Paolo Bonzini
2022-02-23 13:40 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 02/18] KVM: x86: do not deliver asynchronous page faults if CR0.PG=0 Paolo Bonzini
2022-02-18 17:12 ` Sean Christopherson
2022-02-23 14:07 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 03/18] KVM: x86/mmu: WARN if PAE roots linger after kvm_mmu_unload Paolo Bonzini
2022-02-18 17:14 ` Sean Christopherson
2022-02-18 17:23 ` Paolo Bonzini
2022-02-23 14:11 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 04/18] KVM: x86/mmu: avoid NULL-pointer dereference on page freeing bugs Paolo Bonzini
2022-02-18 17:15 ` Sean Christopherson
2022-02-23 14:12 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 05/18] KVM: x86/mmu: use struct kvm_mmu_root_info for mmu->root Paolo Bonzini
2022-02-23 14:39 ` Maxim Levitsky
2022-02-23 15:42 ` Sean Christopherson
2022-02-17 21:03 ` [PATCH v2 06/18] KVM: x86/mmu: do not consult levels when freeing roots Paolo Bonzini
2022-02-18 17:27 ` Sean Christopherson
2022-02-23 14:59 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 07/18] KVM: x86/mmu: Do not use guest root level in audit Paolo Bonzini
2022-02-18 18:37 ` Sean Christopherson
2022-02-18 18:46 ` Paolo Bonzini
2022-02-23 15:02 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 08/18] KVM: x86/mmu: do not pass vcpu to root freeing functions Paolo Bonzini
2022-02-18 18:39 ` Sean Christopherson
2022-02-23 15:16 ` Maxim Levitsky
2022-02-23 15:48 ` Sean Christopherson
2022-02-17 21:03 ` [PATCH v2 09/18] KVM: x86/mmu: look for a cached PGD when going from 32-bit to 64-bit Paolo Bonzini
2022-02-18 18:08 ` Sean Christopherson
2022-02-23 16:01 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 10/18] KVM: x86/mmu: load new PGD after the shadow MMU is initialized Paolo Bonzini
2022-02-18 23:59 ` Sean Christopherson
2022-02-23 16:20 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 11/18] KVM: x86/mmu: Always use current mmu's role when loading new PGD Paolo Bonzini
2022-02-18 23:59 ` Sean Christopherson
2022-02-23 16:23 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 12/18] KVM: x86/mmu: clear MMIO cache when unloading the MMU Paolo Bonzini
2022-02-18 23:59 ` Sean Christopherson
2022-02-23 16:32 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 13/18] KVM: x86: reset and reinitialize the MMU in __set_sregs_common Paolo Bonzini
2022-02-19 0:22 ` Sean Christopherson
2022-02-23 16:48 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 14/18] KVM: x86/mmu: avoid indirect call for get_cr3 Paolo Bonzini
2022-02-18 20:30 ` Sean Christopherson
2022-02-19 10:03 ` Paolo Bonzini
2022-02-24 11:02 ` Maxim Levitsky
2022-02-24 15:12 ` Sean Christopherson
2022-02-24 15:14 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 15/18] KVM: x86/mmu: rename kvm_mmu_new_pgd, introduce variant that calls get_guest_pgd Paolo Bonzini
2022-02-18 9:39 ` Paolo Bonzini
2022-02-18 21:00 ` Sean Christopherson
2022-02-24 15:41 ` Maxim Levitsky
2022-02-25 17:40 ` Sean Christopherson
2022-02-17 21:03 ` [PATCH v2 16/18] KVM: x86: introduce KVM_REQ_MMU_UPDATE_ROOT Paolo Bonzini
2022-02-18 21:45 ` Sean Christopherson
2022-02-19 7:54 ` Paolo Bonzini
2022-02-22 16:06 ` Sean Christopherson
2022-02-24 15:50 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 17/18] KVM: x86: flush TLB separately from MMU reset Paolo Bonzini
2022-02-18 23:57 ` Sean Christopherson
2022-02-21 15:01 ` Paolo Bonzini
2022-02-24 16:11 ` Maxim Levitsky
2022-02-17 21:03 ` [PATCH v2 18/18] KVM: x86: do not unload MMU roots on all role changes Paolo Bonzini
2022-02-24 16:25 ` Maxim Levitsky
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