From: Will Deacon <will@kernel.org>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: Marc Zyngier <maz@kernel.org>,
Colton Lewis <coltonlewis@google.com>,
kvm@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev
Subject: Re: [PATCH 3/3] KVM: arm64: Skip break phase when we have FEAT_BBM level 2
Date: Thu, 8 Jun 2023 18:21:13 +0100 [thread overview]
Message-ID: <20230608172112.GA1606@willie-the-truck> (raw)
In-Reply-To: <ZH5VQMEoiHEITmF4@linux.dev>
On Mon, Jun 05, 2023 at 02:36:00PM -0700, Oliver Upton wrote:
> On Sun, Jun 04, 2023 at 09:23:39AM +0100, Marc Zyngier wrote:
> > On Fri, 02 Jun 2023 18:01:47 +0100, Colton Lewis <coltonlewis@google.com> wrote:
> > > +static bool stage2_try_make_pte(const struct kvm_pgtable_visit_ctx *ctx, struct kvm_s2_mmu *mmu, kvm_pte_t new)
> > > {
> > > struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops;
> > >
> > > - WARN_ON(!stage2_pte_is_locked(*ctx->ptep));
> > > + if (!stage2_has_bbm_level2())
> > > + WARN_ON(!stage2_pte_is_locked(*ctx->ptep));
> > > +
> > > + if (!stage2_try_set_pte(ctx, new))
> > > + return false;
> > > +
> > > + if (kvm_pte_table(ctx->old, ctx->level))
> > > + kvm_call_hyp(__kvm_tlb_flush_vmid, mmu);
> > > + else if (kvm_pte_valid(ctx->old) && !stage2_pte_perms_equal(ctx->old, new))
> > > + kvm_call_hyp(__kvm_tlb_flush_vmid_ipa_nsh, mmu, ctx->addr, ctx->level);
> >
> > Why a non-shareable invalidation? Nothing in this code captures the
> > rationale for it. What if the permission change was a *restriction* of
> > the permission? It should absolutely be global, and not local.
>
> IIRC, Colton was testing largely with permission relaxation, and had
> forward progress issues b.c. the stale TLB entry was never invalidated
> in response to a permission fault.
Would the series at:
https://lore.kernel.org/r/5d8e1f752051173d2d1b5c3e14b54eb3506ed3ef.1684892404.git-series.apopple@nvidia.com
help with that?
Will
next prev parent reply other threads:[~2023-06-08 17:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-02 17:01 [PATCH 0/3] Relax break-before-make use with FEAT_BBM Colton Lewis
2023-06-02 17:01 ` [PATCH 1/3] arm64: Add a capability for FEAT_BBM level 2 Colton Lewis
2023-06-05 15:07 ` Robin Murphy
2023-06-02 17:01 ` [PATCH 2/3] KVM: arm64: Clear possible conflict aborts Colton Lewis
2023-06-09 15:44 ` Oliver Upton
2023-06-02 17:01 ` [PATCH 3/3] KVM: arm64: Skip break phase when we have FEAT_BBM level 2 Colton Lewis
2023-06-04 8:23 ` Marc Zyngier
2023-06-05 21:36 ` Oliver Upton
2023-06-08 17:21 ` Will Deacon [this message]
2023-06-09 14:59 ` Oliver Upton
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